6cd003c3f05ec318092b766fbc0e6322175911e2
[sfrench/cifs-2.6.git] / fs / btrfs / file.c
1 /*
2  * Copyright (C) 2007 Oracle.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public
6  * License v2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public
14  * License along with this program; if not, write to the
15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16  * Boston, MA 021110-1307, USA.
17  */
18
19 #include <linux/fs.h>
20 #include <linux/pagemap.h>
21 #include <linux/highmem.h>
22 #include <linux/time.h>
23 #include <linux/init.h>
24 #include <linux/string.h>
25 #include <linux/backing-dev.h>
26 #include <linux/mpage.h>
27 #include <linux/aio.h>
28 #include <linux/falloc.h>
29 #include <linux/swap.h>
30 #include <linux/writeback.h>
31 #include <linux/statfs.h>
32 #include <linux/compat.h>
33 #include <linux/slab.h>
34 #include <linux/btrfs.h>
35 #include "ctree.h"
36 #include "disk-io.h"
37 #include "transaction.h"
38 #include "btrfs_inode.h"
39 #include "print-tree.h"
40 #include "tree-log.h"
41 #include "locking.h"
42 #include "volumes.h"
43
44 static struct kmem_cache *btrfs_inode_defrag_cachep;
45 /*
46  * when auto defrag is enabled we
47  * queue up these defrag structs to remember which
48  * inodes need defragging passes
49  */
50 struct inode_defrag {
51         struct rb_node rb_node;
52         /* objectid */
53         u64 ino;
54         /*
55          * transid where the defrag was added, we search for
56          * extents newer than this
57          */
58         u64 transid;
59
60         /* root objectid */
61         u64 root;
62
63         /* last offset we were able to defrag */
64         u64 last_offset;
65
66         /* if we've wrapped around back to zero once already */
67         int cycled;
68 };
69
70 static int __compare_inode_defrag(struct inode_defrag *defrag1,
71                                   struct inode_defrag *defrag2)
72 {
73         if (defrag1->root > defrag2->root)
74                 return 1;
75         else if (defrag1->root < defrag2->root)
76                 return -1;
77         else if (defrag1->ino > defrag2->ino)
78                 return 1;
79         else if (defrag1->ino < defrag2->ino)
80                 return -1;
81         else
82                 return 0;
83 }
84
85 /* pop a record for an inode into the defrag tree.  The lock
86  * must be held already
87  *
88  * If you're inserting a record for an older transid than an
89  * existing record, the transid already in the tree is lowered
90  *
91  * If an existing record is found the defrag item you
92  * pass in is freed
93  */
94 static int __btrfs_add_inode_defrag(struct inode *inode,
95                                     struct inode_defrag *defrag)
96 {
97         struct btrfs_root *root = BTRFS_I(inode)->root;
98         struct inode_defrag *entry;
99         struct rb_node **p;
100         struct rb_node *parent = NULL;
101         int ret;
102
103         p = &root->fs_info->defrag_inodes.rb_node;
104         while (*p) {
105                 parent = *p;
106                 entry = rb_entry(parent, struct inode_defrag, rb_node);
107
108                 ret = __compare_inode_defrag(defrag, entry);
109                 if (ret < 0)
110                         p = &parent->rb_left;
111                 else if (ret > 0)
112                         p = &parent->rb_right;
113                 else {
114                         /* if we're reinserting an entry for
115                          * an old defrag run, make sure to
116                          * lower the transid of our existing record
117                          */
118                         if (defrag->transid < entry->transid)
119                                 entry->transid = defrag->transid;
120                         if (defrag->last_offset > entry->last_offset)
121                                 entry->last_offset = defrag->last_offset;
122                         return -EEXIST;
123                 }
124         }
125         set_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags);
126         rb_link_node(&defrag->rb_node, parent, p);
127         rb_insert_color(&defrag->rb_node, &root->fs_info->defrag_inodes);
128         return 0;
129 }
130
131 static inline int __need_auto_defrag(struct btrfs_root *root)
132 {
133         if (!btrfs_test_opt(root, AUTO_DEFRAG))
134                 return 0;
135
136         if (btrfs_fs_closing(root->fs_info))
137                 return 0;
138
139         return 1;
140 }
141
142 /*
143  * insert a defrag record for this inode if auto defrag is
144  * enabled
145  */
146 int btrfs_add_inode_defrag(struct btrfs_trans_handle *trans,
147                            struct inode *inode)
148 {
149         struct btrfs_root *root = BTRFS_I(inode)->root;
150         struct inode_defrag *defrag;
151         u64 transid;
152         int ret;
153
154         if (!__need_auto_defrag(root))
155                 return 0;
156
157         if (test_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags))
158                 return 0;
159
160         if (trans)
161                 transid = trans->transid;
162         else
163                 transid = BTRFS_I(inode)->root->last_trans;
164
165         defrag = kmem_cache_zalloc(btrfs_inode_defrag_cachep, GFP_NOFS);
166         if (!defrag)
167                 return -ENOMEM;
168
169         defrag->ino = btrfs_ino(inode);
170         defrag->transid = transid;
171         defrag->root = root->root_key.objectid;
172
173         spin_lock(&root->fs_info->defrag_inodes_lock);
174         if (!test_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags)) {
175                 /*
176                  * If we set IN_DEFRAG flag and evict the inode from memory,
177                  * and then re-read this inode, this new inode doesn't have
178                  * IN_DEFRAG flag. At the case, we may find the existed defrag.
179                  */
180                 ret = __btrfs_add_inode_defrag(inode, defrag);
181                 if (ret)
182                         kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
183         } else {
184                 kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
185         }
186         spin_unlock(&root->fs_info->defrag_inodes_lock);
187         return 0;
188 }
189
190 /*
191  * Requeue the defrag object. If there is a defrag object that points to
192  * the same inode in the tree, we will merge them together (by
193  * __btrfs_add_inode_defrag()) and free the one that we want to requeue.
194  */
195 static void btrfs_requeue_inode_defrag(struct inode *inode,
196                                        struct inode_defrag *defrag)
197 {
198         struct btrfs_root *root = BTRFS_I(inode)->root;
199         int ret;
200
201         if (!__need_auto_defrag(root))
202                 goto out;
203
204         /*
205          * Here we don't check the IN_DEFRAG flag, because we need merge
206          * them together.
207          */
208         spin_lock(&root->fs_info->defrag_inodes_lock);
209         ret = __btrfs_add_inode_defrag(inode, defrag);
210         spin_unlock(&root->fs_info->defrag_inodes_lock);
211         if (ret)
212                 goto out;
213         return;
214 out:
215         kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
216 }
217
218 /*
219  * pick the defragable inode that we want, if it doesn't exist, we will get
220  * the next one.
221  */
222 static struct inode_defrag *
223 btrfs_pick_defrag_inode(struct btrfs_fs_info *fs_info, u64 root, u64 ino)
224 {
225         struct inode_defrag *entry = NULL;
226         struct inode_defrag tmp;
227         struct rb_node *p;
228         struct rb_node *parent = NULL;
229         int ret;
230
231         tmp.ino = ino;
232         tmp.root = root;
233
234         spin_lock(&fs_info->defrag_inodes_lock);
235         p = fs_info->defrag_inodes.rb_node;
236         while (p) {
237                 parent = p;
238                 entry = rb_entry(parent, struct inode_defrag, rb_node);
239
240                 ret = __compare_inode_defrag(&tmp, entry);
241                 if (ret < 0)
242                         p = parent->rb_left;
243                 else if (ret > 0)
244                         p = parent->rb_right;
245                 else
246                         goto out;
247         }
248
249         if (parent && __compare_inode_defrag(&tmp, entry) > 0) {
250                 parent = rb_next(parent);
251                 if (parent)
252                         entry = rb_entry(parent, struct inode_defrag, rb_node);
253                 else
254                         entry = NULL;
255         }
256 out:
257         if (entry)
258                 rb_erase(parent, &fs_info->defrag_inodes);
259         spin_unlock(&fs_info->defrag_inodes_lock);
260         return entry;
261 }
262
263 void btrfs_cleanup_defrag_inodes(struct btrfs_fs_info *fs_info)
264 {
265         struct inode_defrag *defrag;
266         struct rb_node *node;
267
268         spin_lock(&fs_info->defrag_inodes_lock);
269         node = rb_first(&fs_info->defrag_inodes);
270         while (node) {
271                 rb_erase(node, &fs_info->defrag_inodes);
272                 defrag = rb_entry(node, struct inode_defrag, rb_node);
273                 kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
274
275                 if (need_resched()) {
276                         spin_unlock(&fs_info->defrag_inodes_lock);
277                         cond_resched();
278                         spin_lock(&fs_info->defrag_inodes_lock);
279                 }
280
281                 node = rb_first(&fs_info->defrag_inodes);
282         }
283         spin_unlock(&fs_info->defrag_inodes_lock);
284 }
285
286 #define BTRFS_DEFRAG_BATCH      1024
287
288 static int __btrfs_run_defrag_inode(struct btrfs_fs_info *fs_info,
289                                     struct inode_defrag *defrag)
290 {
291         struct btrfs_root *inode_root;
292         struct inode *inode;
293         struct btrfs_key key;
294         struct btrfs_ioctl_defrag_range_args range;
295         int num_defrag;
296         int index;
297         int ret;
298
299         /* get the inode */
300         key.objectid = defrag->root;
301         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
302         key.offset = (u64)-1;
303
304         index = srcu_read_lock(&fs_info->subvol_srcu);
305
306         inode_root = btrfs_read_fs_root_no_name(fs_info, &key);
307         if (IS_ERR(inode_root)) {
308                 ret = PTR_ERR(inode_root);
309                 goto cleanup;
310         }
311
312         key.objectid = defrag->ino;
313         btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
314         key.offset = 0;
315         inode = btrfs_iget(fs_info->sb, &key, inode_root, NULL);
316         if (IS_ERR(inode)) {
317                 ret = PTR_ERR(inode);
318                 goto cleanup;
319         }
320         srcu_read_unlock(&fs_info->subvol_srcu, index);
321
322         /* do a chunk of defrag */
323         clear_bit(BTRFS_INODE_IN_DEFRAG, &BTRFS_I(inode)->runtime_flags);
324         memset(&range, 0, sizeof(range));
325         range.len = (u64)-1;
326         range.start = defrag->last_offset;
327
328         sb_start_write(fs_info->sb);
329         num_defrag = btrfs_defrag_file(inode, NULL, &range, defrag->transid,
330                                        BTRFS_DEFRAG_BATCH);
331         sb_end_write(fs_info->sb);
332         /*
333          * if we filled the whole defrag batch, there
334          * must be more work to do.  Queue this defrag
335          * again
336          */
337         if (num_defrag == BTRFS_DEFRAG_BATCH) {
338                 defrag->last_offset = range.start;
339                 btrfs_requeue_inode_defrag(inode, defrag);
340         } else if (defrag->last_offset && !defrag->cycled) {
341                 /*
342                  * we didn't fill our defrag batch, but
343                  * we didn't start at zero.  Make sure we loop
344                  * around to the start of the file.
