2633150e41b963f4fc449a02e68819a532018b67
[sfrench/cifs-2.6.git] / fs / ext4 / inode.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/fs/ext4/inode.c
4  *
5  * Copyright (C) 1992, 1993, 1994, 1995
6  * Remy Card (card@masi.ibp.fr)
7  * Laboratoire MASI - Institut Blaise Pascal
8  * Universite Pierre et Marie Curie (Paris VI)
9  *
10  *  from
11  *
12  *  linux/fs/minix/inode.c
13  *
14  *  Copyright (C) 1991, 1992  Linus Torvalds
15  *
16  *  64-bit file support on 64-bit platforms by Jakub Jelinek
17  *      (jj@sunsite.ms.mff.cuni.cz)
18  *
19  *  Assorted race fixes, rewrite of ext4_get_block() by Al Viro, 2000
20  */
21
22 #include <linux/fs.h>
23 #include <linux/time.h>
24 #include <linux/highuid.h>
25 #include <linux/pagemap.h>
26 #include <linux/dax.h>
27 #include <linux/quotaops.h>
28 #include <linux/string.h>
29 #include <linux/buffer_head.h>
30 #include <linux/writeback.h>
31 #include <linux/pagevec.h>
32 #include <linux/mpage.h>
33 #include <linux/namei.h>
34 #include <linux/uio.h>
35 #include <linux/bio.h>
36 #include <linux/workqueue.h>
37 #include <linux/kernel.h>
38 #include <linux/printk.h>
39 #include <linux/slab.h>
40 #include <linux/bitops.h>
41 #include <linux/iomap.h>
42
43 #include "ext4_jbd2.h"
44 #include "xattr.h"
45 #include "acl.h"
46 #include "truncate.h"
47
48 #include <trace/events/ext4.h>
49
50 #define MPAGE_DA_EXTENT_TAIL 0x01
51
52 static __u32 ext4_inode_csum(struct inode *inode, struct ext4_inode *raw,
53                               struct ext4_inode_info *ei)
54 {
55         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
56         __u32 csum;
57         __u16 dummy_csum = 0;
58         int offset = offsetof(struct ext4_inode, i_checksum_lo);
59         unsigned int csum_size = sizeof(dummy_csum);
60
61         csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)raw, offset);
62         csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum, csum_size);
63         offset += csum_size;
64         csum = ext4_chksum(sbi, csum, (__u8 *)raw + offset,
65                            EXT4_GOOD_OLD_INODE_SIZE - offset);
66
67         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
68                 offset = offsetof(struct ext4_inode, i_checksum_hi);
69                 csum = ext4_chksum(sbi, csum, (__u8 *)raw +
70                                    EXT4_GOOD_OLD_INODE_SIZE,
71                                    offset - EXT4_GOOD_OLD_INODE_SIZE);
72                 if (EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi)) {
73                         csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum,
74                                            csum_size);
75                         offset += csum_size;
76                 }
77                 csum = ext4_chksum(sbi, csum, (__u8 *)raw + offset,
78                                    EXT4_INODE_SIZE(inode->i_sb) - offset);
79         }
80
81         return csum;
82 }
83
84 static int ext4_inode_csum_verify(struct inode *inode, struct ext4_inode *raw,
85                                   struct ext4_inode_info *ei)
86 {
87         __u32 provided, calculated;
88
89         if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
90             cpu_to_le32(EXT4_OS_LINUX) ||
91             !ext4_has_metadata_csum(inode->i_sb))
92                 return 1;
93
94         provided = le16_to_cpu(raw->i_checksum_lo);
95         calculated = ext4_inode_csum(inode, raw, ei);
96         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
97             EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
98                 provided |= ((__u32)le16_to_cpu(raw->i_checksum_hi)) << 16;
99         else
100                 calculated &= 0xFFFF;
101
102         return provided == calculated;
103 }
104
105 static void ext4_inode_csum_set(struct inode *inode, struct ext4_inode *raw,
106                                 struct ext4_inode_info *ei)
107 {
108         __u32 csum;
109
110         if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
111             cpu_to_le32(EXT4_OS_LINUX) ||
112             !ext4_has_metadata_csum(inode->i_sb))
113                 return;
114
115         csum = ext4_inode_csum(inode, raw, ei);
116         raw->i_checksum_lo = cpu_to_le16(csum & 0xFFFF);
117         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
118             EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
119                 raw->i_checksum_hi = cpu_to_le16(csum >> 16);
120 }
121
122 static inline int ext4_begin_ordered_truncate(struct inode *inode,
123                                               loff_t new_size)
124 {
125         trace_ext4_begin_ordered_truncate(inode, new_size);
126         /*
127          * If jinode is zero, then we never opened the file for
128          * writing, so there's no need to call
129          * jbd2_journal_begin_ordered_truncate() since there's no
130          * outstanding writes we need to flush.
131          */
132         if (!EXT4_I(inode)->jinode)
133                 return 0;
134         return jbd2_journal_begin_ordered_truncate(EXT4_JOURNAL(inode),
135                                                    EXT4_I(inode)->jinode,
136                                                    new_size);
137 }
138
139 static void ext4_invalidatepage(struct page *page, unsigned int offset,
140                                 unsigned int length);
141 static int __ext4_journalled_writepage(struct page *page, unsigned int len);
142 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh);
143 static int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
144                                   int pextents);
145
146 /*
147  * Test whether an inode is a fast symlink.
148  * A fast symlink has its symlink data stored in ext4_inode_info->i_data.
149  */
150 int ext4_inode_is_fast_symlink(struct inode *inode)
151 {
152         return S_ISLNK(inode->i_mode) && inode->i_size &&
153                (inode->i_size < EXT4_N_BLOCKS * 4);
154 }
155
156 /*
157  * Restart the transaction associated with *handle.  This does a commit,
158  * so before we call here everything must be consistently dirtied against
159  * this transaction.
160  */
161 int ext4_truncate_restart_trans(handle_t *handle, struct inode *inode,
162                                  int nblocks)
163 {
164         int ret;
165
166         /*
167          * Drop i_data_sem to avoid deadlock with ext4_map_blocks.  At this
168          * moment, get_block can be called only for blocks inside i_size since
169          * page cache has been already dropped and writes are blocked by
170          * i_mutex. So we can safely drop the i_data_sem here.
171          */
172         BUG_ON(EXT4_JOURNAL(inode) == NULL);
173         jbd_debug(2, "restarting handle %p\n", handle);
174         up_write(&EXT4_I(inode)->i_data_sem);
175         ret = ext4_journal_restart(handle, nblocks);
176         down_write(&EXT4_I(inode)->i_data_sem);
177         ext4_discard_preallocations(inode);
178
179         return ret;
180 }
181
182 /*
183  * Called at the last iput() if i_nlink is zero.
184  */
185 void ext4_evict_inode(struct inode *inode)
186 {
187         handle_t *handle;
188         int err;
189         int extra_credits = 3;
190         struct ext4_xattr_inode_array *ea_inode_array = NULL;
191
192         trace_ext4_evict_inode(inode);
193
194         if (inode->i_nlink) {
195                 /*
196                  * When journalling data dirty buffers are tracked only in the
197                  * journal. So although mm thinks everything is clean and
198                  * ready for reaping the inode might still have some pages to
199                  * write in the running transaction or waiting to be
200                  * checkpointed. Thus calling jbd2_journal_invalidatepage()
201                  * (via truncate_inode_pages()) to discard these buffers can
202                  * cause data loss. Also even if we did not discard these
203                  * buffers, we would have no way to find them after the inode
204                  * is reaped and thus user could see stale data if he tries to
205                  * read them before the transaction is checkpointed. So be
206                  * careful and force everything to disk here... We use
207                  * ei->i_datasync_tid to store the newest transaction
208                  * containing inode's data.
209                  *
210                  * Note that directories do not have this problem because they
211                  * don't use page cache.
212                  */
213                 if (inode->i_ino != EXT4_JOURNAL_INO &&
214                     ext4_should_journal_data(inode) &&
215                     (S_ISLNK(inode->i_mode) || S_ISREG(inode->i_mode)) &&
216                     inode->i_data.nrpages) {
217                         journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
218                         tid_t commit_tid = EXT4_I(inode)->i_datasync_tid;
219
220                         jbd2_complete_transaction(journal, commit_tid);
221                         filemap_write_and_wait(&inode->i_data);
222                 }
223                 truncate_inode_pages_final(&inode->i_data);
224
225                 goto no_delete;
226         }
227
228         if (is_bad_inode(inode))
229                 goto no_delete;
230         dquot_initialize(inode);
231
232         if (ext4_should_order_data(inode))
233                 ext4_begin_ordered_truncate(inode, 0);
234         truncate_inode_pages_final(&inode->i_data);
235
236         /*
237          * Protect us against freezing - iput() caller didn't have to have any
238          * protection against it
239          */
240         sb_start_intwrite(inode->i_sb);
241
242         if (!IS_NOQUOTA(inode))
243                 extra_credits += EXT4_MAXQUOTAS_DEL_BLOCKS(inode->i_sb);
244
245         handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE,
246                                  ext4_blocks_for_truncate(inode)+extra_credits);
247         if (IS_ERR(handle)) {
248                 ext4_std_error(inode->i_sb, PTR_ERR(handle));
249                 /*
250                  * If we're going to skip the normal cleanup, we still need to
251                  * make sure that the in-core orphan linked list is properly
252                  * cleaned up.
253                  */
254                 ext4_orphan_del(NULL, inode);
255                 sb_end_intwrite(inode->i_sb);
256                 goto no_delete;
257         }
258
259         if (IS_SYNC(inode))
260                 ext4_handle_sync(handle);
261
262         /*
263          * Set inode->i_size to 0 before calling ext4_truncate(). We need
264          * special handling of symlinks here because i_size is used to
265          * determine whether ext4_inode_info->i_data contains symlink data or
266          * block mappings. Setting i_size to 0 will remove its fast symlink
267          * status. Erase i_data so that it becomes a valid empty block map.
268          */
269         if (ext4_inode_is_fast_symlink(inode))
270                 memset(EXT4_I(inode)->i_data, 0, sizeof(EXT4_I(inode)->i_data));
271         inode->i_size = 0;
272         err = ext4_mark_inode_dirty(handle, inode);
273         if (err) {
274                 ext4_warning(inode->i_sb,
275                              "couldn't mark inode dirty (err %d)", err);
276                 goto stop_handle;
277         }
278         if (inode->i_blocks) {
279                 err = ext4_truncate(inode);
280                 if (err) {
281                         ext4_error(inode->i_sb,
282                                    "couldn't truncate inode %lu (err %d)",
283                                    inode->i_ino, err);
284                         goto stop_handle;
285                 }
286         }
287
288         /* Remove xattr references. */
289         err = ext4_xattr_delete_inode(handle, inode, &ea_inode_array,
290                                       extra_credits);
291         if (err) {
292                 ext4_warning(inode->i_sb, "xattr delete (err %d)", err);
293 stop_handle:
294                 ext4_journal_stop(handle);
295                 ext4_orphan_del(NULL, inode);
296                 sb_end_intwrite(inode->i_sb);
297                 ext4_xattr_inode_array_free(ea_inode_array);
298                 goto no_delete;
299         }
300
301         /*
302          * Kill off the orphan record which ext4_truncate created.
303          * AKPM: I think this can be inside the above `if'.
304          * Note that ext4_orphan_del() has to be able to cope with the
305          * deletion of a non-existent orphan - this is because we don't
306          * know if ext4_truncate() actually created an orphan record.
307          * (Well, we could do this if we need to, but heck - it works)
308          */
309         ext4_orphan_del(handle, inode);
310         EXT4_I(inode)->i_dtime  = get_seconds();
311
312         /*
313          * One subtle ordering requirement: if anything has gone wrong
314          * (transaction abort, IO errors, whatever), then we can still
315          * do these next steps (the fs will already have been marked as
316          * having errors), but we can't free the inode if the mark_dirty
317          * fails.
318          */
319         if (ext4_mark_inode_dirty(handle, inode))
320                 /* If that failed, just do the required in-core inode clear. */
321                 ext4_clear_inode(inode);
322         else
323                 ext4_free_inode(handle, inode);
324         ext4_journal_stop(handle);
325         sb_end_intwrite(inode->i_sb);
326         ext4_xattr_inode_array_free(ea_inode_array);
327         return;
328 no_delete:
329         ext4_clear_inode(inode);        /* We must guarantee clearing of inode... */
330 }
331
332 #ifdef CONFIG_QUOTA
333 qsize_t *ext4_get_reserved_space(struct inode *inode)
334 {
335         return &EXT4_I(inode)->i_reserved_quota;
336 }
337 #endif
338
339 /*
340  * Called with i_data_sem down, which is important since we can call
341  * ext4_discard_preallocations() from here.
342  */
343 void ext4_da_update_reserve_space(struct inode *inode,
344                                         int used, int quota_claim)
345 {
346         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
347         struct ext4_inode_info *ei = EXT4_I(inode);
348
349         spin_lock(&ei->i_block_reservation_lock);
350         trace_ext4_da_update_reserve_space(inode, used, quota_claim);
351         if (unlikely(used > ei->i_reserved_data_blocks)) {
352                 ext4_warning(inode->i_sb, "%s: ino %lu, used %d "
353                          "with only %d reserved data blocks",
354                          __func__, inode->i_ino, used,
355                          ei->i_reserved_data_blocks);
356                 WARN_ON(1);
357                 used = ei->i_reserved_data_blocks;
358         }
359
360         /* Update per-inode reservations */
361         ei->i_reserved_data_blocks -= used;
362         percpu_counter_sub(&sbi->s_dirtyclusters_counter, used);
363
364         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
365
366         /* Update quota subsystem for data blocks */
367         if (quota_claim)
368                 dquot_claim_block(inode, EXT4_C2B(sbi, used));
369         else {
370                 /*
371                  * We did fallocate with an offset that is already delayed
372                  * allocated. So on delayed allocated writeback we should
373                  * not re-claim the quota for fallocated blocks.
374                  */
375                 dquot_release_reservation_block(inode, EXT4_C2B(sbi, used));
376         }
377
378         /*
379          * If we have done all the pending block allocations and if
380          * there aren't any writers on the inode, we can discard the
381          * inode's preallocations.
382          */
383         if ((ei->i_reserved_data_blocks == 0) &&
384             (atomic_read(&inode->i_writecount) == 0))
385                 ext4_discard_preallocations(inode);
386 }
387
388 static int __check_block_validity(struct inode *inode, const char *func,
389                                 unsigned int line,
390                                 struct ext4_map_blocks *map)
391 {
392         if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), map->m_pblk,
393                                    map->m_len)) {
394                 ext4_error_inode(inode, func, line, map->m_pblk,
395                                  "lblock %lu mapped to illegal pblock "
396                                  "(length %d)", (unsigned long) map->m_lblk,
397                                  map->m_len);
398                 return -EFSCORRUPTED;
399         }
400         return 0;
401 }
402
403 int ext4_issue_zeroout(struct inode *inode, ext4_lblk_t lblk, ext4_fsblk_t pblk,
404                        ext4_lblk_t len)
405 {
406         int ret;
407
408         if (ext4_encrypted_inode(inode))
409                 return fscrypt_zeroout_range(inode, lblk, pblk, len);
410
411         ret = sb_issue_zeroout(inode->i_sb, pblk, len, GFP_NOFS);
412         if (ret > 0)
413                 ret = 0;
414
415         return ret;
416 }
417
418 #define check_block_validity(inode, map)        \
419         __check_block_validity((inode), __func__, __LINE__, (map))
420
421 #ifdef ES_AGGRESSIVE_TEST
422 static void ext4_map_blocks_es_recheck(handle_t *handle,
423                                        struct inode *inode,
424                                        struct ext4_map_blocks *es_map,
425                                        struct ext4_map_blocks *map,
426                                        int flags)
427 {
428         int retval;
429
430         map->m_flags = 0;
431         /*
432          * There is a race window that the result is not the same.
433          * e.g. xfstests #223 when dioread_nolock enables.  The reason
434          * is that we lookup a block mapping in extent status tree with
435          * out taking i_data_sem.  So at the time the unwritten extent
436          * could be converted.
437          */
438         down_read(&EXT4_I(inode)->i_data_sem);
439         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
440                 retval = ext4_ext_map_blocks(handle, inode, map, flags &
441                                              EXT4_GET_BLOCKS_KEEP_SIZE);
442         } else {
443                 retval = ext4_ind_map_blocks(handle, inode, map, flags &
444                                              EXT4_GET_BLOCKS_KEEP_SIZE);
445         }
446         up_read((&EXT4_I(inode)->i_data_sem));
447
448         /*
449          * We don't check m_len because extent will be collpased in status
450          * tree.  So the m_len might not equal.
451          */
452         if (es_map->m_lblk != map->m_lblk ||
453             es_map->m_flags != map->m_flags ||
454             es_map->m_pblk != map->m_pblk) {
455                 printk("ES cache assertion failed for inode: %lu "
456                        "es_cached ex [%d/%d/%llu/%x] != "
457                        "found ex [%d/%d/%llu/%x] retval %d flags %x\n",
458                        inode->i_ino, es_map->m_lblk, es_map->m_len,
459                        es_map->m_pblk, es_map->m_flags, map->m_lblk,
460                        map->m_len, map->m_pblk, map->m_flags,
461                        retval, flags);
462         }
463 }
464 #endif /* ES_AGGRESSIVE_TEST */
465
466 /*
467  * The ext4_map_blocks() function tries to look up the requested blocks,
468  * and returns if the blocks are already mapped.
