Merge git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable
[pandora-kernel.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/falloc.h>
28 #include <linux/swap.h>
29 #include <linux/writeback.h>
30 #include <linux/statfs.h>
31 #include <linux/compat.h>
32 #include <linux/slab.h>
33 #include "ctree.h"
34 #include "disk-io.h"
35 #include "transaction.h"
36 #include "btrfs_inode.h"
37 #include "ioctl.h"
38 #include "print-tree.h"
39 #include "tree-log.h"
40 #include "locking.h"
41 #include "compat.h"
42
43
44 /* simple helper to fault in pages and copy.  This should go away
45  * and be replaced with calls into generic code.
46  */
47 static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
48                                          int write_bytes,
49                                          struct page **prepared_pages,
50                                          struct iov_iter *i)
51 {
52         size_t copied = 0;
53         int pg = 0;
54         int offset = pos & (PAGE_CACHE_SIZE - 1);
55         int total_copied = 0;
56
57         while (write_bytes > 0) {
58                 size_t count = min_t(size_t,
59                                      PAGE_CACHE_SIZE - offset, write_bytes);
60                 struct page *page = prepared_pages[pg];
61                 /*
62                  * Copy data from userspace to the current page
63                  *
64                  * Disable pagefault to avoid recursive lock since
65                  * the pages are already locked
66                  */
67                 pagefault_disable();
68                 copied = iov_iter_copy_from_user_atomic(page, i, offset, count);
69                 pagefault_enable();
70
71                 /* Flush processor's dcache for this page */
72                 flush_dcache_page(page);
73                 iov_iter_advance(i, copied);
74                 write_bytes -= copied;
75                 total_copied += copied;
76
77                 /* Return to btrfs_file_aio_write to fault page */
78                 if (unlikely(copied == 0)) {
79                         break;
80                 }
81
82                 if (unlikely(copied < PAGE_CACHE_SIZE - offset)) {
83                         offset += copied;
84                 } else {
85                         pg++;
86                         offset = 0;
87                 }
88         }
89         return total_copied;
90 }
91
92 /*
93  * unlocks pages after btrfs_file_write is done with them
94  */
95 static noinline void btrfs_drop_pages(struct page **pages, size_t num_pages)
96 {
97         size_t i;
98         for (i = 0; i < num_pages; i++) {
99                 if (!pages[i])
100                         break;
101                 /* page checked is some magic around finding pages that
102                  * have been modified without going through btrfs_set_page_dirty
103                  * clear it here
104                  */
105                 ClearPageChecked(pages[i]);
106                 unlock_page(pages[i]);
107                 mark_page_accessed(pages[i]);
108                 page_cache_release(pages[i]);
109         }
110 }
111
112 /*
113  * after copy_from_user, pages need to be dirtied and we need to make
114  * sure holes are created between the current EOF and the start of
115  * any next extents (if required).
116  *
117  * this also makes the decision about creating an inline extent vs
118  * doing real data extents, marking pages dirty and delalloc as required.
119  */
120 static noinline int dirty_and_release_pages(struct btrfs_trans_handle *trans,
121                                    struct btrfs_root *root,
122                                    struct file *file,
123                                    struct page **pages,
124                                    size_t num_pages,
125                                    loff_t pos,
126                                    size_t write_bytes)
127 {
128         int err = 0;
129         int i;
130         struct inode *inode = fdentry(file)->d_inode;
131         u64 num_bytes;
132         u64 start_pos;
133         u64 end_of_last_block;
134         u64 end_pos = pos + write_bytes;
135         loff_t isize = i_size_read(inode);
136
137         start_pos = pos & ~((u64)root->sectorsize - 1);
138         num_bytes = (write_bytes + pos - start_pos +
139                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
140
141         end_of_last_block = start_pos + num_bytes - 1;
142         err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
143                                         NULL);
144         BUG_ON(err);
145
146         for (i = 0; i < num_pages; i++) {
147                 struct page *p = pages[i];
148                 SetPageUptodate(p);
149                 ClearPageChecked(p);
150                 set_page_dirty(p);
151         }
152         if (end_pos > isize) {
153                 i_size_write(inode, end_pos);
154                 /* we've only changed i_size in ram, and we haven't updated
155                  * the disk i_size.  There is no need to log the inode
156                  * at this time.
157                  */
158         }
159         return 0;
160 }
161
162 /*
163  * this drops all the extents in the cache that intersect the range
164  * [start, end].  Existing extents are split as required.