345                  */
346                 defrag->last_offset = 0;
347                 defrag->cycled = 1;
348                 btrfs_requeue_inode_defrag(inode, defrag);
349         } else {
350                 kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
351         }
352
353         iput(inode);
354         return 0;
355 cleanup:
356         srcu_read_unlock(&fs_info->subvol_srcu, index);
357         kmem_cache_free(btrfs_inode_defrag_cachep, defrag);
358         return ret;
359 }
360
361 /*
362  * run through the list of inodes in the FS that need
363  * defragging
364  */
365 int btrfs_run_defrag_inodes(struct btrfs_fs_info *fs_info)
366 {
367         struct inode_defrag *defrag;
368         u64 first_ino = 0;
369         u64 root_objectid = 0;
370
371         atomic_inc(&fs_info->defrag_running);
372         while (1) {
373                 /* Pause the auto defragger. */
374                 if (test_bit(BTRFS_FS_STATE_REMOUNTING,
375                              &fs_info->fs_state))
376                         break;
377
378                 if (!__need_auto_defrag(fs_info->tree_root))
379                         break;
380
381                 /* find an inode to defrag */
382                 defrag = btrfs_pick_defrag_inode(fs_info, root_objectid,
383                                                  first_ino);
384                 if (!defrag) {
385                         if (root_objectid || first_ino) {
386                                 root_objectid = 0;
387                                 first_ino = 0;
388                                 continue;
389                         } else {
390                                 break;
391                         }
392                 }
393
394                 first_ino = defrag->ino + 1;
395                 root_objectid = defrag->root;
396
397                 __btrfs_run_defrag_inode(fs_info, defrag);
398         }
399         atomic_dec(&fs_info->defrag_running);
400
401         /*
402          * during unmount, we use the transaction_wait queue to
403          * wait for the defragger to stop
404          */
405         wake_up(&fs_info->transaction_wait);
406         return 0;
407 }
408
409 /* simple helper to fault in pages and copy.  This should go away
410  * and be replaced with calls into generic code.
411  */
412 static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
413                                          size_t write_bytes,
414                                          struct page **prepared_pages,
415                                          struct iov_iter *i)
416 {
417         size_t copied = 0;
418         size_t total_copied = 0;
419         int pg = 0;
420         int offset = pos & (PAGE_CACHE_SIZE - 1);
421
422         while (write_bytes > 0) {
423                 size_t count = min_t(size_t,
424                                      PAGE_CACHE_SIZE - offset, write_bytes);
425                 struct page *page = prepared_pages[pg];
426                 /*
427                  * Copy data from userspace to the current page
428                  *
429                  * Disable pagefault to avoid recursive lock since
430                  * the pages are already locked
431                  */
432                 pagefault_disable();
433                 copied = iov_iter_copy_from_user_atomic(page, i, offset, count);
434                 pagefault_enable();
435
436                 /* Flush processor's dcache for this page */
437                 flush_dcache_page(page);
438
439                 /*
440                  * if we get a partial write, we can end up with
441                  * partially up to date pages.  These add
442                  * a lot of complexity, so make sure they don't
443                  * happen by forcing this copy to be retried.
444                  *
445                  * The rest of the btrfs_file_write code will fall
446                  * back to page at a time copies after we return 0.
447                  */
448                 if (!PageUptodate(page) && copied < count)
449                         copied = 0;
450
451                 iov_iter_advance(i, copied);
452                 write_bytes -= copied;
453                 total_copied += copied;
454
455                 /* Return to btrfs_file_aio_write to fault page */
456                 if (unlikely(copied == 0))
457                         break;
458
459                 if (unlikely(copied < PAGE_CACHE_SIZE - offset)) {
460                         offset += copied;
461                 } else {
462                         pg++;
463                         offset = 0;
464                 }
465         }
466         return total_copied;
467 }
468
469 /*
470  * unlocks pages after btrfs_file_write is done with them
471  */
472 static void btrfs_drop_pages(struct page **pages, size_t num_pages)
473 {
474         size_t i;
475         for (i = 0; i < num_pages; i++) {
476                 /* page checked is some magic around finding pages that
477                  * have been modified without going through btrfs_set_page_dirty
478                  * clear it here
479                  */
480                 ClearPageChecked(pages[i]);
481                 unlock_page(pages[i]);
482                 mark_page_accessed(pages[i]);
483                 page_cache_release(pages[i]);
484         }
485 }
486
487 /*
488  * after copy_from_user, pages need to be dirtied and we need to make
489  * sure holes are created between the current EOF and the start of
490  * any next extents (if required).
491  *
492  * this also makes the decision about creating an inline extent vs
493  * doing real data extents, marking pages dirty and delalloc as required.
494  */
495 int btrfs_dirty_pages(struct btrfs_root *root, struct inode *inode,
496                              struct page **pages, size_t num_pages,
497                              loff_t pos, size_t write_bytes,
498                              struct extent_state **cached)
499 {
500         int err = 0;
501         int i;
502         u64 num_bytes;
503         u64 start_pos;
504         u64 end_of_last_block;
505         u64 end_pos = pos + write_bytes;
506         loff_t isize = i_size_read(inode);
507
508         start_pos = pos & ~((u64)root->sectorsize - 1);
509         num_bytes = ALIGN(write_bytes + pos - start_pos, root->sectorsize);
510
511         end_of_last_block = start_pos + num_bytes - 1;
512         err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
513                                         cached);
514         if (err)
515                 return err;
516
517         for (i = 0; i < num_pages; i++) {
518                 struct page *p = pages[i];
519                 SetPageUptodate(p);
520                 ClearPageChecked(p);
521                 set_page_dirty(p);
522         }
523
524         /*
525          * we've only changed i_size in ram, and we haven't updated
526          * the disk i_size.  There is no need to log the inode
527          * at this time.
528          */
529         if (end_pos > isize)
530                 i_size_write(inode, end_pos);
531         return 0;
532 }
533
534 /*
535  * this drops all the extents in the cache that intersect the range
536  * [start, end].  Existing extents are split as required.
537  */
538 void btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
539                              int skip_pinned)
540 {
541         struct extent_map *em;
542         struct extent_map *split = NULL;
543         struct extent_map *split2 = NULL;
544         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
545         u64 len = end - start + 1;
546         u64 gen;
547         int ret;
548         int testend = 1;
549         unsigned long flags;
550         int compressed = 0;
551         bool modified;
552
553         WARN_ON(end < start);
554         if (end == (u64)-1) {
555                 len = (u64)-1;
556                 testend = 0;
557         }
558         while (1) {
559                 int no_splits = 0;
560
561                 modified = false;
562                 if (!split)
563                         split = alloc_extent_map();
564                 if (!split2)
565                         split2 = alloc_extent_map();
566                 if (!split || !split2)
567                         no_splits = 1;
568
569                 write_lock(&em_tree->lock);
570                 em = lookup_extent_mapping(em_tree, start, len);
571                 if (!em) {
572                         write_unlock(&em_tree->lock);
573                         break;
574                 }
575                 flags = em->flags;
576                 gen = em->generation;
577                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
578                         if (testend && em->start + em->len >= start + len) {
579                                 free_extent_map(em);
580                                 write_unlock(&em_tree->lock);
581                                 break;
582                         }
583                         start = em->start + em->len;
584                         if (testend)
585                                 len = start + len - (em->start + em->len);
586                         free_extent_map(em);
587                         write_unlock(&em_tree->lock);
588                         continue;
589                 }
590                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
591                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
592                 clear_bit(EXTENT_FLAG_LOGGING, &flags);
593                 modified = !list_empty(&em->list);
594                 remove_extent_mapping(em_tree, em);
595                 if (no_splits)
596                         goto next;
597
598                 if (em->start < start) {
599                         split->start = em->start;
600                         split->len = start - em->start;
601
602                         if (em->block_start < EXTENT_MAP_LAST_BYTE) {
603                                 split->orig_start = em->orig_start;
604                                 split->block_start = em->block_start;
605
606                                 if (compressed)
607                                         split->block_len = em->block_len;
608                                 else
609                                         split->block_len = split->len;
610                                 split->orig_block_len = max(split->block_len,
611                                                 em->orig_block_len);
612                                 split->ram_bytes = em->ram_bytes;
613                         } else {
614                                 split->orig_start = split->start;
615                                 split->block_len = 0;
616                                 split->block_start = em->block_start;
617                                 split->orig_block_len = 0;
618                                 split->ram_bytes = split->len;
619                         }
620
621                         split->generation = gen;
622                         split->bdev = em->bdev;
623                         split->flags = flags;
624                         split->compress_type = em->compress_type;
625                         ret = add_extent_mapping(em_tree, split, modified);
626                         BUG_ON(ret); /* Logic error */
627                         free_extent_map(split);
628                         split = split2;
629                         split2 = NULL;
630                 }
631                 if (testend && em->start + em->len > start + len) {
632                         u64 diff = start + len - em->start;
633
634                         split->start = start + len;
635                         split->len = em->start + em->len - (start + len);
636                         split->bdev = em->bdev;
637                         split->flags = flags;
638                         split->compress_type = em->compress_type;
639                         split->generation = gen;
640
641                         if (em->block_start < EXTENT_MAP_LAST_BYTE) {
642                                 split->orig_block_len = max(em->block_len,
643                                                     em->orig_block_len);
644
645                                 split->ram_bytes = em->ram_bytes;
646                                 if (compressed) {
647                                         split->block_len = em->block_len;
648                                         split->block_start = em->block_start;
649                                         split->orig_start = em->orig_start;
650                                 } else {
651                                         split->block_len = split->len;
652                                         split->block_start = em->block_start
653                                                 + diff;
654                                         split->orig_start = em->orig_start;
655                                 }
656                         } else {
657                                 split->ram_bytes = split->len;
658                                 split->orig_start = split->start;
659                                 split->block_len = 0;
660                                 split->block_start = em->block_start;
661                                 split->orig_block_len = 0;
662                         }
663
664                         ret = add_extent_mapping(em_tree, split, modified);
665                         BUG_ON(ret); /* Logic error */
666                         free_extent_map(split);
667                         split = NULL;
668                 }
669 next:
670                 write_unlock(&em_tree->lock);
671
672                 /* once for us */
673                 free_extent_map(em);
674                 /* once for the tree*/
675                 free_extent_map(em);
676         }
677         if (split)
678                 free_extent_map(split);
679         if (split2)
680                 free_extent_map(split2);
681 }
682
683 /*
684  * this is very complex, but the basic idea is to drop all extents
685  * in the range start - end.  hint_block is filled in with a block number
686  * that would be a good hint to the block allocator for this file.
687  *
688  * If an extent intersects the range but is not entirely inside the range
689  * it is either truncated or split.  Anything entirely inside the range
690  * is deleted from the tree.