469  *
470  * Otherwise it takes the write lock of the i_data_sem and allocate blocks
471  * and store the allocated blocks in the result buffer head and mark it
472  * mapped.
473  *
474  * If file type is extents based, it will call ext4_ext_map_blocks(),
475  * Otherwise, call with ext4_ind_map_blocks() to handle indirect mapping
476  * based files
477  *
478  * On success, it returns the number of blocks being mapped or allocated.  if
479  * create==0 and the blocks are pre-allocated and unwritten, the resulting @map
480  * is marked as unwritten. If the create == 1, it will mark @map as mapped.
481  *
482  * It returns 0 if plain look up failed (blocks have not been allocated), in
483  * that case, @map is returned as unmapped but we still do fill map->m_len to
484  * indicate the length of a hole starting at map->m_lblk.
485  *
486  * It returns the error in case of allocation failure.
487  */
488 int ext4_map_blocks(handle_t *handle, struct inode *inode,
489                     struct ext4_map_blocks *map, int flags)
490 {
491         struct extent_status es;
492         int retval;
493         int ret = 0;
494 #ifdef ES_AGGRESSIVE_TEST
495         struct ext4_map_blocks orig_map;
496
497         memcpy(&orig_map, map, sizeof(*map));
498 #endif
499
500         map->m_flags = 0;
501         ext_debug("ext4_map_blocks(): inode %lu, flag %d, max_blocks %u,"
502                   "logical block %lu\n", inode->i_ino, flags, map->m_len,
503                   (unsigned long) map->m_lblk);
504
505         /*
506          * ext4_map_blocks returns an int, and m_len is an unsigned int
507          */
508         if (unlikely(map->m_len > INT_MAX))
509                 map->m_len = INT_MAX;
510
511         /* We can handle the block number less than EXT_MAX_BLOCKS */
512         if (unlikely(map->m_lblk >= EXT_MAX_BLOCKS))
513                 return -EFSCORRUPTED;
514
515         /* Lookup extent status tree firstly */
516         if (ext4_es_lookup_extent(inode, map->m_lblk, &es)) {
517                 if (ext4_es_is_written(&es) || ext4_es_is_unwritten(&es)) {
518                         map->m_pblk = ext4_es_pblock(&es) +
519                                         map->m_lblk - es.es_lblk;
520                         map->m_flags |= ext4_es_is_written(&es) ?
521                                         EXT4_MAP_MAPPED : EXT4_MAP_UNWRITTEN;
522                         retval = es.es_len - (map->m_lblk - es.es_lblk);
523                         if (retval > map->m_len)
524                                 retval = map->m_len;
525                         map->m_len = retval;
526                 } else if (ext4_es_is_delayed(&es) || ext4_es_is_hole(&es)) {
527                         map->m_pblk = 0;
528                         retval = es.es_len - (map->m_lblk - es.es_lblk);
529                         if (retval > map->m_len)
530                                 retval = map->m_len;
531                         map->m_len = retval;
532                         retval = 0;
533                 } else {
534                         BUG_ON(1);
535                 }
536 #ifdef ES_AGGRESSIVE_TEST
537                 ext4_map_blocks_es_recheck(handle, inode, map,
538                                            &orig_map, flags);
539 #endif
540                 goto found;
541         }
542
543         /*
544          * Try to see if we can get the block without requesting a new
545          * file system block.
546          */
547         down_read(&EXT4_I(inode)->i_data_sem);
548         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
549                 retval = ext4_ext_map_blocks(handle, inode, map, flags &
550                                              EXT4_GET_BLOCKS_KEEP_SIZE);
551         } else {
552                 retval = ext4_ind_map_blocks(handle, inode, map, flags &
553                                              EXT4_GET_BLOCKS_KEEP_SIZE);
554         }
555         if (retval > 0) {
556                 unsigned int status;
557
558                 if (unlikely(retval != map->m_len)) {
559                         ext4_warning(inode->i_sb,
560                                      "ES len assertion failed for inode "
561                                      "%lu: retval %d != map->m_len %d",
562                                      inode->i_ino, retval, map->m_len);
563                         WARN_ON(1);
564                 }
565
566                 status = map->m_flags & EXT4_MAP_UNWRITTEN ?
567                                 EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
568                 if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
569                     !(status & EXTENT_STATUS_WRITTEN) &&
570                     ext4_find_delalloc_range(inode, map->m_lblk,
571                                              map->m_lblk + map->m_len - 1))
572                         status |= EXTENT_STATUS_DELAYED;
573                 ret = ext4_es_insert_extent(inode, map->m_lblk,
574                                             map->m_len, map->m_pblk, status);
575                 if (ret < 0)
576                         retval = ret;
577         }
578         up_read((&EXT4_I(inode)->i_data_sem));
579
580 found:
581         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
582                 ret = check_block_validity(inode, map);
583                 if (ret != 0)
584                         return ret;
585         }
586
587         /* If it is only a block(s) look up */
588         if ((flags & EXT4_GET_BLOCKS_CREATE) == 0)
589                 return retval;
590
591         /*
592          * Returns if the blocks have already allocated
593          *
594          * Note that if blocks have been preallocated
595          * ext4_ext_get_block() returns the create = 0
596          * with buffer head unmapped.
597          */
598         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED)
599                 /*
600                  * If we need to convert extent to unwritten
601                  * we continue and do the actual work in
602                  * ext4_ext_map_blocks()
603                  */
604                 if (!(flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN))
605                         return retval;
606
607         /*
608          * Here we clear m_flags because after allocating an new extent,
609          * it will be set again.
610          */
611         map->m_flags &= ~EXT4_MAP_FLAGS;
612
613         /*
614          * New blocks allocate and/or writing to unwritten extent
615          * will possibly result in updating i_data, so we take
616          * the write lock of i_data_sem, and call get_block()
617          * with create == 1 flag.
618          */
619         down_write(&EXT4_I(inode)->i_data_sem);
620
621         /*
622          * We need to check for EXT4 here because migrate
623          * could have changed the inode type in between
624          */
625         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
626                 retval = ext4_ext_map_blocks(handle, inode, map, flags);
627         } else {
628                 retval = ext4_ind_map_blocks(handle, inode, map, flags);
629
630                 if (retval > 0 && map->m_flags & EXT4_MAP_NEW) {
631                         /*
632                          * We allocated new blocks which will result in
633                          * i_data's format changing.  Force the migrate
634                          * to fail by clearing migrate flags
635                          */
636                         ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
637                 }
638
639                 /*
640                  * Update reserved blocks/metadata blocks after successful
641                  * block allocation which had been deferred till now. We don't
642                  * support fallocate for non extent files. So we can update
643                  * reserve space here.
644                  */
645                 if ((retval > 0) &&
646                         (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE))
647                         ext4_da_update_reserve_space(inode, retval, 1);
648         }
649
650         if (retval > 0) {
651                 unsigned int status;
652
653                 if (unlikely(retval != map->m_len)) {
654                         ext4_warning(inode->i_sb,
655                                      "ES len assertion failed for inode "
656                                      "%lu: retval %d != map->m_len %d",
657                                      inode->i_ino, retval, map->m_len);
658                         WARN_ON(1);
659                 }
660
661                 /*
662                  * We have to zeroout blocks before inserting them into extent
663                  * status tree. Otherwise someone could look them up there and
664                  * use them before they are really zeroed. We also have to
665                  * unmap metadata before zeroing as otherwise writeback can
666                  * overwrite zeros with stale data from block device.
667                  */
668                 if (flags & EXT4_GET_BLOCKS_ZERO &&
669                     map->m_flags & EXT4_MAP_MAPPED &&
670                     map->m_flags & EXT4_MAP_NEW) {
671                         clean_bdev_aliases(inode->i_sb->s_bdev, map->m_pblk,
672                                            map->m_len);
673                         ret = ext4_issue_zeroout(inode, map->m_lblk,
674                                                  map->m_pblk, map->m_len);
675                         if (ret) {
676                                 retval = ret;
677                                 goto out_sem;
678                         }
679                 }
680
681                 /*
682                  * If the extent has been zeroed out, we don't need to update
683                  * extent status tree.
684                  */
685                 if ((flags & EXT4_GET_BLOCKS_PRE_IO) &&
686                     ext4_es_lookup_extent(inode, map->m_lblk, &es)) {
687                         if (ext4_es_is_written(&es))
688                                 goto out_sem;
689                 }
690                 status = map->m_flags & EXT4_MAP_UNWRITTEN ?
691                                 EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
692                 if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
693                     !(status & EXTENT_STATUS_WRITTEN) &&
694                     ext4_find_delalloc_range(inode, map->m_lblk,
695                                              map->m_lblk + map->m_len - 1))
696                         status |= EXTENT_STATUS_DELAYED;
697                 ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
698                                             map->m_pblk, status);
699                 if (ret < 0) {
700                         retval = ret;
701                         goto out_sem;
702                 }
703         }
704
705 out_sem:
706         up_write((&EXT4_I(inode)->i_data_sem));
707         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
708                 ret = check_block_validity(inode, map);
709                 if (ret != 0)
710                         return ret;
711
712                 /*
713                  * Inodes with freshly allocated blocks where contents will be
714                  * visible after transaction commit must be on transaction's
715                  * ordered data list.
716                  */
717                 if (map->m_flags & EXT4_MAP_NEW &&
718                     !(map->m_flags & EXT4_MAP_UNWRITTEN) &&
719                     !(flags & EXT4_GET_BLOCKS_ZERO) &&
720                     !ext4_is_quota_file(inode) &&
721                     ext4_should_order_data(inode)) {
722                         if (flags & EXT4_GET_BLOCKS_IO_SUBMIT)
723                                 ret = ext4_jbd2_inode_add_wait(handle, inode);
724                         else
725                                 ret = ext4_jbd2_inode_add_write(handle, inode);
726                         if (ret)
727                                 return ret;
728                 }
729         }
730         return retval;
731 }
732
733 /*
734  * Update EXT4_MAP_FLAGS in bh->b_state. For buffer heads attached to pages
735  * we have to be careful as someone else may be manipulating b_state as well.
736  */
737 static void ext4_update_bh_state(struct buffer_head *bh, unsigned long flags)
738 {
739         unsigned long old_state;
740         unsigned long new_state;
741
742         flags &= EXT4_MAP_FLAGS;
743
744         /* Dummy buffer_head? Set non-atomically. */
745         if (!bh->b_page) {
746                 bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | flags;
747                 return;
748         }
749         /*
750          * Someone else may be modifying b_state. Be careful! This is ugly but
751          * once we get rid of using bh as a container for mapping information
752          * to pass to / from get_block functions, this can go away.
753          */
754         do {
755                 old_state = READ_ONCE(bh->b_state);
756                 new_state = (old_state & ~EXT4_MAP_FLAGS) | flags;
757         } while (unlikely(
758                  cmpxchg(&bh->b_state, old_state, new_state) != old_state));
759 }
760
761 static int _ext4_get_block(struct inode *inode, sector_t iblock,
762                            struct buffer_head *bh, int flags)
763 {
764         struct ext4_map_blocks map;
765         int ret = 0;
766
767         if (ext4_has_inline_data(inode))
768                 return -ERANGE;
769
770         map.m_lblk = iblock;
771         map.m_len = bh->b_size >> inode->i_blkbits;
772
773         ret = ext4_map_blocks(ext4_journal_current_handle(), inode, &map,
774                               flags);
775         if (ret > 0) {
776                 map_bh(bh, inode->i_sb, map.m_pblk);
777                 ext4_update_bh_state(bh, map.m_flags);
778                 bh->b_size = inode->i_sb->s_blocksize * map.m_len;
779                 ret = 0;
780         } else if (ret == 0) {
781                 /* hole case, need to fill in bh->b_size */
782                 bh->b_size = inode->i_sb->s_blocksize * map.m_len;
783         }
784         return ret;
785 }
786
787 int ext4_get_block(struct inode *inode, sector_t iblock,
788                    struct buffer_head *bh, int create)
789 {
790         return _ext4_get_block(inode, iblock, bh,
791                                create ? EXT4_GET_BLOCKS_CREATE : 0);
792 }
793
794 /*
795  * Get block function used when preparing for buffered write if we require
796  * creating an unwritten extent if blocks haven't been allocated.  The extent
797  * will be converted to written after the IO is complete.
798  */
799 int ext4_get_block_unwritten(struct inode *inode, sector_t iblock,
800                              struct buffer_head *bh_result, int create)
801 {
802         ext4_debug("ext4_get_block_unwritten: inode %lu, create flag %d\n",
803                    inode->i_ino, create);
804         return _ext4_get_block(inode, iblock, bh_result,
805                                EXT4_GET_BLOCKS_IO_CREATE_EXT);
806 }
807
808 /* Maximum number of blocks we map for direct IO at once. */
809 #define DIO_MAX_BLOCKS 4096
810
811 /*
812  * Get blocks function for the cases that need to start a transaction -
813  * generally difference cases of direct IO and DAX IO. It also handles retries
814  * in case of ENOSPC.
815  */
816 static int ext4_get_block_trans(struct inode *inode, sector_t iblock,
817                                 struct buffer_head *bh_result, int flags)
818 {
819         int dio_credits;
820         handle_t *handle;
821         int retries = 0;
822         int ret;
823
824         /* Trim mapping request to maximum we can map at once for DIO */
825         if (bh_result->b_size >> inode->i_blkbits > DIO_MAX_BLOCKS)
826                 bh_result->b_size = DIO_MAX_BLOCKS << inode->i_blkbits;
827         dio_credits = ext4_chunk_trans_blocks(inode,
828                                       bh_result->b_size >> inode->i_blkbits);
829 retry:
830         handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, dio_credits);
831         if (IS_ERR(handle))
832                 return PTR_ERR(handle);
833
834         ret = _ext4_get_block(inode, iblock, bh_result, flags);
835         ext4_journal_stop(handle);
836
837         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
838                 goto retry;
839         return ret;
840 }
841
842 /* Get block function for DIO reads and writes to inodes without extents */
843 int ext4_dio_get_block(struct inode *inode, sector_t iblock,
844                        struct buffer_head *bh, int create)
845 {
846         /* We don't expect handle for direct IO */
847         WARN_ON_ONCE(ext4_journal_current_handle());
848
849         if (!create)
850                 return _ext4_get_block(inode, iblock, bh, 0);
851         return ext4_get_block_trans(inode, iblock, bh, EXT4_GET_BLOCKS_CREATE);
852 }
853
854 /*
855  * Get block function for AIO DIO writes when we create unwritten extent if
856  * blocks are not allocated yet. The extent will be converted to written
857  * after IO is complete.
858  */
859 static int ext4_dio_get_block_unwritten_async(struct inode *inode,
860                 sector_t iblock, struct buffer_head *bh_result, int create)
861 {
862         int ret;
863
864         /* We don't expect handle for direct IO */
865         WARN_ON_ONCE(ext4_journal_current_handle());
866
867         ret = ext4_get_block_trans(inode, iblock, bh_result,
868                                    EXT4_GET_BLOCKS_IO_CREATE_EXT);
869
870         /*
871          * When doing DIO using unwritten extents, we need io_end to convert
872          * unwritten extents to written on IO completion. We allocate io_end
873          * once we spot unwritten extent and store it in b_private. Generic
874          * DIO code keeps b_private set and furthermore passes the value to
875          * our completion callback in 'private' argument.
876          */
877         if (!ret && buffer_unwritten(bh_result)) {
878                 if (!bh_result->b_private) {
879                         ext4_io_end_t *io_end;
880
881                         io_end = ext4_init_io_end(inode, GFP_KERNEL);
882                         if (!io_end)
883                                 return -ENOMEM;
884                         bh_result->b_private = io_end;
885                         ext4_set_io_unwritten_flag(inode, io_end);
886                 }
887                 set_buffer_defer_completion(bh_result);
888         }
889
890         return ret;
891 }
892
893 /*
894  * Get block function for non-AIO DIO writes when we create unwritten extent if
895  * blocks are not allocated yet. The extent will be converted to written
896  * after IO is complete by ext4_direct_IO_write().
897  */
898 static int ext4_dio_get_block_unwritten_sync(struct inode *inode,
899                 sector_t iblock, struct buffer_head *bh_result, int create)
900 {
901         int ret;
902
903         /* We don't expect handle for direct IO */
904         WARN_ON_ONCE(ext4_journal_current_handle());
905
906         ret = ext4_get_block_trans(inode, iblock, bh_result,
907                                    EXT4_GET_BLOCKS_IO_CREATE_EXT);
908
909         /*
910          * Mark inode as having pending DIO writes to unwritten extents.
911          * ext4_direct_IO_write() checks this flag and converts extents to
912          * written.