165  */
166 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
167                             int skip_pinned)
168 {
169         struct extent_map *em;
170         struct extent_map *split = NULL;
171         struct extent_map *split2 = NULL;
172         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
173         u64 len = end - start + 1;
174         int ret;
175         int testend = 1;
176         unsigned long flags;
177         int compressed = 0;
178
179         WARN_ON(end < start);
180         if (end == (u64)-1) {
181                 len = (u64)-1;
182                 testend = 0;
183         }
184         while (1) {
185                 if (!split)
186                         split = alloc_extent_map(GFP_NOFS);
187                 if (!split2)
188                         split2 = alloc_extent_map(GFP_NOFS);
189                 BUG_ON(!split || !split2);
190
191                 write_lock(&em_tree->lock);
192                 em = lookup_extent_mapping(em_tree, start, len);
193                 if (!em) {
194                         write_unlock(&em_tree->lock);
195                         break;
196                 }
197                 flags = em->flags;
198                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
199                         if (testend && em->start + em->len >= start + len) {
200                                 free_extent_map(em);
201                                 write_unlock(&em_tree->lock);
202                                 break;
203                         }
204                         start = em->start + em->len;
205                         if (testend)
206                                 len = start + len - (em->start + em->len);
207                         free_extent_map(em);
208                         write_unlock(&em_tree->lock);
209                         continue;
210                 }
211                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
212                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
213                 remove_extent_mapping(em_tree, em);
214
215                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
216                     em->start < start) {
217                         split->start = em->start;
218                         split->len = start - em->start;
219                         split->orig_start = em->orig_start;
220                         split->block_start = em->block_start;
221
222                         if (compressed)
223                                 split->block_len = em->block_len;
224                         else
225                                 split->block_len = split->len;
226
227                         split->bdev = em->bdev;
228                         split->flags = flags;
229                         split->compress_type = em->compress_type;
230                         ret = add_extent_mapping(em_tree, split);
231                         BUG_ON(ret);
232                         free_extent_map(split);
233                         split = split2;
234                         split2 = NULL;
235                 }
236                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
237                     testend && em->start + em->len > start + len) {
238                         u64 diff = start + len - em->start;
239
240                         split->start = start + len;
241                         split->len = em->start + em->len - (start + len);
242                         split->bdev = em->bdev;
243                         split->flags = flags;
244                         split->compress_type = em->compress_type;
245
246                         if (compressed) {
247                                 split->block_len = em->block_len;
248                                 split->block_start = em->block_start;
249                                 split->orig_start = em->orig_start;
250                         } else {
251                                 split->block_len = split->len;
252                                 split->block_start = em->block_start + diff;
253                                 split->orig_start = split->start;
254                         }
255
256                         ret = add_extent_mapping(em_tree, split);
257                         BUG_ON(ret);
258                         free_extent_map(split);
259                         split = NULL;
260                 }
261                 write_unlock(&em_tree->lock);
262
263                 /* once for us */
264                 free_extent_map(em);
265                 /* once for the tree*/
266                 free_extent_map(em);
267         }
268         if (split)
269                 free_extent_map(split);
270         if (split2)
271                 free_extent_map(split2);
272         return 0;
273 }
274
275 /*
276  * this is very complex, but the basic idea is to drop all extents
277  * in the range start - end.  hint_block is filled in with a block number
278  * that would be a good hint to the block allocator for this file.
279  *
280  * If an extent intersects the range but is not entirely inside the range
281  * it is either truncated or split.  Anything entirely inside the range
282  * is deleted from the tree.
283  */
284 int btrfs_drop_extents(struct btrfs_trans_handle *trans, struct inode *inode,
285                        u64 start, u64 end, u64 *hint_byte, int drop_cache)
286 {
287         struct btrfs_root *root = BTRFS_I(inode)->root;
288         struct extent_buffer *leaf;
289         struct btrfs_file_extent_item *fi;
290         struct btrfs_path *path;
291         struct btrfs_key key;
292         struct btrfs_key new_key;
293         u64 search_start = start;
294         u64 disk_bytenr = 0;
295         u64 num_bytes = 0;
296         u64 extent_offset = 0;
297         u64 extent_end = 0;
298         int del_nr = 0;
299         int del_slot = 0;
300         int extent_type;
301         int recow;
302         int ret;
303
304         if (drop_cache)
305                 btrfs_drop_extent_cache(inode, start, end - 1, 0);
306
307         path = btrfs_alloc_path();
308         if (!path)
309                 return -ENOMEM;
310
311         while (1) {
312                 recow = 0;
313                 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
314                                                search_start, -1);
315                 if (ret < 0)
316                         break;
317                 if (ret > 0 && path->slots[0] > 0 && search_start == start) {
318                         leaf = path->nodes[0];
319                         btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1);
320                         if (key.objectid == inode->i_ino &&
321                             key.type == BTRFS_EXTENT_DATA_KEY)
322                                 path->slots[0]--;
323                 }
324                 ret = 0;
325 next_slot:
326                 leaf = path->nodes[0];
327                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
328                         BUG_ON(del_nr > 0);
329                         ret = btrfs_next_leaf(root, path);
330                         if (ret < 0)
331                                 break;
332                         if (ret > 0) {
333                                 ret = 0;
334                                 break;
335                         }
336                         leaf = path->nodes[0];
337                         recow = 1;
338                 }
339
340                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
341                 if (key.objectid > inode->i_ino ||
342                     key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end)
343                         break;
344
345                 fi = btrfs_item_ptr(leaf, path->slots[0],
346                                     struct btrfs_file_extent_item);
347                 extent_type = btrfs_file_extent_type(leaf, fi);
348
349                 if (extent_type == BTRFS_FILE_EXTENT_REG ||
350                     extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
351                         disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
352                         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
353                         extent_offset = btrfs_file_extent_offset(leaf, fi);
354                         extent_end = key.offset +
355                                 btrfs_file_extent_num_bytes(leaf, fi);
356                 } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
357                         extent_end = key.offset +
358                                 btrfs_file_extent_inline_len(leaf, fi);
359                 } else {
360                         WARN_ON(1);
361                         extent_end = search_start;
362                 }
363
364                 if (extent_end <= search_start) {
365                         path->slots[0]++;
366                         goto next_slot;
367                 }
368