691  */
692 int __btrfs_drop_extents(struct btrfs_trans_handle *trans,
693                          struct btrfs_root *root, struct inode *inode,
694                          struct btrfs_path *path, u64 start, u64 end,
695                          u64 *drop_end, int drop_cache)
696 {
697         struct extent_buffer *leaf;
698         struct btrfs_file_extent_item *fi;
699         struct btrfs_key key;
700         struct btrfs_key new_key;
701         u64 ino = btrfs_ino(inode);
702         u64 search_start = start;
703         u64 disk_bytenr = 0;
704         u64 num_bytes = 0;
705         u64 extent_offset = 0;
706         u64 extent_end = 0;
707         int del_nr = 0;
708         int del_slot = 0;
709         int extent_type;
710         int recow;
711         int ret;
712         int modify_tree = -1;
713         int update_refs = (root->ref_cows || root == root->fs_info->tree_root);
714         int found = 0;
715
716         if (drop_cache)
717                 btrfs_drop_extent_cache(inode, start, end - 1, 0);
718
719         if (start >= BTRFS_I(inode)->disk_i_size)
720                 modify_tree = 0;
721
722         while (1) {
723                 recow = 0;
724                 ret = btrfs_lookup_file_extent(trans, root, path, ino,
725                                                search_start, modify_tree);
726                 if (ret < 0)
727                         break;
728                 if (ret > 0 && path->slots[0] > 0 && search_start == start) {
729                         leaf = path->nodes[0];
730                         btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
731                         if (key.objectid == ino &&
732                             key.type == BTRFS_EXTENT_DATA_KEY)
733                                 path->slots[0]--;
734                 }
735                 ret = 0;
736 next_slot:
737                 leaf = path->nodes[0];
738                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
739                         BUG_ON(del_nr > 0);
740                         ret = btrfs_next_leaf(root, path);
741                         if (ret < 0)
742                                 break;
743                         if (ret > 0) {
744                                 ret = 0;
745                                 break;
746                         }
747                         leaf = path->nodes[0];
748                         recow = 1;
749                 }
750
751                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
752                 if (key.objectid > ino ||
753                     key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end)
754                         break;
755
756                 fi = btrfs_item_ptr(leaf, path->slots[0],
757                                     struct btrfs_file_extent_item);
758                 extent_type = btrfs_file_extent_type(leaf, fi);
759
760                 if (extent_type == BTRFS_FILE_EXTENT_REG ||
761                     extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
762                         disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
763                         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
764                         extent_offset = btrfs_file_extent_offset(leaf, fi);
765                         extent_end = key.offset +
766                                 btrfs_file_extent_num_bytes(leaf, fi);
767                 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
768                         extent_end = key.offset +
769                                 btrfs_file_extent_inline_len(leaf, fi);
770                 } else {
771                         WARN_ON(1);
772                         extent_end = search_start;
773                 }
774
775                 if (extent_end <= search_start) {
776                         path->slots[0]++;
777                         goto next_slot;
778                 }
779
780                 found = 1;
781                 search_start = max(key.offset, start);
782                 if (recow || !modify_tree) {
783                         modify_tree = -1;
784                         btrfs_release_path(path);
785                         continue;
786                 }
787
788                 /*
789                  *     | - range to drop - |
790                  *  | -------- extent -------- |
791                  */
792                 if (start > key.offset && end < extent_end) {
793                         BUG_ON(del_nr > 0);
794                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
795
796                         memcpy(&new_key, &key, sizeof(new_key));
797                         new_key.offset = start;
798                         ret = btrfs_duplicate_item(trans, root, path,
799                                                    &new_key);
800                         if (ret == -EAGAIN) {
801                                 btrfs_release_path(path);
802                                 continue;
803                         }
804                         if (ret < 0)
805                                 break;
806
807                         leaf = path->nodes[0];
808                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
809                                             struct btrfs_file_extent_item);
810                         btrfs_set_file_extent_num_bytes(leaf, fi,
811                                                         start - key.offset);
812
813                         fi = btrfs_item_ptr(leaf, path->slots[0],
814                                             struct btrfs_file_extent_item);
815
816                         extent_offset += start - key.offset;
817                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
818                         btrfs_set_file_extent_num_bytes(leaf, fi,
819                                                         extent_end - start);
820                         btrfs_mark_buffer_dirty(leaf);
821
822                         if (update_refs && disk_bytenr > 0) {
823                                 ret = btrfs_inc_extent_ref(trans, root,
824                                                 disk_bytenr, num_bytes, 0,
825                                                 root->root_key.objectid,
826                                                 new_key.objectid,
827                                                 start - extent_offset, 0);
828                                 BUG_ON(ret); /* -ENOMEM */
829                         }
830                         key.offset = start;
831                 }
832                 /*
833                  *  | ---- range to drop ----- |
834                  *      | -------- extent -------- |
835                  */
836                 if (start <= key.offset && end < extent_end) {
837                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
838
839                         memcpy(&new_key, &key, sizeof(new_key));
840                         new_key.offset = end;
841                         btrfs_set_item_key_safe(root, path, &new_key);
842
843                         extent_offset += end - key.offset;
844                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
845                         btrfs_set_file_extent_num_bytes(leaf, fi,
846                                                         extent_end - end);
847                         btrfs_mark_buffer_dirty(leaf);
848                         if (update_refs && disk_bytenr > 0)
849                                 inode_sub_bytes(inode, end - key.offset);
850                         break;
851                 }
852
853                 search_start = extent_end;
854                 /*
855                  *       | ---- range to drop ----- |
856                  *  | -------- extent -------- |
857                  */
858                 if (start > key.offset && end >= extent_end) {
859                         BUG_ON(del_nr > 0);
860                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
861
862                         btrfs_set_file_extent_num_bytes(leaf, fi,
863                                                         start - key.offset);
864                         btrfs_mark_buffer_dirty(leaf);
865                         if (update_refs && disk_bytenr > 0)
866                                 inode_sub_bytes(inode, extent_end - start);
867                         if (end == extent_end)
868                                 break;
869
870                         path->slots[0]++;
871                         goto next_slot;
872                 }
873
874                 /*
875                  *  | ---- range to drop ----- |
876                  *    | ------ extent ------ |
877                  */
878                 if (start <= key.offset && end >= extent_end) {
879                         if (del_nr == 0) {
880                                 del_slot = path->slots[0];
881                                 del_nr = 1;
882                         } else {
883                                 BUG_ON(del_slot + del_nr != path->slots[0]);
884                                 del_nr++;
885                         }
886
887                         if (update_refs &&
888                             extent_type == BTRFS_FILE_EXTENT_INLINE) {
889                                 inode_sub_bytes(inode,
890                                                 extent_end - key.offset);
891                                 extent_end = ALIGN(extent_end,
892                                                    root->sectorsize);
893                         } else if (update_refs && disk_bytenr > 0) {
894                                 ret = btrfs_free_extent(trans, root,
895                                                 disk_bytenr, num_bytes, 0,
896                                                 root->root_key.objectid,
897                                                 key.objectid, key.offset -
898                                                 extent_offset, 0);
899                                 BUG_ON(ret); /* -ENOMEM */
900                                 inode_sub_bytes(inode,
901                                                 extent_end - key.offset);
902                         }
903
904                         if (end == extent_end)
905                                 break;
906
907                         if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
908                                 path->slots[0]++;
909                                 goto next_slot;
910                         }
911
912                         ret = btrfs_del_items(trans, root, path, del_slot,
913                                               del_nr);
914                         if (ret) {
915                                 btrfs_abort_transaction(trans, root, ret);
916                                 break;
917                         }
918
919                         del_nr = 0;
920                         del_slot = 0;
921
922                         btrfs_release_path(path);
923                         continue;
924                 }
925
926                 BUG_ON(1);
927         }
928
929         if (!ret && del_nr > 0) {
930                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
931                 if (ret)
932                         btrfs_abort_transaction(trans, root, ret);
933         }
934
935         if (drop_end)
936                 *drop_end = found ? min(end, extent_end) : end;
937         btrfs_release_path(path);
938         return ret;
939 }
940
941 int btrfs_drop_extents(struct btrfs_trans_handle *trans,
942                        struct btrfs_root *root, struct inode *inode, u64 start,
943                        u64 end, int drop_cache)
944 {
945         struct btrfs_path *path;
946         int ret;
947
948         path = btrfs_alloc_path();
949         if (!path)
950                 return -ENOMEM;
951         ret = __btrfs_drop_extents(trans, root, inode, path, start, end, NULL,
952                                    drop_cache);
953         btrfs_free_path(path);
954         return ret;
955 }
956
957 static int extent_mergeable(struct extent_buffer *leaf, int slot,
958                             u64 objectid, u64 bytenr, u64 orig_offset,
959                             u64 *start, u64 *end)
960 {
961         struct btrfs_file_extent_item *fi;
962         struct btrfs_key key;
963         u64 extent_end;
964
965         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
966                 return 0;
967
968         btrfs_item_key_to_cpu(leaf, &key, slot);
969         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
970                 return 0;
971
972         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
973         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
974             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
975             btrfs_file_extent_offset(leaf, fi) != key.offset - orig_offset ||
976             btrfs_file_extent_compression(leaf, fi) ||
977             btrfs_file_extent_encryption(leaf, fi) ||
978             btrfs_file_extent_other_encoding(leaf, fi))
979                 return 0;
980
981         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
982         if ((*start && *start != key.offset) || (*end && *end != extent_end))
983                 return 0;
984
985         *start = key.offset;
986         *end = extent_end;
987         return 1;
988 }
989
990 /*
991  * Mark extent in the range start - end as written.
992  *
993  * This changes extent type from 'pre-allocated' to 'regular'. If only
994  * part of extent is marked as written, the extent will be split into
995  * two or three.