913          */
914         if (!ret && buffer_unwritten(bh_result))
915                 ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
916
917         return ret;
918 }
919
920 static int ext4_dio_get_block_overwrite(struct inode *inode, sector_t iblock,
921                    struct buffer_head *bh_result, int create)
922 {
923         int ret;
924
925         ext4_debug("ext4_dio_get_block_overwrite: inode %lu, create flag %d\n",
926                    inode->i_ino, create);
927         /* We don't expect handle for direct IO */
928         WARN_ON_ONCE(ext4_journal_current_handle());
929
930         ret = _ext4_get_block(inode, iblock, bh_result, 0);
931         /*
932          * Blocks should have been preallocated! ext4_file_write_iter() checks
933          * that.
934          */
935         WARN_ON_ONCE(!buffer_mapped(bh_result) || buffer_unwritten(bh_result));
936
937         return ret;
938 }
939
940
941 /*
942  * `handle' can be NULL if create is zero
943  */
944 struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
945                                 ext4_lblk_t block, int map_flags)
946 {
947         struct ext4_map_blocks map;
948         struct buffer_head *bh;
949         int create = map_flags & EXT4_GET_BLOCKS_CREATE;
950         int err;
951
952         J_ASSERT(handle != NULL || create == 0);
953
954         map.m_lblk = block;
955         map.m_len = 1;
956         err = ext4_map_blocks(handle, inode, &map, map_flags);
957
958         if (err == 0)
959                 return create ? ERR_PTR(-ENOSPC) : NULL;
960         if (err < 0)
961                 return ERR_PTR(err);
962
963         bh = sb_getblk(inode->i_sb, map.m_pblk);
964         if (unlikely(!bh))
965                 return ERR_PTR(-ENOMEM);
966         if (map.m_flags & EXT4_MAP_NEW) {
967                 J_ASSERT(create != 0);
968                 J_ASSERT(handle != NULL);
969
970                 /*
971                  * Now that we do not always journal data, we should
972                  * keep in mind whether this should always journal the
973                  * new buffer as metadata.  For now, regular file
974                  * writes use ext4_get_block instead, so it's not a
975                  * problem.
976                  */
977                 lock_buffer(bh);
978                 BUFFER_TRACE(bh, "call get_create_access");
979                 err = ext4_journal_get_create_access(handle, bh);
980                 if (unlikely(err)) {
981                         unlock_buffer(bh);
982                         goto errout;
983                 }
984                 if (!buffer_uptodate(bh)) {
985                         memset(bh->b_data, 0, inode->i_sb->s_blocksize);
986                         set_buffer_uptodate(bh);
987                 }
988                 unlock_buffer(bh);
989                 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
990                 err = ext4_handle_dirty_metadata(handle, inode, bh);
991                 if (unlikely(err))
992                         goto errout;
993         } else
994                 BUFFER_TRACE(bh, "not a new buffer");
995         return bh;
996 errout:
997         brelse(bh);
998         return ERR_PTR(err);
999 }
1000
1001 struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
1002                                ext4_lblk_t block, int map_flags)
1003 {
1004         struct buffer_head *bh;
1005
1006         bh = ext4_getblk(handle, inode, block, map_flags);
1007         if (IS_ERR(bh))
1008                 return bh;
1009         if (!bh || buffer_uptodate(bh))
1010                 return bh;
1011         ll_rw_block(REQ_OP_READ, REQ_META | REQ_PRIO, 1, &bh);
1012         wait_on_buffer(bh);
1013         if (buffer_uptodate(bh))
1014                 return bh;
1015         put_bh(bh);
1016         return ERR_PTR(-EIO);
1017 }
1018
1019 /* Read a contiguous batch of blocks. */
1020 int ext4_bread_batch(struct inode *inode, ext4_lblk_t block, int bh_count,
1021                      bool wait, struct buffer_head **bhs)
1022 {
1023         int i, err;
1024
1025         for (i = 0; i < bh_count; i++) {
1026                 bhs[i] = ext4_getblk(NULL, inode, block + i, 0 /* map_flags */);
1027                 if (IS_ERR(bhs[i])) {
1028                         err = PTR_ERR(bhs[i]);
1029                         bh_count = i;
1030                         goto out_brelse;
1031                 }
1032         }
1033
1034         for (i = 0; i < bh_count; i++)
1035                 /* Note that NULL bhs[i] is valid because of holes. */
1036                 if (bhs[i] && !buffer_uptodate(bhs[i]))
1037                         ll_rw_block(REQ_OP_READ, REQ_META | REQ_PRIO, 1,
1038                                     &bhs[i]);
1039
1040         if (!wait)
1041                 return 0;
1042
1043         for (i = 0; i < bh_count; i++)
1044                 if (bhs[i])
1045                         wait_on_buffer(bhs[i]);
1046
1047         for (i = 0; i < bh_count; i++) {
1048                 if (bhs[i] && !buffer_uptodate(bhs[i])) {
1049                         err = -EIO;
1050                         goto out_brelse;
1051                 }
1052         }
1053         return 0;
1054
1055 out_brelse:
1056         for (i = 0; i < bh_count; i++) {
1057                 brelse(bhs[i]);
1058                 bhs[i] = NULL;
1059         }
1060         return err;
1061 }
1062
1063 int ext4_walk_page_buffers(handle_t *handle,
1064                            struct buffer_head *head,
1065                            unsigned from,
1066                            unsigned to,
1067                            int *partial,
1068                            int (*fn)(handle_t *handle,
1069                                      struct buffer_head *bh))
1070 {
1071         struct buffer_head *bh;
1072         unsigned block_start, block_end;
1073         unsigned blocksize = head->b_size;
1074         int err, ret = 0;
1075         struct buffer_head *next;
1076
1077         for (bh = head, block_start = 0;
1078              ret == 0 && (bh != head || !block_start);
1079              block_start = block_end, bh = next) {
1080                 next = bh->b_this_page;
1081                 block_end = block_start + blocksize;
1082                 if (block_end <= from || block_start >= to) {
1083                         if (partial && !buffer_uptodate(bh))
1084                                 *partial = 1;
1085                         continue;
1086                 }
1087                 err = (*fn)(handle, bh);
1088                 if (!ret)
1089                         ret = err;
1090         }
1091         return ret;
1092 }
1093
1094 /*
1095  * To preserve ordering, it is essential that the hole instantiation and
1096  * the data write be encapsulated in a single transaction.  We cannot
1097  * close off a transaction and start a new one between the ext4_get_block()
1098  * and the commit_write().  So doing the jbd2_journal_start at the start of
1099  * prepare_write() is the right place.
1100  *
1101  * Also, this function can nest inside ext4_writepage().  In that case, we
1102  * *know* that ext4_writepage() has generated enough buffer credits to do the
1103  * whole page.  So we won't block on the journal in that case, which is good,
1104  * because the caller may be PF_MEMALLOC.
1105  *
1106  * By accident, ext4 can be reentered when a transaction is open via
1107  * quota file writes.  If we were to commit the transaction while thus
1108  * reentered, there can be a deadlock - we would be holding a quota
1109  * lock, and the commit would never complete if another thread had a
1110  * transaction open and was blocking on the quota lock - a ranking
1111  * violation.
1112  *
1113  * So what we do is to rely on the fact that jbd2_journal_stop/journal_start
1114  * will _not_ run commit under these circumstances because handle->h_ref
1115  * is elevated.  We'll still have enough credits for the tiny quotafile
1116  * write.
1117  */
1118 int do_journal_get_write_access(handle_t *handle,
1119                                 struct buffer_head *bh)
1120 {
1121         int dirty = buffer_dirty(bh);
1122         int ret;
1123
1124         if (!buffer_mapped(bh) || buffer_freed(bh))
1125                 return 0;
1126         /*
1127          * __block_write_begin() could have dirtied some buffers. Clean
1128          * the dirty bit as jbd2_journal_get_write_access() could complain
1129          * otherwise about fs integrity issues. Setting of the dirty bit
1130          * by __block_write_begin() isn't a real problem here as we clear
1131          * the bit before releasing a page lock and thus writeback cannot
1132          * ever write the buffer.
1133          */
1134         if (dirty)
1135                 clear_buffer_dirty(bh);
1136         BUFFER_TRACE(bh, "get write access");
1137         ret = ext4_journal_get_write_access(handle, bh);
1138         if (!ret && dirty)
1139                 ret = ext4_handle_dirty_metadata(handle, NULL, bh);
1140         return ret;
1141 }
1142
1143 #ifdef CONFIG_EXT4_FS_ENCRYPTION
1144 static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
1145                                   get_block_t *get_block)
1146 {
1147         unsigned from = pos & (PAGE_SIZE - 1);
1148         unsigned to = from + len;
1149         struct inode *inode = page->mapping->host;
1150         unsigned block_start, block_end;
1151         sector_t block;
1152         int err = 0;
1153         unsigned blocksize = inode->i_sb->s_blocksize;
1154         unsigned bbits;
1155         struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
1156         bool decrypt = false;
1157
1158         BUG_ON(!PageLocked(page));
1159         BUG_ON(from > PAGE_SIZE);
1160         BUG_ON(to > PAGE_SIZE);
1161         BUG_ON(from > to);
1162
1163         if (!page_has_buffers(page))
1164                 create_empty_buffers(page, blocksize, 0);
1165         head = page_buffers(page);
1166         bbits = ilog2(blocksize);
1167         block = (sector_t)page->index << (PAGE_SHIFT - bbits);
1168
1169         for (bh = head, block_start = 0; bh != head || !block_start;
1170             block++, block_start = block_end, bh = bh->b_this_page) {
1171                 block_end = block_start + blocksize;
1172                 if (block_end <= from || block_start >= to) {
1173                         if (PageUptodate(page)) {
1174                                 if (!buffer_uptodate(bh))
1175                                         set_buffer_uptodate(bh);
1176                         }
1177                         continue;
1178                 }
1179                 if (buffer_new(bh))
1180                         clear_buffer_new(bh);
1181                 if (!buffer_mapped(bh)) {
1182                         WARN_ON(bh->b_size != blocksize);
1183                         err = get_block(inode, block, bh, 1);
1184                         if (err)
1185                                 break;
1186                         if (buffer_new(bh)) {
1187                                 clean_bdev_bh_alias(bh);
1188                                 if (PageUptodate(page)) {
1189                                         clear_buffer_new(bh);
1190                                         set_buffer_uptodate(bh);
1191                                         mark_buffer_dirty(bh);
1192                                         continue;
1193                                 }
1194                                 if (block_end > to || block_start < from)
1195                                         zero_user_segments(page, to, block_end,
1196                                                            block_start, from);
1197                                 continue;
1198                         }
1199                 }
1200                 if (PageUptodate(page)) {
1201                         if (!buffer_uptodate(bh))
1202                                 set_buffer_uptodate(bh);
1203                         continue;
1204                 }
1205                 if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
1206                     !buffer_unwritten(bh) &&
1207                     (block_start < from || block_end > to)) {
1208                         ll_rw_block(REQ_OP_READ, 0, 1, &bh);
1209                         *wait_bh++ = bh;
1210                         decrypt = ext4_encrypted_inode(inode) &&
1211                                 S_ISREG(inode->i_mode);
1212                 }
1213         }
1214         /*
1215          * If we issued read requests, let them complete.
1216          */
1217         while (wait_bh > wait) {
1218                 wait_on_buffer(*--wait_bh);
1219                 if (!buffer_uptodate(*wait_bh))
1220                         err = -EIO;
1221         }
1222         if (unlikely(err))
1223                 page_zero_new_buffers(page, from, to);
1224         else if (decrypt)
1225                 err = fscrypt_decrypt_page(page->mapping->host, page,
1226                                 PAGE_SIZE, 0, page->index);
1227         return err;
1228 }
1229 #endif
1230
1231 static int ext4_write_begin(struct file *file, struct address_space *mapping,
1232                             loff_t pos, unsigned len, unsigned flags,
1233                             struct page **pagep, void **fsdata)
1234 {
1235         struct inode *inode = mapping->host;
1236         int ret, needed_blocks;
1237         handle_t *handle;
1238         int retries = 0;
1239         struct page *page;
1240         pgoff_t index;
1241         unsigned from, to;
1242
1243         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
1244                 return -EIO;
1245
1246         trace_ext4_write_begin(inode, pos, len, flags);
1247         /*
1248          * Reserve one block more for addition to orphan list in case
1249          * we allocate blocks but write fails for some reason
1250          */
1251         needed_blocks = ext4_writepage_trans_blocks(inode) + 1;
1252         index = pos >> PAGE_SHIFT;
1253         from = pos & (PAGE_SIZE - 1);
1254         to = from + len;
1255
1256         if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
1257                 ret = ext4_try_to_write_inline_data(mapping, inode, pos, len,
1258                                                     flags, pagep);
1259                 if (ret < 0)
1260                         return ret;
1261                 if (ret == 1)
1262                         return 0;
1263         }
1264
1265         /*
1266          * grab_cache_page_write_begin() can take a long time if the
1267          * system is thrashing due to memory pressure, or if the page
1268          * is being written back.  So grab it first before we start
1269          * the transaction handle.  This also allows us to allocate
1270          * the page (if needed) without using GFP_NOFS.
1271          */
1272 retry_grab:
1273         page = grab_cache_page_write_begin(mapping, index, flags);
1274         if (!page)
1275                 return -ENOMEM;
1276         unlock_page(page);
1277
1278 retry_journal:
1279         handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE, needed_blocks);
1280         if (IS_ERR(handle)) {
1281                 put_page(page);
1282                 return PTR_ERR(handle);
1283         }
1284
1285         lock_page(page);
1286         if (page->mapping != mapping) {
1287                 /* The page got truncated from under us */
1288                 unlock_page(page);
1289                 put_page(page);
1290                 ext4_journal_stop(handle);
1291                 goto retry_grab;
1292         }
1293         /* In case writeback began while the page was unlocked */
1294         wait_for_stable_page(page);
1295
1296 #ifdef CONFIG_EXT4_FS_ENCRYPTION
1297         if (ext4_should_dioread_nolock(inode))
1298                 ret = ext4_block_write_begin(page, pos, len,
1299                                              ext4_get_block_unwritten);
1300         else
1301                 ret = ext4_block_write_begin(page, pos, len,
1302                                              ext4_get_block);
1303 #else
1304         if (ext4_should_dioread_nolock(inode))
1305                 ret = __block_write_begin(page, pos, len,
1306                                           ext4_get_block_unwritten);
1307         else
1308                 ret = __block_write_begin(page, pos, len, ext4_get_block);
1309 #endif
1310         if (!ret && ext4_should_journal_data(inode)) {
1311                 ret = ext4_walk_page_buffers(handle, page_buffers(page),
1312                                              from, to, NULL,
1313                                              do_journal_get_write_access);
1314         }
1315
1316         if (ret) {
1317                 unlock_page(page);
1318                 /*
1319                  * __block_write_begin may have instantiated a few blocks
1320                  * outside i_size.  Trim these off again. Don't need
1321                  * i_size_read because we hold i_mutex.
1322                  *
1323                  * Add inode to orphan list in case we crash before
1324                  * truncate finishes
1325                  */
1326                 if (pos + len > inode->i_size && ext4_can_truncate(inode))
1327                         ext4_orphan_add(handle, inode);
1328
1329                 ext4_journal_stop(handle);
1330                 if (pos + len > inode->i_size) {
1331                         ext4_truncate_failed_write(inode);
1332                         /*
1333                          * If truncate failed early the inode might
1334                          * still be on the orphan list; we need to
1335                          * make sure the inode is removed from the
1336                          * orphan list in that case.
1337                          */
1338                         if (inode->i_nlink)
1339                                 ext4_orphan_del(NULL, inode);
1340                 }
1341
1342                 if (ret == -ENOSPC &&
1343                     ext4_should_retry_alloc(inode->i_sb, &retries))
1344                         goto retry_journal;
1345                 put_page(page);
1346                 return ret;
1347         }
1348         *pagep = page;
1349         return ret;
1350 }
1351
1352 /* For write_end() in data=journal mode */
1353 static int write_end_fn(handle_t *handle, struct buffer_head *bh)
1354 {
1355         int ret;
1356         if (!buffer_mapped(bh) || buffer_freed(bh))
1357                 return 0;
1358         set_buffer_uptodate(bh);
1359         ret = ext4_handle_dirty_metadata(handle, NULL, bh);
1360         clear_buffer_meta(bh);
1361         clear_buffer_prio(bh);
1362         return ret;
1363 }
1364
1365 /*
1366  * We need to pick up the new inode size which generic_commit_write gave us
1367  * `file' can be NULL - eg, when called from page_symlink().
1368  *
1369  * ext4 never places buffers on inode->i_mapping->private_list.  metadata
1370  * buffers are managed internally.
1371  */
1372 static int ext4_write_end(struct file *file,
1373                           struct address_space *mapping,
1374                           loff_t pos, unsigned len, unsigned copied,
1375                           struct page *page, void *fsdata)
1376 {
1377         handle_t *handle = ext4_journal_current_handle();
1378         struct inode *inode = mapping->host;
1379         loff_t old_size = inode->i_size;
1380         int ret = 0, ret2;
1381         int i_size_changed = 0;
1382
1383         trace_ext4_write_end(inode, pos, len, copied);
1384         if (ext4_has_inline_data(inode)) {
1385                 ret = ext4_write_inline_data_end(inode, pos, len,
1386                                                  copied, page);
1387                 if (ret < 0) {
1388                         unlock_page(page);
1389                         put_page(page);
1390                         goto errout;
1391                 }
1392                 copied = ret;
1393         } else
1394                 copied = block_write_end(file, mapping, pos,
1395                                          len, copied, page, fsdata);
1396         /*
1397          * it's important to update i_size while still holding page lock:
1398          * page writeout could otherwise come in and zero beyond i_size.