369                 search_start = max(key.offset, start);
370                 if (recow) {
371                         btrfs_release_path(root, path);
372                         continue;
373                 }
374
375                 /*
376                  *     | - range to drop - |
377                  *  | -------- extent -------- |
378                  */
379                 if (start > key.offset && end < extent_end) {
380                         BUG_ON(del_nr > 0);
381                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
382
383                         memcpy(&new_key, &key, sizeof(new_key));
384                         new_key.offset = start;
385                         ret = btrfs_duplicate_item(trans, root, path,
386                                                    &new_key);
387                         if (ret == -EAGAIN) {
388                                 btrfs_release_path(root, path);
389                                 continue;
390                         }
391                         if (ret < 0)
392                                 break;
393
394                         leaf = path->nodes[0];
395                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
396                                             struct btrfs_file_extent_item);
397                         btrfs_set_file_extent_num_bytes(leaf, fi,
398                                                         start - key.offset);
399
400                         fi = btrfs_item_ptr(leaf, path->slots[0],
401                                             struct btrfs_file_extent_item);
402
403                         extent_offset += start - key.offset;
404                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
405                         btrfs_set_file_extent_num_bytes(leaf, fi,
406                                                         extent_end - start);
407                         btrfs_mark_buffer_dirty(leaf);
408
409                         if (disk_bytenr > 0) {
410                                 ret = btrfs_inc_extent_ref(trans, root,
411                                                 disk_bytenr, num_bytes, 0,
412                                                 root->root_key.objectid,
413                                                 new_key.objectid,
414                                                 start - extent_offset);
415                                 BUG_ON(ret);
416                                 *hint_byte = disk_bytenr;
417                         }
418                         key.offset = start;
419                 }
420                 /*
421                  *  | ---- range to drop ----- |
422                  *      | -------- extent -------- |
423                  */
424                 if (start <= key.offset && end < extent_end) {
425                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
426
427                         memcpy(&new_key, &key, sizeof(new_key));
428                         new_key.offset = end;
429                         btrfs_set_item_key_safe(trans, root, path, &new_key);
430
431                         extent_offset += end - key.offset;
432                         btrfs_set_file_extent_offset(leaf, fi, extent_offset);
433                         btrfs_set_file_extent_num_bytes(leaf, fi,
434                                                         extent_end - end);
435                         btrfs_mark_buffer_dirty(leaf);
436                         if (disk_bytenr > 0) {
437                                 inode_sub_bytes(inode, end - key.offset);
438                                 *hint_byte = disk_bytenr;
439                         }
440                         break;
441                 }
442
443                 search_start = extent_end;
444                 /*
445                  *       | ---- range to drop ----- |
446                  *  | -------- extent -------- |
447                  */
448                 if (start > key.offset && end >= extent_end) {
449                         BUG_ON(del_nr > 0);
450                         BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE);
451
452                         btrfs_set_file_extent_num_bytes(leaf, fi,
453                                                         start - key.offset);
454                         btrfs_mark_buffer_dirty(leaf);
455                         if (disk_bytenr > 0) {
456                                 inode_sub_bytes(inode, extent_end - start);
457                                 *hint_byte = disk_bytenr;
458                         }
459                         if (end == extent_end)
460                                 break;
461
462                         path->slots[0]++;
463                         goto next_slot;
464                 }
465
466                 /*
467                  *  | ---- range to drop ----- |
468                  *    | ------ extent ------ |
469                  */
470                 if (start <= key.offset && end >= extent_end) {
471                         if (del_nr == 0) {
472                                 del_slot = path->slots[0];
473                                 del_nr = 1;
474                         } else {
475                                 BUG_ON(del_slot + del_nr != path->slots[0]);
476                                 del_nr++;
477                         }
478
479                         if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
480                                 inode_sub_bytes(inode,
481                                                 extent_end - key.offset);
482                                 extent_end = ALIGN(extent_end,
483                                                    root->sectorsize);
484                         } else if (disk_bytenr > 0) {
485                                 ret = btrfs_free_extent(trans, root,
486                                                 disk_bytenr, num_bytes, 0,
487                                                 root->root_key.objectid,
488                                                 key.objectid, key.offset -
489                                                 extent_offset);
490                                 BUG_ON(ret);
491                                 inode_sub_bytes(inode,
492                                                 extent_end - key.offset);
493                                 *hint_byte = disk_bytenr;
494                         }
495
496                         if (end == extent_end)
497                                 break;
498
499                         if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) {
500                                 path->slots[0]++;
501                                 goto next_slot;
502                         }
503
504                         ret = btrfs_del_items(trans, root, path, del_slot,
505                                               del_nr);
506                         BUG_ON(ret);
507
508                         del_nr = 0;
509                         del_slot = 0;
510
511                         btrfs_release_path(root, path);
512                         continue;
513                 }
514
515                 BUG_ON(1);
516         }
517
518         if (del_nr > 0) {
519                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
520                 BUG_ON(ret);
521         }
522
523         btrfs_free_path(path);
524         return ret;
525 }
526
527 static int extent_mergeable(struct extent_buffer *leaf, int slot,
528                             u64 objectid, u64 bytenr, u64 orig_offset,
529                             u64 *start, u64 *end)
530 {
531         struct btrfs_file_extent_item *fi;
532         struct btrfs_key key;
533         u64 extent_end;
534
535         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
536                 return 0;
537
538         btrfs_item_key_to_cpu(leaf, &key, slot);
539         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
540                 return 0;
541
542         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
543         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
544             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
545             btrfs_file_extent_offset(leaf, fi) != key.offset - orig_offset ||
546             btrfs_file_extent_compression(leaf, fi) ||
547             btrfs_file_extent_encryption(leaf, fi) ||
548             btrfs_file_extent_other_encoding(leaf, fi))
549                 return 0;
550
551         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
552         if ((*start && *start != key.offset) || (*end && *end != extent_end))
553                 return 0;
554
555         *start = key.offset;
556         *end = extent_end;
557         return 1;
558 }
559
560 /*
561  * Mark extent in the range start - end as written.
562  *
563  * This changes extent type from 'pre-allocated' to 'regular'. If only
564  * part of extent is marked as written, the extent will be split into
565  * two or three.