996  */
997 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
998                               struct inode *inode, u64 start, u64 end)
999 {
1000         struct btrfs_root *root = BTRFS_I(inode)->root;
1001         struct extent_buffer *leaf;
1002         struct btrfs_path *path;
1003         struct btrfs_file_extent_item *fi;
1004         struct btrfs_key key;
1005         struct btrfs_key new_key;
1006         u64 bytenr;
1007         u64 num_bytes;
1008         u64 extent_end;
1009         u64 orig_offset;
1010         u64 other_start;
1011         u64 other_end;
1012         u64 split;
1013         int del_nr = 0;
1014         int del_slot = 0;
1015         int recow;
1016         int ret;
1017         u64 ino = btrfs_ino(inode);
1018
1019         path = btrfs_alloc_path();
1020         if (!path)
1021                 return -ENOMEM;
1022 again:
1023         recow = 0;
1024         split = start;
1025         key.objectid = ino;
1026         key.type = BTRFS_EXTENT_DATA_KEY;
1027         key.offset = split;
1028
1029         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
1030         if (ret < 0)
1031                 goto out;
1032         if (ret > 0 && path->slots[0] > 0)
1033                 path->slots[0]--;
1034
1035         leaf = path->nodes[0];
1036         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
1037         BUG_ON(key.objectid != ino || key.type != BTRFS_EXTENT_DATA_KEY);
1038         fi = btrfs_item_ptr(leaf, path->slots[0],
1039                             struct btrfs_file_extent_item);
1040         BUG_ON(btrfs_file_extent_type(leaf, fi) !=
1041                BTRFS_FILE_EXTENT_PREALLOC);
1042         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
1043         BUG_ON(key.offset > start || extent_end < end);
1044
1045         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
1046         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
1047         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
1048         memcpy(&new_key, &key, sizeof(new_key));
1049
1050         if (start == key.offset && end < extent_end) {
1051                 other_start = 0;
1052                 other_end = start;
1053                 if (extent_mergeable(leaf, path->slots[0] - 1,
1054                                      ino, bytenr, orig_offset,
1055                                      &other_start, &other_end)) {
1056                         new_key.offset = end;
1057                         btrfs_set_item_key_safe(root, path, &new_key);
1058                         fi = btrfs_item_ptr(leaf, path->slots[0],
1059                                             struct btrfs_file_extent_item);
1060                         btrfs_set_file_extent_generation(leaf, fi,
1061                                                          trans->transid);
1062                         btrfs_set_file_extent_num_bytes(leaf, fi,
1063                                                         extent_end - end);
1064                         btrfs_set_file_extent_offset(leaf, fi,
1065                                                      end - orig_offset);
1066                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
1067                                             struct btrfs_file_extent_item);
1068                         btrfs_set_file_extent_generation(leaf, fi,
1069                                                          trans->transid);
1070                         btrfs_set_file_extent_num_bytes(leaf, fi,
1071                                                         end - other_start);
1072                         btrfs_mark_buffer_dirty(leaf);
1073                         goto out;
1074                 }
1075         }
1076
1077         if (start > key.offset && end == extent_end) {
1078                 other_start = end;
1079                 other_end = 0;
1080                 if (extent_mergeable(leaf, path->slots[0] + 1,
1081                                      ino, bytenr, orig_offset,
1082                                      &other_start, &other_end)) {
1083                         fi = btrfs_item_ptr(leaf, path->slots[0],
1084                                             struct btrfs_file_extent_item);
1085                         btrfs_set_file_extent_num_bytes(leaf, fi,
1086                                                         start - key.offset);
1087                         btrfs_set_file_extent_generation(leaf, fi,
1088                                                          trans->transid);
1089                         path->slots[0]++;
1090                         new_key.offset = start;
1091                         btrfs_set_item_key_safe(root, path, &new_key);
1092
1093                         fi = btrfs_item_ptr(leaf, path->slots[0],
1094                                             struct btrfs_file_extent_item);
1095                         btrfs_set_file_extent_generation(leaf, fi,
1096                                                          trans->transid);
1097                         btrfs_set_file_extent_num_bytes(leaf, fi,
1098                                                         other_end - start);
1099                         btrfs_set_file_extent_offset(leaf, fi,
1100                                                      start - orig_offset);
1101                         btrfs_mark_buffer_dirty(leaf);
1102                         goto out;
1103                 }
1104         }
1105
1106         while (start > key.offset || end < extent_end) {
1107                 if (key.offset == start)
1108                         split = end;
1109
1110                 new_key.offset = split;
1111                 ret = btrfs_duplicate_item(trans, root, path, &new_key);
1112                 if (ret == -EAGAIN) {
1113                         btrfs_release_path(path);
1114                         goto again;
1115                 }
1116                 if (ret < 0) {
1117                         btrfs_abort_transaction(trans, root, ret);
1118                         goto out;
1119                 }
1120
1121                 leaf = path->nodes[0];
1122                 fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
1123                                     struct btrfs_file_extent_item);
1124                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1125                 btrfs_set_file_extent_num_bytes(leaf, fi,
1126                                                 split - key.offset);
1127
1128                 fi = btrfs_item_ptr(leaf, path->slots[0],
1129                                     struct btrfs_file_extent_item);
1130
1131                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1132                 btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
1133                 btrfs_set_file_extent_num_bytes(leaf, fi,
1134                                                 extent_end - split);
1135                 btrfs_mark_buffer_dirty(leaf);
1136
1137                 ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
1138                                            root->root_key.objectid,
1139                                            ino, orig_offset, 0);
1140                 BUG_ON(ret); /* -ENOMEM */
1141
1142                 if (split == start) {
1143                         key.offset = start;
1144                 } else {
1145                         BUG_ON(start != key.offset);
1146                         path->slots[0]--;
1147                         extent_end = end;
1148                 }
1149                 recow = 1;
1150         }
1151
1152         other_start = end;
1153         other_end = 0;
1154         if (extent_mergeable(leaf, path->slots[0] + 1,
1155                              ino, bytenr, orig_offset,
1156                              &other_start, &other_end)) {
1157                 if (recow) {
1158                         btrfs_release_path(path);
1159                         goto again;
1160                 }
1161                 extent_end = other_end;
1162                 del_slot = path->slots[0] + 1;
1163                 del_nr++;
1164                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1165                                         0, root->root_key.objectid,
1166                                         ino, orig_offset, 0);
1167                 BUG_ON(ret); /* -ENOMEM */
1168         }
1169         other_start = 0;
1170         other_end = start;
1171         if (extent_mergeable(leaf, path->slots[0] - 1,
1172                              ino, bytenr, orig_offset,
1173                              &other_start, &other_end)) {
1174                 if (recow) {
1175                         btrfs_release_path(path);
1176                         goto again;
1177                 }
1178                 key.offset = other_start;
1179                 del_slot = path->slots[0];
1180                 del_nr++;
1181                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
1182                                         0, root->root_key.objectid,
1183                                         ino, orig_offset, 0);
1184                 BUG_ON(ret); /* -ENOMEM */
1185         }
1186         if (del_nr == 0) {
1187                 fi = btrfs_item_ptr(leaf, path->slots[0],
1188                            struct btrfs_file_extent_item);
1189                 btrfs_set_file_extent_type(leaf, fi,
1190                                            BTRFS_FILE_EXTENT_REG);
1191                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1192                 btrfs_mark_buffer_dirty(leaf);
1193         } else {
1194                 fi = btrfs_item_ptr(leaf, del_slot - 1,
1195                            struct btrfs_file_extent_item);
1196                 btrfs_set_file_extent_type(leaf, fi,
1197                                            BTRFS_FILE_EXTENT_REG);
1198                 btrfs_set_file_extent_generation(leaf, fi, trans->transid);
1199                 btrfs_set_file_extent_num_bytes(leaf, fi,
1200                                                 extent_end - key.offset);
1201                 btrfs_mark_buffer_dirty(leaf);
1202
1203                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
1204                 if (ret < 0) {
1205                         btrfs_abort_transaction(trans, root, ret);
1206                         goto out;
1207                 }
1208         }
1209 out:
1210         btrfs_free_path(path);
1211         return 0;
1212 }
1213
1214 /*
1215  * on error we return an unlocked page and the error value
1216  * on success we return a locked page and 0
1217  */
1218 static int prepare_uptodate_page(struct page *page, u64 pos,
1219                                  bool force_uptodate)
1220 {
1221         int ret = 0;
1222
1223         if (((pos & (PAGE_CACHE_SIZE - 1)) || force_uptodate) &&
1224             !PageUptodate(page)) {
1225                 ret = btrfs_readpage(NULL, page);
1226                 if (ret)
1227                         return ret;
1228                 lock_page(page);
1229                 if (!PageUptodate(page)) {
1230                         unlock_page(page);
1231                         return -EIO;
1232                 }
1233         }
1234         return 0;
1235 }
1236
1237 /*
1238  * this just gets pages into the page cache and locks them down.
1239  */
1240 static noinline int prepare_pages(struct inode *inode, struct page **pages,
1241                                   size_t num_pages, loff_t pos,
1242                                   size_t write_bytes, bool force_uptodate)
1243 {
1244         int i;
1245         unsigned long index = pos >> PAGE_CACHE_SHIFT;
1246         gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);
1247         int err;
1248         int faili;
1249
1250         for (i = 0; i < num_pages; i++) {
1251                 pages[i] = find_or_create_page(inode->i_mapping, index + i,
1252                                                mask | __GFP_WRITE);
1253                 if (!pages[i]) {
1254                         faili = i - 1;
1255                         err = -ENOMEM;
1256                         goto fail;
1257                 }
1258
1259                 if (i == 0)
1260                         err = prepare_uptodate_page(pages[i], pos,
1261                                                     force_uptodate);
1262                 if (i == num_pages - 1)
1263                         err = prepare_uptodate_page(pages[i],
1264                                                     pos + write_bytes, false);
1265                 if (err) {
1266                         page_cache_release(pages[i]);
1267                         faili = i - 1;
1268                         goto fail;
1269                 }
1270                 wait_on_page_writeback(pages[i]);
1271         }
1272
1273         return 0;
1274 fail:
1275         while (faili >= 0) {
1276                 unlock_page(pages[faili]);
1277                 page_cache_release(pages[faili]);
1278                 faili--;
1279         }
1280         return err;
1281
1282 }
1283
1284 /*
1285  * This function locks the extent and properly waits for data=ordered extents
1286  * to finish before allowing the pages to be modified if need.
