mm: make pagevec_lookup() update index
[sfrench/cifs-2.6.git] / fs / ext4 / inode.c
1 /*
2  *  linux/fs/ext4/inode.c
3  *
4  * Copyright (C) 1992, 1993, 1994, 1995
5  * Remy Card (card@masi.ibp.fr)
6  * Laboratoire MASI - Institut Blaise Pascal
7  * Universite Pierre et Marie Curie (Paris VI)
8  *
9  *  from
10  *
11  *  linux/fs/minix/inode.c
12  *
13  *  Copyright (C) 1991, 1992  Linus Torvalds
14  *
15  *  64-bit file support on 64-bit platforms by Jakub Jelinek
16  *      (jj@sunsite.ms.mff.cuni.cz)
17  *
18  *  Assorted race fixes, rewrite of ext4_get_block() by Al Viro, 2000
19  */
20
21 #include <linux/fs.h>
22 #include <linux/time.h>
23 #include <linux/highuid.h>
24 #include <linux/pagemap.h>
25 #include <linux/dax.h>
26 #include <linux/quotaops.h>
27 #include <linux/string.h>
28 #include <linux/buffer_head.h>
29 #include <linux/writeback.h>
30 #include <linux/pagevec.h>
31 #include <linux/mpage.h>
32 #include <linux/namei.h>
33 #include <linux/uio.h>
34 #include <linux/bio.h>
35 #include <linux/workqueue.h>
36 #include <linux/kernel.h>
37 #include <linux/printk.h>
38 #include <linux/slab.h>
39 #include <linux/bitops.h>
40 #include <linux/iomap.h>
41
42 #include "ext4_jbd2.h"
43 #include "xattr.h"
44 #include "acl.h"
45 #include "truncate.h"
46
47 #include <trace/events/ext4.h>
48
49 #define MPAGE_DA_EXTENT_TAIL 0x01
50
51 static __u32 ext4_inode_csum(struct inode *inode, struct ext4_inode *raw,
52                               struct ext4_inode_info *ei)
53 {
54         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
55         __u32 csum;
56         __u16 dummy_csum = 0;
57         int offset = offsetof(struct ext4_inode, i_checksum_lo);
58         unsigned int csum_size = sizeof(dummy_csum);
59
60         csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)raw, offset);
61         csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum, csum_size);
62         offset += csum_size;
63         csum = ext4_chksum(sbi, csum, (__u8 *)raw + offset,
64                            EXT4_GOOD_OLD_INODE_SIZE - offset);
65
66         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
67                 offset = offsetof(struct ext4_inode, i_checksum_hi);
68                 csum = ext4_chksum(sbi, csum, (__u8 *)raw +
69                                    EXT4_GOOD_OLD_INODE_SIZE,
70                                    offset - EXT4_GOOD_OLD_INODE_SIZE);
71                 if (EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi)) {
72                         csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum,
73                                            csum_size);
74                         offset += csum_size;
75                 }
76                 csum = ext4_chksum(sbi, csum, (__u8 *)raw + offset,
77                                    EXT4_INODE_SIZE(inode->i_sb) - offset);
78         }
79
80         return csum;
81 }
82
83 static int ext4_inode_csum_verify(struct inode *inode, struct ext4_inode *raw,
84                                   struct ext4_inode_info *ei)
85 {
86         __u32 provided, calculated;
87
88         if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
89             cpu_to_le32(EXT4_OS_LINUX) ||
90             !ext4_has_metadata_csum(inode->i_sb))
91                 return 1;
92
93         provided = le16_to_cpu(raw->i_checksum_lo);
94         calculated = ext4_inode_csum(inode, raw, ei);
95         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
96             EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
97                 provided |= ((__u32)le16_to_cpu(raw->i_checksum_hi)) << 16;
98         else
99                 calculated &= 0xFFFF;
100
101         return provided == calculated;
102 }
103
104 static void ext4_inode_csum_set(struct inode *inode, struct ext4_inode *raw,
105                                 struct ext4_inode_info *ei)
106 {
107         __u32 csum;
108
109         if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
110             cpu_to_le32(EXT4_OS_LINUX) ||
111             !ext4_has_metadata_csum(inode->i_sb))
112                 return;
113
114         csum = ext4_inode_csum(inode, raw, ei);
115         raw->i_checksum_lo = cpu_to_le16(csum & 0xFFFF);
116         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
117             EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
118                 raw->i_checksum_hi = cpu_to_le16(csum >> 16);
119 }
120
121 static inline int ext4_begin_ordered_truncate(struct inode *inode,
122                                               loff_t new_size)
123 {
124         trace_ext4_begin_ordered_truncate(inode, new_size);
125         /*
126          * If jinode is zero, then we never opened the file for
127          * writing, so there's no need to call
128          * jbd2_journal_begin_ordered_truncate() since there's no
129          * outstanding writes we need to flush.
130          */
131         if (!EXT4_I(inode)->jinode)
132                 return 0;
133         return jbd2_journal_begin_ordered_truncate(EXT4_JOURNAL(inode),
134                                                    EXT4_I(inode)->jinode,
135                                                    new_size);
136 }
137
138 static void ext4_invalidatepage(struct page *page, unsigned int offset,
139                                 unsigned int length);
140 static int __ext4_journalled_writepage(struct page *page, unsigned int len);
141 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh);
142 static int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
143                                   int pextents);
144
145 /*
146  * Test whether an inode is a fast symlink.
147  * A fast symlink has its symlink data stored in ext4_inode_info->i_data.
148  */
149 int ext4_inode_is_fast_symlink(struct inode *inode)
150 {
151         return S_ISLNK(inode->i_mode) && inode->i_size &&
152                (inode->i_size < EXT4_N_BLOCKS * 4);
153 }
154
155 /*
156  * Restart the transaction associated with *handle.  This does a commit,
157  * so before we call here everything must be consistently dirtied against
158  * this transaction.
159  */
160 int ext4_truncate_restart_trans(handle_t *handle, struct inode *inode,
161                                  int nblocks)
162 {
163         int ret;
164
165         /*
166          * Drop i_data_sem to avoid deadlock with ext4_map_blocks.  At this
167          * moment, get_block can be called only for blocks inside i_size since
168          * page cache has been already dropped and writes are blocked by
169          * i_mutex. So we can safely drop the i_data_sem here.
170          */
171         BUG_ON(EXT4_JOURNAL(inode) == NULL);
172         jbd_debug(2, "restarting handle %p\n", handle);
173         up_write(&EXT4_I(inode)->i_data_sem);
174         ret = ext4_journal_restart(handle, nblocks);
175         down_write(&EXT4_I(inode)->i_data_sem);
176         ext4_discard_preallocations(inode);
177
178         return ret;
179 }
180
181 /*
182  * Called at the last iput() if i_nlink is zero.
183  */
184 void ext4_evict_inode(struct inode *inode)
185 {
186         handle_t *handle;
187         int err;
188         int extra_credits = 3;
189         struct ext4_xattr_inode_array *ea_inode_array = NULL;
190
191         trace_ext4_evict_inode(inode);
192
193         if (inode->i_nlink) {
194                 /*
195                  * When journalling data dirty buffers are tracked only in the
196                  * journal. So although mm thinks everything is clean and
197                  * ready for reaping the inode might still have some pages to
198                  * write in the running transaction or waiting to be
199                  * checkpointed. Thus calling jbd2_journal_invalidatepage()
200                  * (via truncate_inode_pages()) to discard these buffers can
201                  * cause data loss. Also even if we did not discard these
202                  * buffers, we would have no way to find them after the inode
203                  * is reaped and thus user could see stale data if he tries to
204                  * read them before the transaction is checkpointed. So be
205                  * careful and force everything to disk here... We use
206                  * ei->i_datasync_tid to store the newest transaction
207                  * containing inode's data.
208                  *
209                  * Note that directories do not have this problem because they
210                  * don't use page cache.
211                  */
212                 if (inode->i_ino != EXT4_JOURNAL_INO &&
213                     ext4_should_journal_data(inode) &&
214                     (S_ISLNK(inode->i_mode) || S_ISREG(inode->i_mode)) &&
215                     inode->i_data.nrpages) {
216                         journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
217                         tid_t commit_tid = EXT4_I(inode)->i_datasync_tid;
218
219                         jbd2_complete_transaction(journal, commit_tid);
220                         filemap_write_and_wait(&inode->i_data);
221                 }
222                 truncate_inode_pages_final(&inode->i_data);
223
224                 goto no_delete;
225         }
226
227         if (is_bad_inode(inode))
228                 goto no_delete;
229         dquot_initialize(inode);
230
231         if (ext4_should_order_data(inode))
232                 ext4_begin_ordered_truncate(inode, 0);
233         truncate_inode_pages_final(&inode->i_data);
234
235         /*
236          * Protect us against freezing - iput() caller didn't have to have any
237          * protection against it
238          */
239         sb_start_intwrite(inode->i_sb);
240
241         if (!IS_NOQUOTA(inode))
242                 extra_credits += EXT4_MAXQUOTAS_DEL_BLOCKS(inode->i_sb);
243
244         handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE,
245                                  ext4_blocks_for_truncate(inode)+extra_credits);
246         if (IS_ERR(handle)) {
247                 ext4_std_error(inode->i_sb, PTR_ERR(handle));
248                 /*
249                  * If we're going to skip the normal cleanup, we still need to
250                  * make sure that the in-core orphan linked list is properly
251                  * cleaned up.
252                  */
253                 ext4_orphan_del(NULL, inode);
254                 sb_end_intwrite(inode->i_sb);
255                 goto no_delete;
256         }
257
258         if (IS_SYNC(inode))
259                 ext4_handle_sync(handle);
260
261         /*
262          * Set inode->i_size to 0 before calling ext4_truncate(). We need
263          * special handling of symlinks here because i_size is used to
264          * determine whether ext4_inode_info->i_data contains symlink data or
265          * block mappings. Setting i_size to 0 will remove its fast symlink
266          * status. Erase i_data so that it becomes a valid empty block map.
267          */
268         if (ext4_inode_is_fast_symlink(inode))
269                 memset(EXT4_I(inode)->i_data, 0, sizeof(EXT4_I(inode)->i_data));
270         inode->i_size = 0;
271         err = ext4_mark_inode_dirty(handle, inode);
272         if (err) {
273                 ext4_warning(inode->i_sb,
274                              "couldn't mark inode dirty (err %d)", err);
275                 goto stop_handle;
276         }
277         if (inode->i_blocks) {
278                 err = ext4_truncate(inode);
279                 if (err) {
280                         ext4_error(inode->i_sb,
281                                    "couldn't truncate inode %lu (err %d)",
282                                    inode->i_ino, err);
283                         goto stop_handle;
284                 }
285         }
286
287         /* Remove xattr references. */
288         err = ext4_xattr_delete_inode(handle, inode, &ea_inode_array,
289                                       extra_credits);
290         if (err) {
291                 ext4_warning(inode->i_sb, "xattr delete (err %d)", err);
292 stop_handle:
293                 ext4_journal_stop(handle);
294                 ext4_orphan_del(NULL, inode);
295                 sb_end_intwrite(inode->i_sb);
296                 ext4_xattr_inode_array_free(ea_inode_array);
297                 goto no_delete;
298         }
299
300         /*
301          * Kill off the orphan record which ext4_truncate created.
302          * AKPM: I think this can be inside the above `if'.
303          * Note that ext4_orphan_del() has to be able to cope with the
304          * deletion of a non-existent orphan - this is because we don't
305          * know if ext4_truncate() actually created an orphan record.
306          * (Well, we could do this if we need to, but heck - it works)
307          */
308         ext4_orphan_del(handle, inode);
309         EXT4_I(inode)->i_dtime  = get_seconds();
310
311         /*
312          * One subtle ordering requirement: if anything has gone wrong
313          * (transaction abort, IO errors, whatever), then we can still
314          * do these next steps (the fs will already have been marked as
315          * having errors), but we can't free the inode if the mark_dirty
316          * fails.