1399          */
1400         i_size_changed = ext4_update_inode_size(inode, pos + copied);
1401         unlock_page(page);
1402         put_page(page);
1403
1404         if (old_size < pos)
1405                 pagecache_isize_extended(inode, old_size, pos);
1406         /*
1407          * Don't mark the inode dirty under page lock. First, it unnecessarily
1408          * makes the holding time of page lock longer. Second, it forces lock
1409          * ordering of page lock and transaction start for journaling
1410          * filesystems.
1411          */
1412         if (i_size_changed)
1413                 ext4_mark_inode_dirty(handle, inode);
1414
1415         if (pos + len > inode->i_size && ext4_can_truncate(inode))
1416                 /* if we have allocated more blocks and copied
1417                  * less. We will have blocks allocated outside
1418                  * inode->i_size. So truncate them
1419                  */
1420                 ext4_orphan_add(handle, inode);
1421 errout:
1422         ret2 = ext4_journal_stop(handle);
1423         if (!ret)
1424                 ret = ret2;
1425
1426         if (pos + len > inode->i_size) {
1427                 ext4_truncate_failed_write(inode);
1428                 /*
1429                  * If truncate failed early the inode might still be
1430                  * on the orphan list; we need to make sure the inode
1431                  * is removed from the orphan list in that case.
1432                  */
1433                 if (inode->i_nlink)
1434                         ext4_orphan_del(NULL, inode);
1435         }
1436
1437         return ret ? ret : copied;
1438 }
1439
1440 /*
1441  * This is a private version of page_zero_new_buffers() which doesn't
1442  * set the buffer to be dirty, since in data=journalled mode we need
1443  * to call ext4_handle_dirty_metadata() instead.
1444  */
1445 static void ext4_journalled_zero_new_buffers(handle_t *handle,
1446                                             struct page *page,
1447                                             unsigned from, unsigned to)
1448 {
1449         unsigned int block_start = 0, block_end;
1450         struct buffer_head *head, *bh;
1451
1452         bh = head = page_buffers(page);
1453         do {
1454                 block_end = block_start + bh->b_size;
1455                 if (buffer_new(bh)) {
1456                         if (block_end > from && block_start < to) {
1457                                 if (!PageUptodate(page)) {
1458                                         unsigned start, size;
1459
1460                                         start = max(from, block_start);
1461                                         size = min(to, block_end) - start;
1462
1463                                         zero_user(page, start, size);
1464                                         write_end_fn(handle, bh);
1465                                 }
1466                                 clear_buffer_new(bh);
1467                         }
1468                 }
1469                 block_start = block_end;
1470                 bh = bh->b_this_page;
1471         } while (bh != head);
1472 }
1473
1474 static int ext4_journalled_write_end(struct file *file,
1475                                      struct address_space *mapping,
1476                                      loff_t pos, unsigned len, unsigned copied,
1477                                      struct page *page, void *fsdata)
1478 {
1479         handle_t *handle = ext4_journal_current_handle();
1480         struct inode *inode = mapping->host;
1481         loff_t old_size = inode->i_size;
1482         int ret = 0, ret2;
1483         int partial = 0;
1484         unsigned from, to;
1485         int size_changed = 0;
1486
1487         trace_ext4_journalled_write_end(inode, pos, len, copied);
1488         from = pos & (PAGE_SIZE - 1);
1489         to = from + len;
1490
1491         BUG_ON(!ext4_handle_valid(handle));
1492
1493         if (ext4_has_inline_data(inode)) {
1494                 ret = ext4_write_inline_data_end(inode, pos, len,
1495                                                  copied, page);
1496                 if (ret < 0) {
1497                         unlock_page(page);
1498                         put_page(page);
1499                         goto errout;
1500                 }
1501                 copied = ret;
1502         } else if (unlikely(copied < len) && !PageUptodate(page)) {
1503                 copied = 0;
1504                 ext4_journalled_zero_new_buffers(handle, page, from, to);
1505         } else {
1506                 if (unlikely(copied < len))
1507                         ext4_journalled_zero_new_buffers(handle, page,
1508                                                          from + copied, to);
1509                 ret = ext4_walk_page_buffers(handle, page_buffers(page), from,
1510                                              from + copied, &partial,
1511                                              write_end_fn);
1512                 if (!partial)
1513                         SetPageUptodate(page);
1514         }
1515         size_changed = ext4_update_inode_size(inode, pos + copied);
1516         ext4_set_inode_state(inode, EXT4_STATE_JDATA);
1517         EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
1518         unlock_page(page);
1519         put_page(page);
1520
1521         if (old_size < pos)
1522                 pagecache_isize_extended(inode, old_size, pos);
1523
1524         if (size_changed) {
1525                 ret2 = ext4_mark_inode_dirty(handle, inode);
1526                 if (!ret)
1527                         ret = ret2;
1528         }
1529
1530         if (pos + len > inode->i_size && ext4_can_truncate(inode))
1531                 /* if we have allocated more blocks and copied
1532                  * less. We will have blocks allocated outside
1533                  * inode->i_size. So truncate them
1534                  */
1535                 ext4_orphan_add(handle, inode);
1536
1537 errout:
1538         ret2 = ext4_journal_stop(handle);
1539         if (!ret)
1540                 ret = ret2;
1541         if (pos + len > inode->i_size) {
1542                 ext4_truncate_failed_write(inode);
1543                 /*
1544                  * If truncate failed early the inode might still be
1545                  * on the orphan list; we need to make sure the inode
1546                  * is removed from the orphan list in that case.
1547                  */
1548                 if (inode->i_nlink)
1549                         ext4_orphan_del(NULL, inode);
1550         }
1551
1552         return ret ? ret : copied;
1553 }
1554
1555 /*
1556  * Reserve space for a single cluster
1557  */
1558 static int ext4_da_reserve_space(struct inode *inode)
1559 {
1560         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1561         struct ext4_inode_info *ei = EXT4_I(inode);
1562         int ret;
1563
1564         /*
1565          * We will charge metadata quota at writeout time; this saves
1566          * us from metadata over-estimation, though we may go over by
1567          * a small amount in the end.  Here we just reserve for data.
1568          */
1569         ret = dquot_reserve_block(inode, EXT4_C2B(sbi, 1));
1570         if (ret)
1571                 return ret;
1572
1573         spin_lock(&ei->i_block_reservation_lock);
1574         if (ext4_claim_free_clusters(sbi, 1, 0)) {
1575                 spin_unlock(&ei->i_block_reservation_lock);
1576                 dquot_release_reservation_block(inode, EXT4_C2B(sbi, 1));
1577                 return -ENOSPC;
1578         }
1579         ei->i_reserved_data_blocks++;
1580         trace_ext4_da_reserve_space(inode);
1581         spin_unlock(&ei->i_block_reservation_lock);
1582
1583         return 0;       /* success */
1584 }
1585
1586 static void ext4_da_release_space(struct inode *inode, int to_free)
1587 {
1588         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1589         struct ext4_inode_info *ei = EXT4_I(inode);
1590
1591         if (!to_free)
1592                 return;         /* Nothing to release, exit */
1593
1594         spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1595
1596         trace_ext4_da_release_space(inode, to_free);
1597         if (unlikely(to_free > ei->i_reserved_data_blocks)) {
1598                 /*
1599                  * if there aren't enough reserved blocks, then the
1600                  * counter is messed up somewhere.  Since this
1601                  * function is called from invalidate page, it's
1602                  * harmless to return without any action.
1603                  */
1604                 ext4_warning(inode->i_sb, "ext4_da_release_space: "
1605                          "ino %lu, to_free %d with only %d reserved "
1606                          "data blocks", inode->i_ino, to_free,
1607                          ei->i_reserved_data_blocks);
1608                 WARN_ON(1);
1609                 to_free = ei->i_reserved_data_blocks;
1610         }
1611         ei->i_reserved_data_blocks -= to_free;
1612
1613         /* update fs dirty data blocks counter */
1614         percpu_counter_sub(&sbi->s_dirtyclusters_counter, to_free);
1615
1616         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1617
1618         dquot_release_reservation_block(inode, EXT4_C2B(sbi, to_free));
1619 }
1620
1621 static void ext4_da_page_release_reservation(struct page *page,
1622                                              unsigned int offset,
1623                                              unsigned int length)
1624 {
1625         int to_release = 0, contiguous_blks = 0;
1626         struct buffer_head *head, *bh;
1627         unsigned int curr_off = 0;
1628         struct inode *inode = page->mapping->host;
1629         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1630         unsigned int stop = offset + length;
1631         int num_clusters;
1632         ext4_fsblk_t lblk;
1633
1634         BUG_ON(stop > PAGE_SIZE || stop < length);
1635
1636         head = page_buffers(page);
1637         bh = head;
1638         do {
1639                 unsigned int next_off = curr_off + bh->b_size;
1640
1641                 if (next_off > stop)
1642                         break;
1643
1644                 if ((offset <= curr_off) && (buffer_delay(bh))) {
1645                         to_release++;
1646                         contiguous_blks++;
1647                         clear_buffer_delay(bh);
1648                 } else if (contiguous_blks) {
1649                         lblk = page->index <<
1650                                (PAGE_SHIFT - inode->i_blkbits);
1651                         lblk += (curr_off >> inode->i_blkbits) -
1652                                 contiguous_blks;
1653                         ext4_es_remove_extent(inode, lblk, contiguous_blks);
1654                         contiguous_blks = 0;
1655                 }
1656                 curr_off = next_off;
1657         } while ((bh = bh->b_this_page) != head);
1658
1659         if (contiguous_blks) {
1660                 lblk = page->index << (PAGE_SHIFT - inode->i_blkbits);
1661                 lblk += (curr_off >> inode->i_blkbits) - contiguous_blks;
1662                 ext4_es_remove_extent(inode, lblk, contiguous_blks);
1663         }
1664
1665         /* If we have released all the blocks belonging to a cluster, then we
1666          * need to release the reserved space for that cluster. */
1667         num_clusters = EXT4_NUM_B2C(sbi, to_release);
1668         while (num_clusters > 0) {
1669                 lblk = (page->index << (PAGE_SHIFT - inode->i_blkbits)) +
1670                         ((num_clusters - 1) << sbi->s_cluster_bits);
1671                 if (sbi->s_cluster_ratio == 1 ||
1672                     !ext4_find_delalloc_cluster(inode, lblk))
1673                         ext4_da_release_space(inode, 1);
1674
1675                 num_clusters--;
1676         }
1677 }
1678
1679 /*
1680  * Delayed allocation stuff
1681  */
1682
1683 struct mpage_da_data {
1684         struct inode *inode;
1685         struct writeback_control *wbc;
1686
1687         pgoff_t first_page;     /* The first page to write */
1688         pgoff_t next_page;      /* Current page to examine */
1689         pgoff_t last_page;      /* Last page to examine */
1690         /*
1691          * Extent to map - this can be after first_page because that can be
1692          * fully mapped. We somewhat abuse m_flags to store whether the extent
1693          * is delalloc or unwritten.
1694          */
1695         struct ext4_map_blocks map;
1696         struct ext4_io_submit io_submit;        /* IO submission data */
1697         unsigned int do_map:1;
1698 };
1699
1700 static void mpage_release_unused_pages(struct mpage_da_data *mpd,
1701                                        bool invalidate)
1702 {
1703         int nr_pages, i;
1704         pgoff_t index, end;
1705         struct pagevec pvec;
1706         struct inode *inode = mpd->inode;
1707         struct address_space *mapping = inode->i_mapping;
1708
1709         /* This is necessary when next_page == 0. */
1710         if (mpd->first_page >= mpd->next_page)
1711                 return;
1712
1713         index = mpd->first_page;
1714         end   = mpd->next_page - 1;
1715         if (invalidate) {
1716                 ext4_lblk_t start, last;
1717                 start = index << (PAGE_SHIFT - inode->i_blkbits);
1718                 last = end << (PAGE_SHIFT - inode->i_blkbits);
1719                 ext4_es_remove_extent(inode, start, last - start + 1);
1720         }
1721
1722         pagevec_init(&pvec, 0);
1723         while (index <= end) {
1724                 nr_pages = pagevec_lookup_range(&pvec, mapping, &index, end);
1725                 if (nr_pages == 0)
1726                         break;
1727                 for (i = 0; i < nr_pages; i++) {
1728                         struct page *page = pvec.pages[i];
1729
1730                         BUG_ON(!PageLocked(page));
1731                         BUG_ON(PageWriteback(page));
1732                         if (invalidate) {
1733                                 if (page_mapped(page))
1734                                         clear_page_dirty_for_io(page);
1735                                 block_invalidatepage(page, 0, PAGE_SIZE);
1736                                 ClearPageUptodate(page);
1737                         }
1738                         unlock_page(page);
1739                 }
1740                 pagevec_release(&pvec);
1741         }
1742 }
1743
1744 static void ext4_print_free_blocks(struct inode *inode)
1745 {
1746         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1747         struct super_block *sb = inode->i_sb;
1748         struct ext4_inode_info *ei = EXT4_I(inode);
1749
1750         ext4_msg(sb, KERN_CRIT, "Total free blocks count %lld",
1751                EXT4_C2B(EXT4_SB(inode->i_sb),
1752                         ext4_count_free_clusters(sb)));
1753         ext4_msg(sb, KERN_CRIT, "Free/Dirty block details");
1754         ext4_msg(sb, KERN_CRIT, "free_blocks=%lld",
1755                (long long) EXT4_C2B(EXT4_SB(sb),
1756                 percpu_counter_sum(&sbi->s_freeclusters_counter)));
1757         ext4_msg(sb, KERN_CRIT, "dirty_blocks=%lld",
1758                (long long) EXT4_C2B(EXT4_SB(sb),
1759                 percpu_counter_sum(&sbi->s_dirtyclusters_counter)));
1760         ext4_msg(sb, KERN_CRIT, "Block reservation details");
1761         ext4_msg(sb, KERN_CRIT, "i_reserved_data_blocks=%u",
1762                  ei->i_reserved_data_blocks);
1763         return;
1764 }
1765
1766 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh)
1767 {
1768         return (buffer_delay(bh) || buffer_unwritten(bh)) && buffer_dirty(bh);
1769 }
1770
1771 /*
1772  * This function is grabs code from the very beginning of
1773  * ext4_map_blocks, but assumes that the caller is from delayed write
1774  * time. This function looks up the requested blocks and sets the
1775  * buffer delay bit under the protection of i_data_sem.
1776  */
1777 static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
1778                               struct ext4_map_blocks *map,
1779                               struct buffer_head *bh)
1780 {
1781         struct extent_status es;
1782         int retval;
1783         sector_t invalid_block = ~((sector_t) 0xffff);
1784 #ifdef ES_AGGRESSIVE_TEST
1785         struct ext4_map_blocks orig_map;
1786
1787         memcpy(&orig_map, map, sizeof(*map));
1788 #endif
1789
1790         if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es))
1791                 invalid_block = ~0;
1792
1793         map->m_flags = 0;
1794         ext_debug("ext4_da_map_blocks(): inode %lu, max_blocks %u,"
1795                   "logical block %lu\n", inode->i_ino, map->m_len,
1796                   (unsigned long) map->m_lblk);
1797
1798         /* Lookup extent status tree firstly */
1799         if (ext4_es_lookup_extent(inode, iblock, &es)) {
1800                 if (ext4_es_is_hole(&es)) {
1801                         retval = 0;
1802                         down_read(&EXT4_I(inode)->i_data_sem);
1803                         goto add_delayed;
1804                 }
1805
1806                 /*
1807                  * Delayed extent could be allocated by fallocate.
1808                  * So we need to check it.
1809                  */
1810                 if (ext4_es_is_delayed(&es) && !ext4_es_is_unwritten(&es)) {
1811                         map_bh(bh, inode->i_sb, invalid_block);
1812                         set_buffer_new(bh);
1813                         set_buffer_delay(bh);
1814                         return 0;
1815                 }
1816
1817                 map->m_pblk = ext4_es_pblock(&es) + iblock - es.es_lblk;
1818                 retval = es.es_len - (iblock - es.es_lblk);
1819                 if (retval > map->m_len)
1820                         retval = map->m_len;
1821                 map->m_len = retval;
1822                 if (ext4_es_is_written(&es))
1823                         map->m_flags |= EXT4_MAP_MAPPED;
1824                 else if (ext4_es_is_unwritten(&es))
1825                         map->m_flags |= EXT4_MAP_UNWRITTEN;
1826                 else
1827                         BUG_ON(1);
1828
1829 #ifdef ES_AGGRESSIVE_TEST
1830                 ext4_map_blocks_es_recheck(NULL, inode, map, &orig_map, 0);
1831 #endif
1832                 return retval;
1833         }
1834
1835         /*
1836          * Try to see if we can get the block without requesting a new
1837          * file system block.