1287  *
1288  * The return value:
1289  * 1 - the extent is locked
1290  * 0 - the extent is not locked, and everything is OK
1291  * -EAGAIN - need re-prepare the pages
1292  * the other < 0 number - Something wrong happens
1293  */
1294 static noinline int
1295 lock_and_cleanup_extent_if_need(struct inode *inode, struct page **pages,
1296                                 size_t num_pages, loff_t pos,
1297                                 u64 *lockstart, u64 *lockend,
1298                                 struct extent_state **cached_state)
1299 {
1300         u64 start_pos;
1301         u64 last_pos;
1302         int i;
1303         int ret = 0;
1304
1305         start_pos = pos & ~((u64)PAGE_CACHE_SIZE - 1);
1306         last_pos = start_pos + ((u64)num_pages << PAGE_CACHE_SHIFT) - 1;
1307
1308         if (start_pos < inode->i_size) {
1309                 struct btrfs_ordered_extent *ordered;
1310                 lock_extent_bits(&BTRFS_I(inode)->io_tree,
1311                                  start_pos, last_pos, 0, cached_state);
1312                 ordered = btrfs_lookup_first_ordered_extent(inode, last_pos);
1313                 if (ordered &&
1314                     ordered->file_offset + ordered->len > start_pos &&
1315                     ordered->file_offset <= last_pos) {
1316                         btrfs_put_ordered_extent(ordered);
1317                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1318                                              start_pos, last_pos,
1319                                              cached_state, GFP_NOFS);
1320                         for (i = 0; i < num_pages; i++) {
1321                                 unlock_page(pages[i]);
1322                                 page_cache_release(pages[i]);
1323                         }
1324                         ret = btrfs_wait_ordered_range(inode, start_pos,
1325                                                 last_pos - start_pos + 1);
1326                         if (ret)
1327                                 return ret;
1328                         else
1329                                 return -EAGAIN;
1330                 }
1331                 if (ordered)
1332                         btrfs_put_ordered_extent(ordered);
1333
1334                 clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos,
1335                                   last_pos, EXTENT_DIRTY | EXTENT_DELALLOC |
1336                                   EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
1337                                   0, 0, cached_state, GFP_NOFS);
1338                 *lockstart = start_pos;
1339                 *lockend = last_pos;
1340                 ret = 1;
1341         }
1342
1343         for (i = 0; i < num_pages; i++) {
1344                 if (clear_page_dirty_for_io(pages[i]))
1345                         account_page_redirty(pages[i]);
1346                 set_page_extent_mapped(pages[i]);
1347                 WARN_ON(!PageLocked(pages[i]));
1348         }
1349
1350         return ret;
1351 }
1352
1353 static noinline int check_can_nocow(struct inode *inode, loff_t pos,
1354                                     size_t *write_bytes)
1355 {
1356         struct btrfs_root *root = BTRFS_I(inode)->root;
1357         struct btrfs_ordered_extent *ordered;
1358         u64 lockstart, lockend;
1359         u64 num_bytes;
1360         int ret;
1361
1362         lockstart = round_down(pos, root->sectorsize);
1363         lockend = lockstart + round_up(*write_bytes, root->sectorsize) - 1;
1364
1365         while (1) {
1366                 lock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend);
1367                 ordered = btrfs_lookup_ordered_range(inode, lockstart,
1368                                                      lockend - lockstart + 1);
1369                 if (!ordered) {
1370                         break;
1371                 }
1372                 unlock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend);
1373                 btrfs_start_ordered_extent(inode, ordered, 1);
1374                 btrfs_put_ordered_extent(ordered);
1375         }
1376
1377         num_bytes = lockend - lockstart + 1;
1378         ret = can_nocow_extent(inode, lockstart, &num_bytes, NULL, NULL, NULL);
1379         if (ret <= 0) {
1380                 ret = 0;
1381         } else {
1382                 clear_extent_bit(&BTRFS_I(inode)->io_tree, lockstart, lockend,
1383                                  EXTENT_DIRTY | EXTENT_DELALLOC |
1384                                  EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, 0, 0,
1385                                  NULL, GFP_NOFS);
1386                 *write_bytes = min_t(size_t, *write_bytes, num_bytes);
1387         }
1388
1389         unlock_extent(&BTRFS_I(inode)->io_tree, lockstart, lockend);
1390
1391         return ret;
1392 }
1393
1394 static noinline ssize_t __btrfs_buffered_write(struct file *file,
1395                                                struct iov_iter *i,
1396                                                loff_t pos)
1397 {
1398         struct inode *inode = file_inode(file);
1399         struct btrfs_root *root = BTRFS_I(inode)->root;
1400         struct page **pages = NULL;
1401         struct extent_state *cached_state = NULL;
1402         u64 release_bytes = 0;
1403         u64 lockstart;
1404         u64 lockend;
1405         unsigned long first_index;
1406         size_t num_written = 0;
1407         int nrptrs;
1408         int ret = 0;
1409         bool only_release_metadata = false;
1410         bool force_page_uptodate = false;
1411         bool need_unlock;
1412
1413         nrptrs = min((iov_iter_count(i) + PAGE_CACHE_SIZE - 1) /
1414                      PAGE_CACHE_SIZE, PAGE_CACHE_SIZE /
1415                      (sizeof(struct page *)));
1416         nrptrs = min(nrptrs, current->nr_dirtied_pause - current->nr_dirtied);
1417         nrptrs = max(nrptrs, 8);
1418         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
1419         if (!pages)
1420                 return -ENOMEM;
1421
1422         first_index = pos >> PAGE_CACHE_SHIFT;
1423
1424         while (iov_iter_count(i) > 0) {
1425                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
1426                 size_t write_bytes = min(iov_iter_count(i),
1427                                          nrptrs * (size_t)PAGE_CACHE_SIZE -
1428                                          offset);
1429                 size_t num_pages = (write_bytes + offset +
1430                                     PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1431                 size_t reserve_bytes;
1432                 size_t dirty_pages;
1433                 size_t copied;
1434
1435                 WARN_ON(num_pages > nrptrs);
1436
1437                 /*
1438                  * Fault pages before locking them in prepare_pages
1439                  * to avoid recursive lock
1440                  */
1441                 if (unlikely(iov_iter_fault_in_readable(i, write_bytes))) {
1442                         ret = -EFAULT;
1443                         break;
1444                 }
1445
1446                 reserve_bytes = num_pages << PAGE_CACHE_SHIFT;
1447                 ret = btrfs_check_data_free_space(inode, reserve_bytes);
1448                 if (ret == -ENOSPC &&
1449                     (BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW |
1450                                               BTRFS_INODE_PREALLOC))) {
1451                         ret = check_can_nocow(inode, pos, &write_bytes);
1452                         if (ret > 0) {
1453                                 only_release_metadata = true;
1454                                 /*
1455                                  * our prealloc extent may be smaller than
1456                                  * write_bytes, so scale down.
1457                                  */
1458                                 num_pages = (write_bytes + offset +
1459                                              PAGE_CACHE_SIZE - 1) >>
1460                                         PAGE_CACHE_SHIFT;
1461                                 reserve_bytes = num_pages << PAGE_CACHE_SHIFT;
1462                                 ret = 0;
1463                         } else {
1464                                 ret = -ENOSPC;
1465                         }
1466                 }
1467
1468                 if (ret)
1469                         break;
1470
1471                 ret = btrfs_delalloc_reserve_metadata(inode, reserve_bytes);
1472                 if (ret) {
1473                         if (!only_release_metadata)
1474                                 btrfs_free_reserved_data_space(inode,
1475                                                                reserve_bytes);
1476                         break;
1477                 }
1478
1479                 release_bytes = reserve_bytes;
1480                 need_unlock = false;
1481 again:
1482                 /*
1483                  * This is going to setup the pages array with the number of
1484                  * pages we want, so we don't really need to worry about the
1485                  * contents of pages from loop to loop
1486                  */
1487                 ret = prepare_pages(inode, pages, num_pages,
1488                                     pos, write_bytes,
1489                                     force_page_uptodate);
1490                 if (ret)
1491                         break;
1492
1493                 ret = lock_and_cleanup_extent_if_need(inode, pages, num_pages,
1494                                                       pos, &lockstart, &lockend,
1495                                                       &cached_state);
1496                 if (ret < 0) {
1497                         if (ret == -EAGAIN)
1498                                 goto again;
1499                         break;
1500                 } else if (ret > 0) {
1501                         need_unlock = true;
1502                         ret = 0;
1503                 }
1504
1505                 copied = btrfs_copy_from_user(pos, num_pages,
1506                                            write_bytes, pages, i);
1507
1508                 /*
1509                  * if we have trouble faulting in the pages, fall
1510                  * back to one page at a time
1511                  */
1512                 if (copied < write_bytes)
1513                         nrptrs = 1;
1514
1515                 if (copied == 0) {
1516                         force_page_uptodate = true;
1517                         dirty_pages = 0;
1518                 } else {
1519                         force_page_uptodate = false;
1520                         dirty_pages = (copied + offset +
1521                                        PAGE_CACHE_SIZE - 1) >>
1522                                        PAGE_CACHE_SHIFT;
1523                 }
1524
1525                 /*
1526                  * If we had a short copy we need to release the excess delaloc
1527                  * bytes we reserved.  We need to increment outstanding_extents
1528                  * because btrfs_delalloc_release_space will decrement it, but
1529                  * we still have an outstanding extent for the chunk we actually
1530                  * managed to copy.
1531                  */
1532                 if (num_pages > dirty_pages) {
1533                         release_bytes = (num_pages - dirty_pages) <<
1534                                 PAGE_CACHE_SHIFT;
1535                         if (copied > 0) {
1536                                 spin_lock(&BTRFS_I(inode)->lock);
1537                                 BTRFS_I(inode)->outstanding_extents++;
1538                                 spin_unlock(&BTRFS_I(inode)->lock);
1539                         }
1540                         if (only_release_metadata)
1541                                 btrfs_delalloc_release_metadata(inode,
1542                                                                 release_bytes);
1543                         else
1544                                 btrfs_delalloc_release_space(inode,
1545                                                              release_bytes);
1546                 }
1547
1548                 release_bytes = dirty_pages << PAGE_CACHE_SHIFT;
1549
1550                 if (copied > 0)
1551                         ret = btrfs_dirty_pages(root, inode, pages,
1552                                                 dirty_pages, pos, copied,
1553                                                 NULL);
1554                 if (need_unlock)
1555                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1556                                              lockstart, lockend, &cached_state,
1557                                              GFP_NOFS);
1558                 btrfs_drop_pages(pages, num_pages);
1559                 if (ret)
1560                         break;
1561
1562                 release_bytes = 0;
1563                 if (only_release_metadata && copied > 0) {
1564                         u64 lockstart = round_down(pos, root->sectorsize);
1565                         u64 lockend = lockstart +
1566                                 (dirty_pages << PAGE_CACHE_SHIFT) - 1;
1567
1568                         set_extent_bit(&BTRFS_I(inode)->io_tree, lockstart,
1569                                        lockend, EXTENT_NORESERVE, NULL,
1570                                        NULL, GFP_NOFS);
1571                         only_release_metadata = false;
1572                 }
1573
1574                 cond_resched();
1575
1576                 balance_dirty_pages_ratelimited(inode->i_mapping);
1577                 if (dirty_pages < (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1578                         btrfs_btree_balance_dirty(root);
1579
1580                 pos += copied;
1581                 num_written += copied;
1582         }
1583
1584         kfree(pages);
1585
1586         if (release_bytes) {
1587                 if (only_release_metadata)
1588                         btrfs_delalloc_release_metadata(inode, release_bytes);
1589                 else
1590                         btrfs_delalloc_release_space(inode, release_bytes);
1591         }
1592
1593         return num_written ? num_written : ret;
1594 }
1595
1596 static ssize_t __btrfs_direct_write(struct kiocb *iocb,
1597                                     const struct iovec *iov,
1598                                     unsigned long nr_segs, loff_t pos,
1599                                     loff_t *ppos, size_t count, size_t ocount)
1600 {
1601         struct file *file = iocb->ki_filp;
1602         struct iov_iter i;
1603         ssize_t written;
1604         ssize_t written_buffered;
1605         loff_t endbyte;
1606         int err;
1607
1608         written = generic_file_direct_write(iocb, iov, &nr_segs, pos, ppos,
1609                                             count, ocount);
1610
1611         if (written < 0 || written == count)
1612                 return written;
1613
1614         pos += written;
1615         count -= written;
1616         iov_iter_init(&i, iov, nr_segs, count, written);
1617         written_buffered = __btrfs_buffered_write(file, &i, pos);
1618         if (written_buffered < 0) {
1619                 err = written_buffered;
1620                 goto out;
1621         }
1622         endbyte = pos + written_buffered - 1;
1623         err = filemap_write_and_wait_range(file->f_mapping, pos, endbyte);
1624         if (err)
1625                 goto out;
1626         written += written_buffered;
1627         *ppos = pos + written_buffered;
1628         invalidate_mapping_pages(file->f_mapping, pos >> PAGE_CACHE_SHIFT,
1629                                  endbyte >> PAGE_CACHE_SHIFT);
1630 out:
1631         return written ? written : err;
1632 }
1633
1634 static void update_time_for_write(struct inode *inode)
1635 {
1636         struct timespec now;
1637
1638         if (IS_NOCMTIME(inode))
1639                 return;
1640
1641         now = current_fs_time(inode->i_sb);
1642         if (!timespec_equal(&inode->i_mtime, &now))
1643                 inode->i_mtime = now;
1644
1645         if (!timespec_equal(&inode->i_ctime, &now))
1646                 inode->i_ctime = now;
1647
1648         if (IS_I_VERSION(inode))
1649                 inode_inc_iversion(inode);
1650 }
1651
1652 static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
1653                                     const struct iovec *iov,
1654                                     unsigned long nr_segs, loff_t pos)
1655 {
1656         struct file *file = iocb->ki_filp;
1657         struct inode *inode = file_inode(file);
1658         struct btrfs_root *root = BTRFS_I(inode)->root;
1659         loff_t *ppos = &iocb->ki_pos;
1660         u64 start_pos;
1661         ssize_t num_written = 0;
1662         ssize_t err = 0;
1663         size_t count, ocount;
1664         bool sync = (file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host);
1665
1666         mutex_lock(&inode->i_mutex);
1667
1668         err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
1669         if (err) {
1670                 mutex_unlock(&inode->i_mutex);
1671                 goto out;
1672         }
1673         count = ocount;
1674
1675         current->backing_dev_info = inode->i_mapping->backing_dev_info;
1676         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
1677         if (err) {
1678                 mutex_unlock(&inode->i_mutex);
1679                 goto out;
1680         }
1681
1682         if (count == 0) {
1683                 mutex_unlock(&inode->i_mutex);
1684                 goto out;
1685         }
1686
1687         err = file_remove_suid(file);
1688         if (err) {
1689                 mutex_unlock(&inode->i_mutex);
1690                 goto out;
1691         }
1692
1693         /*
1694          * If BTRFS flips readonly due to some impossible error
1695          * (fs_info->fs_state now has BTRFS_SUPER_FLAG_ERROR),
1696          * although we have opened a file as writable, we have
1697          * to stop this write operation to ensure FS consistency.