566  */
567 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
568                               struct inode *inode, u64 start, u64 end)
569 {
570         struct btrfs_root *root = BTRFS_I(inode)->root;
571         struct extent_buffer *leaf;
572         struct btrfs_path *path;
573         struct btrfs_file_extent_item *fi;
574         struct btrfs_key key;
575         struct btrfs_key new_key;
576         u64 bytenr;
577         u64 num_bytes;
578         u64 extent_end;
579         u64 orig_offset;
580         u64 other_start;
581         u64 other_end;
582         u64 split;
583         int del_nr = 0;
584         int del_slot = 0;
585         int recow;
586         int ret;
587
588         btrfs_drop_extent_cache(inode, start, end - 1, 0);
589
590         path = btrfs_alloc_path();
591         BUG_ON(!path);
592 again:
593         recow = 0;
594         split = start;
595         key.objectid = inode->i_ino;
596         key.type = BTRFS_EXTENT_DATA_KEY;
597         key.offset = split;
598
599         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
600         if (ret > 0 && path->slots[0] > 0)
601                 path->slots[0]--;
602
603         leaf = path->nodes[0];
604         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
605         BUG_ON(key.objectid != inode->i_ino ||
606                key.type != BTRFS_EXTENT_DATA_KEY);
607         fi = btrfs_item_ptr(leaf, path->slots[0],
608                             struct btrfs_file_extent_item);
609         BUG_ON(btrfs_file_extent_type(leaf, fi) !=
610                BTRFS_FILE_EXTENT_PREALLOC);
611         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
612         BUG_ON(key.offset > start || extent_end < end);
613
614         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
615         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
616         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
617         memcpy(&new_key, &key, sizeof(new_key));
618
619         if (start == key.offset && end < extent_end) {
620                 other_start = 0;
621                 other_end = start;
622                 if (extent_mergeable(leaf, path->slots[0] - 1,
623                                      inode->i_ino, bytenr, orig_offset,
624                                      &other_start, &other_end)) {
625                         new_key.offset = end;
626                         btrfs_set_item_key_safe(trans, root, path, &new_key);
627                         fi = btrfs_item_ptr(leaf, path->slots[0],
628                                             struct btrfs_file_extent_item);
629                         btrfs_set_file_extent_num_bytes(leaf, fi,
630                                                         extent_end - end);
631                         btrfs_set_file_extent_offset(leaf, fi,
632                                                      end - orig_offset);
633                         fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
634                                             struct btrfs_file_extent_item);
635                         btrfs_set_file_extent_num_bytes(leaf, fi,
636                                                         end - other_start);
637                         btrfs_mark_buffer_dirty(leaf);
638                         goto out;
639                 }
640         }
641
642         if (start > key.offset && end == extent_end) {
643                 other_start = end;
644                 other_end = 0;
645                 if (extent_mergeable(leaf, path->slots[0] + 1,
646                                      inode->i_ino, bytenr, orig_offset,
647                                      &other_start, &other_end)) {
648                         fi = btrfs_item_ptr(leaf, path->slots[0],
649                                             struct btrfs_file_extent_item);
650                         btrfs_set_file_extent_num_bytes(leaf, fi,
651                                                         start - key.offset);
652                         path->slots[0]++;
653                         new_key.offset = start;
654                         btrfs_set_item_key_safe(trans, root, path, &new_key);
655
656                         fi = btrfs_item_ptr(leaf, path->slots[0],
657                                             struct btrfs_file_extent_item);
658                         btrfs_set_file_extent_num_bytes(leaf, fi,
659                                                         other_end - start);
660                         btrfs_set_file_extent_offset(leaf, fi,
661                                                      start - orig_offset);
662                         btrfs_mark_buffer_dirty(leaf);
663                         goto out;
664                 }
665         }
666
667         while (start > key.offset || end < extent_end) {
668                 if (key.offset == start)
669                         split = end;
670
671                 new_key.offset = split;
672                 ret = btrfs_duplicate_item(trans, root, path, &new_key);
673                 if (ret == -EAGAIN) {
674                         btrfs_release_path(root, path);
675                         goto again;
676                 }
677                 BUG_ON(ret < 0);
678
679                 leaf = path->nodes[0];
680                 fi = btrfs_item_ptr(leaf, path->slots[0] - 1,
681                                     struct btrfs_file_extent_item);
682                 btrfs_set_file_extent_num_bytes(leaf, fi,
683                                                 split - key.offset);
684
685                 fi = btrfs_item_ptr(leaf, path->slots[0],
686                                     struct btrfs_file_extent_item);
687
688                 btrfs_set_file_extent_offset(leaf, fi, split - orig_offset);
689                 btrfs_set_file_extent_num_bytes(leaf, fi,
690                                                 extent_end - split);
691                 btrfs_mark_buffer_dirty(leaf);
692
693                 ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
694                                            root->root_key.objectid,
695                                            inode->i_ino, orig_offset);
696                 BUG_ON(ret);
697
698                 if (split == start) {
699                         key.offset = start;
700                 } else {
701                         BUG_ON(start != key.offset);
702                         path->slots[0]--;
703                         extent_end = end;
704                 }
705                 recow = 1;
706         }
707
708         other_start = end;
709         other_end = 0;
710         if (extent_mergeable(leaf, path->slots[0] + 1,
711                              inode->i_ino, bytenr, orig_offset,
712                              &other_start, &other_end)) {
713                 if (recow) {
714                         btrfs_release_path(root, path);
715                         goto again;
716                 }
717                 extent_end = other_end;
718                 del_slot = path->slots[0] + 1;
719                 del_nr++;
720                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
721                                         0, root->root_key.objectid,
722                                         inode->i_ino, orig_offset);
723                 BUG_ON(ret);
724         }
725         other_start = 0;
726         other_end = start;
727         if (extent_mergeable(leaf, path->slots[0] - 1,
728                              inode->i_ino, bytenr, orig_offset,
729                              &other_start, &other_end)) {
730                 if (recow) {
731                         btrfs_release_path(root, path);
732                         goto again;
733                 }
734                 key.offset = other_start;
735                 del_slot = path->slots[0];
736                 del_nr++;
737                 ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
738                                         0, root->root_key.objectid,
739                                         inode->i_ino, orig_offset);
740                 BUG_ON(ret);
741         }
742         if (del_nr == 0) {
743                 fi = btrfs_item_ptr(leaf, path->slots[0],
744                            struct btrfs_file_extent_item);
745                 btrfs_set_file_extent_type(leaf, fi,
746                                            BTRFS_FILE_EXTENT_REG);
747                 btrfs_mark_buffer_dirty(leaf);
748         } else {
749                 fi = btrfs_item_ptr(leaf, del_slot - 1,
750                            struct btrfs_file_extent_item);
751                 btrfs_set_file_extent_type(leaf, fi,
752                                            BTRFS_FILE_EXTENT_REG);
753                 btrfs_set_file_extent_num_bytes(leaf, fi,
754                                                 extent_end - key.offset);
755                 btrfs_mark_buffer_dirty(leaf);
756
757                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
758                 BUG_ON(ret);
759         }
760 out:
761         btrfs_free_path(path);
762         return 0;
763 }
764
765 /*
766  * this gets pages into the page cache and locks them down, it also properly
767  * waits for data=ordered extents to finish before allowing the pages to be
768  * modified.