317          */
318         if (ext4_mark_inode_dirty(handle, inode))
319                 /* If that failed, just do the required in-core inode clear. */
320                 ext4_clear_inode(inode);
321         else
322                 ext4_free_inode(handle, inode);
323         ext4_journal_stop(handle);
324         sb_end_intwrite(inode->i_sb);
325         ext4_xattr_inode_array_free(ea_inode_array);
326         return;
327 no_delete:
328         ext4_clear_inode(inode);        /* We must guarantee clearing of inode... */
329 }
330
331 #ifdef CONFIG_QUOTA
332 qsize_t *ext4_get_reserved_space(struct inode *inode)
333 {
334         return &EXT4_I(inode)->i_reserved_quota;
335 }
336 #endif
337
338 /*
339  * Called with i_data_sem down, which is important since we can call
340  * ext4_discard_preallocations() from here.
341  */
342 void ext4_da_update_reserve_space(struct inode *inode,
343                                         int used, int quota_claim)
344 {
345         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
346         struct ext4_inode_info *ei = EXT4_I(inode);
347
348         spin_lock(&ei->i_block_reservation_lock);
349         trace_ext4_da_update_reserve_space(inode, used, quota_claim);
350         if (unlikely(used > ei->i_reserved_data_blocks)) {
351                 ext4_warning(inode->i_sb, "%s: ino %lu, used %d "
352                          "with only %d reserved data blocks",
353                          __func__, inode->i_ino, used,
354                          ei->i_reserved_data_blocks);
355                 WARN_ON(1);
356                 used = ei->i_reserved_data_blocks;
357         }
358
359         /* Update per-inode reservations */
360         ei->i_reserved_data_blocks -= used;
361         percpu_counter_sub(&sbi->s_dirtyclusters_counter, used);
362
363         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
364
365         /* Update quota subsystem for data blocks */
366         if (quota_claim)
367                 dquot_claim_block(inode, EXT4_C2B(sbi, used));
368         else {
369                 /*
370                  * We did fallocate with an offset that is already delayed
371                  * allocated. So on delayed allocated writeback we should
372                  * not re-claim the quota for fallocated blocks.
373                  */
374                 dquot_release_reservation_block(inode, EXT4_C2B(sbi, used));
375         }
376
377         /*
378          * If we have done all the pending block allocations and if
379          * there aren't any writers on the inode, we can discard the
380          * inode's preallocations.
381          */
382         if ((ei->i_reserved_data_blocks == 0) &&
383             (atomic_read(&inode->i_writecount) == 0))
384                 ext4_discard_preallocations(inode);
385 }
386
387 static int __check_block_validity(struct inode *inode, const char *func,
388                                 unsigned int line,
389                                 struct ext4_map_blocks *map)
390 {
391         if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), map->m_pblk,
392                                    map->m_len)) {
393                 ext4_error_inode(inode, func, line, map->m_pblk,
394                                  "lblock %lu mapped to illegal pblock "
395                                  "(length %d)", (unsigned long) map->m_lblk,
396                                  map->m_len);
397                 return -EFSCORRUPTED;
398         }
399         return 0;
400 }
401
402 int ext4_issue_zeroout(struct inode *inode, ext4_lblk_t lblk, ext4_fsblk_t pblk,
403                        ext4_lblk_t len)
404 {
405         int ret;
406
407         if (ext4_encrypted_inode(inode))
408                 return fscrypt_zeroout_range(inode, lblk, pblk, len);
409
410         ret = sb_issue_zeroout(inode->i_sb, pblk, len, GFP_NOFS);
411         if (ret > 0)
412                 ret = 0;
413
414         return ret;
415 }
416
417 #define check_block_validity(inode, map)        \
418         __check_block_validity((inode), __func__, __LINE__, (map))
419
420 #ifdef ES_AGGRESSIVE_TEST
421 static void ext4_map_blocks_es_recheck(handle_t *handle,
422                                        struct inode *inode,
423                                        struct ext4_map_blocks *es_map,
424                                        struct ext4_map_blocks *map,
425                                        int flags)
426 {
427         int retval;
428
429         map->m_flags = 0;
430         /*
431          * There is a race window that the result is not the same.
432          * e.g. xfstests #223 when dioread_nolock enables.  The reason
433          * is that we lookup a block mapping in extent status tree with
434          * out taking i_data_sem.  So at the time the unwritten extent
435          * could be converted.
436          */
437         down_read(&EXT4_I(inode)->i_data_sem);
438         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
439                 retval = ext4_ext_map_blocks(handle, inode, map, flags &
440                                              EXT4_GET_BLOCKS_KEEP_SIZE);
441         } else {
442                 retval = ext4_ind_map_blocks(handle, inode, map, flags &
443                                              EXT4_GET_BLOCKS_KEEP_SIZE);
444         }
445         up_read((&EXT4_I(inode)->i_data_sem));
446
447         /*
448          * We don't check m_len because extent will be collpased in status
449          * tree.  So the m_len might not equal.
450          */
451         if (es_map->m_lblk != map->m_lblk ||
452             es_map->m_flags != map->m_flags ||
453             es_map->m_pblk != map->m_pblk) {
454                 printk("ES cache assertion failed for inode: %lu "
455                        "es_cached ex [%d/%d/%llu/%x] != "
456                        "found ex [%d/%d/%llu/%x] retval %d flags %x\n",
457                        inode->i_ino, es_map->m_lblk, es_map->m_len,
458                        es_map->m_pblk, es_map->m_flags, map->m_lblk,
459                        map->m_len, map->m_pblk, map->m_flags,
460                        retval, flags);
461         }
462 }
463 #endif /* ES_AGGRESSIVE_TEST */
464
465 /*
466  * The ext4_map_blocks() function tries to look up the requested blocks,
467  * and returns if the blocks are already mapped.
468  *
469  * Otherwise it takes the write lock of the i_data_sem and allocate blocks
470  * and store the allocated blocks in the result buffer head and mark it
471  * mapped.
472  *
473  * If file type is extents based, it will call ext4_ext_map_blocks(),
474  * Otherwise, call with ext4_ind_map_blocks() to handle indirect mapping
475  * based files
476  *
477  * On success, it returns the number of blocks being mapped or allocated.  if
478  * create==0 and the blocks are pre-allocated and unwritten, the resulting @map
479  * is marked as unwritten. If the create == 1, it will mark @map as mapped.
480  *
481  * It returns 0 if plain look up failed (blocks have not been allocated), in
482  * that case, @map is returned as unmapped but we still do fill map->m_len to
483  * indicate the length of a hole starting at map->m_lblk.
484  *
485  * It returns the error in case of allocation failure.
486  */
487 int ext4_map_blocks(handle_t *handle, struct inode *inode,
488                     struct ext4_map_blocks *map, int flags)
489 {
490         struct extent_status es;
491         int retval;
492         int ret = 0;
493 #ifdef ES_AGGRESSIVE_TEST
494         struct ext4_map_blocks orig_map;
495
496         memcpy(&orig_map, map, sizeof(*map));
497 #endif
498
499         map->m_flags = 0;
500         ext_debug("ext4_map_blocks(): inode %lu, flag %d, max_blocks %u,"
501                   "logical block %lu\n", inode->i_ino, flags, map->m_len,
502                   (unsigned long) map->m_lblk);
503
504         /*
505          * ext4_map_blocks returns an int, and m_len is an unsigned int
506          */
507         if (unlikely(map->m_len > INT_MAX))
508                 map->m_len = INT_MAX;
509
510         /* We can handle the block number less than EXT_MAX_BLOCKS */
511         if (unlikely(map->m_lblk >= EXT_MAX_BLOCKS))
512                 return -EFSCORRUPTED;
513
514         /* Lookup extent status tree firstly */
515         if (ext4_es_lookup_extent(inode, map->m_lblk, &es)) {
516                 if (ext4_es_is_written(&es) || ext4_es_is_unwritten(&es)) {
517                         map->m_pblk = ext4_es_pblock(&es) +
518                                         map->m_lblk - es.es_lblk;
519                         map->m_flags |= ext4_es_is_written(&es) ?
520                                         EXT4_MAP_MAPPED : EXT4_MAP_UNWRITTEN;
521                         retval = es.es_len - (map->m_lblk - es.es_lblk);
522                         if (retval > map->m_len)
523                                 retval = map->m_len;
524                         map->m_len = retval;
525                 } else if (ext4_es_is_delayed(&es) || ext4_es_is_hole(&es)) {
526                         map->m_pblk = 0;
527                         retval = es.es_len - (map->m_lblk - es.es_lblk);
528                         if (retval > map->m_len)
529                                 retval = map->m_len;
530                         map->m_len = retval;
531                         retval = 0;
532                 } else {
533                         BUG_ON(1);
534                 }
535 #ifdef ES_AGGRESSIVE_TEST
536                 ext4_map_blocks_es_recheck(handle, inode, map,
537                                            &orig_map, flags);
538 #endif
539                 goto found;
540         }
541
542         /*
543          * Try to see if we can get the block without requesting a new
544          * file system block.
545          */
546         down_read(&EXT4_I(inode)->i_data_sem);
547         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
548                 retval = ext4_ext_map_blocks(handle, inode, map, flags &
549                                              EXT4_GET_BLOCKS_KEEP_SIZE);
550         } else {
551                 retval = ext4_ind_map_blocks(handle, inode, map, flags &
552                                              EXT4_GET_BLOCKS_KEEP_SIZE);
553         }
554         if (retval > 0) {
555                 unsigned int status;
556
557                 if (unlikely(retval != map->m_len)) {
558                         ext4_warning(inode->i_sb,
559                                      "ES len assertion failed for inode "
560                                      "%lu: retval %d != map->m_len %d",
561                                      inode->i_ino, retval, map->m_len);
562                         WARN_ON(1);
563                 }
564
565                 status = map->m_flags & EXT4_MAP_UNWRITTEN ?
566                                 EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
567                 if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
568                     !(status & EXTENT_STATUS_WRITTEN) &&
569                     ext4_find_delalloc_range(inode, map->m_lblk,
570                                              map->m_lblk + map->m_len - 1))
571                         status |= EXTENT_STATUS_DELAYED;
572                 ret = ext4_es_insert_extent(inode, map->m_lblk,
573                                             map->m_len, map->m_pblk, status);
574                 if (ret < 0)
575                         retval = ret;
576         }
577         up_read((&EXT4_I(inode)->i_data_sem));
578
579 found:
580         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
581                 ret = check_block_validity(inode, map);
582                 if (ret != 0)
583                         return ret;
584         }
585
586         /* If it is only a block(s) look up */
587         if ((flags & EXT4_GET_BLOCKS_CREATE) == 0)
588                 return retval;
589
590         /*
591          * Returns if the blocks have already allocated
592          *
593          * Note that if blocks have been preallocated
594          * ext4_ext_get_block() returns the create = 0
595          * with buffer head unmapped.
596          */
597         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED)
598                 /*
599                  * If we need to convert extent to unwritten
600                  * we continue and do the actual work in
601                  * ext4_ext_map_blocks()
602                  */
603                 if (!(flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN))
604                         return retval;
605
606         /*
607          * Here we clear m_flags because after allocating an new extent,
608          * it will be set again.
609          */
610         map->m_flags &= ~EXT4_MAP_FLAGS;
611
612         /*
613          * New blocks allocate and/or writing to unwritten extent
614          * will possibly result in updating i_data, so we take
615          * the write lock of i_data_sem, and call get_block()
616          * with create == 1 flag.