1698          */
1699         if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state)) {
1700                 mutex_unlock(&inode->i_mutex);
1701                 err = -EROFS;
1702                 goto out;
1703         }
1704
1705         /*
1706          * We reserve space for updating the inode when we reserve space for the
1707          * extent we are going to write, so we will enospc out there.  We don't
1708          * need to start yet another transaction to update the inode as we will
1709          * update the inode when we finish writing whatever data we write.
1710          */
1711         update_time_for_write(inode);
1712
1713         start_pos = round_down(pos, root->sectorsize);
1714         if (start_pos > i_size_read(inode)) {
1715                 err = btrfs_cont_expand(inode, i_size_read(inode), start_pos);
1716                 if (err) {
1717                         mutex_unlock(&inode->i_mutex);
1718                         goto out;
1719                 }
1720         }
1721
1722         if (sync)
1723                 atomic_inc(&BTRFS_I(inode)->sync_writers);
1724
1725         if (unlikely(file->f_flags & O_DIRECT)) {
1726                 num_written = __btrfs_direct_write(iocb, iov, nr_segs,
1727                                                    pos, ppos, count, ocount);
1728         } else {
1729                 struct iov_iter i;
1730
1731                 iov_iter_init(&i, iov, nr_segs, count, num_written);
1732
1733                 num_written = __btrfs_buffered_write(file, &i, pos);
1734                 if (num_written > 0)
1735                         *ppos = pos + num_written;
1736         }
1737
1738         mutex_unlock(&inode->i_mutex);
1739
1740         /*
1741          * we want to make sure fsync finds this change
1742          * but we haven't joined a transaction running right now.
1743          *
1744          * Later on, someone is sure to update the inode and get the
1745          * real transid recorded.
1746          *
1747          * We set last_trans now to the fs_info generation + 1,
1748          * this will either be one more than the running transaction
1749          * or the generation used for the next transaction if there isn't
1750          * one running right now.
1751          *
1752          * We also have to set last_sub_trans to the current log transid,
1753          * otherwise subsequent syncs to a file that's been synced in this
1754          * transaction will appear to have already occured.
1755          */
1756         BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1757         BTRFS_I(inode)->last_sub_trans = root->log_transid;
1758         if (num_written > 0) {
1759                 err = generic_write_sync(file, pos, num_written);
1760                 if (err < 0 && num_written > 0)
1761                         num_written = err;
1762         }
1763
1764         if (sync)
1765                 atomic_dec(&BTRFS_I(inode)->sync_writers);
1766 out:
1767         current->backing_dev_info = NULL;
1768         return num_written ? num_written : err;
1769 }
1770
1771 int btrfs_release_file(struct inode *inode, struct file *filp)
1772 {
1773         /*
1774          * ordered_data_close is set by settattr when we are about to truncate
1775          * a file from a non-zero size to a zero size.  This tries to
1776          * flush down new bytes that may have been written if the
1777          * application were using truncate to replace a file in place.
1778          */
1779         if (test_and_clear_bit(BTRFS_INODE_ORDERED_DATA_CLOSE,
1780                                &BTRFS_I(inode)->runtime_flags)) {
1781                 struct btrfs_trans_handle *trans;
1782                 struct btrfs_root *root = BTRFS_I(inode)->root;
1783
1784                 /*
1785                  * We need to block on a committing transaction to keep us from
1786                  * throwing a ordered operation on to the list and causing
1787                  * something like sync to deadlock trying to flush out this
1788                  * inode.
1789                  */
1790                 trans = btrfs_start_transaction(root, 0);
1791                 if (IS_ERR(trans))
1792                         return PTR_ERR(trans);
1793                 btrfs_add_ordered_operation(trans, BTRFS_I(inode)->root, inode);
1794                 btrfs_end_transaction(trans, root);
1795                 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1796                         filemap_flush(inode->i_mapping);
1797         }
1798         if (filp->private_data)
1799                 btrfs_ioctl_trans_end(filp);
1800         return 0;
1801 }
1802
1803 /*
1804  * fsync call for both files and directories.  This logs the inode into
1805  * the tree log instead of forcing full commits whenever possible.
1806  *
1807  * It needs to call filemap_fdatawait so that all ordered extent updates are
1808  * in the metadata btree are up to date for copying to the log.
1809  *
1810  * It drops the inode mutex before doing the tree log commit.  This is an
1811  * important optimization for directories because holding the mutex prevents
1812  * new operations on the dir while we write to disk.
1813  */
1814 int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
1815 {
1816         struct dentry *dentry = file->f_path.dentry;
1817         struct inode *inode = dentry->d_inode;
1818         struct btrfs_root *root = BTRFS_I(inode)->root;
1819         int ret = 0;
1820         struct btrfs_trans_handle *trans;
1821         bool full_sync = 0;
1822
1823         trace_btrfs_sync_file(file, datasync);
1824
1825         /*
1826          * We write the dirty pages in the range and wait until they complete
1827          * out of the ->i_mutex. If so, we can flush the dirty pages by
1828          * multi-task, and make the performance up.  See
1829          * btrfs_wait_ordered_range for an explanation of the ASYNC check.
1830          */
1831         atomic_inc(&BTRFS_I(inode)->sync_writers);
1832         ret = filemap_fdatawrite_range(inode->i_mapping, start, end);
1833         if (!ret && test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
1834                              &BTRFS_I(inode)->runtime_flags))
1835                 ret = filemap_fdatawrite_range(inode->i_mapping, start, end);
1836         atomic_dec(&BTRFS_I(inode)->sync_writers);
1837         if (ret)
1838                 return ret;
1839
1840         mutex_lock(&inode->i_mutex);
1841
1842         /*
1843          * We flush the dirty pages again to avoid some dirty pages in the
1844          * range being left.
1845          */
1846         atomic_inc(&root->log_batch);
1847         full_sync = test_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
1848                              &BTRFS_I(inode)->runtime_flags);
1849         if (full_sync) {
1850                 ret = btrfs_wait_ordered_range(inode, start, end - start + 1);
1851                 if (ret) {
1852                         mutex_unlock(&inode->i_mutex);
1853                         goto out;
1854                 }
1855         }
1856         atomic_inc(&root->log_batch);
1857
1858         /*
1859          * check the transaction that last modified this inode
1860          * and see if its already been committed
1861          */
1862         if (!BTRFS_I(inode)->last_trans) {
1863                 mutex_unlock(&inode->i_mutex);
1864                 goto out;
1865         }
1866
1867         /*
1868          * if the last transaction that changed this file was before
1869          * the current transaction, we can bail out now without any
1870          * syncing
1871          */
1872         smp_mb();
1873         if (btrfs_inode_in_log(inode, root->fs_info->generation) ||
1874             BTRFS_I(inode)->last_trans <=
1875             root->fs_info->last_trans_committed) {
1876                 BTRFS_I(inode)->last_trans = 0;
1877
1878                 /*
1879                  * We'v had everything committed since the last time we were
1880                  * modified so clear this flag in case it was set for whatever
1881                  * reason, it's no longer relevant.
1882                  */
1883                 clear_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
1884                           &BTRFS_I(inode)->runtime_flags);
1885                 mutex_unlock(&inode->i_mutex);
1886                 goto out;
1887         }
1888
1889         /*
1890          * ok we haven't committed the transaction yet, lets do a commit
1891          */
1892         if (file->private_data)
1893                 btrfs_ioctl_trans_end(file);
1894
1895         trans = btrfs_start_transaction(root, 0);
1896         if (IS_ERR(trans)) {
1897                 ret = PTR_ERR(trans);
1898                 mutex_unlock(&inode->i_mutex);
1899                 goto out;
1900         }
1901
1902         ret = btrfs_log_dentry_safe(trans, root, dentry);
1903         if (ret < 0) {
1904                 /* Fallthrough and commit/free transaction. */
1905                 ret = 1;
1906         }
1907
1908         /* we've logged all the items and now have a consistent
1909          * version of the file in the log.  It is possible that
1910          * someone will come in and modify the file, but that's
1911          * fine because the log is consistent on disk, and we
1912          * have references to all of the file's extents
1913          *
1914          * It is possible that someone will come in and log the
1915          * file again, but that will end up using the synchronization
1916          * inside btrfs_sync_log to keep things safe.