1838          */
1839         down_read(&EXT4_I(inode)->i_data_sem);
1840         if (ext4_has_inline_data(inode))
1841                 retval = 0;
1842         else if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
1843                 retval = ext4_ext_map_blocks(NULL, inode, map, 0);
1844         else
1845                 retval = ext4_ind_map_blocks(NULL, inode, map, 0);
1846
1847 add_delayed:
1848         if (retval == 0) {
1849                 int ret;
1850                 /*
1851                  * XXX: __block_prepare_write() unmaps passed block,
1852                  * is it OK?
1853                  */
1854                 /*
1855                  * If the block was allocated from previously allocated cluster,
1856                  * then we don't need to reserve it again. However we still need
1857                  * to reserve metadata for every block we're going to write.
1858                  */
1859                 if (EXT4_SB(inode->i_sb)->s_cluster_ratio == 1 ||
1860                     !ext4_find_delalloc_cluster(inode, map->m_lblk)) {
1861                         ret = ext4_da_reserve_space(inode);
1862                         if (ret) {
1863                                 /* not enough space to reserve */
1864                                 retval = ret;
1865                                 goto out_unlock;
1866                         }
1867                 }
1868
1869                 ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
1870                                             ~0, EXTENT_STATUS_DELAYED);
1871                 if (ret) {
1872                         retval = ret;
1873                         goto out_unlock;
1874                 }
1875
1876                 map_bh(bh, inode->i_sb, invalid_block);
1877                 set_buffer_new(bh);
1878                 set_buffer_delay(bh);
1879         } else if (retval > 0) {
1880                 int ret;
1881                 unsigned int status;
1882
1883                 if (unlikely(retval != map->m_len)) {
1884                         ext4_warning(inode->i_sb,
1885                                      "ES len assertion failed for inode "
1886                                      "%lu: retval %d != map->m_len %d",
1887                                      inode->i_ino, retval, map->m_len);
1888                         WARN_ON(1);
1889                 }
1890
1891                 status = map->m_flags & EXT4_MAP_UNWRITTEN ?
1892                                 EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
1893                 ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
1894                                             map->m_pblk, status);
1895                 if (ret != 0)
1896                         retval = ret;
1897         }
1898
1899 out_unlock:
1900         up_read((&EXT4_I(inode)->i_data_sem));
1901
1902         return retval;
1903 }
1904
1905 /*
1906  * This is a special get_block_t callback which is used by
1907  * ext4_da_write_begin().  It will either return mapped block or
1908  * reserve space for a single block.
1909  *
1910  * For delayed buffer_head we have BH_Mapped, BH_New, BH_Delay set.
1911  * We also have b_blocknr = -1 and b_bdev initialized properly
1912  *
1913  * For unwritten buffer_head we have BH_Mapped, BH_New, BH_Unwritten set.
1914  * We also have b_blocknr = physicalblock mapping unwritten extent and b_bdev
1915  * initialized properly.
1916  */
1917 int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
1918                            struct buffer_head *bh, int create)
1919 {
1920         struct ext4_map_blocks map;
1921         int ret = 0;
1922
1923         BUG_ON(create == 0);
1924         BUG_ON(bh->b_size != inode->i_sb->s_blocksize);
1925
1926         map.m_lblk = iblock;
1927         map.m_len = 1;
1928
1929         /*
1930          * first, we need to know whether the block is allocated already
1931          * preallocated blocks are unmapped but should treated
1932          * the same as allocated blocks.
1933          */
1934         ret = ext4_da_map_blocks(inode, iblock, &map, bh);
1935         if (ret <= 0)
1936                 return ret;
1937
1938         map_bh(bh, inode->i_sb, map.m_pblk);
1939         ext4_update_bh_state(bh, map.m_flags);
1940
1941         if (buffer_unwritten(bh)) {
1942                 /* A delayed write to unwritten bh should be marked
1943                  * new and mapped.  Mapped ensures that we don't do
1944                  * get_block multiple times when we write to the same
1945                  * offset and new ensures that we do proper zero out
1946                  * for partial write.
1947                  */
1948                 set_buffer_new(bh);
1949                 set_buffer_mapped(bh);
1950         }
1951         return 0;
1952 }
1953
1954 static int bget_one(handle_t *handle, struct buffer_head *bh)
1955 {
1956         get_bh(bh);
1957         return 0;
1958 }
1959
1960 static int bput_one(handle_t *handle, struct buffer_head *bh)
1961 {
1962         put_bh(bh);
1963         return 0;
1964 }
1965
1966 static int __ext4_journalled_writepage(struct page *page,
1967                                        unsigned int len)
1968 {
1969         struct address_space *mapping = page->mapping;
1970         struct inode *inode = mapping->host;
1971         struct buffer_head *page_bufs = NULL;
1972         handle_t *handle = NULL;
1973         int ret = 0, err = 0;
1974         int inline_data = ext4_has_inline_data(inode);
1975         struct buffer_head *inode_bh = NULL;
1976
1977         ClearPageChecked(page);
1978
1979         if (inline_data) {
1980                 BUG_ON(page->index != 0);
1981                 BUG_ON(len > ext4_get_max_inline_size(inode));
1982                 inode_bh = ext4_journalled_write_inline_data(inode, len, page);
1983                 if (inode_bh == NULL)
1984                         goto out;
1985         } else {
1986                 page_bufs = page_buffers(page);
1987                 if (!page_bufs) {
1988                         BUG();
1989                         goto out;
1990                 }
1991                 ext4_walk_page_buffers(handle, page_bufs, 0, len,
1992                                        NULL, bget_one);
1993         }
1994         /*
1995          * We need to release the page lock before we start the
1996          * journal, so grab a reference so the page won't disappear
1997          * out from under us.
1998          */
1999         get_page(page);
2000         unlock_page(page);
2001
2002         handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
2003                                     ext4_writepage_trans_blocks(inode));
2004         if (IS_ERR(handle)) {
2005                 ret = PTR_ERR(handle);
2006                 put_page(page);
2007                 goto out_no_pagelock;
2008         }
2009         BUG_ON(!ext4_handle_valid(handle));
2010
2011         lock_page(page);
2012         put_page(page);
2013         if (page->mapping != mapping) {
2014                 /* The page got truncated from under us */
2015                 ext4_journal_stop(handle);
2016                 ret = 0;
2017                 goto out;
2018         }
2019
2020         if (inline_data) {
2021                 BUFFER_TRACE(inode_bh, "get write access");
2022                 ret = ext4_journal_get_write_access(handle, inode_bh);
2023
2024                 err = ext4_handle_dirty_metadata(handle, inode, inode_bh);
2025
2026         } else {
2027                 ret = ext4_walk_page_buffers(handle, page_bufs, 0, len, NULL,
2028                                              do_journal_get_write_access);
2029
2030                 err = ext4_walk_page_buffers(handle, page_bufs, 0, len, NULL,
2031                                              write_end_fn);
2032         }
2033         if (ret == 0)
2034                 ret = err;
2035         EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
2036         err = ext4_journal_stop(handle);
2037         if (!ret)
2038                 ret = err;
2039
2040         if (!ext4_has_inline_data(inode))
2041                 ext4_walk_page_buffers(NULL, page_bufs, 0, len,
2042                                        NULL, bput_one);
2043         ext4_set_inode_state(inode, EXT4_STATE_JDATA);
2044 out:
2045         unlock_page(page);
2046 out_no_pagelock:
2047         brelse(inode_bh);
2048         return ret;
2049 }
2050
2051 /*
2052  * Note that we don't need to start a transaction unless we're journaling data
2053  * because we should have holes filled from ext4_page_mkwrite(). We even don't
2054  * need to file the inode to the transaction's list in ordered mode because if
2055  * we are writing back data added by write(), the inode is already there and if
2056  * we are writing back data modified via mmap(), no one guarantees in which
2057  * transaction the data will hit the disk. In case we are journaling data, we
2058  * cannot start transaction directly because transaction start ranks above page
2059  * lock so we have to do some magic.
2060  *
2061  * This function can get called via...
2062  *   - ext4_writepages after taking page lock (have journal handle)
2063  *   - journal_submit_inode_data_buffers (no journal handle)
2064  *   - shrink_page_list via the kswapd/direct reclaim (no journal handle)
2065  *   - grab_page_cache when doing write_begin (have journal handle)
2066  *
2067  * We don't do any block allocation in this function. If we have page with
2068  * multiple blocks we need to write those buffer_heads that are mapped. This
2069  * is important for mmaped based write. So if we do with blocksize 1K
2070  * truncate(f, 1024);
2071  * a = mmap(f, 0, 4096);
2072  * a[0] = 'a';
2073  * truncate(f, 4096);
2074  * we have in the page first buffer_head mapped via page_mkwrite call back
2075  * but other buffer_heads would be unmapped but dirty (dirty done via the
2076  * do_wp_page). So writepage should write the first block. If we modify
2077  * the mmap area beyond 1024 we will again get a page_fault and the
2078  * page_mkwrite callback will do the block allocation and mark the
2079  * buffer_heads mapped.
2080  *
2081  * We redirty the page if we have any buffer_heads that is either delay or
2082  * unwritten in the page.
2083  *
2084  * We can get recursively called as show below.
2085  *
2086  *      ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
2087  *              ext4_writepage()
2088  *
2089  * But since we don't do any block allocation we should not deadlock.
2090  * Page also have the dirty flag cleared so we don't get recurive page_lock.
2091  */
2092 static int ext4_writepage(struct page *page,
2093                           struct writeback_control *wbc)
2094 {
2095         int ret = 0;
2096         loff_t size;
2097         unsigned int len;
2098         struct buffer_head *page_bufs = NULL;
2099         struct inode *inode = page->mapping->host;
2100         struct ext4_io_submit io_submit;
2101         bool keep_towrite = false;
2102
2103         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb)))) {
2104                 ext4_invalidatepage(page, 0, PAGE_SIZE);
2105                 unlock_page(page);
2106                 return -EIO;
2107         }
2108
2109         trace_ext4_writepage(page);
2110         size = i_size_read(inode);
2111         if (page->index == size >> PAGE_SHIFT)
2112                 len = size & ~PAGE_MASK;
2113         else
2114                 len = PAGE_SIZE;
2115
2116         page_bufs = page_buffers(page);
2117         /*
2118          * We cannot do block allocation or other extent handling in this
2119          * function. If there are buffers needing that, we have to redirty
2120          * the page. But we may reach here when we do a journal commit via
2121          * journal_submit_inode_data_buffers() and in that case we must write
2122          * allocated buffers to achieve data=ordered mode guarantees.
2123          *
2124          * Also, if there is only one buffer per page (the fs block
2125          * size == the page size), if one buffer needs block
2126          * allocation or needs to modify the extent tree to clear the
2127          * unwritten flag, we know that the page can't be written at
2128          * all, so we might as well refuse the write immediately.
2129          * Unfortunately if the block size != page size, we can't as
2130          * easily detect this case using ext4_walk_page_buffers(), but
2131          * for the extremely common case, this is an optimization that
2132          * skips a useless round trip through ext4_bio_write_page().
2133          */
2134         if (ext4_walk_page_buffers(NULL, page_bufs, 0, len, NULL,
2135                                    ext4_bh_delay_or_unwritten)) {
2136                 redirty_page_for_writepage(wbc, page);
2137                 if ((current->flags & PF_MEMALLOC) ||
2138                     (inode->i_sb->s_blocksize == PAGE_SIZE)) {
2139                         /*
2140                          * For memory cleaning there's no point in writing only
2141                          * some buffers. So just bail out. Warn if we came here
2142                          * from direct reclaim.
2143                          */
2144                         WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD))
2145                                                         == PF_MEMALLOC);
2146                         unlock_page(page);
2147                         return 0;
2148                 }
2149                 keep_towrite = true;
2150         }
2151
2152         if (PageChecked(page) && ext4_should_journal_data(inode))
2153                 /*
2154                  * It's mmapped pagecache.  Add buffers and journal it.  There
2155                  * doesn't seem much point in redirtying the page here.
2156                  */
2157                 return __ext4_journalled_writepage(page, len);
2158
2159         ext4_io_submit_init(&io_submit, wbc);
2160         io_submit.io_end = ext4_init_io_end(inode, GFP_NOFS);
2161         if (!io_submit.io_end) {
2162                 redirty_page_for_writepage(wbc, page);
2163                 unlock_page(page);
2164                 return -ENOMEM;
2165         }
2166         ret = ext4_bio_write_page(&io_submit, page, len, wbc, keep_towrite);
2167         ext4_io_submit(&io_submit);
2168         /* Drop io_end reference we got from init */
2169         ext4_put_io_end_defer(io_submit.io_end);
2170         return ret;
2171 }
2172
2173 static int mpage_submit_page(struct mpage_da_data *mpd, struct page *page)
2174 {
2175         int len;
2176         loff_t size;
2177         int err;
2178
2179         BUG_ON(page->index != mpd->first_page);
2180         clear_page_dirty_for_io(page);
2181         /*
2182          * We have to be very careful here!  Nothing protects writeback path
2183          * against i_size changes and the page can be writeably mapped into
2184          * page tables. So an application can be growing i_size and writing
2185          * data through mmap while writeback runs. clear_page_dirty_for_io()
2186          * write-protects our page in page tables and the page cannot get
2187          * written to again until we release page lock. So only after
2188          * clear_page_dirty_for_io() we are safe to sample i_size for
2189          * ext4_bio_write_page() to zero-out tail of the written page. We rely
2190          * on the barrier provided by TestClearPageDirty in
2191          * clear_page_dirty_for_io() to make sure i_size is really sampled only
2192          * after page tables are updated.
2193          */
2194         size = i_size_read(mpd->inode);
2195         if (page->index == size >> PAGE_SHIFT)
2196                 len = size & ~PAGE_MASK;
2197         else
2198                 len = PAGE_SIZE;
2199         err = ext4_bio_write_page(&mpd->io_submit, page, len, mpd->wbc, false);
2200         if (!err)
2201                 mpd->wbc->nr_to_write--;
2202         mpd->first_page++;
2203
2204         return err;
2205 }
2206
2207 #define BH_FLAGS ((1 << BH_Unwritten) | (1 << BH_Delay))
2208
2209 /*
2210  * mballoc gives us at most this number of blocks...
2211  * XXX: That seems to be only a limitation of ext4_mb_normalize_request().
2212  * The rest of mballoc seems to handle chunks up to full group size.
2213  */
2214 #define MAX_WRITEPAGES_EXTENT_LEN 2048
2215
2216 /*
2217  * mpage_add_bh_to_extent - try to add bh to extent of blocks to map
2218  *
2219  * @mpd - extent of blocks
2220  * @lblk - logical number of the block in the file
2221  * @bh - buffer head we want to add to the extent
2222  *
2223  * The function is used to collect contig. blocks in the same state. If the
2224  * buffer doesn't require mapping for writeback and we haven't started the
2225  * extent of buffers to map yet, the function returns 'true' immediately - the
2226  * caller can write the buffer right away. Otherwise the function returns true
2227  * if the block has been added to the extent, false if the block couldn't be
2228  * added.
2229  */
2230 static bool mpage_add_bh_to_extent(struct mpage_da_data *mpd, ext4_lblk_t lblk,
2231                                    struct buffer_head *bh)
2232 {
2233         struct ext4_map_blocks *map = &mpd->map;
2234
2235         /* Buffer that doesn't need mapping for writeback? */
2236         if (!buffer_dirty(bh) || !buffer_mapped(bh) ||
2237             (!buffer_delay(bh) && !buffer_unwritten(bh))) {
2238                 /* So far no extent to map => we write the buffer right away */
2239                 if (map->m_len == 0)
2240                         return true;
2241                 return false;
2242         }
2243
2244         /* First block in the extent? */
2245         if (map->m_len == 0) {
2246                 /* We cannot map unless handle is started... */
2247                 if (!mpd->do_map)
2248                         return false;
2249                 map->m_lblk = lblk;
2250                 map->m_len = 1;
2251                 map->m_flags = bh->b_state & BH_FLAGS;
2252                 return true;
2253         }
2254
2255         /* Don't go larger than mballoc is willing to allocate */
2256         if (map->m_len >= MAX_WRITEPAGES_EXTENT_LEN)
2257                 return false;
2258
2259         /* Can we merge the block to our big extent? */
2260         if (lblk == map->m_lblk + map->m_len &&
2261             (bh->b_state & BH_FLAGS) == map->m_flags) {
2262                 map->m_len++;
2263                 return true;
2264         }
2265         return false;
2266 }
2267
2268 /*
2269  * mpage_process_page_bufs - submit page buffers for IO or add them to extent
2270  *
2271  * @mpd - extent of blocks for mapping
2272  * @head - the first buffer in the page
2273  * @bh - buffer we should start processing from
2274  * @lblk - logical number of the block in the file corresponding to @bh
2275  *
2276  * Walk through page buffers from @bh upto @head (exclusive) and either submit
2277  * the page for IO if all buffers in this page were mapped and there's no
2278  * accumulated extent of buffers to map or add buffers in the page to the
2279  * extent of buffers to map. The function returns 1 if the caller can continue
2280  * by processing the next page, 0 if it should stop adding buffers to the
2281  * extent to map because we cannot extend it anymore. It can also return value
2282  * < 0 in case of error during IO submission.