617          */
618         down_write(&EXT4_I(inode)->i_data_sem);
619
620         /*
621          * We need to check for EXT4 here because migrate
622          * could have changed the inode type in between
623          */
624         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
625                 retval = ext4_ext_map_blocks(handle, inode, map, flags);
626         } else {
627                 retval = ext4_ind_map_blocks(handle, inode, map, flags);
628
629                 if (retval > 0 && map->m_flags & EXT4_MAP_NEW) {
630                         /*
631                          * We allocated new blocks which will result in
632                          * i_data's format changing.  Force the migrate
633                          * to fail by clearing migrate flags
634                          */
635                         ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
636                 }
637
638                 /*
639                  * Update reserved blocks/metadata blocks after successful
640                  * block allocation which had been deferred till now. We don't
641                  * support fallocate for non extent files. So we can update
642                  * reserve space here.
643                  */
644                 if ((retval > 0) &&
645                         (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE))
646                         ext4_da_update_reserve_space(inode, retval, 1);
647         }
648
649         if (retval > 0) {
650                 unsigned int status;
651
652                 if (unlikely(retval != map->m_len)) {
653                         ext4_warning(inode->i_sb,
654                                      "ES len assertion failed for inode "
655                                      "%lu: retval %d != map->m_len %d",
656                                      inode->i_ino, retval, map->m_len);
657                         WARN_ON(1);
658                 }
659
660                 /*
661                  * We have to zeroout blocks before inserting them into extent
662                  * status tree. Otherwise someone could look them up there and
663                  * use them before they are really zeroed. We also have to
664                  * unmap metadata before zeroing as otherwise writeback can
665                  * overwrite zeros with stale data from block device.
666                  */
667                 if (flags & EXT4_GET_BLOCKS_ZERO &&
668                     map->m_flags & EXT4_MAP_MAPPED &&
669                     map->m_flags & EXT4_MAP_NEW) {
670                         clean_bdev_aliases(inode->i_sb->s_bdev, map->m_pblk,
671                                            map->m_len);
672                         ret = ext4_issue_zeroout(inode, map->m_lblk,
673                                                  map->m_pblk, map->m_len);
674                         if (ret) {
675                                 retval = ret;
676                                 goto out_sem;
677                         }
678                 }
679
680                 /*
681                  * If the extent has been zeroed out, we don't need to update
682                  * extent status tree.
683                  */
684                 if ((flags & EXT4_GET_BLOCKS_PRE_IO) &&
685                     ext4_es_lookup_extent(inode, map->m_lblk, &es)) {
686                         if (ext4_es_is_written(&es))
687                                 goto out_sem;
688                 }
689                 status = map->m_flags & EXT4_MAP_UNWRITTEN ?
690                                 EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
691                 if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
692                     !(status & EXTENT_STATUS_WRITTEN) &&
693                     ext4_find_delalloc_range(inode, map->m_lblk,
694                                              map->m_lblk + map->m_len - 1))
695                         status |= EXTENT_STATUS_DELAYED;
696                 ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
697                                             map->m_pblk, status);
698                 if (ret < 0) {
699                         retval = ret;
700                         goto out_sem;
701                 }
702         }
703
704 out_sem:
705         up_write((&EXT4_I(inode)->i_data_sem));
706         if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
707                 ret = check_block_validity(inode, map);
708                 if (ret != 0)
709                         return ret;
710
711                 /*
712                  * Inodes with freshly allocated blocks where contents will be
713                  * visible after transaction commit must be on transaction's
714                  * ordered data list.
715                  */
716                 if (map->m_flags & EXT4_MAP_NEW &&
717                     !(map->m_flags & EXT4_MAP_UNWRITTEN) &&
718                     !(flags & EXT4_GET_BLOCKS_ZERO) &&
719                     !ext4_is_quota_file(inode) &&
720                     ext4_should_order_data(inode)) {
721                         if (flags & EXT4_GET_BLOCKS_IO_SUBMIT)
722                                 ret = ext4_jbd2_inode_add_wait(handle, inode);
723                         else
724                                 ret = ext4_jbd2_inode_add_write(handle, inode);
725                         if (ret)
726                                 return ret;
727                 }
728         }
729         return retval;
730 }
731
732 /*
733  * Update EXT4_MAP_FLAGS in bh->b_state. For buffer heads attached to pages
734  * we have to be careful as someone else may be manipulating b_state as well.
735  */
736 static void ext4_update_bh_state(struct buffer_head *bh, unsigned long flags)
737 {
738         unsigned long old_state;
739         unsigned long new_state;
740
741         flags &= EXT4_MAP_FLAGS;
742
743         /* Dummy buffer_head? Set non-atomically. */
744         if (!bh->b_page) {
745                 bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | flags;
746                 return;
747         }
748         /*
749          * Someone else may be modifying b_state. Be careful! This is ugly but
750          * once we get rid of using bh as a container for mapping information
751          * to pass to / from get_block functions, this can go away.
752          */
753         do {
754                 old_state = READ_ONCE(bh->b_state);
755                 new_state = (old_state & ~EXT4_MAP_FLAGS) | flags;
756         } while (unlikely(
757                  cmpxchg(&bh->b_state, old_state, new_state) != old_state));
758 }
759
760 static int _ext4_get_block(struct inode *inode, sector_t iblock,
761                            struct buffer_head *bh, int flags)
762 {
763         struct ext4_map_blocks map;
764         int ret = 0;
765
766         if (ext4_has_inline_data(inode))
767                 return -ERANGE;
768
769         map.m_lblk = iblock;
770         map.m_len = bh->b_size >> inode->i_blkbits;
771
772         ret = ext4_map_blocks(ext4_journal_current_handle(), inode, &map,
773                               flags);
774         if (ret > 0) {
775                 map_bh(bh, inode->i_sb, map.m_pblk);
776                 ext4_update_bh_state(bh, map.m_flags);
777                 bh->b_size = inode->i_sb->s_blocksize * map.m_len;
778                 ret = 0;
779         } else if (ret == 0) {
780                 /* hole case, need to fill in bh->b_size */
781                 bh->b_size = inode->i_sb->s_blocksize * map.m_len;
782         }
783         return ret;
784 }
785
786 int ext4_get_block(struct inode *inode, sector_t iblock,
787                    struct buffer_head *bh, int create)
788 {
789         return _ext4_get_block(inode, iblock, bh,
790                                create ? EXT4_GET_BLOCKS_CREATE : 0);
791 }
792
793 /*
794  * Get block function used when preparing for buffered write if we require
795  * creating an unwritten extent if blocks haven't been allocated.  The extent
796  * will be converted to written after the IO is complete.
797  */
798 int ext4_get_block_unwritten(struct inode *inode, sector_t iblock,
799                              struct buffer_head *bh_result, int create)
800 {
801         ext4_debug("ext4_get_block_unwritten: inode %lu, create flag %d\n",
802                    inode->i_ino, create);
803         return _ext4_get_block(inode, iblock, bh_result,
804                                EXT4_GET_BLOCKS_IO_CREATE_EXT);
805 }
806
807 /* Maximum number of blocks we map for direct IO at once. */
808 #define DIO_MAX_BLOCKS 4096
809
810 /*
811  * Get blocks function for the cases that need to start a transaction -
812  * generally difference cases of direct IO and DAX IO. It also handles retries
813  * in case of ENOSPC.
814  */
815 static int ext4_get_block_trans(struct inode *inode, sector_t iblock,
816                                 struct buffer_head *bh_result, int flags)
817 {
818         int dio_credits;
819         handle_t *handle;
820         int retries = 0;
821         int ret;
822
823         /* Trim mapping request to maximum we can map at once for DIO */
824         if (bh_result->b_size >> inode->i_blkbits > DIO_MAX_BLOCKS)
825                 bh_result->b_size = DIO_MAX_BLOCKS << inode->i_blkbits;
826         dio_credits = ext4_chunk_trans_blocks(inode,
827                                       bh_result->b_size >> inode->i_blkbits);
828 retry:
829         handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, dio_credits);
830         if (IS_ERR(handle))
831                 return PTR_ERR(handle);
832
833         ret = _ext4_get_block(inode, iblock, bh_result, flags);
834         ext4_journal_stop(handle);
835
836         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
837                 goto retry;
838         return ret;
839 }
840
841 /* Get block function for DIO reads and writes to inodes without extents */
842 int ext4_dio_get_block(struct inode *inode, sector_t iblock,
843                        struct buffer_head *bh, int create)
844 {
845         /* We don't expect handle for direct IO */
846         WARN_ON_ONCE(ext4_journal_current_handle());
847
848         if (!create)
849                 return _ext4_get_block(inode, iblock, bh, 0);
850         return ext4_get_block_trans(inode, iblock, bh, EXT4_GET_BLOCKS_CREATE);
851 }
852
853 /*
854  * Get block function for AIO DIO writes when we create unwritten extent if
855  * blocks are not allocated yet. The extent will be converted to written
856  * after IO is complete.
857  */
858 static int ext4_dio_get_block_unwritten_async(struct inode *inode,
859                 sector_t iblock, struct buffer_head *bh_result, int create)
860 {
861         int ret;
862
863         /* We don't expect handle for direct IO */
864         WARN_ON_ONCE(ext4_journal_current_handle());
865
866         ret = ext4_get_block_trans(inode, iblock, bh_result,
867                                    EXT4_GET_BLOCKS_IO_CREATE_EXT);
868
869         /*
870          * When doing DIO using unwritten extents, we need io_end to convert
871          * unwritten extents to written on IO completion. We allocate io_end
872          * once we spot unwritten extent and store it in b_private. Generic
873          * DIO code keeps b_private set and furthermore passes the value to
874          * our completion callback in 'private' argument.
875          */
876         if (!ret && buffer_unwritten(bh_result)) {
877                 if (!bh_result->b_private) {
878                         ext4_io_end_t *io_end;
879
880                         io_end = ext4_init_io_end(inode, GFP_KERNEL);
881                         if (!io_end)
882                                 return -ENOMEM;
883                         bh_result->b_private = io_end;
884                         ext4_set_io_unwritten_flag(inode, io_end);
885                 }
886                 set_buffer_defer_completion(bh_result);
887         }
888
889         return ret;
890 }
891
892 /*
893  * Get block function for non-AIO DIO writes when we create unwritten extent if
894  * blocks are not allocated yet. The extent will be converted to written
895  * after IO is complete by ext4_direct_IO_write().
896  */
897 static int ext4_dio_get_block_unwritten_sync(struct inode *inode,
898                 sector_t iblock, struct buffer_head *bh_result, int create)
899 {
900         int ret;
901
902         /* We don't expect handle for direct IO */
903         WARN_ON_ONCE(ext4_journal_current_handle());
904
905         ret = ext4_get_block_trans(inode, iblock, bh_result,
906                                    EXT4_GET_BLOCKS_IO_CREATE_EXT);
907
908         /*
909          * Mark inode as having pending DIO writes to unwritten extents.
910          * ext4_direct_IO_write() checks this flag and converts extents to
911          * written.
912          */
913         if (!ret && buffer_unwritten(bh_result))
914                 ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
915
916         return ret;
917 }
918
919 static int ext4_dio_get_block_overwrite(struct inode *inode, sector_t iblock,
920                    struct buffer_head *bh_result, int create)
921 {
922         int ret;
923
924         ext4_debug("ext4_dio_get_block_overwrite: inode %lu, create flag %d\n",
925                    inode->i_ino, create);
926         /* We don't expect handle for direct IO */
927         WARN_ON_ONCE(ext4_journal_current_handle());
928
929         ret = _ext4_get_block(inode, iblock, bh_result, 0);
930         /*
931          * Blocks should have been preallocated! ext4_file_write_iter() checks
932          * that.