769  */
770 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
771                          struct page **pages, size_t num_pages,
772                          loff_t pos, unsigned long first_index,
773                          unsigned long last_index, size_t write_bytes)
774 {
775         struct extent_state *cached_state = NULL;
776         int i;
777         unsigned long index = pos >> PAGE_CACHE_SHIFT;
778         struct inode *inode = fdentry(file)->d_inode;
779         int err = 0;
780         u64 start_pos;
781         u64 last_pos;
782
783         start_pos = pos & ~((u64)root->sectorsize - 1);
784         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
785
786         if (start_pos > inode->i_size) {
787                 err = btrfs_cont_expand(inode, start_pos);
788                 if (err)
789                         return err;
790         }
791
792         memset(pages, 0, num_pages * sizeof(struct page *));
793 again:
794         for (i = 0; i < num_pages; i++) {
795                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
796                 if (!pages[i]) {
797                         int c;
798                         for (c = i - 1; c >= 0; c--) {
799                                 unlock_page(pages[c]);
800                                 page_cache_release(pages[c]);
801                         }
802                         return -ENOMEM;
803                 }
804                 wait_on_page_writeback(pages[i]);
805         }
806         if (start_pos < inode->i_size) {
807                 struct btrfs_ordered_extent *ordered;
808                 lock_extent_bits(&BTRFS_I(inode)->io_tree,
809                                  start_pos, last_pos - 1, 0, &cached_state,
810                                  GFP_NOFS);
811                 ordered = btrfs_lookup_first_ordered_extent(inode,
812                                                             last_pos - 1);
813                 if (ordered &&
814                     ordered->file_offset + ordered->len > start_pos &&
815                     ordered->file_offset < last_pos) {
816                         btrfs_put_ordered_extent(ordered);
817                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
818                                              start_pos, last_pos - 1,
819                                              &cached_state, GFP_NOFS);
820                         for (i = 0; i < num_pages; i++) {
821                                 unlock_page(pages[i]);
822                                 page_cache_release(pages[i]);
823                         }
824                         btrfs_wait_ordered_range(inode, start_pos,
825                                                  last_pos - start_pos);
826                         goto again;
827                 }
828                 if (ordered)
829                         btrfs_put_ordered_extent(ordered);
830
831                 clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos,
832                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
833                                   EXTENT_DO_ACCOUNTING, 0, 0, &cached_state,
834                                   GFP_NOFS);
835                 unlock_extent_cached(&BTRFS_I(inode)->io_tree,
836                                      start_pos, last_pos - 1, &cached_state,
837                                      GFP_NOFS);
838         }
839         for (i = 0; i < num_pages; i++) {
840                 clear_page_dirty_for_io(pages[i]);
841                 set_page_extent_mapped(pages[i]);
842                 WARN_ON(!PageLocked(pages[i]));
843         }
844         return 0;
845 }
846
847 static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
848                                     const struct iovec *iov,
849                                     unsigned long nr_segs, loff_t pos)
850 {
851         struct file *file = iocb->ki_filp;
852         struct inode *inode = fdentry(file)->d_inode;
853         struct btrfs_root *root = BTRFS_I(inode)->root;
854         struct page *pinned[2];
855         struct page **pages = NULL;
856         struct iov_iter i;
857         loff_t *ppos = &iocb->ki_pos;
858         loff_t start_pos;
859         ssize_t num_written = 0;
860         ssize_t err = 0;
861         size_t count;
862         size_t ocount;
863         int ret = 0;
864         int nrptrs;
865         unsigned long first_index;
866         unsigned long last_index;
867         int will_write;
868         int buffered = 0;
869         int copied = 0;
870         int dirty_pages = 0;
871
872         will_write = ((file->f_flags & O_DSYNC) || IS_SYNC(inode) ||
873                       (file->f_flags & O_DIRECT));
874
875         pinned[0] = NULL;
876         pinned[1] = NULL;
877
878         start_pos = pos;
879
880         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
881
882         mutex_lock(&inode->i_mutex);
883
884         err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
885         if (err)
886                 goto out;
887         count = ocount;
888
889         current->backing_dev_info = inode->i_mapping->backing_dev_info;
890         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
891         if (err)
892                 goto out;
893
894         if (count == 0)
895                 goto out;
896
897         err = file_remove_suid(file);
898         if (err)
899                 goto out;
900
901         /*
902          * If BTRFS flips readonly due to some impossible error
903          * (fs_info->fs_state now has BTRFS_SUPER_FLAG_ERROR),
904          * although we have opened a file as writable, we have
905          * to stop this write operation to ensure FS consistency.