2283  */
2284 static int mpage_process_page_bufs(struct mpage_da_data *mpd,
2285                                    struct buffer_head *head,
2286                                    struct buffer_head *bh,
2287                                    ext4_lblk_t lblk)
2288 {
2289         struct inode *inode = mpd->inode;
2290         int err;
2291         ext4_lblk_t blocks = (i_size_read(inode) + i_blocksize(inode) - 1)
2292                                                         >> inode->i_blkbits;
2293
2294         do {
2295                 BUG_ON(buffer_locked(bh));
2296
2297                 if (lblk >= blocks || !mpage_add_bh_to_extent(mpd, lblk, bh)) {
2298                         /* Found extent to map? */
2299                         if (mpd->map.m_len)
2300                                 return 0;
2301                         /* Buffer needs mapping and handle is not started? */
2302                         if (!mpd->do_map)
2303                                 return 0;
2304                         /* Everything mapped so far and we hit EOF */
2305                         break;
2306                 }
2307         } while (lblk++, (bh = bh->b_this_page) != head);
2308         /* So far everything mapped? Submit the page for IO. */
2309         if (mpd->map.m_len == 0) {
2310                 err = mpage_submit_page(mpd, head->b_page);
2311                 if (err < 0)
2312                         return err;
2313         }
2314         return lblk < blocks;
2315 }
2316
2317 /*
2318  * mpage_map_buffers - update buffers corresponding to changed extent and
2319  *                     submit fully mapped pages for IO
2320  *
2321  * @mpd - description of extent to map, on return next extent to map
2322  *
2323  * Scan buffers corresponding to changed extent (we expect corresponding pages
2324  * to be already locked) and update buffer state according to new extent state.
2325  * We map delalloc buffers to their physical location, clear unwritten bits,
2326  * and mark buffers as uninit when we perform writes to unwritten extents
2327  * and do extent conversion after IO is finished. If the last page is not fully
2328  * mapped, we update @map to the next extent in the last page that needs
2329  * mapping. Otherwise we submit the page for IO.
2330  */
2331 static int mpage_map_and_submit_buffers(struct mpage_da_data *mpd)
2332 {
2333         struct pagevec pvec;
2334         int nr_pages, i;
2335         struct inode *inode = mpd->inode;
2336         struct buffer_head *head, *bh;
2337         int bpp_bits = PAGE_SHIFT - inode->i_blkbits;
2338         pgoff_t start, end;
2339         ext4_lblk_t lblk;
2340         sector_t pblock;
2341         int err;
2342
2343         start = mpd->map.m_lblk >> bpp_bits;
2344         end = (mpd->map.m_lblk + mpd->map.m_len - 1) >> bpp_bits;
2345         lblk = start << bpp_bits;
2346         pblock = mpd->map.m_pblk;
2347
2348         pagevec_init(&pvec, 0);
2349         while (start <= end) {
2350                 nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping,
2351                                                 &start, end);
2352                 if (nr_pages == 0)
2353                         break;
2354                 for (i = 0; i < nr_pages; i++) {
2355                         struct page *page = pvec.pages[i];
2356
2357                         bh = head = page_buffers(page);
2358                         do {
2359                                 if (lblk < mpd->map.m_lblk)
2360                                         continue;
2361                                 if (lblk >= mpd->map.m_lblk + mpd->map.m_len) {
2362                                         /*
2363                                          * Buffer after end of mapped extent.
2364                                          * Find next buffer in the page to map.
2365                                          */
2366                                         mpd->map.m_len = 0;
2367                                         mpd->map.m_flags = 0;
2368                                         /*
2369                                          * FIXME: If dioread_nolock supports
2370                                          * blocksize < pagesize, we need to make
2371                                          * sure we add size mapped so far to
2372                                          * io_end->size as the following call
2373                                          * can submit the page for IO.
2374                                          */
2375                                         err = mpage_process_page_bufs(mpd, head,
2376                                                                       bh, lblk);
2377                                         pagevec_release(&pvec);
2378                                         if (err > 0)
2379                                                 err = 0;
2380                                         return err;
2381                                 }
2382                                 if (buffer_delay(bh)) {
2383                                         clear_buffer_delay(bh);
2384                                         bh->b_blocknr = pblock++;
2385                                 }
2386                                 clear_buffer_unwritten(bh);
2387                         } while (lblk++, (bh = bh->b_this_page) != head);
2388
2389                         /*
2390                          * FIXME: This is going to break if dioread_nolock
2391                          * supports blocksize < pagesize as we will try to
2392                          * convert potentially unmapped parts of inode.
2393                          */
2394                         mpd->io_submit.io_end->size += PAGE_SIZE;
2395                         /* Page fully mapped - let IO run! */
2396                         err = mpage_submit_page(mpd, page);
2397                         if (err < 0) {
2398                                 pagevec_release(&pvec);
2399                                 return err;
2400                         }
2401                 }
2402                 pagevec_release(&pvec);
2403         }
2404         /* Extent fully mapped and matches with page boundary. We are done. */
2405         mpd->map.m_len = 0;
2406         mpd->map.m_flags = 0;
2407         return 0;
2408 }
2409
2410 static int mpage_map_one_extent(handle_t *handle, struct mpage_da_data *mpd)
2411 {
2412         struct inode *inode = mpd->inode;
2413         struct ext4_map_blocks *map = &mpd->map;
2414         int get_blocks_flags;
2415         int err, dioread_nolock;
2416
2417         trace_ext4_da_write_pages_extent(inode, map);
2418         /*
2419          * Call ext4_map_blocks() to allocate any delayed allocation blocks, or
2420          * to convert an unwritten extent to be initialized (in the case
2421          * where we have written into one or more preallocated blocks).  It is
2422          * possible that we're going to need more metadata blocks than
2423          * previously reserved. However we must not fail because we're in
2424          * writeback and there is nothing we can do about it so it might result
2425          * in data loss.  So use reserved blocks to allocate metadata if
2426          * possible.
2427          *
2428          * We pass in the magic EXT4_GET_BLOCKS_DELALLOC_RESERVE if
2429          * the blocks in question are delalloc blocks.  This indicates
2430          * that the blocks and quotas has already been checked when
2431          * the data was copied into the page cache.
2432          */
2433         get_blocks_flags = EXT4_GET_BLOCKS_CREATE |
2434                            EXT4_GET_BLOCKS_METADATA_NOFAIL |
2435                            EXT4_GET_BLOCKS_IO_SUBMIT;
2436         dioread_nolock = ext4_should_dioread_nolock(inode);
2437         if (dioread_nolock)
2438                 get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
2439         if (map->m_flags & (1 << BH_Delay))
2440                 get_blocks_flags |= EXT4_GET_BLOCKS_DELALLOC_RESERVE;
2441
2442         err = ext4_map_blocks(handle, inode, map, get_blocks_flags);
2443         if (err < 0)
2444                 return err;
2445         if (dioread_nolock && (map->m_flags & EXT4_MAP_UNWRITTEN)) {
2446                 if (!mpd->io_submit.io_end->handle &&
2447                     ext4_handle_valid(handle)) {
2448                         mpd->io_submit.io_end->handle = handle->h_rsv_handle;
2449                         handle->h_rsv_handle = NULL;
2450                 }
2451                 ext4_set_io_unwritten_flag(inode, mpd->io_submit.io_end);
2452         }
2453
2454         BUG_ON(map->m_len == 0);
2455         if (map->m_flags & EXT4_MAP_NEW) {
2456                 clean_bdev_aliases(inode->i_sb->s_bdev, map->m_pblk,
2457                                    map->m_len);
2458         }
2459         return 0;
2460 }
2461
2462 /*
2463  * mpage_map_and_submit_extent - map extent starting at mpd->lblk of length
2464  *                               mpd->len and submit pages underlying it for IO
2465  *
2466  * @handle - handle for journal operations
2467  * @mpd - extent to map
2468  * @give_up_on_write - we set this to true iff there is a fatal error and there
2469  *                     is no hope of writing the data. The caller should discard
2470  *                     dirty pages to avoid infinite loops.
2471  *
2472  * The function maps extent starting at mpd->lblk of length mpd->len. If it is
2473  * delayed, blocks are allocated, if it is unwritten, we may need to convert
2474  * them to initialized or split the described range from larger unwritten
2475  * extent. Note that we need not map all the described range since allocation
2476  * can return less blocks or the range is covered by more unwritten extents. We
2477  * cannot map more because we are limited by reserved transaction credits. On
2478  * the other hand we always make sure that the last touched page is fully
2479  * mapped so that it can be written out (and thus forward progress is
2480  * guaranteed). After mapping we submit all mapped pages for IO.
2481  */
2482 static int mpage_map_and_submit_extent(handle_t *handle,
2483                                        struct mpage_da_data *mpd,
2484                                        bool *give_up_on_write)
2485 {
2486         struct inode *inode = mpd->inode;
2487         struct ext4_map_blocks *map = &mpd->map;
2488         int err;
2489         loff_t disksize;
2490         int progress = 0;
2491
2492         mpd->io_submit.io_end->offset =
2493                                 ((loff_t)map->m_lblk) << inode->i_blkbits;
2494         do {
2495                 err = mpage_map_one_extent(handle, mpd);
2496                 if (err < 0) {
2497                         struct super_block *sb = inode->i_sb;
2498
2499                         if (ext4_forced_shutdown(EXT4_SB(sb)) ||
2500                             EXT4_SB(sb)->s_mount_flags & EXT4_MF_FS_ABORTED)
2501                                 goto invalidate_dirty_pages;
2502                         /*
2503                          * Let the uper layers retry transient errors.
2504                          * In the case of ENOSPC, if ext4_count_free_blocks()
2505                          * is non-zero, a commit should free up blocks.
2506                          */
2507                         if ((err == -ENOMEM) ||
2508                             (err == -ENOSPC && ext4_count_free_clusters(sb))) {
2509                                 if (progress)
2510                                         goto update_disksize;
2511                                 return err;
2512                         }
2513                         ext4_msg(sb, KERN_CRIT,
2514                                  "Delayed block allocation failed for "
2515                                  "inode %lu at logical offset %llu with"
2516                                  " max blocks %u with error %d",
2517                                  inode->i_ino,
2518                                  (unsigned long long)map->m_lblk,
2519                                  (unsigned)map->m_len, -err);
2520                         ext4_msg(sb, KERN_CRIT,
2521                                  "This should not happen!! Data will "
2522                                  "be lost\n");
2523                         if (err == -ENOSPC)
2524                                 ext4_print_free_blocks(inode);
2525                 invalidate_dirty_pages:
2526                         *give_up_on_write = true;
2527                         return err;
2528                 }
2529                 progress = 1;
2530                 /*
2531                  * Update buffer state, submit mapped pages, and get us new
2532                  * extent to map
2533                  */
2534                 err = mpage_map_and_submit_buffers(mpd);
2535                 if (err < 0)
2536                         goto update_disksize;
2537         } while (map->m_len);
2538
2539 update_disksize:
2540         /*
2541          * Update on-disk size after IO is submitted.  Races with
2542          * truncate are avoided by checking i_size under i_data_sem.
2543          */
2544         disksize = ((loff_t)mpd->first_page) << PAGE_SHIFT;
2545         if (disksize > EXT4_I(inode)->i_disksize) {
2546                 int err2;
2547                 loff_t i_size;
2548
2549                 down_write(&EXT4_I(inode)->i_data_sem);
2550                 i_size = i_size_read(inode);
2551                 if (disksize > i_size)
2552                         disksize = i_size;
2553                 if (disksize > EXT4_I(inode)->i_disksize)
2554                         EXT4_I(inode)->i_disksize = disksize;
2555                 up_write(&EXT4_I(inode)->i_data_sem);
2556                 err2 = ext4_mark_inode_dirty(handle, inode);
2557                 if (err2)
2558                         ext4_error(inode->i_sb,
2559                                    "Failed to mark inode %lu dirty",
2560                                    inode->i_ino);
2561                 if (!err)
2562                         err = err2;
2563         }
2564         return err;
2565 }
2566
2567 /*
2568  * Calculate the total number of credits to reserve for one writepages
2569  * iteration. This is called from ext4_writepages(). We map an extent of
2570  * up to MAX_WRITEPAGES_EXTENT_LEN blocks and then we go on and finish mapping
2571  * the last partial page. So in total we can map MAX_WRITEPAGES_EXTENT_LEN +
2572  * bpp - 1 blocks in bpp different extents.
2573  */
2574 static int ext4_da_writepages_trans_blocks(struct inode *inode)
2575 {
2576         int bpp = ext4_journal_blocks_per_page(inode);
2577
2578         return ext4_meta_trans_blocks(inode,
2579                                 MAX_WRITEPAGES_EXTENT_LEN + bpp - 1, bpp);
2580 }
2581
2582 /*
2583  * mpage_prepare_extent_to_map - find & lock contiguous range of dirty pages
2584  *                               and underlying extent to map
2585  *
2586  * @mpd - where to look for pages
2587  *
2588  * Walk dirty pages in the mapping. If they are fully mapped, submit them for
2589  * IO immediately. When we find a page which isn't mapped we start accumulating
2590  * extent of buffers underlying these pages that needs mapping (formed by
2591  * either delayed or unwritten buffers). We also lock the pages containing
2592  * these buffers. The extent found is returned in @mpd structure (starting at
2593  * mpd->lblk with length mpd->len blocks).
2594  *
2595  * Note that this function can attach bios to one io_end structure which are
2596  * neither logically nor physically contiguous. Although it may seem as an
2597  * unnecessary complication, it is actually inevitable in blocksize < pagesize
2598  * case as we need to track IO to all buffers underlying a page in one io_end.
2599  */
2600 static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd)
2601 {
2602         struct address_space *mapping = mpd->inode->i_mapping;
2603         struct pagevec pvec;
2604         unsigned int nr_pages;
2605         long left = mpd->wbc->nr_to_write;
2606         pgoff_t index = mpd->first_page;
2607         pgoff_t end = mpd->last_page;
2608         int tag;
2609         int i, err = 0;
2610         int blkbits = mpd->inode->i_blkbits;
2611         ext4_lblk_t lblk;
2612         struct buffer_head *head;
2613
2614         if (mpd->wbc->sync_mode == WB_SYNC_ALL || mpd->wbc->tagged_writepages)
2615                 tag = PAGECACHE_TAG_TOWRITE;
2616         else
2617                 tag = PAGECACHE_TAG_DIRTY;
2618
2619         pagevec_init(&pvec, 0);
2620         mpd->map.m_len = 0;
2621         mpd->next_page = index;
2622         while (index <= end) {
2623                 nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
2624                               min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
2625                 if (nr_pages == 0)
2626                         goto out;
2627
2628                 for (i = 0; i < nr_pages; i++) {
2629                         struct page *page = pvec.pages[i];
2630
2631                         /*
2632                          * At this point, the page may be truncated or
2633                          * invalidated (changing page->mapping to NULL), or
2634                          * even swizzled back from swapper_space to tmpfs file
2635                          * mapping. However, page->index will not change
2636                          * because we have a reference on the page.
2637                          */
2638                         if (page->index > end)
2639                                 goto out;
2640
2641                         /*
2642                          * Accumulated enough dirty pages? This doesn't apply
2643                          * to WB_SYNC_ALL mode. For integrity sync we have to
2644                          * keep going because someone may be concurrently
2645                          * dirtying pages, and we might have synced a lot of
2646                          * newly appeared dirty pages, but have not synced all
2647                          * of the old dirty pages.