933          */
934         WARN_ON_ONCE(!buffer_mapped(bh_result) || buffer_unwritten(bh_result));
935
936         return ret;
937 }
938
939
940 /*
941  * `handle' can be NULL if create is zero
942  */
943 struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
944                                 ext4_lblk_t block, int map_flags)
945 {
946         struct ext4_map_blocks map;
947         struct buffer_head *bh;
948         int create = map_flags & EXT4_GET_BLOCKS_CREATE;
949         int err;
950
951         J_ASSERT(handle != NULL || create == 0);
952
953         map.m_lblk = block;
954         map.m_len = 1;
955         err = ext4_map_blocks(handle, inode, &map, map_flags);
956
957         if (err == 0)
958                 return create ? ERR_PTR(-ENOSPC) : NULL;
959         if (err < 0)
960                 return ERR_PTR(err);
961
962         bh = sb_getblk(inode->i_sb, map.m_pblk);
963         if (unlikely(!bh))
964                 return ERR_PTR(-ENOMEM);
965         if (map.m_flags & EXT4_MAP_NEW) {
966                 J_ASSERT(create != 0);
967                 J_ASSERT(handle != NULL);
968
969                 /*
970                  * Now that we do not always journal data, we should
971                  * keep in mind whether this should always journal the
972                  * new buffer as metadata.  For now, regular file
973                  * writes use ext4_get_block instead, so it's not a
974                  * problem.
975                  */
976                 lock_buffer(bh);
977                 BUFFER_TRACE(bh, "call get_create_access");
978                 err = ext4_journal_get_create_access(handle, bh);
979                 if (unlikely(err)) {
980                         unlock_buffer(bh);
981                         goto errout;
982                 }
983                 if (!buffer_uptodate(bh)) {
984                         memset(bh->b_data, 0, inode->i_sb->s_blocksize);
985                         set_buffer_uptodate(bh);
986                 }
987                 unlock_buffer(bh);
988                 BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
989                 err = ext4_handle_dirty_metadata(handle, inode, bh);
990                 if (unlikely(err))
991                         goto errout;
992         } else
993                 BUFFER_TRACE(bh, "not a new buffer");
994         return bh;
995 errout:
996         brelse(bh);
997         return ERR_PTR(err);
998 }
999
1000 struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
1001                                ext4_lblk_t block, int map_flags)
1002 {
1003         struct buffer_head *bh;
1004
1005         bh = ext4_getblk(handle, inode, block, map_flags);
1006         if (IS_ERR(bh))
1007                 return bh;
1008         if (!bh || buffer_uptodate(bh))
1009                 return bh;
1010         ll_rw_block(REQ_OP_READ, REQ_META | REQ_PRIO, 1, &bh);
1011         wait_on_buffer(bh);
1012         if (buffer_uptodate(bh))
1013                 return bh;
1014         put_bh(bh);
1015         return ERR_PTR(-EIO);
1016 }
1017
1018 /* Read a contiguous batch of blocks. */
1019 int ext4_bread_batch(struct inode *inode, ext4_lblk_t block, int bh_count,
1020                      bool wait, struct buffer_head **bhs)
1021 {
1022         int i, err;
1023
1024         for (i = 0; i < bh_count; i++) {
1025                 bhs[i] = ext4_getblk(NULL, inode, block + i, 0 /* map_flags */);
1026                 if (IS_ERR(bhs[i])) {
1027                         err = PTR_ERR(bhs[i]);
1028                         bh_count = i;
1029                         goto out_brelse;
1030                 }
1031         }
1032
1033         for (i = 0; i < bh_count; i++)
1034                 /* Note that NULL bhs[i] is valid because of holes. */
1035                 if (bhs[i] && !buffer_uptodate(bhs[i]))
1036                         ll_rw_block(REQ_OP_READ, REQ_META | REQ_PRIO, 1,
1037                                     &bhs[i]);
1038
1039         if (!wait)
1040                 return 0;
1041
1042         for (i = 0; i < bh_count; i++)
1043                 if (bhs[i])
1044                         wait_on_buffer(bhs[i]);
1045
1046         for (i = 0; i < bh_count; i++) {
1047                 if (bhs[i] && !buffer_uptodate(bhs[i])) {
1048                         err = -EIO;
1049                         goto out_brelse;
1050                 }
1051         }
1052         return 0;
1053
1054 out_brelse:
1055         for (i = 0; i < bh_count; i++) {
1056                 brelse(bhs[i]);
1057                 bhs[i] = NULL;
1058         }
1059         return err;
1060 }
1061
1062 int ext4_walk_page_buffers(handle_t *handle,
1063                            struct buffer_head *head,
1064                            unsigned from,
1065                            unsigned to,
1066                            int *partial,
1067                            int (*fn)(handle_t *handle,
1068                                      struct buffer_head *bh))
1069 {
1070         struct buffer_head *bh;
1071         unsigned block_start, block_end;
1072         unsigned blocksize = head->b_size;
1073         int err, ret = 0;
1074         struct buffer_head *next;
1075
1076         for (bh = head, block_start = 0;
1077              ret == 0 && (bh != head || !block_start);
1078              block_start = block_end, bh = next) {
1079                 next = bh->b_this_page;
1080                 block_end = block_start + blocksize;
1081                 if (block_end <= from || block_start >= to) {
1082                         if (partial && !buffer_uptodate(bh))
1083                                 *partial = 1;
1084                         continue;
1085                 }
1086                 err = (*fn)(handle, bh);
1087                 if (!ret)
1088                         ret = err;
1089         }
1090         return ret;
1091 }
1092
1093 /*
1094  * To preserve ordering, it is essential that the hole instantiation and
1095  * the data write be encapsulated in a single transaction.  We cannot
1096  * close off a transaction and start a new one between the ext4_get_block()
1097  * and the commit_write().  So doing the jbd2_journal_start at the start of
1098  * prepare_write() is the right place.
1099  *
1100  * Also, this function can nest inside ext4_writepage().  In that case, we
1101  * *know* that ext4_writepage() has generated enough buffer credits to do the
1102  * whole page.  So we won't block on the journal in that case, which is good,
1103  * because the caller may be PF_MEMALLOC.
1104  *
1105  * By accident, ext4 can be reentered when a transaction is open via
1106  * quota file writes.  If we were to commit the transaction while thus
1107  * reentered, there can be a deadlock - we would be holding a quota
1108  * lock, and the commit would never complete if another thread had a
1109  * transaction open and was blocking on the quota lock - a ranking
1110  * violation.
1111  *
1112  * So what we do is to rely on the fact that jbd2_journal_stop/journal_start
1113  * will _not_ run commit under these circumstances because handle->h_ref
1114  * is elevated.  We'll still have enough credits for the tiny quotafile
1115  * write.
1116  */
1117 int do_journal_get_write_access(handle_t *handle,
1118                                 struct buffer_head *bh)
1119 {
1120         int dirty = buffer_dirty(bh);
1121         int ret;
1122
1123         if (!buffer_mapped(bh) || buffer_freed(bh))
1124                 return 0;
1125         /*
1126          * __block_write_begin() could have dirtied some buffers. Clean
1127          * the dirty bit as jbd2_journal_get_write_access() could complain
1128          * otherwise about fs integrity issues. Setting of the dirty bit
1129          * by __block_write_begin() isn't a real problem here as we clear
1130          * the bit before releasing a page lock and thus writeback cannot
1131          * ever write the buffer.
1132          */
1133         if (dirty)
1134                 clear_buffer_dirty(bh);
1135         BUFFER_TRACE(bh, "get write access");
1136         ret = ext4_journal_get_write_access(handle, bh);
1137         if (!ret && dirty)
1138                 ret = ext4_handle_dirty_metadata(handle, NULL, bh);
1139         return ret;
1140 }
1141
1142 #ifdef CONFIG_EXT4_FS_ENCRYPTION
1143 static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
1144                                   get_block_t *get_block)
1145 {
1146         unsigned from = pos & (PAGE_SIZE - 1);
1147         unsigned to = from + len;
1148         struct inode *inode = page->mapping->host;
1149         unsigned block_start, block_end;
1150         sector_t block;
1151         int err = 0;
1152         unsigned blocksize = inode->i_sb->s_blocksize;
1153         unsigned bbits;
1154         struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
1155         bool decrypt = false;
1156
1157         BUG_ON(!PageLocked(page));
1158         BUG_ON(from > PAGE_SIZE);
1159         BUG_ON(to > PAGE_SIZE);
1160         BUG_ON(from > to);
1161
1162         if (!page_has_buffers(page))
1163                 create_empty_buffers(page, blocksize, 0);
1164         head = page_buffers(page);
1165         bbits = ilog2(blocksize);
1166         block = (sector_t)page->index << (PAGE_SHIFT - bbits);
1167
1168         for (bh = head, block_start = 0; bh != head || !block_start;
1169             block++, block_start = block_end, bh = bh->b_this_page) {
1170                 block_end = block_start + blocksize;
1171                 if (block_end <= from || block_start >= to) {
1172                         if (PageUptodate(page)) {
1173                                 if (!buffer_uptodate(bh))
1174                                         set_buffer_uptodate(bh);
1175                         }
1176                         continue;
1177                 }
1178                 if (buffer_new(bh))
1179                         clear_buffer_new(bh);
1180                 if (!buffer_mapped(bh)) {
1181                         WARN_ON(bh->b_size != blocksize);
1182                         err = get_block(inode, block, bh, 1);
1183                         if (err)
1184                                 break;
1185                         if (buffer_new(bh)) {
1186                                 clean_bdev_bh_alias(bh);
1187                                 if (PageUptodate(page)) {
1188                                         clear_buffer_new(bh);
1189                                         set_buffer_uptodate(bh);
1190                                         mark_buffer_dirty(bh);
1191                                         continue;
1192                                 }
1193                                 if (block_end > to || block_start < from)
1194                                         zero_user_segments(page, to, block_end,
1195                                                            block_start, from);
1196                                 continue;
1197                         }
1198                 }
1199                 if (PageUptodate(page)) {
1200                         if (!buffer_uptodate(bh))
1201                                 set_buffer_uptodate(bh);
1202                         continue;
1203                 }
1204                 if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
1205                     !buffer_unwritten(bh) &&
1206                     (block_start < from || block_end > to)) {
1207                         ll_rw_block(REQ_OP_READ, 0, 1, &bh);
1208                         *wait_bh++ = bh;
1209                         decrypt = ext4_encrypted_inode(inode) &&
1210                                 S_ISREG(inode->i_mode);
1211                 }
1212         }
1213         /*
1214          * If we issued read requests, let them complete.
1215          */
1216         while (wait_bh > wait) {
1217                 wait_on_buffer(*--wait_bh);
1218                 if (!buffer_uptodate(*wait_bh))
1219                         err = -EIO;
1220         }
1221         if (unlikely(err))
1222                 page_zero_new_buffers(page, from, to);
1223         else if (decrypt)
1224                 err = fscrypt_decrypt_page(page->mapping->host, page,
1225                                 PAGE_SIZE, 0, page->index);
1226         return err;
1227 }
1228 #endif
1229
1230 static int ext4_write_begin(struct file *file, struct address_space *mapping,
1231                             loff_t pos, unsigned len, unsigned flags,
1232                             struct page **pagep, void **fsdata)
1233 {
1234         struct inode *inode = mapping->host;
1235         int ret, needed_blocks;
1236         handle_t *handle;
1237         int retries = 0;
1238         struct page *page;
1239         pgoff_t index;
1240         unsigned from, to;
1241
1242         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
1243                 return -EIO;
1244
1245         trace_ext4_write_begin(inode, pos, len, flags);
1246         /*
1247          * Reserve one block more for addition to orphan list in case
1248          * we allocate blocks but write fails for some reason
1249          */
1250         needed_blocks = ext4_writepage_trans_blocks(inode) + 1;
1251         index = pos >> PAGE_SHIFT;
1252         from = pos & (PAGE_SIZE - 1);
1253         to = from + len;
1254
1255         if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
1256                 ret = ext4_try_to_write_inline_data(mapping, inode, pos, len,
1257                                                     flags, pagep);
1258                 if (ret < 0)
1259                         return ret;
1260                 if (ret == 1)
1261                         return 0;
1262         }
1263
1264         /*
1265          * grab_cache_page_write_begin() can take a long time if the
1266          * system is thrashing due to memory pressure, or if the page
1267          * is being written back.  So grab it first before we start
1268          * the transaction handle.  This also allows us to allocate
1269          * the page (if needed) without using GFP_NOFS.