906          */
907         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
908                 err = -EROFS;
909                 goto out;
910         }
911
912         file_update_time(file);
913         BTRFS_I(inode)->sequence++;
914
915         if (unlikely(file->f_flags & O_DIRECT)) {
916                 num_written = generic_file_direct_write(iocb, iov, &nr_segs,
917                                                         pos, ppos, count,
918                                                         ocount);
919                 /*
920                  * the generic O_DIRECT will update in-memory i_size after the
921                  * DIOs are done.  But our endio handlers that update the on
922                  * disk i_size never update past the in memory i_size.  So we
923                  * need one more update here to catch any additions to the
924                  * file
925                  */
926                 if (inode->i_size != BTRFS_I(inode)->disk_i_size) {
927                         btrfs_ordered_update_i_size(inode, inode->i_size, NULL);
928                         mark_inode_dirty(inode);
929                 }
930
931                 if (num_written < 0) {
932                         ret = num_written;
933                         num_written = 0;
934                         goto out;
935                 } else if (num_written == count) {
936                         /* pick up pos changes done by the generic code */
937                         pos = *ppos;
938                         goto out;
939                 }
940                 /*
941                  * We are going to do buffered for the rest of the range, so we
942                  * need to make sure to invalidate the buffered pages when we're
943                  * done.
944                  */
945                 buffered = 1;
946                 pos += num_written;
947         }
948
949         iov_iter_init(&i, iov, nr_segs, count, num_written);
950         nrptrs = min((iov_iter_count(&i) + PAGE_CACHE_SIZE - 1) /
951                      PAGE_CACHE_SIZE, PAGE_CACHE_SIZE /
952                      (sizeof(struct page *)));
953         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
954         if (!pages) {
955                 ret = -ENOMEM;
956                 goto out;
957         }
958
959         /* generic_write_checks can change our pos */
960         start_pos = pos;
961
962         first_index = pos >> PAGE_CACHE_SHIFT;
963         last_index = (pos + iov_iter_count(&i)) >> PAGE_CACHE_SHIFT;
964
965         /*
966          * there are lots of better ways to do this, but this code
967          * makes sure the first and last page in the file range are
968          * up to date and ready for cow
969          */
970         if ((pos & (PAGE_CACHE_SIZE - 1))) {
971                 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
972                 if (!PageUptodate(pinned[0])) {
973                         ret = btrfs_readpage(NULL, pinned[0]);
974                         BUG_ON(ret);
975                         wait_on_page_locked(pinned[0]);
976                 } else {
977                         unlock_page(pinned[0]);
978                 }
979         }
980         if ((pos + iov_iter_count(&i)) & (PAGE_CACHE_SIZE - 1)) {
981                 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
982                 if (!PageUptodate(pinned[1])) {
983                         ret = btrfs_readpage(NULL, pinned[1]);
984                         BUG_ON(ret);
985                         wait_on_page_locked(pinned[1]);
986                 } else {
987                         unlock_page(pinned[1]);
988                 }
989         }
990
991         while (iov_iter_count(&i) > 0) {
992                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
993                 size_t write_bytes = min(iov_iter_count(&i),
994                                          nrptrs * (size_t)PAGE_CACHE_SIZE -
995                                          offset);
996                 size_t num_pages = (write_bytes + offset +
997                                     PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
998
999                 WARN_ON(num_pages > nrptrs);
1000                 memset(pages, 0, sizeof(struct page *) * nrptrs);
1001
1002                 /*
1003                  * Fault pages before locking them in prepare_pages
1004                  * to avoid recursive lock
1005                  */
1006                 if (unlikely(iov_iter_fault_in_readable(&i, write_bytes))) {
1007                         ret = -EFAULT;
1008                         goto out;
1009                 }
1010
1011                 ret = btrfs_delalloc_reserve_space(inode,
1012                                         num_pages << PAGE_CACHE_SHIFT);
1013                 if (ret)
1014                         goto out;
1015
1016                 ret = prepare_pages(root, file, pages, num_pages,
1017                                     pos, first_index, last_index,
1018                                     write_bytes);
1019                 if (ret) {
1020                         btrfs_delalloc_release_space(inode,
1021                                         num_pages << PAGE_CACHE_SHIFT);
1022                         goto out;
1023                 }
1024
1025                 copied = btrfs_copy_from_user(pos, num_pages,
1026                                            write_bytes, pages, &i);
1027                 dirty_pages = (copied + offset + PAGE_CACHE_SIZE - 1) >>
1028                                 PAGE_CACHE_SHIFT;
1029
1030                 if (num_pages > dirty_pages) {
1031                         if (copied > 0)
1032                                 atomic_inc(
1033                                         &BTRFS_I(inode)->outstanding_extents);
1034                         btrfs_delalloc_release_space(inode,
1035                                         (num_pages - dirty_pages) <<
1036                                         PAGE_CACHE_SHIFT);
1037                 }
1038
1039                 if (copied > 0) {
1040                         dirty_and_release_pages(NULL, root, file, pages,
1041                                                 dirty_pages, pos, copied);
1042                 }
1043
1044                 btrfs_drop_pages(pages, num_pages);
1045
1046                 if (copied > 0) {
1047                         if (will_write) {
1048                                 filemap_fdatawrite_range(inode->i_mapping, pos,
1049                                                          pos + copied - 1);
1050                         } else {
1051                                 balance_dirty_pages_ratelimited_nr(
1052                                                         inode->i_mapping,
1053                                                         dirty_pages);
1054                                 if (dirty_pages <
1055                                 (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1056                                         btrfs_btree_balance_dirty(root, 1);
1057                                 btrfs_throttle(root);
1058                         }
1059                 }
1060
1061                 pos += copied;
1062                 num_written += copied;
1063
1064                 cond_resched();
1065         }
1066 out:
1067         mutex_unlock(&inode->i_mutex);
1068         if (ret)
1069                 err = ret;
1070
1071         kfree(pages);
1072         if (pinned[0])
1073                 page_cache_release(pinned[0]);
1074         if (pinned[1])
1075                 page_cache_release(pinned[1]);
1076         *ppos = pos;
1077
1078         /*
1079          * we want to make sure fsync finds this change
1080          * but we haven't joined a transaction running right now.
1081          *
1082          * Later on, someone is sure to update the inode and get the
1083          * real transid recorded.