2648                          */
2649                         if (mpd->wbc->sync_mode == WB_SYNC_NONE && left <= 0)
2650                                 goto out;
2651
2652                         /* If we can't merge this page, we are done. */
2653                         if (mpd->map.m_len > 0 && mpd->next_page != page->index)
2654                                 goto out;
2655
2656                         lock_page(page);
2657                         /*
2658                          * If the page is no longer dirty, or its mapping no
2659                          * longer corresponds to inode we are writing (which
2660                          * means it has been truncated or invalidated), or the
2661                          * page is already under writeback and we are not doing
2662                          * a data integrity writeback, skip the page
2663                          */
2664                         if (!PageDirty(page) ||
2665                             (PageWriteback(page) &&
2666                              (mpd->wbc->sync_mode == WB_SYNC_NONE)) ||
2667                             unlikely(page->mapping != mapping)) {
2668                                 unlock_page(page);
2669                                 continue;
2670                         }
2671
2672                         wait_on_page_writeback(page);
2673                         BUG_ON(PageWriteback(page));
2674
2675                         if (mpd->map.m_len == 0)
2676                                 mpd->first_page = page->index;
2677                         mpd->next_page = page->index + 1;
2678                         /* Add all dirty buffers to mpd */
2679                         lblk = ((ext4_lblk_t)page->index) <<
2680                                 (PAGE_SHIFT - blkbits);
2681                         head = page_buffers(page);
2682                         err = mpage_process_page_bufs(mpd, head, head, lblk);
2683                         if (err <= 0)
2684                                 goto out;
2685                         err = 0;
2686                         left--;
2687                 }
2688                 pagevec_release(&pvec);
2689                 cond_resched();
2690         }
2691         return 0;
2692 out:
2693         pagevec_release(&pvec);
2694         return err;
2695 }
2696
2697 static int __writepage(struct page *page, struct writeback_control *wbc,
2698                        void *data)
2699 {
2700         struct address_space *mapping = data;
2701         int ret = ext4_writepage(page, wbc);
2702         mapping_set_error(mapping, ret);
2703         return ret;
2704 }
2705
2706 static int ext4_writepages(struct address_space *mapping,
2707                            struct writeback_control *wbc)
2708 {
2709         pgoff_t writeback_index = 0;
2710         long nr_to_write = wbc->nr_to_write;
2711         int range_whole = 0;
2712         int cycled = 1;
2713         handle_t *handle = NULL;
2714         struct mpage_da_data mpd;
2715         struct inode *inode = mapping->host;
2716         int needed_blocks, rsv_blocks = 0, ret = 0;
2717         struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
2718         bool done;
2719         struct blk_plug plug;
2720         bool give_up_on_write = false;
2721
2722         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
2723                 return -EIO;
2724
2725         percpu_down_read(&sbi->s_journal_flag_rwsem);
2726         trace_ext4_writepages(inode, wbc);
2727
2728         if (dax_mapping(mapping)) {
2729                 ret = dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev,
2730                                                   wbc);
2731                 goto out_writepages;
2732         }
2733
2734         /*
2735          * No pages to write? This is mainly a kludge to avoid starting
2736          * a transaction for special inodes like journal inode on last iput()
2737          * because that could violate lock ordering on umount
2738          */
2739         if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
2740                 goto out_writepages;
2741
2742         if (ext4_should_journal_data(inode)) {
2743                 struct blk_plug plug;
2744
2745                 blk_start_plug(&plug);
2746                 ret = write_cache_pages(mapping, wbc, __writepage, mapping);
2747                 blk_finish_plug(&plug);
2748                 goto out_writepages;
2749         }
2750
2751         /*
2752          * If the filesystem has aborted, it is read-only, so return
2753          * right away instead of dumping stack traces later on that
2754          * will obscure the real source of the problem.  We test
2755          * EXT4_MF_FS_ABORTED instead of sb->s_flag's MS_RDONLY because
2756          * the latter could be true if the filesystem is mounted
2757          * read-only, and in that case, ext4_writepages should
2758          * *never* be called, so if that ever happens, we would want
2759          * the stack trace.
2760          */
2761         if (unlikely(ext4_forced_shutdown(EXT4_SB(mapping->host->i_sb)) ||
2762                      sbi->s_mount_flags & EXT4_MF_FS_ABORTED)) {
2763                 ret = -EROFS;
2764                 goto out_writepages;
2765         }
2766
2767         if (ext4_should_dioread_nolock(inode)) {
2768                 /*
2769                  * We may need to convert up to one extent per block in
2770                  * the page and we may dirty the inode.
2771                  */
2772                 rsv_blocks = 1 + (PAGE_SIZE >> inode->i_blkbits);
2773         }
2774
2775         /*
2776          * If we have inline data and arrive here, it means that
2777          * we will soon create the block for the 1st page, so
2778          * we'd better clear the inline data here.
2779          */
2780         if (ext4_has_inline_data(inode)) {
2781                 /* Just inode will be modified... */
2782                 handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
2783                 if (IS_ERR(handle)) {
2784                         ret = PTR_ERR(handle);
2785                         goto out_writepages;
2786                 }
2787                 BUG_ON(ext4_test_inode_state(inode,
2788                                 EXT4_STATE_MAY_INLINE_DATA));
2789                 ext4_destroy_inline_data(handle, inode);
2790                 ext4_journal_stop(handle);
2791         }
2792
2793         if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
2794                 range_whole = 1;
2795
2796         if (wbc->range_cyclic) {
2797                 writeback_index = mapping->writeback_index;
2798                 if (writeback_index)
2799                         cycled = 0;
2800                 mpd.first_page = writeback_index;
2801                 mpd.last_page = -1;
2802         } else {
2803                 mpd.first_page = wbc->range_start >> PAGE_SHIFT;
2804                 mpd.last_page = wbc->range_end >> PAGE_SHIFT;
2805         }
2806
2807         mpd.inode = inode;
2808         mpd.wbc = wbc;
2809         ext4_io_submit_init(&mpd.io_submit, wbc);
2810 retry:
2811         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
2812                 tag_pages_for_writeback(mapping, mpd.first_page, mpd.last_page);
2813         done = false;
2814         blk_start_plug(&plug);
2815
2816         /*
2817          * First writeback pages that don't need mapping - we can avoid
2818          * starting a transaction unnecessarily and also avoid being blocked
2819          * in the block layer on device congestion while having transaction
2820          * started.
2821          */
2822         mpd.do_map = 0;
2823         mpd.io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
2824         if (!mpd.io_submit.io_end) {
2825                 ret = -ENOMEM;
2826                 goto unplug;
2827         }
2828         ret = mpage_prepare_extent_to_map(&mpd);
2829         /* Submit prepared bio */
2830         ext4_io_submit(&mpd.io_submit);
2831         ext4_put_io_end_defer(mpd.io_submit.io_end);
2832         mpd.io_submit.io_end = NULL;
2833         /* Unlock pages we didn't use */
2834         mpage_release_unused_pages(&mpd, false);
2835         if (ret < 0)
2836                 goto unplug;
2837
2838         while (!done && mpd.first_page <= mpd.last_page) {
2839                 /* For each extent of pages we use new io_end */
2840                 mpd.io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
2841                 if (!mpd.io_submit.io_end) {
2842                         ret = -ENOMEM;
2843                         break;
2844                 }
2845
2846                 /*
2847                  * We have two constraints: We find one extent to map and we
2848                  * must always write out whole page (makes a difference when
2849                  * blocksize < pagesize) so that we don't block on IO when we
2850                  * try to write out the rest of the page. Journalled mode is
2851                  * not supported by delalloc.
2852                  */
2853                 BUG_ON(ext4_should_journal_data(inode));
2854                 needed_blocks = ext4_da_writepages_trans_blocks(inode);
2855
2856                 /* start a new transaction */
2857                 handle = ext4_journal_start_with_reserve(inode,
2858                                 EXT4_HT_WRITE_PAGE, needed_blocks, rsv_blocks);
2859                 if (IS_ERR(handle)) {
2860                         ret = PTR_ERR(handle);
2861                         ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
2862                                "%ld pages, ino %lu; err %d", __func__,
2863                                 wbc->nr_to_write, inode->i_ino, ret);
2864                         /* Release allocated io_end */
2865                         ext4_put_io_end(mpd.io_submit.io_end);
2866                         mpd.io_submit.io_end = NULL;
2867                         break;
2868                 }
2869                 mpd.do_map = 1;
2870
2871                 trace_ext4_da_write_pages(inode, mpd.first_page, mpd.wbc);
2872                 ret = mpage_prepare_extent_to_map(&mpd);
2873                 if (!ret) {
2874                         if (mpd.map.m_len)
2875                                 ret = mpage_map_and_submit_extent(handle, &mpd,
2876                                         &give_up_on_write);
2877                         else {
2878                                 /*
2879                                  * We scanned the whole range (or exhausted
2880                                  * nr_to_write), submitted what was mapped and
2881                                  * didn't find anything needing mapping. We are
2882                                  * done.
2883                                  */
2884                                 done = true;
2885                         }
2886                 }
2887                 /*
2888                  * Caution: If the handle is synchronous,
2889                  * ext4_journal_stop() can wait for transaction commit
2890                  * to finish which may depend on writeback of pages to
2891                  * complete or on page lock to be released.  In that
2892                  * case, we have to wait until after after we have
2893                  * submitted all the IO, released page locks we hold,
2894                  * and dropped io_end reference (for extent conversion
2895                  * to be able to complete) before stopping the handle.
2896                  */
2897                 if (!ext4_handle_valid(handle) || handle->h_sync == 0) {
2898                         ext4_journal_stop(handle);
2899                         handle = NULL;
2900                         mpd.do_map = 0;
2901                 }
2902                 /* Submit prepared bio */
2903                 ext4_io_submit(&mpd.io_submit);
2904                 /* Unlock pages we didn't use */
2905                 mpage_release_unused_pages(&mpd, give_up_on_write);
2906                 /*
2907                  * Drop our io_end reference we got from init. We have
2908                  * to be careful and use deferred io_end finishing if
2909                  * we are still holding the transaction as we can
2910                  * release the last reference to io_end which may end
2911                  * up doing unwritten extent conversion.
2912                  */
2913                 if (handle) {
2914                         ext4_put_io_end_defer(mpd.io_submit.io_end);
2915                         ext4_journal_stop(handle);
2916                 } else
2917                         ext4_put_io_end(mpd.io_submit.io_end);
2918                 mpd.io_submit.io_end = NULL;
2919
2920                 if (ret == -ENOSPC && sbi->s_journal) {
2921                         /*
2922                          * Commit the transaction which would
2923                          * free blocks released in the transaction
2924                          * and try again
2925                          */
2926                         jbd2_journal_force_commit_nested(sbi->s_journal);
2927                         ret = 0;
2928                         continue;
2929                 }
2930                 /* Fatal error - ENOMEM, EIO... */
2931                 if (ret)
2932                         break;
2933         }
2934 unplug:
2935         blk_finish_plug(&plug);
2936         if (!ret && !cycled && wbc->nr_to_write > 0) {
2937                 cycled = 1;
2938                 mpd.last_page = writeback_index - 1;
2939                 mpd.first_page = 0;
2940                 goto retry;
2941         }
2942
2943         /* Update index */
2944         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
2945                 /*
2946                  * Set the writeback_index so that range_cyclic
2947                  * mode will write it back later
2948                  */
2949                 mapping->writeback_index = mpd.first_page;
2950
2951 out_writepages:
2952         trace_ext4_writepages_result(inode, wbc, ret,
2953                                      nr_to_write - wbc->nr_to_write);
2954         percpu_up_read(&sbi->s_journal_flag_rwsem);
2955         return ret;
2956 }
2957
2958 static int ext4_nonda_switch(struct super_block *sb)
2959 {
2960         s64 free_clusters, dirty_clusters;
2961         struct ext4_sb_info *sbi = EXT4_SB(sb);
2962
2963         /*
2964          * switch to non delalloc mode if we are running low
2965          * on free block. The free block accounting via percpu
2966          * counters can get slightly wrong with percpu_counter_batch getting
2967          * accumulated on each CPU without updating global counters
2968          * Delalloc need an accurate free block accounting. So switch
2969          * to non delalloc when we are near to error range.
2970          */
2971         free_clusters =
2972                 percpu_counter_read_positive(&sbi->s_freeclusters_counter);
2973         dirty_clusters =
2974                 percpu_counter_read_positive(&sbi->s_dirtyclusters_counter);
2975         /*
2976          * Start pushing delalloc when 1/2 of free blocks are dirty.
2977          */
2978         if (dirty_clusters && (free_clusters < 2 * dirty_clusters))
2979                 try_to_writeback_inodes_sb(sb, WB_REASON_FS_FREE_SPACE);
2980
2981         if (2 * free_clusters < 3 * dirty_clusters ||
2982             free_clusters < (dirty_clusters + EXT4_FREECLUSTERS_WATERMARK)) {
2983                 /*
2984                  * free block count is less than 150% of dirty blocks
2985                  * or free blocks is less than watermark
2986                  */
2987                 return 1;
2988         }
2989         return 0;
2990 }
2991
2992 /* We always reserve for an inode update; the superblock could be there too */
2993 static int ext4_da_write_credits(struct inode *inode, loff_t pos, unsigned len)
2994 {
2995         if (likely(ext4_has_feature_large_file(inode->i_sb)))
2996                 return 1;
2997
2998         if (pos + len <= 0x7fffffffULL)
2999                 return 1;
3000
3001         /* We might need to update the superblock to set LARGE_FILE */
3002         return 2;
3003 }
3004
3005 static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
3006                                loff_t pos, unsigned len, unsigned flags,
3007                                struct page **pagep, void **fsdata)
3008 {
3009         int ret, retries = 0;
3010         struct page *page;
3011         pgoff_t index;
3012         struct inode *inode = mapping->host;
3013         handle_t *handle;
3014
3015         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
3016                 return -EIO;
3017
3018         index = pos >> PAGE_SHIFT;
3019
3020         if (ext4_nonda_switch(inode->i_sb) ||
3021             S_ISLNK(inode->i_mode)) {
3022                 *fsdata = (void *)FALL_BACK_TO_NONDELALLOC;
3023                 return ext4_write_begin(file, mapping, pos,
3024                                         len, flags, pagep, fsdata);
3025         }
3026         *fsdata = (void *)0;
3027         trace_ext4_da_write_begin(inode, pos, len, flags);
3028
3029         if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
3030                 ret = ext4_da_write_inline_data_begin(mapping, inode,
3031                                                       pos, len, flags,
3032                                                       pagep, fsdata);
3033                 if (ret < 0)
3034                         return ret;
3035                 if (ret == 1)
3036                         return 0;
3037         }
3038
3039         /*
3040          * grab_cache_page_write_begin() can take a long time if the
3041          * system is thrashing due to memory pressure, or if the page
3042          * is being written back.  So grab it first before we start
3043          * the transaction handle.  This also allows us to allocate
3044          * the page (if needed) without using GFP_NOFS.
3045          */
3046 retry_grab:
3047         page = grab_cache_page_write_begin(mapping, index, flags);
3048         if (!page)
3049                 return -ENOMEM;
3050         unlock_page(page);
3051
3052         /*
3053          * With delayed allocation, we don't log the i_disksize update
3054          * if there is delayed block allocation. But we still need
3055          * to journalling the i_disksize update if writes to the end
3056          * of file which has an already mapped buffer.
3057          */
3058 retry_journal:
3059         handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
3060                                 ext4_da_write_credits(inode, pos, len));
3061         if (IS_ERR(handle)) {
3062                 put_page(page);
3063                 return PTR_ERR(handle);
3064         }
3065
3066         lock_page(page);
3067         if (page->mapping != mapping) {
3068                 /* The page got truncated from under us */
3069                 unlock_page(page);
3070                 put_page(page);
3071                 ext4_journal_stop(handle);
3072                 goto retry_grab;
3073         }
3074         /* In case writeback began while the page was unlocked */
3075         wait_for_stable_page(page);
3076
3077 #ifdef CONFIG_EXT4_FS_ENCRYPTION
3078         ret = ext4_block_write_begin(page, pos, len,
3079                                      ext4_da_get_block_prep);
3080 #else
3081         ret = __block_write_begin(page, pos, len, ext4_da_get_block_prep);
3082 #endif
3083         if (ret < 0) {
3084                 unlock_page(page);
3085                 ext4_journal_stop(handle);
3086                 /*
3087                  * block_write_begin may have instantiated a few blocks
3088                  * outside i_size.  Trim these off again. Don't need
3089                  * i_size_read because we hold i_mutex.
3090                  */
3091                 if (pos + len > inode->i_size)
3092                         ext4_truncate_failed_write(inode);
3093
3094                 if (ret == -ENOSPC &&
3095                     ext4_should_retry_alloc(inode->i_sb, &retries))
3096                         goto retry_journal;
3097
3098                 put_page(page);
3099                 return ret;
3100         }
3101
3102         *pagep = page;
3103         return ret;
3104 }
3105
3106 /*
3107  * Check if we should update i_disksize
3108  * when write to the end of file but not require block allocation
3109  */
3110 static int ext4_da_should_update_i_disksize(struct page *page,
3111                                             unsigned long offset)
3112 {
3113         struct buffer_head *bh;
3114         struct inode *inode = page->mapping->host;
3115         unsigned int idx;
3116         int i;
3117
3118         bh = page_buffers(page);
3119         idx = offset >> inode->i_blkbits;
3120
3121         for (i = 0; i < idx; i++)
3122                 bh = bh->b_this_page;
3123
3124         if (!buffer_mapped(bh) || (buffer_delay(bh)) || buffer_unwritten(bh))
3125                 return 0;
3126         return 1;
3127 }
3128
3129 static int ext4_da_write_end(struct file *file,
3130                              struct address_space *mapping,
3131                              loff_t pos, unsigned len, unsigned copied,
3132                              struct page *page, void *fsdata)
3133 {
3134         struct inode *inode = mapping->host;
3135         int ret = 0, ret2;
3136         handle_t *handle = ext4_journal_current_handle();
3137         loff_t new_i_size;
3138         unsigned long start, end;
3139         int write_mode = (int)(unsigned long)fsdata;
3140
3141         if (write_mode == FALL_BACK_TO_NONDELALLOC)
3142                 return ext4_write_end(file, mapping, pos,
3143                                       len, copied, page, fsdata);
3144
3145         trace_ext4_da_write_end(inode, pos, len, copied);
3146         start = pos & (PAGE_SIZE - 1);
3147         end = start + copied - 1;
3148
3149         /*
3150          * generic_write_end() will run mark_inode_dirty() if i_size
3151          * changes.  So let's piggyback the i_disksize mark_inode_dirty
3152          * into that.