1270          */
1271 retry_grab:
1272         page = grab_cache_page_write_begin(mapping, index, flags);
1273         if (!page)
1274                 return -ENOMEM;
1275         unlock_page(page);
1276
1277 retry_journal:
1278         handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE, needed_blocks);
1279         if (IS_ERR(handle)) {
1280                 put_page(page);
1281                 return PTR_ERR(handle);
1282         }
1283
1284         lock_page(page);
1285         if (page->mapping != mapping) {
1286                 /* The page got truncated from under us */
1287                 unlock_page(page);
1288                 put_page(page);
1289                 ext4_journal_stop(handle);
1290                 goto retry_grab;
1291         }
1292         /* In case writeback began while the page was unlocked */
1293         wait_for_stable_page(page);
1294
1295 #ifdef CONFIG_EXT4_FS_ENCRYPTION
1296         if (ext4_should_dioread_nolock(inode))
1297                 ret = ext4_block_write_begin(page, pos, len,
1298                                              ext4_get_block_unwritten);
1299         else
1300                 ret = ext4_block_write_begin(page, pos, len,
1301                                              ext4_get_block);
1302 #else
1303         if (ext4_should_dioread_nolock(inode))
1304                 ret = __block_write_begin(page, pos, len,
1305                                           ext4_get_block_unwritten);
1306         else
1307                 ret = __block_write_begin(page, pos, len, ext4_get_block);
1308 #endif
1309         if (!ret && ext4_should_journal_data(inode)) {
1310                 ret = ext4_walk_page_buffers(handle, page_buffers(page),
1311                                              from, to, NULL,
1312                                              do_journal_get_write_access);
1313         }
1314
1315         if (ret) {
1316                 unlock_page(page);
1317                 /*
1318                  * __block_write_begin may have instantiated a few blocks
1319                  * outside i_size.  Trim these off again. Don't need
1320                  * i_size_read because we hold i_mutex.
1321                  *
1322                  * Add inode to orphan list in case we crash before
1323                  * truncate finishes
1324                  */
1325                 if (pos + len > inode->i_size && ext4_can_truncate(inode))
1326                         ext4_orphan_add(handle, inode);
1327
1328                 ext4_journal_stop(handle);
1329                 if (pos + len > inode->i_size) {
1330                         ext4_truncate_failed_write(inode);
1331                         /*
1332                          * If truncate failed early the inode might
1333                          * still be on the orphan list; we need to
1334                          * make sure the inode is removed from the
1335                          * orphan list in that case.
1336                          */
1337                         if (inode->i_nlink)
1338                                 ext4_orphan_del(NULL, inode);
1339                 }
1340
1341                 if (ret == -ENOSPC &&
1342                     ext4_should_retry_alloc(inode->i_sb, &retries))
1343                         goto retry_journal;
1344                 put_page(page);
1345                 return ret;
1346         }
1347         *pagep = page;
1348         return ret;
1349 }
1350
1351 /* For write_end() in data=journal mode */
1352 static int write_end_fn(handle_t *handle, struct buffer_head *bh)
1353 {
1354         int ret;
1355         if (!buffer_mapped(bh) || buffer_freed(bh))
1356                 return 0;
1357         set_buffer_uptodate(bh);
1358         ret = ext4_handle_dirty_metadata(handle, NULL, bh);
1359         clear_buffer_meta(bh);
1360         clear_buffer_prio(bh);
1361         return ret;
1362 }
1363
1364 /*
1365  * We need to pick up the new inode size which generic_commit_write gave us
1366  * `file' can be NULL - eg, when called from page_symlink().
1367  *
1368  * ext4 never places buffers on inode->i_mapping->private_list.  metadata
1369  * buffers are managed internally.
1370  */
1371 static int ext4_write_end(struct file *file,
1372                           struct address_space *mapping,
1373                           loff_t pos, unsigned len, unsigned copied,
1374                           struct page *page, void *fsdata)
1375 {
1376         handle_t *handle = ext4_journal_current_handle();
1377         struct inode *inode = mapping->host;
1378         loff_t old_size = inode->i_size;
1379         int ret = 0, ret2;
1380         int i_size_changed = 0;
1381
1382         trace_ext4_write_end(inode, pos, len, copied);
1383         if (ext4_has_inline_data(inode)) {
1384                 ret = ext4_write_inline_data_end(inode, pos, len,
1385                                                  copied, page);
1386                 if (ret < 0) {
1387                         unlock_page(page);
1388                         put_page(page);
1389                         goto errout;
1390                 }
1391                 copied = ret;
1392         } else
1393                 copied = block_write_end(file, mapping, pos,
1394                                          len, copied, page, fsdata);
1395         /*
1396          * it's important to update i_size while still holding page lock:
1397          * page writeout could otherwise come in and zero beyond i_size.
1398          */
1399         i_size_changed = ext4_update_inode_size(inode, pos + copied);
1400         unlock_page(page);
1401         put_page(page);
1402
1403         if (old_size < pos)
1404                 pagecache_isize_extended(inode, old_size, pos);
1405         /*
1406          * Don't mark the inode dirty under page lock. First, it unnecessarily
1407          * makes the holding time of page lock longer. Second, it forces lock
1408          * ordering of page lock and transaction start for journaling
1409          * filesystems.
1410          */
1411         if (i_size_changed)
1412                 ext4_mark_inode_dirty(handle, inode);
1413
1414         if (pos + len > inode->i_size && ext4_can_truncate(inode))
1415                 /* if we have allocated more blocks and copied
1416                  * less. We will have blocks allocated outside
1417                  * inode->i_size. So truncate them
1418                  */
1419                 ext4_orphan_add(handle, inode);
1420 errout:
1421         ret2 = ext4_journal_stop(handle);
1422         if (!ret)
1423                 ret = ret2;
1424
1425         if (pos + len > inode->i_size) {
1426                 ext4_truncate_failed_write(inode);
1427                 /*
1428                  * If truncate failed early the inode might still be
1429                  * on the orphan list; we need to make sure the inode
1430                  * is removed from the orphan list in that case.
1431                  */
1432                 if (inode->i_nlink)
1433                         ext4_orphan_del(NULL, inode);
1434         }
1435
1436         return ret ? ret : copied;
1437 }
1438
1439 /*
1440  * This is a private version of page_zero_new_buffers() which doesn't
1441  * set the buffer to be dirty, since in data=journalled mode we need
1442  * to call ext4_handle_dirty_metadata() instead.
1443  */
1444 static void ext4_journalled_zero_new_buffers(handle_t *handle,
1445                                             struct page *page,
1446                                             unsigned from, unsigned to)
1447 {
1448         unsigned int block_start = 0, block_end;
1449         struct buffer_head *head, *bh;
1450
1451         bh = head = page_buffers(page);
1452         do {
1453                 block_end = block_start + bh->b_size;
1454                 if (buffer_new(bh)) {
1455                         if (block_end > from && block_start < to) {
1456                                 if (!PageUptodate(page)) {
1457                                         unsigned start, size;
1458
1459                                         start = max(from, block_start);
1460                                         size = min(to, block_end) - start;
1461
1462                                         zero_user(page, start, size);
1463                                         write_end_fn(handle, bh);
1464                                 }
1465                                 clear_buffer_new(bh);
1466                         }
1467                 }
1468                 block_start = block_end;
1469                 bh = bh->b_this_page;
1470         } while (bh != head);
1471 }
1472
1473 static int ext4_journalled_write_end(struct file *file,
1474                                      struct address_space *mapping,
1475                                      loff_t pos, unsigned len, unsigned copied,
1476                                      struct page *page, void *fsdata)
1477 {
1478         handle_t *handle = ext4_journal_current_handle();
1479         struct inode *inode = mapping->host;
1480         loff_t old_size = inode->i_size;
1481         int ret = 0, ret2;
1482         int partial = 0;
1483         unsigned from, to;
1484         int size_changed = 0;
1485
1486         trace_ext4_journalled_write_end(inode, pos, len, copied);
1487         from = pos & (PAGE_SIZE - 1);
1488         to = from + len;
1489
1490         BUG_ON(!ext4_handle_valid(handle));
1491
1492         if (ext4_has_inline_data(inode)) {
1493                 ret = ext4_write_inline_data_end(inode, pos, len,
1494                                                  copied, page);
1495                 if (ret < 0) {
1496                         unlock_page(page);
1497                         put_page(page);
1498                         goto errout;
1499                 }
1500                 copied = ret;
1501         } else if (unlikely(copied < len) && !PageUptodate(page)) {
1502                 copied = 0;
1503                 ext4_journalled_zero_new_buffers(handle, page, from, to);
1504         } else {
1505                 if (unlikely(copied < len))
1506                         ext4_journalled_zero_new_buffers(handle, page,
1507                                                          from + copied, to);
1508                 ret = ext4_walk_page_buffers(handle, page_buffers(page), from,
1509                                              from + copied, &partial,
1510                                              write_end_fn);
1511                 if (!partial)
1512                         SetPageUptodate(page);
1513         }
1514         size_changed = ext4_update_inode_size(inode, pos + copied);
1515         ext4_set_inode_state(inode, EXT4_STATE_JDATA);
1516         EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
1517         unlock_page(page);
1518         put_page(page);
1519
1520         if (old_size < pos)
1521                 pagecache_isize_extended(inode, old_size, pos);
1522
1523         if (size_changed) {
1524                 ret2 = ext4_mark_inode_dirty(handle, inode);
1525                 if (!ret)
1526                         ret = ret2;
1527         }
1528
1529         if (pos + len > inode->i_size && ext4_can_truncate(inode))
1530                 /* if we have allocated more blocks and copied
1531                  * less. We will have blocks allocated outside
1532                  * inode->i_size. So truncate them
1533                  */
1534                 ext4_orphan_add(handle, inode);
1535
1536 errout:
1537         ret2 = ext4_journal_stop(handle);
1538         if (!ret)
1539                 ret = ret2;
1540         if (pos + len > inode->i_size) {
1541                 ext4_truncate_failed_write(inode);
1542                 /*
1543                  * If truncate failed early the inode might still be
1544                  * on the orphan list; we need to make sure the inode
1545                  * is removed from the orphan list in that case.
1546                  */
1547                 if (inode->i_nlink)
1548                         ext4_orphan_del(NULL, inode);
1549         }
1550
1551         return ret ? ret : copied;
1552 }
1553
1554 /*
1555  * Reserve space for a single cluster
1556  */
1557 static int ext4_da_reserve_space(struct inode *inode)
1558 {
1559         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1560         struct ext4_inode_info *ei = EXT4_I(inode);
1561         int ret;
1562
1563         /*
1564          * We will charge metadata quota at writeout time; this saves
1565          * us from metadata over-estimation, though we may go over by
1566          * a small amount in the end.  Here we just reserve for data.
1567          */
1568         ret = dquot_reserve_block(inode, EXT4_C2B(sbi, 1));
1569         if (ret)
1570                 return ret;
1571
1572         spin_lock(&ei->i_block_reservation_lock);
1573         if (ext4_claim_free_clusters(sbi, 1, 0)) {
1574                 spin_unlock(&ei->i_block_reservation_lock);
1575                 dquot_release_reservation_block(inode, EXT4_C2B(sbi, 1));
1576                 return -ENOSPC;
1577         }
1578         ei->i_reserved_data_blocks++;
1579         trace_ext4_da_reserve_space(inode);
1580         spin_unlock(&ei->i_block_reservation_lock);
1581
1582         return 0;       /* success */
1583 }
1584
1585 static void ext4_da_release_space(struct inode *inode, int to_free)
1586 {
1587         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1588         struct ext4_inode_info *ei = EXT4_I(inode);
1589
1590         if (!to_free)
1591                 return;         /* Nothing to release, exit */
1592
1593         spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1594
1595         trace_ext4_da_release_space(inode, to_free);
1596         if (unlikely(to_free > ei->i_reserved_data_blocks)) {
1597                 /*
1598                  * if there aren't enough reserved blocks, then the
1599                  * counter is messed up somewhere.  Since this
1600                  * function is called from invalidate page, it's
1601                  * harmless to return without any action.
