const: mark struct vm_struct_operations
[linux-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/swap.h>
28 #include <linux/writeback.h>
29 #include <linux/statfs.h>
30 #include <linux/compat.h>
31 #include "ctree.h"
32 #include "disk-io.h"
33 #include "transaction.h"
34 #include "btrfs_inode.h"
35 #include "ioctl.h"
36 #include "print-tree.h"
37 #include "tree-log.h"
38 #include "locking.h"
39 #include "compat.h"
40
41
42 /* simple helper to fault in pages and copy.  This should go away
43  * and be replaced with calls into generic code.
44  */
45 static noinline int btrfs_copy_from_user(loff_t pos, int num_pages,
46                                          int write_bytes,
47                                          struct page **prepared_pages,
48                                          const char __user *buf)
49 {
50         long page_fault = 0;
51         int i;
52         int offset = pos & (PAGE_CACHE_SIZE - 1);
53
54         for (i = 0; i < num_pages && write_bytes > 0; i++, offset = 0) {
55                 size_t count = min_t(size_t,
56                                      PAGE_CACHE_SIZE - offset, write_bytes);
57                 struct page *page = prepared_pages[i];
58                 fault_in_pages_readable(buf, count);
59
60                 /* Copy data from userspace to the current page */
61                 kmap(page);
62                 page_fault = __copy_from_user(page_address(page) + offset,
63                                               buf, count);
64                 /* Flush processor's dcache for this page */
65                 flush_dcache_page(page);
66                 kunmap(page);
67                 buf += count;
68                 write_bytes -= count;
69
70                 if (page_fault)
71                         break;
72         }
73         return page_fault ? -EFAULT : 0;
74 }
75
76 /*
77  * unlocks pages after btrfs_file_write is done with them
78  */
79 static noinline void btrfs_drop_pages(struct page **pages, size_t num_pages)
80 {
81         size_t i;
82         for (i = 0; i < num_pages; i++) {
83                 if (!pages[i])
84                         break;
85                 /* page checked is some magic around finding pages that
86                  * have been modified without going through btrfs_set_page_dirty
87                  * clear it here
88                  */
89                 ClearPageChecked(pages[i]);
90                 unlock_page(pages[i]);
91                 mark_page_accessed(pages[i]);
92                 page_cache_release(pages[i]);
93         }
94 }
95
96 /*
97  * after copy_from_user, pages need to be dirtied and we need to make
98  * sure holes are created between the current EOF and the start of
99  * any next extents (if required).
100  *
101  * this also makes the decision about creating an inline extent vs
102  * doing real data extents, marking pages dirty and delalloc as required.
103  */
104 static noinline int dirty_and_release_pages(struct btrfs_trans_handle *trans,
105                                    struct btrfs_root *root,
106                                    struct file *file,
107                                    struct page **pages,
108                                    size_t num_pages,
109                                    loff_t pos,
110                                    size_t write_bytes)
111 {
112         int err = 0;
113         int i;
114         struct inode *inode = fdentry(file)->d_inode;
115         u64 num_bytes;
116         u64 start_pos;
117         u64 end_of_last_block;
118         u64 end_pos = pos + write_bytes;
119         loff_t isize = i_size_read(inode);
120
121         start_pos = pos & ~((u64)root->sectorsize - 1);
122         num_bytes = (write_bytes + pos - start_pos +
123                     root->sectorsize - 1) & ~((u64)root->sectorsize - 1);
124
125         end_of_last_block = start_pos + num_bytes - 1;
126         btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block);
127         for (i = 0; i < num_pages; i++) {
128                 struct page *p = pages[i];
129                 SetPageUptodate(p);
130                 ClearPageChecked(p);
131                 set_page_dirty(p);
132         }
133         if (end_pos > isize) {
134                 i_size_write(inode, end_pos);
135                 /* we've only changed i_size in ram, and we haven't updated
136                  * the disk i_size.  There is no need to log the inode
137                  * at this time.
138                  */
139         }
140         return err;
141 }
142
143 /*
144  * this drops all the extents in the cache that intersect the range
145  * [start, end].  Existing extents are split as required.