1084          *
1085          * We set last_trans now to the fs_info generation + 1,
1086          * this will either be one more than the running transaction
1087          * or the generation used for the next transaction if there isn't
1088          * one running right now.
1089          */
1090         BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1091
1092         if (num_written > 0 && will_write) {
1093                 struct btrfs_trans_handle *trans;
1094
1095                 err = btrfs_wait_ordered_range(inode, start_pos, num_written);
1096                 if (err)
1097                         num_written = err;
1098
1099                 if ((file->f_flags & O_DSYNC) || IS_SYNC(inode)) {
1100                         trans = btrfs_start_transaction(root, 0);
1101                         if (IS_ERR(trans)) {
1102                                 num_written = PTR_ERR(trans);
1103                                 goto done;
1104                         }
1105                         mutex_lock(&inode->i_mutex);
1106                         ret = btrfs_log_dentry_safe(trans, root,
1107                                                     file->f_dentry);
1108                         mutex_unlock(&inode->i_mutex);
1109                         if (ret == 0) {
1110                                 ret = btrfs_sync_log(trans, root);
1111                                 if (ret == 0)
1112                                         btrfs_end_transaction(trans, root);
1113                                 else
1114                                         btrfs_commit_transaction(trans, root);
1115                         } else if (ret != BTRFS_NO_LOG_SYNC) {
1116                                 btrfs_commit_transaction(trans, root);
1117                         } else {
1118                                 btrfs_end_transaction(trans, root);
1119                         }
1120                 }
1121                 if (file->f_flags & O_DIRECT && buffered) {
1122                         invalidate_mapping_pages(inode->i_mapping,
1123                               start_pos >> PAGE_CACHE_SHIFT,
1124                              (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
1125                 }
1126         }
1127 done:
1128         current->backing_dev_info = NULL;
1129         return num_written ? num_written : err;
1130 }
1131
1132 int btrfs_release_file(struct inode *inode, struct file *filp)
1133 {
1134         /*
1135          * ordered_data_close is set by settattr when we are about to truncate
1136          * a file from a non-zero size to a zero size.  This tries to
1137          * flush down new bytes that may have been written if the
1138          * application were using truncate to replace a file in place.
1139          */
1140         if (BTRFS_I(inode)->ordered_data_close) {
1141                 BTRFS_I(inode)->ordered_data_close = 0;
1142                 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1143                 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1144                         filemap_flush(inode->i_mapping);
1145         }
1146         if (filp->private_data)
1147                 btrfs_ioctl_trans_end(filp);
1148         return 0;
1149 }
1150
1151 /*
1152  * fsync call for both files and directories.  This logs the inode into
1153  * the tree log instead of forcing full commits whenever possible.
1154  *
1155  * It needs to call filemap_fdatawait so that all ordered extent updates are
1156  * in the metadata btree are up to date for copying to the log.
1157  *
1158  * It drops the inode mutex before doing the tree log commit.  This is an
1159  * important optimization for directories because holding the mutex prevents
1160  * new operations on the dir while we write to disk.
1161  */
1162 int btrfs_sync_file(struct file *file, int datasync)
1163 {
1164         struct dentry *dentry = file->f_path.dentry;
1165         struct inode *inode = dentry->d_inode;
1166         struct btrfs_root *root = BTRFS_I(inode)->root;
1167         int ret = 0;
1168         struct btrfs_trans_handle *trans;
1169
1170
1171         /* we wait first, since the writeback may change the inode */
1172         root->log_batch++;
1173         /* the VFS called filemap_fdatawrite for us */
1174         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1175         root->log_batch++;
1176
1177         /*
1178          * check the transaction that last modified this inode
1179          * and see if its already been committed
1180          */
1181         if (!BTRFS_I(inode)->last_trans)
1182                 goto out;
1183
1184         /*
1185          * if the last transaction that changed this file was before
1186          * the current transaction, we can bail out now without any
1187          * syncing
1188          */
1189         mutex_lock(&root->fs_info->trans_mutex);
1190         if (BTRFS_I(inode)->last_trans <=
1191             root->fs_info->last_trans_committed) {
1192                 BTRFS_I(inode)->last_trans = 0;
1193                 mutex_unlock(&root->fs_info->trans_mutex);
1194                 goto out;
1195         }
1196         mutex_unlock(&root->fs_info->trans_mutex);
1197
1198         /*
1199          * ok we haven't committed the transaction yet, lets do a commit
1200          */
1201         if (file->private_data)
1202                 btrfs_ioctl_trans_end(file);
1203
1204         trans = btrfs_start_transaction(root, 0);
1205         if (IS_ERR(trans)) {
1206                 ret = PTR_ERR(trans);
1207                 goto out;
1208         }
1209
1210         ret = btrfs_log_dentry_safe(trans, root, dentry);
1211         if (ret < 0)
1212                 goto out;
1213
1214         /* we've logged all the items and now have a consistent
1215          * version of the file in the log.  It is possible that
1216          * someone will come in and modify the file, but that's
1217          * fine because the log is consistent on disk, and we
1218          * have references to all of the file's extents
1219          *
1220          * It is possible that someone will come in and log the
1221          * file again, but that will end up using the synchronization
1222          * inside btrfs_sync_log to keep things safe.