1602                  */
1603                 ext4_warning(inode->i_sb, "ext4_da_release_space: "
1604                          "ino %lu, to_free %d with only %d reserved "
1605                          "data blocks", inode->i_ino, to_free,
1606                          ei->i_reserved_data_blocks);
1607                 WARN_ON(1);
1608                 to_free = ei->i_reserved_data_blocks;
1609         }
1610         ei->i_reserved_data_blocks -= to_free;
1611
1612         /* update fs dirty data blocks counter */
1613         percpu_counter_sub(&sbi->s_dirtyclusters_counter, to_free);
1614
1615         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1616
1617         dquot_release_reservation_block(inode, EXT4_C2B(sbi, to_free));
1618 }
1619
1620 static void ext4_da_page_release_reservation(struct page *page,
1621                                              unsigned int offset,
1622                                              unsigned int length)
1623 {
1624         int to_release = 0, contiguous_blks = 0;
1625         struct buffer_head *head, *bh;
1626         unsigned int curr_off = 0;
1627         struct inode *inode = page->mapping->host;
1628         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1629         unsigned int stop = offset + length;
1630         int num_clusters;
1631         ext4_fsblk_t lblk;
1632
1633         BUG_ON(stop > PAGE_SIZE || stop < length);
1634
1635         head = page_buffers(page);
1636         bh = head;
1637         do {
1638                 unsigned int next_off = curr_off + bh->b_size;
1639
1640                 if (next_off > stop)
1641                         break;
1642
1643                 if ((offset <= curr_off) && (buffer_delay(bh))) {
1644                         to_release++;
1645                         contiguous_blks++;
1646                         clear_buffer_delay(bh);
1647                 } else if (contiguous_blks) {
1648                         lblk = page->index <<
1649                                (PAGE_SHIFT - inode->i_blkbits);
1650                         lblk += (curr_off >> inode->i_blkbits) -
1651                                 contiguous_blks;
1652                         ext4_es_remove_extent(inode, lblk, contiguous_blks);
1653                         contiguous_blks = 0;
1654                 }
1655                 curr_off = next_off;
1656         } while ((bh = bh->b_this_page) != head);
1657
1658         if (contiguous_blks) {
1659                 lblk = page->index << (PAGE_SHIFT - inode->i_blkbits);
1660                 lblk += (curr_off >> inode->i_blkbits) - contiguous_blks;
1661                 ext4_es_remove_extent(inode, lblk, contiguous_blks);
1662         }
1663
1664         /* If we have released all the blocks belonging to a cluster, then we
1665          * need to release the reserved space for that cluster. */
1666         num_clusters = EXT4_NUM_B2C(sbi, to_release);
1667         while (num_clusters > 0) {
1668                 lblk = (page->index << (PAGE_SHIFT - inode->i_blkbits)) +
1669                         ((num_clusters - 1) << sbi->s_cluster_bits);
1670                 if (sbi->s_cluster_ratio == 1 ||
1671                     !ext4_find_delalloc_cluster(inode, lblk))
1672                         ext4_da_release_space(inode, 1);
1673
1674                 num_clusters--;
1675         }
1676 }
1677
1678 /*
1679  * Delayed allocation stuff
1680  */
1681
1682 struct mpage_da_data {
1683         struct inode *inode;
1684         struct writeback_control *wbc;
1685
1686         pgoff_t first_page;     /* The first page to write */
1687         pgoff_t next_page;      /* Current page to examine */
1688         pgoff_t last_page;      /* Last page to examine */
1689         /*
1690          * Extent to map - this can be after first_page because that can be
1691          * fully mapped. We somewhat abuse m_flags to store whether the extent
1692          * is delalloc or unwritten.
1693          */
1694         struct ext4_map_blocks map;
1695         struct ext4_io_submit io_submit;        /* IO submission data */
1696         unsigned int do_map:1;
1697 };
1698
1699 static void mpage_release_unused_pages(struct mpage_da_data *mpd,
1700                                        bool invalidate)
1701 {
1702         int nr_pages, i;
1703         pgoff_t index, end;
1704         struct pagevec pvec;
1705         struct inode *inode = mpd->inode;
1706         struct address_space *mapping = inode->i_mapping;
1707
1708         /* This is necessary when next_page == 0. */
1709         if (mpd->first_page >= mpd->next_page)
1710                 return;
1711
1712         index = mpd->first_page;
1713         end   = mpd->next_page - 1;
1714         if (invalidate) {
1715                 ext4_lblk_t start, last;
1716                 start = index << (PAGE_SHIFT - inode->i_blkbits);
1717                 last = end << (PAGE_SHIFT - inode->i_blkbits);
1718                 ext4_es_remove_extent(inode, start, last - start + 1);
1719         }
1720
1721         pagevec_init(&pvec, 0);
1722         while (index <= end) {
1723                 nr_pages = pagevec_lookup(&pvec, mapping, &index, PAGEVEC_SIZE);
1724                 if (nr_pages == 0)
1725                         break;
1726                 for (i = 0; i < nr_pages; i++) {
1727                         struct page *page = pvec.pages[i];
1728                         if (page->index > end)
1729                                 break;
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(&pvec, inode->i_mapping, &start,
2351                                           PAGEVEC_SIZE);
2352                 if (nr_pages == 0)
2353                         break;
2354                 for (i = 0; i < nr_pages; i++) {
2355                         struct page *page = pvec.pages[i];
2356
2357                         if (page->index > end)
2358                                 break;
2359                         bh = head = page_buffers(page);
2360                         do {
2361                                 if (lblk < mpd->map.m_lblk)
2362                                         continue;
2363                                 if (lblk >= mpd->map.m_lblk + mpd->map.m_len) {
2364                                         /*
2365                                          * Buffer after end of mapped extent.
2366                                          * Find next buffer in the page to map.
2367                                          */
2368                                         mpd->map.m_len = 0;
2369                                         mpd->map.m_flags = 0;
2370                                         /*
2371                                          * FIXME: If dioread_nolock supports
2372                                          * blocksize < pagesize, we need to make
2373                                          * sure we add size mapped so far to
2374                                          * io_end->size as the following call
2375                                          * can submit the page for IO.
2376                                          */
2377                                         err = mpage_process_page_bufs(mpd, head,
2378                                                                       bh, lblk);
2379                                         pagevec_release(&pvec);
2380                                         if (err > 0)
2381                                                 err = 0;
2382                                         return err;
2383                                 }
2384                                 if (buffer_delay(bh)) {
2385                                         clear_buffer_delay(bh);
2386                                         bh->b_blocknr = pblock++;
2387                                 }
2388                                 clear_buffer_unwritten(bh);
2389                         } while (lblk++, (bh = bh->b_this_page) != head);
2390
2391                         /*
2392                          * FIXME: This is going to break if dioread_nolock
2393                          * supports blocksize < pagesize as we will try to
2394                          * convert potentially unmapped parts of inode.
2395                          */
2396                         mpd->io_submit.io_end->size += PAGE_SIZE;
2397                         /* Page fully mapped - let IO run! */
2398                         err = mpage_submit_page(mpd, page);
2399                         if (err < 0) {
2400                                 pagevec_release(&pvec);
2401                                 return err;
2402                         }
2403                 }
2404                 pagevec_release(&pvec);
2405         }
2406         /* Extent fully mapped and matches with page boundary. We are done. */
2407         mpd->map.m_len = 0;
2408         mpd->map.m_flags = 0;
2409         return 0;
2410 }
2411
2412 static int mpage_map_one_extent(handle_t *handle, struct mpage_da_data *mpd)
2413 {
2414         struct inode *inode = mpd->inode;
2415         struct ext4_map_blocks *map = &mpd->map;
2416         int get_blocks_flags;
2417         int err, dioread_nolock;
2418
2419         trace_ext4_da_write_pages_extent(inode, map);
2420         /*
2421          * Call ext4_map_blocks() to allocate any delayed allocation blocks, or
2422          * to convert an unwritten extent to be initialized (in the case
2423          * where we have written into one or more preallocated blocks).  It is
2424          * possible that we're going to need more metadata blocks than
2425          * previously reserved. However we must not fail because we're in
2426          * writeback and there is nothing we can do about it so it might result
2427          * in data loss.  So use reserved blocks to allocate metadata if
2428          * possible.
2429          *
2430          * We pass in the magic EXT4_GET_BLOCKS_DELALLOC_RESERVE if
2431          * the blocks in question are delalloc blocks.  This indicates
2432          * that the blocks and quotas has already been checked when
2433          * the data was copied into the page cache.
2434          */
2435         get_blocks_flags = EXT4_GET_BLOCKS_CREATE |
2436                            EXT4_GET_BLOCKS_METADATA_NOFAIL |
2437                            EXT4_GET_BLOCKS_IO_SUBMIT;
2438         dioread_nolock = ext4_should_dioread_nolock(inode);
2439         if (dioread_nolock)
2440                 get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
2441         if (map->m_flags & (1 << BH_Delay))
2442                 get_blocks_flags |= EXT4_GET_BLOCKS_DELALLOC_RESERVE;
2443
2444         err = ext4_map_blocks(handle, inode, map, get_blocks_flags);
2445         if (err < 0)
2446                 return err;
2447         if (dioread_nolock && (map->m_flags & EXT4_MAP_UNWRITTEN)) {
2448                 if (!mpd->io_submit.io_end->handle &&
2449                     ext4_handle_valid(handle)) {
2450                         mpd->io_submit.io_end->handle = handle->h_rsv_handle;
2451                         handle->h_rsv_handle = NULL;
2452                 }
2453                 ext4_set_io_unwritten_flag(inode, mpd->io_submit.io_end);
2454         }
2455
2456         BUG_ON(map->m_len == 0);
2457         if (map->m_flags & EXT4_MAP_NEW) {
2458                 clean_bdev_aliases(inode->i_sb->s_bdev, map->m_pblk,
2459                                    map->m_len);
2460         }
2461         return 0;
2462 }
2463
2464 /*
2465  * mpage_map_and_submit_extent - map extent starting at mpd->lblk of length
2466  *                               mpd->len and submit pages underlying it for IO
2467  *
2468  * @handle - handle for journal operations
2469  * @mpd - extent to map
2470  * @give_up_on_write - we set this to true iff there is a fatal error and there
2471  *                     is no hope of writing the data. The caller should discard
2472  *                     dirty pages to avoid infinite loops.
2473  *
2474  * The function maps extent starting at mpd->lblk of length mpd->len. If it is
2475  * delayed, blocks are allocated, if it is unwritten, we may need to convert
2476  * them to initialized or split the described range from larger unwritten
2477  * extent. Note that we need not map all the described range since allocation
2478  * can return less blocks or the range is covered by more unwritten extents. We
2479  * cannot map more because we are limited by reserved transaction credits. On
2480  * the other hand we always make sure that the last touched page is fully
2481  * mapped so that it can be written out (and thus forward progress is
2482  * guaranteed). After mapping we submit all mapped pages for IO.
2483  */
2484 static int mpage_map_and_submit_extent(handle_t *handle,
2485                                        struct mpage_da_data *mpd,
2486                                        bool *give_up_on_write)
2487 {
2488         struct inode *inode = mpd->inode;
2489         struct ext4_map_blocks *map = &mpd->map;
2490         int err;
2491         loff_t disksize;
2492         int progress = 0;
2493
2494         mpd->io_submit.io_end->offset =
2495                                 ((loff_t)map->m_lblk) << inode->i_blkbits;
2496         do {
2497                 err = mpage_map_one_extent(handle, mpd);
2498                 if (err < 0) {
2499                         struct super_block *sb = inode->i_sb;
2500
2501                         if (ext4_forced_shutdown(EXT4_SB(sb)) ||
2502                             EXT4_SB(sb)->s_mount_flags & EXT4_MF_FS_ABORTED)
2503                                 goto invalidate_dirty_pages;
2504                         /*
2505                          * Let the uper layers retry transient errors.