1917          */
1918         mutex_unlock(&inode->i_mutex);
1919
1920         if (ret != BTRFS_NO_LOG_SYNC) {
1921                 if (!ret) {
1922                         ret = btrfs_sync_log(trans, root);
1923                         if (!ret) {
1924                                 ret = btrfs_end_transaction(trans, root);
1925                                 goto out;
1926                         }
1927                 }
1928                 if (!full_sync) {
1929                         ret = btrfs_wait_ordered_range(inode, start,
1930                                                        end - start + 1);
1931                         if (ret)
1932                                 goto out;
1933                 }
1934                 ret = btrfs_commit_transaction(trans, root);
1935         } else {
1936                 ret = btrfs_end_transaction(trans, root);
1937         }
1938 out:
1939         return ret > 0 ? -EIO : ret;
1940 }
1941
1942 static const struct vm_operations_struct btrfs_file_vm_ops = {
1943         .fault          = filemap_fault,
1944         .page_mkwrite   = btrfs_page_mkwrite,
1945         .remap_pages    = generic_file_remap_pages,
1946 };
1947
1948 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1949 {
1950         struct address_space *mapping = filp->f_mapping;
1951
1952         if (!mapping->a_ops->readpage)
1953                 return -ENOEXEC;
1954
1955         file_accessed(filp);
1956         vma->vm_ops = &btrfs_file_vm_ops;
1957
1958         return 0;
1959 }
1960
1961 static int hole_mergeable(struct inode *inode, struct extent_buffer *leaf,
1962                           int slot, u64 start, u64 end)
1963 {
1964         struct btrfs_file_extent_item *fi;
1965         struct btrfs_key key;
1966
1967         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
1968                 return 0;
1969
1970         btrfs_item_key_to_cpu(leaf, &key, slot);
1971         if (key.objectid != btrfs_ino(inode) ||
1972             key.type != BTRFS_EXTENT_DATA_KEY)
1973                 return 0;
1974
1975         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
1976
1977         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG)
1978                 return 0;
1979
1980         if (btrfs_file_extent_disk_bytenr(leaf, fi))
1981                 return 0;
1982
1983         if (key.offset == end)
1984                 return 1;
1985         if (key.offset + btrfs_file_extent_num_bytes(leaf, fi) == start)
1986                 return 1;
1987         return 0;
1988 }
1989
1990 static int fill_holes(struct btrfs_trans_handle *trans, struct inode *inode,
1991                       struct btrfs_path *path, u64 offset, u64 end)
1992 {
1993         struct btrfs_root *root = BTRFS_I(inode)->root;
1994         struct extent_buffer *leaf;
1995         struct btrfs_file_extent_item *fi;
1996         struct extent_map *hole_em;
1997         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
1998         struct btrfs_key key;
1999         int ret;
2000
2001         if (btrfs_fs_incompat(root->fs_info, NO_HOLES))
2002                 goto out;
2003
2004         key.objectid = btrfs_ino(inode);
2005         key.type = BTRFS_EXTENT_DATA_KEY;
2006         key.offset = offset;
2007
2008         ret = btrfs_search_slot(trans, root, &key, path, 0, 1);
2009         if (ret < 0)
2010                 return ret;
2011         BUG_ON(!ret);
2012
2013         leaf = path->nodes[0];
2014         if (hole_mergeable(inode, leaf, path->slots[0]-1, offset, end)) {
2015                 u64 num_bytes;
2016
2017                 path->slots[0]--;
2018                 fi = btrfs_item_ptr(leaf, path->slots[0],
2019                                     struct btrfs_file_extent_item);
2020                 num_bytes = btrfs_file_extent_num_bytes(leaf, fi) +
2021                         end - offset;
2022                 btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes);
2023                 btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
2024                 btrfs_set_file_extent_offset(leaf, fi, 0);
2025                 btrfs_mark_buffer_dirty(leaf);
2026                 goto out;
2027         }
2028
2029         if (hole_mergeable(inode, leaf, path->slots[0]+1, offset, end)) {
2030                 u64 num_bytes;
2031
2032                 path->slots[0]++;
2033                 key.offset = offset;
2034                 btrfs_set_item_key_safe(root, path, &key);
2035                 fi = btrfs_item_ptr(leaf, path->slots[0],
2036                                     struct btrfs_file_extent_item);
2037                 num_bytes = btrfs_file_extent_num_bytes(leaf, fi) + end -
2038                         offset;
2039                 btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes);
2040                 btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
2041                 btrfs_set_file_extent_offset(leaf, fi, 0);
2042                 btrfs_mark_buffer_dirty(leaf);
2043                 goto out;
2044         }
2045         btrfs_release_path(path);
2046
2047         ret = btrfs_insert_file_extent(trans, root, btrfs_ino(inode), offset,
2048                                        0, 0, end - offset, 0, end - offset,
2049                                        0, 0, 0);
2050         if (ret)
2051                 return ret;
2052
2053 out:
2054         btrfs_release_path(path);
2055
2056         hole_em = alloc_extent_map();
2057         if (!hole_em) {
2058                 btrfs_drop_extent_cache(inode, offset, end - 1, 0);
2059                 set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
2060                         &BTRFS_I(inode)->runtime_flags);
2061         } else {
2062                 hole_em->start = offset;
2063                 hole_em->len = end - offset;
2064                 hole_em->ram_bytes = hole_em->len;
2065                 hole_em->orig_start = offset;
2066
2067                 hole_em->block_start = EXTENT_MAP_HOLE;
2068                 hole_em->block_len = 0;
2069                 hole_em->orig_block_len = 0;
2070                 hole_em->bdev = root->fs_info->fs_devices->latest_bdev;
2071                 hole_em->compress_type = BTRFS_COMPRESS_NONE;
2072                 hole_em->generation = trans->transid;
2073
2074                 do {
2075                         btrfs_drop_extent_cache(inode, offset, end - 1, 0);
2076                         write_lock(&em_tree->lock);
2077                         ret = add_extent_mapping(em_tree, hole_em, 1);
2078                         write_unlock(&em_tree->lock);
2079                 } while (ret == -EEXIST);
2080                 free_extent_map(hole_em);
2081                 if (ret)
2082                         set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
2083                                 &BTRFS_I(inode)->runtime_flags);
2084         }
2085
2086         return 0;
2087 }
2088
2089 static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
2090 {
2091         struct btrfs_root *root = BTRFS_I(inode)->root;
2092         struct extent_state *cached_state = NULL;
2093         struct btrfs_path *path;
2094         struct btrfs_block_rsv *rsv;
2095         struct btrfs_trans_handle *trans;
2096         u64 lockstart = round_up(offset, BTRFS_I(inode)->root->sectorsize);
2097         u64 lockend = round_down(offset + len,
2098                                  BTRFS_I(inode)->root->sectorsize) - 1;
2099         u64 cur_offset = lockstart;
2100         u64 min_size = btrfs_calc_trunc_metadata_size(root, 1);
2101         u64 drop_end;
2102         int ret = 0;
2103         int err = 0;
2104         int rsv_count;
2105         bool same_page = ((offset >> PAGE_CACHE_SHIFT) ==
2106                           ((offset + len - 1) >> PAGE_CACHE_SHIFT));
2107         bool no_holes = btrfs_fs_incompat(root->fs_info, NO_HOLES);
2108
2109         ret = btrfs_wait_ordered_range(inode, offset, len);
2110         if (ret)
2111                 return ret;
2112
2113         mutex_lock(&inode->i_mutex);
2114         /*
2115          * We needn't truncate any page which is beyond the end of the file
2116          * because we are sure there is no data there.
2117          */
2118         /*
2119          * Only do this if we are in the same page and we aren't doing the
2120          * entire page.
2121          */
2122         if (same_page && len < PAGE_CACHE_SIZE) {
2123                 if (offset < round_up(inode->i_size, PAGE_CACHE_SIZE))
2124                         ret = btrfs_truncate_page(inode, offset, len, 0);
2125                 mutex_unlock(&inode->i_mutex);
2126                 return ret;
2127         }
2128
2129         /* zero back part of the first page */
2130         if (offset < round_up(inode->i_size, PAGE_CACHE_SIZE)) {
2131                 ret = btrfs_truncate_page(inode, offset, 0, 0);
2132                 if (ret) {
2133                         mutex_unlock(&inode->i_mutex);
2134                         return ret;
2135                 }
2136         }
2137
2138         /* zero the front end of the last page */
2139         if (offset + len < round_up(inode->i_size, PAGE_CACHE_SIZE)) {
2140                 ret = btrfs_truncate_page(inode, offset + len, 0, 1);
2141                 if (ret) {
2142                         mutex_unlock(&inode->i_mutex);
2143                         return ret;
2144                 }
2145         }
2146
2147         if (lockend < lockstart) {
2148                 mutex_unlock(&inode->i_mutex);
2149                 return 0;
2150         }
2151
2152         while (1) {
2153                 struct btrfs_ordered_extent *ordered;
2154
2155                 truncate_pagecache_range(inode, lockstart, lockend);
2156
2157                 lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend,
2158                                  0, &cached_state);
2159                 ordered = btrfs_lookup_first_ordered_extent(inode, lockend);
2160
2161                 /*
2162                  * We need to make sure we have no ordered extents in this range
2163                  * and nobody raced in and read a page in this range, if we did
2164                  * we need to try again.
2165                  */
2166                 if ((!ordered ||
2167                     (ordered->file_offset + ordered->len < lockstart ||
2168                      ordered->file_offset > lockend)) &&
2169                      !test_range_bit(&BTRFS_I(inode)->io_tree, lockstart,
2170                                      lockend, EXTENT_UPTODATE, 0,
2171                                      cached_state)) {
2172                         if (ordered)
2173                                 btrfs_put_ordered_extent(ordered);
2174                         break;
2175                 }
2176                 if (ordered)
2177                         btrfs_put_ordered_extent(ordered);
2178                 unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart,
2179                                      lockend, &cached_state, GFP_NOFS);
2180                 ret = btrfs_wait_ordered_range(inode, lockstart,
2181                                                lockend - lockstart + 1);
2182                 if (ret) {
2183                         mutex_unlock(&inode->i_mutex);
2184                         return ret;
2185                 }
2186         }
2187
2188         path = btrfs_alloc_path();
2189         if (!path) {
2190                 ret = -ENOMEM;
2191                 goto out;
2192         }
2193
2194         rsv = btrfs_alloc_block_rsv(root, BTRFS_BLOCK_RSV_TEMP);
2195         if (!rsv) {
2196                 ret = -ENOMEM;
2197                 goto out_free;
2198         }
2199         rsv->size = btrfs_calc_trunc_metadata_size(root, 1);
2200         rsv->failfast = 1;
2201
2202         /*
2203          * 1 - update the inode
2204          * 1 - removing the extents in the range
2205          * 1 - adding the hole extent if no_holes isn't set
2206          */
2207         rsv_count = no_holes ? 2 : 3;
2208         trans = btrfs_start_transaction(root, rsv_count);
2209         if (IS_ERR(trans)) {
2210                 err = PTR_ERR(trans);
2211                 goto out_free;
2212         }
2213
2214         ret = btrfs_block_rsv_migrate(&root->fs_info->trans_block_rsv, rsv,
2215                                       min_size);
2216         BUG_ON(ret);
2217         trans->block_rsv = rsv;
2218
2219         while (cur_offset < lockend) {
2220                 ret = __btrfs_drop_extents(trans, root, inode, path,
2221                                            cur_offset, lockend + 1,
2222                                            &drop_end, 1);
2223                 if (ret != -ENOSPC)
2224                         break;
2225
2226                 trans->block_rsv = &root->fs_info->trans_block_rsv;
2227
2228                 ret = fill_holes(trans, inode, path, cur_offset, drop_end);
2229                 if (ret) {
2230                         err = ret;
2231                         break;
2232                 }
2233
2234                 cur_offset = drop_end;
2235
2236                 ret = btrfs_update_inode(trans, root, inode);
2237                 if (ret) {
2238                         err = ret;
2239                         break;
2240                 }
2241
2242                 btrfs_end_transaction(trans, root);
2243                 btrfs_btree_balance_dirty(root);
2244
2245                 trans = btrfs_start_transaction(root, rsv_count);
2246                 if (IS_ERR(trans)) {
2247                         ret = PTR_ERR(trans);
2248                         trans = NULL;
2249                         break;
2250                 }
2251
2252                 ret = btrfs_block_rsv_migrate(&root->fs_info->trans_block_rsv,
2253                                               rsv, min_size);
2254                 BUG_ON(ret);    /* shouldn't happen */
2255                 trans->block_rsv = rsv;
2256         }
2257
2258         if (ret) {
2259                 err = ret;
2260                 goto out_trans;
2261         }
2262
2263         trans->block_rsv = &root->fs_info->trans_block_rsv;
2264         ret = fill_holes(trans, inode, path, cur_offset, drop_end);
2265         if (ret) {
2266                 err = ret;
2267                 goto out_trans;
2268         }
2269
2270 out_trans:
2271         if (!trans)
2272                 goto out_free;
2273
2274         inode_inc_iversion(inode);
2275         inode->i_mtime = inode->i_ctime = CURRENT_TIME;
2276
2277         trans->block_rsv = &root->fs_info->trans_block_rsv;
2278         ret = btrfs_update_inode(trans, root, inode);
2279         btrfs_end_transaction(trans, root);
2280         btrfs_btree_balance_dirty(root);
2281 out_free:
2282         btrfs_free_path(path);
2283         btrfs_free_block_rsv(root, rsv);
2284 out:
2285         unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
2286                              &cached_state, GFP_NOFS);
2287         mutex_unlock(&inode->i_mutex);
2288         if (ret && !err)
2289                 err = ret;
2290         return err;
2291 }
2292
2293 static long btrfs_fallocate(struct file *file, int mode,
2294                             loff_t offset, loff_t len)
2295 {
2296         struct inode *inode = file_inode(file);
2297         struct extent_state *cached_state = NULL;
2298         struct btrfs_root *root = BTRFS_I(inode)->root;
2299         u64 cur_offset;
2300         u64 last_byte;
2301         u64 alloc_start;
2302         u64 alloc_end;
2303         u64 alloc_hint = 0;
2304         u64 locked_end;
2305         struct extent_map *em;
2306         int blocksize = BTRFS_I(inode)->root->sectorsize;
2307         int ret;
2308
2309         alloc_start = round_down(offset, blocksize);
2310         alloc_end = round_up(offset + len, blocksize);
2311
2312         /* Make sure we aren't being give some crap mode */
2313         if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
2314                 return -EOPNOTSUPP;
2315
2316         if (mode & FALLOC_FL_PUNCH_HOLE)
2317                 return btrfs_punch_hole(inode, offset, len);
2318
2319         /*
2320          * Make sure we have enough space before we do the
2321          * allocation.