3153          */
3154         new_i_size = pos + copied;
3155         if (copied && new_i_size > EXT4_I(inode)->i_disksize) {
3156                 if (ext4_has_inline_data(inode) ||
3157                     ext4_da_should_update_i_disksize(page, end)) {
3158                         ext4_update_i_disksize(inode, new_i_size);
3159                         /* We need to mark inode dirty even if
3160                          * new_i_size is less that inode->i_size
3161                          * bu greater than i_disksize.(hint delalloc)
3162                          */
3163                         ext4_mark_inode_dirty(handle, inode);
3164                 }
3165         }
3166
3167         if (write_mode != CONVERT_INLINE_DATA &&
3168             ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA) &&
3169             ext4_has_inline_data(inode))
3170                 ret2 = ext4_da_write_inline_data_end(inode, pos, len, copied,
3171                                                      page);
3172         else
3173                 ret2 = generic_write_end(file, mapping, pos, len, copied,
3174                                                         page, fsdata);
3175
3176         copied = ret2;
3177         if (ret2 < 0)
3178                 ret = ret2;
3179         ret2 = ext4_journal_stop(handle);
3180         if (!ret)
3181                 ret = ret2;
3182
3183         return ret ? ret : copied;
3184 }
3185
3186 static void ext4_da_invalidatepage(struct page *page, unsigned int offset,
3187                                    unsigned int length)
3188 {
3189         /*
3190          * Drop reserved blocks
3191          */
3192         BUG_ON(!PageLocked(page));
3193         if (!page_has_buffers(page))
3194                 goto out;
3195
3196         ext4_da_page_release_reservation(page, offset, length);
3197
3198 out:
3199         ext4_invalidatepage(page, offset, length);
3200
3201         return;
3202 }
3203
3204 /*
3205  * Force all delayed allocation blocks to be allocated for a given inode.
3206  */
3207 int ext4_alloc_da_blocks(struct inode *inode)
3208 {
3209         trace_ext4_alloc_da_blocks(inode);
3210
3211         if (!EXT4_I(inode)->i_reserved_data_blocks)
3212                 return 0;
3213
3214         /*
3215          * We do something simple for now.  The filemap_flush() will
3216          * also start triggering a write of the data blocks, which is
3217          * not strictly speaking necessary (and for users of
3218          * laptop_mode, not even desirable).  However, to do otherwise
3219          * would require replicating code paths in:
3220          *
3221          * ext4_writepages() ->
3222          *    write_cache_pages() ---> (via passed in callback function)
3223          *        __mpage_da_writepage() -->
3224          *           mpage_add_bh_to_extent()
3225          *           mpage_da_map_blocks()
3226          *
3227          * The problem is that write_cache_pages(), located in
3228          * mm/page-writeback.c, marks pages clean in preparation for
3229          * doing I/O, which is not desirable if we're not planning on
3230          * doing I/O at all.
3231          *
3232          * We could call write_cache_pages(), and then redirty all of
3233          * the pages by calling redirty_page_for_writepage() but that
3234          * would be ugly in the extreme.  So instead we would need to
3235          * replicate parts of the code in the above functions,
3236          * simplifying them because we wouldn't actually intend to
3237          * write out the pages, but rather only collect contiguous
3238          * logical block extents, call the multi-block allocator, and
3239          * then update the buffer heads with the block allocations.
3240          *
3241          * For now, though, we'll cheat by calling filemap_flush(),
3242          * which will map the blocks, and start the I/O, but not
3243          * actually wait for the I/O to complete.
3244          */
3245         return filemap_flush(inode->i_mapping);
3246 }
3247
3248 /*
3249  * bmap() is special.  It gets used by applications such as lilo and by
3250  * the swapper to find the on-disk block of a specific piece of data.
3251  *
3252  * Naturally, this is dangerous if the block concerned is still in the
3253  * journal.  If somebody makes a swapfile on an ext4 data-journaling
3254  * filesystem and enables swap, then they may get a nasty shock when the
3255  * data getting swapped to that swapfile suddenly gets overwritten by
3256  * the original zero's written out previously to the journal and
3257  * awaiting writeback in the kernel's buffer cache.
3258  *
3259  * So, if we see any bmap calls here on a modified, data-journaled file,
3260  * take extra steps to flush any blocks which might be in the cache.
3261  */
3262 static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
3263 {
3264         struct inode *inode = mapping->host;
3265         journal_t *journal;
3266         int err;
3267
3268         /*
3269          * We can get here for an inline file via the FIBMAP ioctl
3270          */
3271         if (ext4_has_inline_data(inode))
3272                 return 0;
3273
3274         if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
3275                         test_opt(inode->i_sb, DELALLOC)) {
3276                 /*
3277                  * With delalloc we want to sync the file
3278                  * so that we can make sure we allocate
3279                  * blocks for file
3280                  */
3281                 filemap_write_and_wait(mapping);
3282         }
3283
3284         if (EXT4_JOURNAL(inode) &&
3285             ext4_test_inode_state(inode, EXT4_STATE_JDATA)) {
3286                 /*
3287                  * This is a REALLY heavyweight approach, but the use of
3288                  * bmap on dirty files is expected to be extremely rare:
3289                  * only if we run lilo or swapon on a freshly made file
3290                  * do we expect this to happen.
3291                  *
3292                  * (bmap requires CAP_SYS_RAWIO so this does not
3293                  * represent an unprivileged user DOS attack --- we'd be
3294                  * in trouble if mortal users could trigger this path at
3295                  * will.)
3296                  *
3297                  * NB. EXT4_STATE_JDATA is not set on files other than
3298                  * regular files.  If somebody wants to bmap a directory
3299                  * or symlink and gets confused because the buffer
3300                  * hasn't yet been flushed to disk, they deserve
3301                  * everything they get.
3302                  */
3303
3304                 ext4_clear_inode_state(inode, EXT4_STATE_JDATA);
3305                 journal = EXT4_JOURNAL(inode);
3306                 jbd2_journal_lock_updates(journal);
3307                 err = jbd2_journal_flush(journal);
3308                 jbd2_journal_unlock_updates(journal);
3309
3310                 if (err)
3311                         return 0;
3312         }
3313
3314         return generic_block_bmap(mapping, block, ext4_get_block);
3315 }
3316
3317 static int ext4_readpage(struct file *file, struct page *page)
3318 {
3319         int ret = -EAGAIN;
3320         struct inode *inode = page->mapping->host;
3321
3322         trace_ext4_readpage(page);
3323
3324         if (ext4_has_inline_data(inode))
3325                 ret = ext4_readpage_inline(inode, page);
3326
3327         if (ret == -EAGAIN)
3328                 return ext4_mpage_readpages(page->mapping, NULL, page, 1);
3329
3330         return ret;
3331 }
3332
3333 static int
3334 ext4_readpages(struct file *file, struct address_space *mapping,
3335                 struct list_head *pages, unsigned nr_pages)
3336 {
3337         struct inode *inode = mapping->host;
3338
3339         /* If the file has inline data, no need to do readpages. */
3340         if (ext4_has_inline_data(inode))
3341                 return 0;
3342
3343         return ext4_mpage_readpages(mapping, pages, NULL, nr_pages);
3344 }
3345
3346 static void ext4_invalidatepage(struct page *page, unsigned int offset,
3347                                 unsigned int length)
3348 {
3349         trace_ext4_invalidatepage(page, offset, length);
3350
3351         /* No journalling happens on data buffers when this function is used */
3352         WARN_ON(page_has_buffers(page) && buffer_jbd(page_buffers(page)));
3353
3354         block_invalidatepage(page, offset, length);
3355 }
3356
3357 static int __ext4_journalled_invalidatepage(struct page *page,
3358                                             unsigned int offset,
3359                                             unsigned int length)
3360 {
3361         journal_t *journal = EXT4_JOURNAL(page->mapping->host);
3362
3363         trace_ext4_journalled_invalidatepage(page, offset, length);
3364
3365         /*
3366          * If it's a full truncate we just forget about the pending dirtying
3367          */
3368         if (offset == 0 && length == PAGE_SIZE)
3369                 ClearPageChecked(page);
3370
3371         return jbd2_journal_invalidatepage(journal, page, offset, length);
3372 }
3373
3374 /* Wrapper for aops... */
3375 static void ext4_journalled_invalidatepage(struct page *page,
3376                                            unsigned int offset,
3377                                            unsigned int length)
3378 {
3379         WARN_ON(__ext4_journalled_invalidatepage(page, offset, length) < 0);
3380 }
3381
3382 static int ext4_releasepage(struct page *page, gfp_t wait)
3383 {
3384         journal_t *journal = EXT4_JOURNAL(page->mapping->host);
3385
3386         trace_ext4_releasepage(page);
3387
3388         /* Page has dirty journalled data -> cannot release */
3389         if (PageChecked(page))
3390                 return 0;
3391         if (journal)
3392                 return jbd2_journal_try_to_free_buffers(journal, page, wait);
3393         else
3394                 return try_to_free_buffers(page);
3395 }
3396
3397 static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
3398                             unsigned flags, struct iomap *iomap)
3399 {
3400         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
3401         unsigned int blkbits = inode->i_blkbits;
3402         unsigned long first_block = offset >> blkbits;
3403         unsigned long last_block = (offset + length - 1) >> blkbits;
3404         struct ext4_map_blocks map;
3405         bool delalloc = false;
3406         int ret;
3407
3408
3409         if (flags & IOMAP_REPORT) {
3410                 if (ext4_has_inline_data(inode)) {
3411                         ret = ext4_inline_data_iomap(inode, iomap);
3412                         if (ret != -EAGAIN) {
3413                                 if (ret == 0 && offset >= iomap->length)
3414                                         ret = -ENOENT;
3415                                 return ret;
3416                         }
3417                 }
3418         } else {
3419                 if (WARN_ON_ONCE(ext4_has_inline_data(inode)))
3420                         return -ERANGE;
3421         }
3422
3423         map.m_lblk = first_block;
3424         map.m_len = last_block - first_block + 1;
3425
3426         if (flags & IOMAP_REPORT) {
3427                 ret = ext4_map_blocks(NULL, inode, &map, 0);
3428                 if (ret < 0)
3429                         return ret;
3430
3431                 if (ret == 0) {
3432                         ext4_lblk_t end = map.m_lblk + map.m_len - 1;
3433                         struct extent_status es;
3434
3435                         ext4_es_find_delayed_extent_range(inode, map.m_lblk, end, &es);
3436
3437                         if (!es.es_len || es.es_lblk > end) {
3438                                 /* entire range is a hole */
3439                         } else if (es.es_lblk > map.m_lblk) {
3440                                 /* range starts with a hole */
3441                                 map.m_len = es.es_lblk - map.m_lblk;
3442                         } else {
3443                                 ext4_lblk_t offs = 0;
3444
3445                                 if (es.es_lblk < map.m_lblk)
3446                                         offs = map.m_lblk - es.es_lblk;
3447                                 map.m_lblk = es.es_lblk + offs;
3448                                 map.m_len = es.es_len - offs;
3449                                 delalloc = true;
3450                         }
3451                 }
3452         } else if (flags & IOMAP_WRITE) {
3453                 int dio_credits;
3454                 handle_t *handle;
3455                 int retries = 0;
3456
3457                 /* Trim mapping request to maximum we can map at once for DIO */
3458                 if (map.m_len > DIO_MAX_BLOCKS)
3459                         map.m_len = DIO_MAX_BLOCKS;
3460                 dio_credits = ext4_chunk_trans_blocks(inode, map.m_len);
3461 retry:
3462                 /*
3463                  * Either we allocate blocks and then we don't get unwritten
3464                  * extent so we have reserved enough credits, or the blocks
3465                  * are already allocated and unwritten and in that case
3466                  * extent conversion fits in the credits as well.
3467                  */
3468                 handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS,
3469                                             dio_credits);
3470                 if (IS_ERR(handle))
3471                         return PTR_ERR(handle);
3472
3473                 ret = ext4_map_blocks(handle, inode, &map,
3474                                       EXT4_GET_BLOCKS_CREATE_ZERO);
3475                 if (ret < 0) {
3476                         ext4_journal_stop(handle);
3477                         if (ret == -ENOSPC &&
3478                             ext4_should_retry_alloc(inode->i_sb, &retries))
3479                                 goto retry;
3480                         return ret;
3481                 }
3482
3483                 /*
3484                  * If we added blocks beyond i_size, we need to make sure they
3485                  * will get truncated if we crash before updating i_size in
3486                  * ext4_iomap_end(). For faults we don't need to do that (and
3487                  * even cannot because for orphan list operations inode_lock is
3488                  * required) - if we happen to instantiate block beyond i_size,
3489                  * it is because we race with truncate which has already added
3490                  * the inode to the orphan list.
3491                  */
3492                 if (!(flags & IOMAP_FAULT) && first_block + map.m_len >
3493                     (i_size_read(inode) + (1 << blkbits) - 1) >> blkbits) {
3494                         int err;
3495
3496                         err = ext4_orphan_add(handle, inode);
3497                         if (err < 0) {
3498                                 ext4_journal_stop(handle);
3499                                 return err;
3500                         }
3501                 }
3502                 ext4_journal_stop(handle);
3503         } else {
3504                 ret = ext4_map_blocks(NULL, inode, &map, 0);
3505                 if (ret < 0)
3506                         return ret;
3507         }
3508
3509         iomap->flags = 0;
3510         iomap->bdev = inode->i_sb->s_bdev;
3511         iomap->dax_dev = sbi->s_daxdev;
3512         iomap->offset = first_block << blkbits;
3513         iomap->length = (u64)map.m_len << blkbits;
3514
3515         if (ret == 0) {
3516                 iomap->type = delalloc ? IOMAP_DELALLOC : IOMAP_HOLE;
3517                 iomap->addr = IOMAP_NULL_ADDR;
3518         } else {
3519                 if (map.m_flags & EXT4_MAP_MAPPED) {
3520                         iomap->type = IOMAP_MAPPED;
3521                 } else if (map.m_flags & EXT4_MAP_UNWRITTEN) {
3522                         iomap->type = IOMAP_UNWRITTEN;
3523                 } else {
3524                         WARN_ON_ONCE(1);
3525                         return -EIO;
3526                 }
3527                 iomap->addr = (u64)map.m_pblk << blkbits;
3528         }
3529
3530         if (map.m_flags & EXT4_MAP_NEW)
3531                 iomap->flags |= IOMAP_F_NEW;
3532
3533         return 0;
3534 }
3535
3536 static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length,
3537                           ssize_t written, unsigned flags, struct iomap *iomap)
3538 {
3539         int ret = 0;
3540         handle_t *handle;
3541         int blkbits = inode->i_blkbits;
3542         bool truncate = false;
3543
3544         if (!(flags & IOMAP_WRITE) || (flags & IOMAP_FAULT))
3545                 return 0;
3546
3547         handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
3548         if (IS_ERR(handle)) {
3549                 ret = PTR_ERR(handle);
3550                 goto orphan_del;
3551         }
3552         if (ext4_update_inode_size(inode, offset + written))
3553                 ext4_mark_inode_dirty(handle, inode);
3554         /*
3555          * We may need to truncate allocated but not written blocks beyond EOF.
3556          */
3557         if (iomap->offset + iomap->length > 
3558             ALIGN(inode->i_size, 1 << blkbits)) {
3559                 ext4_lblk_t written_blk, end_blk;
3560
3561                 written_blk = (offset + written) >> blkbits;
3562                 end_blk = (offset + length) >> blkbits;
3563                 if (written_blk < end_blk && ext4_can_truncate(inode))
3564                         truncate = true;
3565         }
3566         /*
3567          * Remove inode from orphan list if we were extending a inode and
3568          * everything went fine.
3569          */
3570         if (!truncate && inode->i_nlink &&
3571             !list_empty(&EXT4_I(inode)->i_orphan))
3572                 ext4_orphan_del(handle, inode);
3573         ext4_journal_stop(handle);
3574         if (truncate) {
3575                 ext4_truncate_failed_write(inode);
3576 orphan_del:
3577                 /*
3578                  * If truncate failed early the inode might still be on the
3579                  * orphan list; we need to make sure the inode is removed from
3580                  * the orphan list in that case.
3581                  */
3582                 if (inode->i_nlink)
3583                         ext4_orphan_del(NULL, inode);
3584         }
3585         return ret;
3586 }
3587
3588 const struct iomap_ops ext4_iomap_ops = {
3589         .iomap_begin            = ext4_iomap_begin,
3590         .iomap_end              = ext4_iomap_end,
3591 };
3592
3593 static int ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
3594                             ssize_t size, void *private)
3595 {
3596         ext4_io_end_t *io_end = private;
3597
3598         /* if not async direct IO just return */
3599         if (!io_end)
3600                 return 0;
3601
3602         ext_debug("ext4_end_io_dio(): io_end 0x%p "
3603                   "for inode %lu, iocb 0x%p, offset %llu, size %zd\n",
3604                   io_end, io_end->inode->i_ino, iocb, offset, size);
3605
3606         /*
3607          * Error during AIO DIO. We cannot convert unwritten extents as the
3608          * data was not written. Just clear the unwritten flag and drop io_end.
3609          */
3610         if (size <= 0) {