2506                          * In the case of ENOSPC, if ext4_count_free_blocks()
2507                          * is non-zero, a commit should free up blocks.
2508                          */
2509                         if ((err == -ENOMEM) ||
2510                             (err == -ENOSPC && ext4_count_free_clusters(sb))) {
2511                                 if (progress)
2512                                         goto update_disksize;
2513                                 return err;
2514                         }
2515                         ext4_msg(sb, KERN_CRIT,
2516                                  "Delayed block allocation failed for "
2517                                  "inode %lu at logical offset %llu with"
2518                                  " max blocks %u with error %d",
2519                                  inode->i_ino,
2520                                  (unsigned long long)map->m_lblk,
2521                                  (unsigned)map->m_len, -err);
2522                         ext4_msg(sb, KERN_CRIT,
2523                                  "This should not happen!! Data will "
2524                                  "be lost\n");
2525                         if (err == -ENOSPC)
2526                                 ext4_print_free_blocks(inode);
2527                 invalidate_dirty_pages:
2528                         *give_up_on_write = true;
2529                         return err;
2530                 }
2531                 progress = 1;
2532                 /*
2533                  * Update buffer state, submit mapped pages, and get us new
2534                  * extent to map
2535                  */
2536                 err = mpage_map_and_submit_buffers(mpd);
2537                 if (err < 0)
2538                         goto update_disksize;
2539         } while (map->m_len);
2540
2541 update_disksize:
2542         /*
2543          * Update on-disk size after IO is submitted.  Races with
2544          * truncate are avoided by checking i_size under i_data_sem.
2545          */
2546         disksize = ((loff_t)mpd->first_page) << PAGE_SHIFT;
2547         if (disksize > EXT4_I(inode)->i_disksize) {
2548                 int err2;
2549                 loff_t i_size;
2550
2551                 down_write(&EXT4_I(inode)->i_data_sem);
2552                 i_size = i_size_read(inode);
2553                 if (disksize > i_size)
2554                         disksize = i_size;
2555                 if (disksize > EXT4_I(inode)->i_disksize)
2556                         EXT4_I(inode)->i_disksize = disksize;
2557                 up_write(&EXT4_I(inode)->i_data_sem);
2558                 err2 = ext4_mark_inode_dirty(handle, inode);
2559                 if (err2)
2560                         ext4_error(inode->i_sb,
2561                                    "Failed to mark inode %lu dirty",
2562                                    inode->i_ino);
2563                 if (!err)
2564                         err = err2;
2565         }
2566         return err;
2567 }
2568
2569 /*
2570  * Calculate the total number of credits to reserve for one writepages
2571  * iteration. This is called from ext4_writepages(). We map an extent of
2572  * up to MAX_WRITEPAGES_EXTENT_LEN blocks and then we go on and finish mapping
2573  * the last partial page. So in total we can map MAX_WRITEPAGES_EXTENT_LEN +
2574  * bpp - 1 blocks in bpp different extents.
2575  */
2576 static int ext4_da_writepages_trans_blocks(struct inode *inode)
2577 {
2578         int bpp = ext4_journal_blocks_per_page(inode);
2579
2580         return ext4_meta_trans_blocks(inode,
2581                                 MAX_WRITEPAGES_EXTENT_LEN + bpp - 1, bpp);
2582 }
2583
2584 /*
2585  * mpage_prepare_extent_to_map - find & lock contiguous range of dirty pages
2586  *                               and underlying extent to map
2587  *
2588  * @mpd - where to look for pages
2589  *
2590  * Walk dirty pages in the mapping. If they are fully mapped, submit them for
2591  * IO immediately. When we find a page which isn't mapped we start accumulating
2592  * extent of buffers underlying these pages that needs mapping (formed by
2593  * either delayed or unwritten buffers). We also lock the pages containing
2594  * these buffers. The extent found is returned in @mpd structure (starting at
2595  * mpd->lblk with length mpd->len blocks).
2596  *
2597  * Note that this function can attach bios to one io_end structure which are
2598  * neither logically nor physically contiguous. Although it may seem as an
2599  * unnecessary complication, it is actually inevitable in blocksize < pagesize
2600  * case as we need to track IO to all buffers underlying a page in one io_end.
2601  */
2602 static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd)
2603 {
2604         struct address_space *mapping = mpd->inode->i_mapping;
2605         struct pagevec pvec;
2606         unsigned int nr_pages;
2607         long left = mpd->wbc->nr_to_write;
2608         pgoff_t index = mpd->first_page;
2609         pgoff_t end = mpd->last_page;
2610         int tag;
2611         int i, err = 0;
2612         int blkbits = mpd->inode->i_blkbits;
2613         ext4_lblk_t lblk;
2614         struct buffer_head *head;
2615
2616         if (mpd->wbc->sync_mode == WB_SYNC_ALL || mpd->wbc->tagged_writepages)
2617                 tag = PAGECACHE_TAG_TOWRITE;
2618         else
2619                 tag = PAGECACHE_TAG_DIRTY;
2620
2621         pagevec_init(&pvec, 0);
2622         mpd->map.m_len = 0;
2623         mpd->next_page = index;
2624         while (index <= end) {
2625                 nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
2626                               min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
2627                 if (nr_pages == 0)
2628                         goto out;
2629
2630                 for (i = 0; i < nr_pages; i++) {
2631                         struct page *page = pvec.pages[i];
2632
2633                         /*
2634                          * At this point, the page may be truncated or
2635                          * invalidated (changing page->mapping to NULL), or
2636                          * even swizzled back from swapper_space to tmpfs file
2637                          * mapping. However, page->index will not change
2638                          * because we have a reference on the page.
2639                          */
2640                         if (page->index > end)
2641                                 goto out;
2642
2643                         /*
2644                          * Accumulated enough dirty pages? This doesn't apply
2645                          * to WB_SYNC_ALL mode. For integrity sync we have to
2646                          * keep going because someone may be concurrently
2647                          * dirtying pages, and we might have synced a lot of
2648                          * newly appeared dirty pages, but have not synced all
2649                          * of the old dirty pages.
2650                          */
2651                         if (mpd->wbc->sync_mode == WB_SYNC_NONE && left <= 0)
2652                                 goto out;
2653
2654                         /* If we can't merge this page, we are done. */
2655                         if (mpd->map.m_len > 0 && mpd->next_page != page->index)
2656                                 goto out;
2657
2658                         lock_page(page);
2659                         /*
2660                          * If the page is no longer dirty, or its mapping no
2661                          * longer corresponds to inode we are writing (which
2662                          * means it has been truncated or invalidated), or the
2663                          * page is already under writeback and we are not doing
2664                          * a data integrity writeback, skip the page
2665                          */
2666                         if (!PageDirty(page) ||
2667                             (PageWriteback(page) &&
2668                              (mpd->wbc->sync_mode == WB_SYNC_NONE)) ||
2669                             unlikely(page->mapping != mapping)) {
2670                                 unlock_page(page);
2671                                 continue;
2672                         }
2673
2674                         wait_on_page_writeback(page);
2675                         BUG_ON(PageWriteback(page));
2676
2677                         if (mpd->map.m_len == 0)
2678                                 mpd->first_page = page->index;
2679                         mpd->next_page = page->index + 1;
2680                         /* Add all dirty buffers to mpd */
2681                         lblk = ((ext4_lblk_t)page->index) <<
2682                                 (PAGE_SHIFT - blkbits);
2683                         head = page_buffers(page);
2684                         err = mpage_process_page_bufs(mpd, head, head, lblk);
2685                         if (err <= 0)
2686                                 goto out;
2687                         err = 0;
2688                         left--;
2689                 }
2690                 pagevec_release(&pvec);
2691                 cond_resched();
2692         }
2693         return 0;
2694 out:
2695         pagevec_release(&pvec);
2696         return err;
2697 }
2698
2699 static int __writepage(struct page *page, struct writeback_control *wbc,
2700                        void *data)
2701 {
2702         struct address_space *mapping = data;
2703         int ret = ext4_writepage(page, wbc);
2704         mapping_set_error(mapping, ret);
2705         return ret;
2706 }
2707
2708 static int ext4_writepages(struct address_space *mapping,
2709                            struct writeback_control *wbc)
2710 {
2711         pgoff_t writeback_index = 0;
2712         long nr_to_write = wbc->nr_to_write;
2713         int range_whole = 0;
2714         int cycled = 1;
2715         handle_t *handle = NULL;
2716         struct mpage_da_data mpd;
2717         struct inode *inode = mapping->host;
2718         int needed_blocks, rsv_blocks = 0, ret = 0;
2719         struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
2720         bool done;
2721         struct blk_plug plug;
2722         bool give_up_on_write = false;
2723
2724         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
2725                 return -EIO;
2726
2727         percpu_down_read(&sbi->s_journal_flag_rwsem);
2728         trace_ext4_writepages(inode, wbc);
2729
2730         if (dax_mapping(mapping)) {
2731                 ret = dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev,
2732                                                   wbc);
2733                 goto out_writepages;
2734         }
2735
2736         /*
2737          * No pages to write? This is mainly a kludge to avoid starting
2738          * a transaction for special inodes like journal inode on last iput()
2739          * because that could violate lock ordering on umount
2740          */
2741         if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
2742                 goto out_writepages;
2743
2744         if (ext4_should_journal_data(inode)) {
2745                 struct blk_plug plug;
2746
2747                 blk_start_plug(&plug);
2748                 ret = write_cache_pages(mapping, wbc, __writepage, mapping);
2749                 blk_finish_plug(&plug);
2750                 goto out_writepages;
2751         }
2752
2753         /*
2754          * If the filesystem has aborted, it is read-only, so return
2755          * right away instead of dumping stack traces later on that
2756          * will obscure the real source of the problem.  We test
2757          * EXT4_MF_FS_ABORTED instead of sb->s_flag's MS_RDONLY because
2758          * the latter could be true if the filesystem is mounted
2759          * read-only, and in that case, ext4_writepages should
2760          * *never* be called, so if that ever happens, we would want
2761          * the stack trace.
2762          */
2763         if (unlikely(ext4_forced_shutdown(EXT4_SB(mapping->host->i_sb)) ||
2764                      sbi->s_mount_flags & EXT4_MF_FS_ABORTED)) {
2765                 ret = -EROFS;
2766                 goto out_writepages;
2767         }
2768
2769         if (ext4_should_dioread_nolock(inode)) {
2770                 /*
2771                  * We may need to convert up to one extent per block in
2772                  * the page and we may dirty the inode.
2773                  */
2774                 rsv_blocks = 1 + (PAGE_SIZE >> inode->i_blkbits);
2775         }
2776
2777         /*
2778          * If we have inline data and arrive here, it means that
2779          * we will soon create the block for the 1st page, so
2780          * we'd better clear the inline data here.
2781          */
2782         if (ext4_has_inline_data(inode)) {
2783                 /* Just inode will be modified... */
2784                 handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
2785                 if (IS_ERR(handle)) {
2786                         ret = PTR_ERR(handle);
2787                         goto out_writepages;
2788                 }
2789                 BUG_ON(ext4_test_inode_state(inode,
2790                                 EXT4_STATE_MAY_INLINE_DATA));
2791                 ext4_destroy_inline_data(handle, inode);
2792                 ext4_journal_stop(handle);
2793         }
2794
2795         if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
2796                 range_whole = 1;
2797
2798         if (wbc->range_cyclic) {
2799                 writeback_index = mapping->writeback_index;
2800                 if (writeback_index)
2801                         cycled = 0;
2802                 mpd.first_page = writeback_index;
2803                 mpd.last_page = -1;
2804         } else {
2805                 mpd.first_page = wbc->range_start >> PAGE_SHIFT;
2806                 mpd.last_page = wbc->range_end >> PAGE_SHIFT;
2807         }
2808
2809         mpd.inode = inode;
2810         mpd.wbc = wbc;
2811         ext4_io_submit_init(&mpd.io_submit, wbc);
2812 retry:
2813         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
2814                 tag_pages_for_writeback(mapping, mpd.first_page, mpd.last_page);
2815         done = false;
2816         blk_start_plug(&plug);
2817
2818         /*
2819          * First writeback pages that don't need mapping - we can avoid
2820          * starting a transaction unnecessarily and also avoid being blocked
2821          * in the block layer on device congestion while having transaction
2822          * started.