2322          */
2323         ret = btrfs_check_data_free_space(inode, alloc_end - alloc_start);
2324         if (ret)
2325                 return ret;
2326         if (root->fs_info->quota_enabled) {
2327                 ret = btrfs_qgroup_reserve(root, alloc_end - alloc_start);
2328                 if (ret)
2329                         goto out_reserve_fail;
2330         }
2331
2332         mutex_lock(&inode->i_mutex);
2333         ret = inode_newsize_ok(inode, alloc_end);
2334         if (ret)
2335                 goto out;
2336
2337         if (alloc_start > inode->i_size) {
2338                 ret = btrfs_cont_expand(inode, i_size_read(inode),
2339                                         alloc_start);
2340                 if (ret)
2341                         goto out;
2342         } else {
2343                 /*
2344                  * If we are fallocating from the end of the file onward we
2345                  * need to zero out the end of the page if i_size lands in the
2346                  * middle of a page.
2347                  */
2348                 ret = btrfs_truncate_page(inode, inode->i_size, 0, 0);
2349                 if (ret)
2350                         goto out;
2351         }
2352
2353         /*
2354          * wait for ordered IO before we have any locks.  We'll loop again
2355          * below with the locks held.
2356          */
2357         ret = btrfs_wait_ordered_range(inode, alloc_start,
2358                                        alloc_end - alloc_start);
2359         if (ret)
2360                 goto out;
2361
2362         locked_end = alloc_end - 1;
2363         while (1) {
2364                 struct btrfs_ordered_extent *ordered;
2365
2366                 /* the extent lock is ordered inside the running
2367                  * transaction
2368                  */
2369                 lock_extent_bits(&BTRFS_I(inode)->io_tree, alloc_start,
2370                                  locked_end, 0, &cached_state);
2371                 ordered = btrfs_lookup_first_ordered_extent(inode,
2372                                                             alloc_end - 1);
2373                 if (ordered &&
2374                     ordered->file_offset + ordered->len > alloc_start &&
2375                     ordered->file_offset < alloc_end) {
2376                         btrfs_put_ordered_extent(ordered);
2377                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
2378                                              alloc_start, locked_end,
2379                                              &cached_state, GFP_NOFS);
2380                         /*
2381                          * we can't wait on the range with the transaction
2382                          * running or with the extent lock held
2383                          */
2384                         ret = btrfs_wait_ordered_range(inode, alloc_start,
2385                                                        alloc_end - alloc_start);
2386                         if (ret)
2387                                 goto out;
2388                 } else {
2389                         if (ordered)
2390                                 btrfs_put_ordered_extent(ordered);
2391                         break;
2392                 }
2393         }
2394
2395         cur_offset = alloc_start;
2396         while (1) {
2397                 u64 actual_end;
2398
2399                 em = btrfs_get_extent(inode, NULL, 0, cur_offset,
2400                                       alloc_end - cur_offset, 0);
2401                 if (IS_ERR_OR_NULL(em)) {
2402                         if (!em)
2403                                 ret = -ENOMEM;
2404                         else
2405                                 ret = PTR_ERR(em);
2406                         break;
2407                 }
2408                 last_byte = min(extent_map_end(em), alloc_end);
2409                 actual_end = min_t(u64, extent_map_end(em), offset + len);
2410                 last_byte = ALIGN(last_byte, blocksize);
2411
2412                 if (em->block_start == EXTENT_MAP_HOLE ||
2413                     (cur_offset >= inode->i_size &&
2414                      !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
2415                         ret = btrfs_prealloc_file_range(inode, mode, cur_offset,
2416                                                         last_byte - cur_offset,
2417                                                         1 << inode->i_blkbits,
2418                                                         offset + len,
2419                                                         &alloc_hint);
2420
2421                         if (ret < 0) {
2422                                 free_extent_map(em);
2423                                 break;
2424                         }
2425                 } else if (actual_end > inode->i_size &&
2426                            !(mode & FALLOC_FL_KEEP_SIZE)) {
2427                         /*
2428                          * We didn't need to allocate any more space, but we
2429                          * still extended the size of the file so we need to
2430                          * update i_size.
2431                          */
2432                         inode->i_ctime = CURRENT_TIME;
2433                         i_size_write(inode, actual_end);
2434                         btrfs_ordered_update_i_size(inode, actual_end, NULL);
2435                 }
2436                 free_extent_map(em);
2437
2438                 cur_offset = last_byte;
2439                 if (cur_offset >= alloc_end) {
2440                         ret = 0;
2441                         break;
2442                 }
2443         }
2444         unlock_extent_cached(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
2445                              &cached_state, GFP_NOFS);
2446 out:
2447         mutex_unlock(&inode->i_mutex);
2448         if (root->fs_info->quota_enabled)
2449                 btrfs_qgroup_free(root, alloc_end - alloc_start);
2450 out_reserve_fail:
2451         /* Let go of our reservation. */
2452         btrfs_free_reserved_data_space(inode, alloc_end - alloc_start);
2453         return ret;
2454 }
2455
2456 static int find_desired_extent(struct inode *inode, loff_t *offset, int whence)
2457 {
2458         struct btrfs_root *root = BTRFS_I(inode)->root;
2459         struct extent_map *em = NULL;
2460         struct extent_state *cached_state = NULL;
2461         u64 lockstart = *offset;
2462         u64 lockend = i_size_read(inode);
2463         u64 start = *offset;
2464         u64 len = i_size_read(inode);
2465         int ret = 0;
2466
2467         lockend = max_t(u64, root->sectorsize, lockend);
2468         if (lockend <= lockstart)
2469                 lockend = lockstart + root->sectorsize;
2470
2471         lockend--;
2472         len = lockend - lockstart + 1;
2473
2474         len = max_t(u64, len, root->sectorsize);
2475         if (inode->i_size == 0)
2476                 return -ENXIO;
2477
2478         lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend, 0,
2479                          &cached_state);
2480
2481         while (start < inode->i_size) {
2482                 em = btrfs_get_extent_fiemap(inode, NULL, 0, start, len, 0);
2483                 if (IS_ERR(em)) {
2484                         ret = PTR_ERR(em);
2485                         em = NULL;
2486                         break;
2487                 }
2488
2489                 if (whence == SEEK_HOLE &&
2490                     (em->block_start == EXTENT_MAP_HOLE ||
2491                      test_bit(EXTENT_FLAG_PREALLOC, &em->flags)))
2492                         break;
2493                 else if (whence == SEEK_DATA &&
2494                            (em->block_start != EXTENT_MAP_HOLE &&
2495                             !test_bit(EXTENT_FLAG_PREALLOC, &em->flags)))
2496                         break;
2497
2498                 start = em->start + em->len;
2499                 free_extent_map(em);
2500                 em = NULL;
2501                 cond_resched();
2502         }
2503         free_extent_map(em);
2504         if (!ret) {
2505                 if (whence == SEEK_DATA && start >= inode->i_size)
2506                         ret = -ENXIO;
2507                 else
2508                         *offset = min_t(loff_t, start, inode->i_size);
2509         }
2510         unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
2511                              &cached_state, GFP_NOFS);
2512         return ret;
2513 }
2514
2515 static loff_t btrfs_file_llseek(struct file *file, loff_t offset, int whence)
2516 {
2517         struct inode *inode = file->f_mapping->host;
2518         int ret;
2519
2520         mutex_lock(&inode->i_mutex);
2521         switch (whence) {
2522         case SEEK_END:
2523         case SEEK_CUR:
2524                 offset = generic_file_llseek(file, offset, whence);
2525                 goto out;
2526         case SEEK_DATA:
2527         case SEEK_HOLE:
2528                 if (offset >= i_size_read(inode)) {
2529                         mutex_unlock(&inode->i_mutex);
2530                         return -ENXIO;
2531                 }
2532
2533                 ret = find_desired_extent(inode, &offset, whence);
2534                 if (ret) {
2535                         mutex_unlock(&inode->i_mutex);
2536                         return ret;
2537                 }
2538         }
2539
2540         offset = vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
2541 out:
2542         mutex_unlock(&inode->i_mutex);
2543         return offset;
2544 }
2545
2546 const struct file_operations btrfs_file_operations = {
2547         .llseek         = btrfs_file_llseek,
2548         .read           = do_sync_read,
2549         .write          = do_sync_write,
2550         .aio_read       = generic_file_aio_read,
2551         .splice_read    = generic_file_splice_read,
2552         .aio_write      = btrfs_file_aio_write,
2553         .mmap           = btrfs_file_mmap,
2554         .open           = generic_file_open,
2555         .release        = btrfs_release_file,
2556         .fsync          = btrfs_sync_file,
2557         .fallocate      = btrfs_fallocate,
2558         .unlocked_ioctl = btrfs_ioctl,
2559 #ifdef CONFIG_COMPAT
2560         .compat_ioctl   = btrfs_ioctl,
2561 #endif
2562 };
2563
2564 void btrfs_auto_defrag_exit(void)
2565 {
2566         if (btrfs_inode_defrag_cachep)
2567                 kmem_cache_destroy(btrfs_inode_defrag_cachep);
2568 }
2569
2570 int btrfs_auto_defrag_init(void)
2571 {
2572         btrfs_inode_defrag_cachep = kmem_cache_create("btrfs_inode_defrag",
2573                                         sizeof(struct inode_defrag), 0,
2574                                         SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
2575                                         NULL);
2576         if (!btrfs_inode_defrag_cachep)
2577                 return -ENOMEM;
2578
2579         return 0;
2580 }