1223          */
1224         mutex_unlock(&dentry->d_inode->i_mutex);
1225
1226         if (ret != BTRFS_NO_LOG_SYNC) {
1227                 if (ret > 0) {
1228                         ret = btrfs_commit_transaction(trans, root);
1229                 } else {
1230                         ret = btrfs_sync_log(trans, root);
1231                         if (ret == 0)
1232                                 ret = btrfs_end_transaction(trans, root);
1233                         else
1234                                 ret = btrfs_commit_transaction(trans, root);
1235                 }
1236         } else {
1237                 ret = btrfs_end_transaction(trans, root);
1238         }
1239         mutex_lock(&dentry->d_inode->i_mutex);
1240 out:
1241         return ret > 0 ? -EIO : ret;
1242 }
1243
1244 static const struct vm_operations_struct btrfs_file_vm_ops = {
1245         .fault          = filemap_fault,
1246         .page_mkwrite   = btrfs_page_mkwrite,
1247 };
1248
1249 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1250 {
1251         struct address_space *mapping = filp->f_mapping;
1252
1253         if (!mapping->a_ops->readpage)
1254                 return -ENOEXEC;
1255
1256         file_accessed(filp);
1257         vma->vm_ops = &btrfs_file_vm_ops;
1258         vma->vm_flags |= VM_CAN_NONLINEAR;
1259
1260         return 0;
1261 }
1262
1263 static long btrfs_fallocate(struct file *file, int mode,
1264                             loff_t offset, loff_t len)
1265 {
1266         struct inode *inode = file->f_path.dentry->d_inode;
1267         struct extent_state *cached_state = NULL;
1268         u64 cur_offset;
1269         u64 last_byte;
1270         u64 alloc_start;
1271         u64 alloc_end;
1272         u64 alloc_hint = 0;
1273         u64 locked_end;
1274         u64 mask = BTRFS_I(inode)->root->sectorsize - 1;
1275         struct extent_map *em;
1276         int ret;
1277
1278         alloc_start = offset & ~mask;
1279         alloc_end =  (offset + len + mask) & ~mask;
1280
1281         /* We only support the FALLOC_FL_KEEP_SIZE mode */
1282         if (mode & ~FALLOC_FL_KEEP_SIZE)
1283                 return -EOPNOTSUPP;
1284
1285         /*
1286          * wait for ordered IO before we have any locks.  We'll loop again
1287          * below with the locks held.
1288          */
1289         btrfs_wait_ordered_range(inode, alloc_start, alloc_end - alloc_start);
1290
1291         mutex_lock(&inode->i_mutex);
1292         ret = inode_newsize_ok(inode, alloc_end);
1293         if (ret)
1294                 goto out;
1295
1296         if (alloc_start > inode->i_size) {
1297                 ret = btrfs_cont_expand(inode, alloc_start);
1298                 if (ret)
1299                         goto out;
1300         }
1301
1302         ret = btrfs_check_data_free_space(inode, alloc_end - alloc_start);
1303         if (ret)
1304                 goto out;
1305
1306         locked_end = alloc_end - 1;
1307         while (1) {
1308                 struct btrfs_ordered_extent *ordered;
1309
1310                 /* the extent lock is ordered inside the running
1311                  * transaction
1312                  */
1313                 lock_extent_bits(&BTRFS_I(inode)->io_tree, alloc_start,
1314                                  locked_end, 0, &cached_state, GFP_NOFS);
1315                 ordered = btrfs_lookup_first_ordered_extent(inode,
1316                                                             alloc_end - 1);
1317                 if (ordered &&
1318                     ordered->file_offset + ordered->len > alloc_start &&
1319                     ordered->file_offset < alloc_end) {
1320                         btrfs_put_ordered_extent(ordered);
1321                         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
1322                                              alloc_start, locked_end,
1323                                              &cached_state, GFP_NOFS);
1324                         /*
1325                          * we can't wait on the range with the transaction
1326                          * running or with the extent lock held
1327                          */
1328                         btrfs_wait_ordered_range(inode, alloc_start,
1329                                                  alloc_end - alloc_start);
1330                 } else {
1331                         if (ordered)
1332                                 btrfs_put_ordered_extent(ordered);
1333                         break;
1334                 }
1335         }
1336
1337         cur_offset = alloc_start;
1338         while (1) {
1339                 em = btrfs_get_extent(inode, NULL, 0, cur_offset,
1340                                       alloc_end - cur_offset, 0);
1341                 BUG_ON(IS_ERR(em) || !em);
1342                 last_byte = min(extent_map_end(em), alloc_end);
1343                 last_byte = (last_byte + mask) & ~mask;
1344                 if (em->block_start == EXTENT_MAP_HOLE ||
1345                     (cur_offset >= inode->i_size &&
1346                      !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))) {
1347                         ret = btrfs_prealloc_file_range(inode, mode, cur_offset,
1348                                                         last_byte - cur_offset,
1349                                                         1 << inode->i_blkbits,
1350                                                         offset + len,
1351                                                         &alloc_hint);
1352                         if (ret < 0) {
1353                                 free_extent_map(em);
1354                                 break;
1355                         }
1356                 }
1357                 free_extent_map(em);
1358
1359                 cur_offset = last_byte;
1360                 if (cur_offset >= alloc_end) {
1361                         ret = 0;
1362                         break;
1363                 }
1364         }
1365         unlock_extent_cached(&BTRFS_I(inode)->io_tree, alloc_start, locked_end,
1366                              &cached_state, GFP_NOFS);
1367
1368         btrfs_free_reserved_data_space(inode, alloc_end - alloc_start);
1369 out:
1370         mutex_unlock(&inode->i_mutex);
1371         return ret;
1372 }
1373
1374 const struct file_operations btrfs_file_operations = {
1375         .llseek         = generic_file_llseek,
1376         .read           = do_sync_read,
1377         .write          = do_sync_write,
1378         .aio_read       = generic_file_aio_read,
1379         .splice_read    = generic_file_splice_read,
1380         .aio_write      = btrfs_file_aio_write,
1381         .mmap           = btrfs_file_mmap,
1382         .open           = generic_file_open,
1383         .release        = btrfs_release_file,
1384         .fsync          = btrfs_sync_file,
1385         .fallocate      = btrfs_fallocate,
1386         .unlocked_ioctl = btrfs_ioctl,
1387 #ifdef CONFIG_COMPAT
1388         .compat_ioctl   = btrfs_ioctl,
1389 #endif
1390 };