2823          */
2824         mpd.do_map = 0;
2825         mpd.io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
2826         if (!mpd.io_submit.io_end) {
2827                 ret = -ENOMEM;
2828                 goto unplug;
2829         }
2830         ret = mpage_prepare_extent_to_map(&mpd);
2831         /* Submit prepared bio */
2832         ext4_io_submit(&mpd.io_submit);
2833         ext4_put_io_end_defer(mpd.io_submit.io_end);
2834         mpd.io_submit.io_end = NULL;
2835         /* Unlock pages we didn't use */
2836         mpage_release_unused_pages(&mpd, false);
2837         if (ret < 0)
2838                 goto unplug;
2839
2840         while (!done && mpd.first_page <= mpd.last_page) {
2841                 /* For each extent of pages we use new io_end */
2842                 mpd.io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
2843                 if (!mpd.io_submit.io_end) {
2844                         ret = -ENOMEM;
2845                         break;
2846                 }
2847
2848                 /*
2849                  * We have two constraints: We find one extent to map and we
2850                  * must always write out whole page (makes a difference when
2851                  * blocksize < pagesize) so that we don't block on IO when we
2852                  * try to write out the rest of the page. Journalled mode is
2853                  * not supported by delalloc.
2854                  */
2855                 BUG_ON(ext4_should_journal_data(inode));
2856                 needed_blocks = ext4_da_writepages_trans_blocks(inode);
2857
2858                 /* start a new transaction */
2859                 handle = ext4_journal_start_with_reserve(inode,
2860                                 EXT4_HT_WRITE_PAGE, needed_blocks, rsv_blocks);
2861                 if (IS_ERR(handle)) {
2862                         ret = PTR_ERR(handle);
2863                         ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
2864                                "%ld pages, ino %lu; err %d", __func__,
2865                                 wbc->nr_to_write, inode->i_ino, ret);
2866                         /* Release allocated io_end */
2867                         ext4_put_io_end(mpd.io_submit.io_end);
2868                         mpd.io_submit.io_end = NULL;
2869                         break;
2870                 }
2871                 mpd.do_map = 1;
2872
2873                 trace_ext4_da_write_pages(inode, mpd.first_page, mpd.wbc);
2874                 ret = mpage_prepare_extent_to_map(&mpd);
2875                 if (!ret) {
2876                         if (mpd.map.m_len)
2877                                 ret = mpage_map_and_submit_extent(handle, &mpd,
2878                                         &give_up_on_write);
2879                         else {
2880                                 /*
2881                                  * We scanned the whole range (or exhausted
2882                                  * nr_to_write), submitted what was mapped and
2883                                  * didn't find anything needing mapping. We are
2884                                  * done.
2885                                  */
2886                                 done = true;
2887                         }
2888                 }
2889                 /*
2890                  * Caution: If the handle is synchronous,
2891                  * ext4_journal_stop() can wait for transaction commit
2892                  * to finish which may depend on writeback of pages to
2893                  * complete or on page lock to be released.  In that
2894                  * case, we have to wait until after after we have
2895                  * submitted all the IO, released page locks we hold,
2896                  * and dropped io_end reference (for extent conversion
2897                  * to be able to complete) before stopping the handle.
2898                  */
2899                 if (!ext4_handle_valid(handle) || handle->h_sync == 0) {
2900                         ext4_journal_stop(handle);
2901                         handle = NULL;
2902                         mpd.do_map = 0;
2903                 }
2904                 /* Submit prepared bio */
2905                 ext4_io_submit(&mpd.io_submit);
2906                 /* Unlock pages we didn't use */
2907                 mpage_release_unused_pages(&mpd, give_up_on_write);
2908                 /*
2909                  * Drop our io_end reference we got from init. We have
2910                  * to be careful and use deferred io_end finishing if
2911                  * we are still holding the transaction as we can
2912                  * release the last reference to io_end which may end
2913                  * up doing unwritten extent conversion.
2914                  */
2915                 if (handle) {
2916                         ext4_put_io_end_defer(mpd.io_submit.io_end);
2917                         ext4_journal_stop(handle);
2918                 } else
2919                         ext4_put_io_end(mpd.io_submit.io_end);
2920                 mpd.io_submit.io_end = NULL;
2921
2922                 if (ret == -ENOSPC && sbi->s_journal) {
2923                         /*
2924                          * Commit the transaction which would
2925                          * free blocks released in the transaction
2926                          * and try again
2927                          */
2928                         jbd2_journal_force_commit_nested(sbi->s_journal);
2929                         ret = 0;
2930                         continue;
2931                 }
2932                 /* Fatal error - ENOMEM, EIO... */
2933                 if (ret)
2934                         break;
2935         }
2936 unplug:
2937         blk_finish_plug(&plug);
2938         if (!ret && !cycled && wbc->nr_to_write > 0) {
2939                 cycled = 1;
2940                 mpd.last_page = writeback_index - 1;
2941                 mpd.first_page = 0;
2942                 goto retry;
2943         }
2944
2945         /* Update index */
2946         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
2947                 /*
2948                  * Set the writeback_index so that range_cyclic
2949                  * mode will write it back later
2950                  */
2951                 mapping->writeback_index = mpd.first_page;
2952
2953 out_writepages:
2954         trace_ext4_writepages_result(inode, wbc, ret,
2955                                      nr_to_write - wbc->nr_to_write);
2956         percpu_up_read(&sbi->s_journal_flag_rwsem);
2957         return ret;
2958 }
2959
2960 static int ext4_nonda_switch(struct super_block *sb)
2961 {
2962         s64 free_clusters, dirty_clusters;
2963         struct ext4_sb_info *sbi = EXT4_SB(sb);
2964
2965         /*
2966          * switch to non delalloc mode if we are running low
2967          * on free block. The free block accounting via percpu
2968          * counters can get slightly wrong with percpu_counter_batch getting
2969          * accumulated on each CPU without updating global counters
2970          * Delalloc need an accurate free block accounting. So switch
2971          * to non delalloc when we are near to error range.
2972          */
2973         free_clusters =
2974                 percpu_counter_read_positive(&sbi->s_freeclusters_counter);
2975         dirty_clusters =
2976                 percpu_counter_read_positive(&sbi->s_dirtyclusters_counter);
2977         /*
2978          * Start pushing delalloc when 1/2 of free blocks are dirty.
2979          */
2980         if (dirty_clusters && (free_clusters < 2 * dirty_clusters))
2981                 try_to_writeback_inodes_sb(sb, WB_REASON_FS_FREE_SPACE);
2982
2983         if (2 * free_clusters < 3 * dirty_clusters ||
2984             free_clusters < (dirty_clusters + EXT4_FREECLUSTERS_WATERMARK)) {
2985                 /*
2986                  * free block count is less than 150% of dirty blocks
2987                  * or free blocks is less than watermark
2988                  */
2989                 return 1;
2990         }
2991         return 0;
2992 }
2993
2994 /* We always reserve for an inode update; the superblock could be there too */
2995 static int ext4_da_write_credits(struct inode *inode, loff_t pos, unsigned len)
2996 {
2997         if (likely(ext4_has_feature_large_file(inode->i_sb)))
2998                 return 1;
2999
3000         if (pos + len <= 0x7fffffffULL)
3001                 return 1;
3002
3003         /* We might need to update the superblock to set LARGE_FILE */
3004         return 2;
3005 }
3006
3007 static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
3008                                loff_t pos, unsigned len, unsigned flags,
3009                                struct page **pagep, void **fsdata)
3010 {
3011         int ret, retries = 0;
3012         struct page *page;
3013         pgoff_t index;
3014         struct inode *inode = mapping->host;
3015         handle_t *handle;
3016
3017         if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
3018                 return -EIO;
3019
3020         index = pos >> PAGE_SHIFT;
3021
3022         if (ext4_nonda_switch(inode->i_sb) ||
3023             S_ISLNK(inode->i_mode)) {
3024                 *fsdata = (void *)FALL_BACK_TO_NONDELALLOC;
3025                 return ext4_write_begin(file, mapping, pos,
3026                                         len, flags, pagep, fsdata);
3027         }
3028         *fsdata = (void *)0;
3029         trace_ext4_da_write_begin(inode, pos, len, flags);
3030
3031         if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
3032                 ret = ext4_da_write_inline_data_begin(mapping, inode,
3033                                                       pos, len, flags,
3034                                                       pagep, fsdata);
3035                 if (ret < 0)
3036                         return ret;
3037                 if (ret == 1)
3038                         return 0;
3039         }
3040
3041         /*
3042          * grab_cache_page_write_begin() can take a long time if the
3043          * system is thrashing due to memory pressure, or if the page
3044          * is being written back.  So grab it first before we start
3045          * the transaction handle.  This also allows us to allocate
3046          * the page (if needed) without using GFP_NOFS.
3047          */
3048 retry_grab:
3049         page = grab_cache_page_write_begin(mapping, index, flags);
3050         if (!page)
3051                 return -ENOMEM;
3052         unlock_page(page);
3053
3054         /*
3055          * With delayed allocation, we don't log the i_disksize update
3056          * if there is delayed block allocation. But we still need
3057          * to journalling the i_disksize update if writes to the end
3058          * of file which has an already mapped buffer.
3059          */
3060 retry_journal:
3061         handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
3062                                 ext4_da_write_credits(inode, pos, len));
3063         if (IS_ERR(handle)) {
3064                 put_page(page);
3065                 return PTR_ERR(handle);
3066         }
3067
3068         lock_page(page);
3069         if (page->mapping != mapping) {
3070                 /* The page got truncated from under us */
3071                 unlock_page(page);
3072                 put_page(page);
3073                 ext4_journal_stop(handle);
3074                 goto retry_grab;
3075         }
3076         /* In case writeback began while the page was unlocked */
3077         wait_for_stable_page(page);
3078
3079 #ifdef CONFIG_EXT4_FS_ENCRYPTION
3080         ret = ext4_block_write_begin(page, pos, len,
3081                                      ext4_da_get_block_prep);
3082 #else
3083         ret = __block_write_begin(page, pos, len, ext4_da_get_block_prep);
3084 #endif
3085         if (ret < 0) {
3086                 unlock_page(page);
3087                 ext4_journal_stop(handle);
3088                 /*
3089                  * block_write_begin may have instantiated a few blocks
3090                  * outside i_size.  Trim these off again. Don't need
3091                  * i_size_read because we hold i_mutex.
3092                  */
3093                 if (pos + len > inode->i_size)
3094                         ext4_truncate_failed_write(inode);
3095
3096                 if (ret == -ENOSPC &&
3097                     ext4_should_retry_alloc(inode->i_sb, &retries))
3098                         goto retry_journal;
3099
3100                 put_page(page);
3101                 return ret;
3102         }
3103
3104         *pagep = page;
3105         return ret;
3106 }
3107
3108 /*
3109  * Check if we should update i_disksize
3110  * when write to the end of file but not require block allocation
3111  */
3112 static int ext4_da_should_update_i_disksize(struct page *page,
3113                                             unsigned long offset)
3114 {
3115         struct buffer_head *bh;
3116         struct inode *inode = page->mapping->host;
3117         unsigned int idx;
3118         int i;
3119
3120         bh = page_buffers(page);
3121         idx = offset >> inode->i_blkbits;
3122
3123         for (i = 0; i < idx; i++)
3124                &n