146  */
147 int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end,
148                             int skip_pinned)
149 {
150         struct extent_map *em;
151         struct extent_map *split = NULL;
152         struct extent_map *split2 = NULL;
153         struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
154         u64 len = end - start + 1;
155         int ret;
156         int testend = 1;
157         unsigned long flags;
158         int compressed = 0;
159
160         WARN_ON(end < start);
161         if (end == (u64)-1) {
162                 len = (u64)-1;
163                 testend = 0;
164         }
165         while (1) {
166                 if (!split)
167                         split = alloc_extent_map(GFP_NOFS);
168                 if (!split2)
169                         split2 = alloc_extent_map(GFP_NOFS);
170
171                 write_lock(&em_tree->lock);
172                 em = lookup_extent_mapping(em_tree, start, len);
173                 if (!em) {
174                         write_unlock(&em_tree->lock);
175                         break;
176                 }
177                 flags = em->flags;
178                 if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) {
179                         if (em->start <= start &&
180                             (!testend || em->start + em->len >= start + len)) {
181                                 free_extent_map(em);
182                                 write_unlock(&em_tree->lock);
183                                 break;
184                         }
185                         if (start < em->start) {
186                                 len = em->start - start;
187                         } else {
188                                 len = start + len - (em->start + em->len);
189                                 start = em->start + em->len;
190                         }
191                         free_extent_map(em);
192                         write_unlock(&em_tree->lock);
193                         continue;
194                 }
195                 compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
196                 clear_bit(EXTENT_FLAG_PINNED, &em->flags);
197                 remove_extent_mapping(em_tree, em);
198
199                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
200                     em->start < start) {
201                         split->start = em->start;
202                         split->len = start - em->start;
203                         split->orig_start = em->orig_start;
204                         split->block_start = em->block_start;
205
206                         if (compressed)
207                                 split->block_len = em->block_len;
208                         else
209                                 split->block_len = split->len;
210
211                         split->bdev = em->bdev;
212                         split->flags = flags;
213                         ret = add_extent_mapping(em_tree, split);
214                         BUG_ON(ret);
215                         free_extent_map(split);
216                         split = split2;
217                         split2 = NULL;
218                 }
219                 if (em->block_start < EXTENT_MAP_LAST_BYTE &&
220                     testend && em->start + em->len > start + len) {
221                         u64 diff = start + len - em->start;
222
223                         split->start = start + len;
224                         split->len = em->start + em->len - (start + len);
225                         split->bdev = em->bdev;
226                         split->flags = flags;
227
228                         if (compressed) {
229                                 split->block_len = em->block_len;
230                                 split->block_start = em->block_start;
231                                 split->orig_start = em->orig_start;
232                         } else {
233                                 split->block_len = split->len;
234                                 split->block_start = em->block_start + diff;
235                                 split->orig_start = split->start;
236                         }
237
238                         ret = add_extent_mapping(em_tree, split);
239                         BUG_ON(ret);
240                         free_extent_map(split);
241                         split = NULL;
242                 }
243                 write_unlock(&em_tree->lock);
244
245                 /* once for us */
246                 free_extent_map(em);
247                 /* once for the tree*/
248                 free_extent_map(em);
249         }
250         if (split)
251                 free_extent_map(split);
252         if (split2)
253                 free_extent_map(split2);
254         return 0;
255 }
256
257 /*
258  * this is very complex, but the basic idea is to drop all extents
259  * in the range start - end.  hint_block is filled in with a block number
260  * that would be a good hint to the block allocator for this file.
261  *
262  * If an extent intersects the range but is not entirely inside the range
263  * it is either truncated or split.  Anything entirely inside the range
264  * is deleted from the tree.
265  *
266  * inline_limit is used to tell this code which offsets in the file to keep
267  * if they contain inline extents.
268  */
269 noinline int btrfs_drop_extents(struct btrfs_trans_handle *trans,
270                        struct btrfs_root *root, struct inode *inode,
271                        u64 start, u64 end, u64 locked_end,
272                        u64 inline_limit, u64 *hint_byte, int drop_cache)
273 {
274         u64 extent_end = 0;
275         u64 search_start = start;
276         u64 ram_bytes = 0;
277         u64 disk_bytenr = 0;
278         u64 orig_locked_end = locked_end;
279         u8 compression;
280         u8 encryption;
281         u16 other_encoding = 0;
282         struct extent_buffer *leaf;
283         struct btrfs_file_extent_item *extent;
284         struct btrfs_path *path;
285         struct btrfs_key key;
286         struct btrfs_file_extent_item old;
287         int keep;
288         int slot;
289         int bookend;
290         int found_type = 0;
291         int found_extent;
292         int found_inline;
293         int recow;
294         int ret;
295
296         inline_limit = 0;
297         if (drop_cache)
298                 btrfs_drop_extent_cache(inode, start, end - 1, 0);
299
300         path = btrfs_alloc_path();
301         if (!path)
302                 return -ENOMEM;
303         while (1) {
304                 recow = 0;
305                 btrfs_release_path(root, path);
306                 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
307                                                search_start, -1);
308                 if (ret < 0)
309                         goto out;
310                 if (ret > 0) {
311                         if (path->slots[0] == 0) {
312                                 ret = 0;
313                                 goto out;
314                         }
315                         path->slots[0]--;
316                 }
317 next_slot:
318                 keep = 0;
319                 bookend = 0;
320                 found_extent = 0;
321                 found_inline = 0;
322                 compression = 0;
323                 encryption = 0;
324                 extent = NULL;
325                 leaf = path->nodes[0];
326                 slot = path->slots[0];
327                 ret = 0;
328                 btrfs_item_key_to_cpu(leaf, &key, slot);
329                 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY &&
330                     key.offset >= end) {
331                         goto out;
332                 }
333                 if (btrfs_key_type(&key) > BTRFS_EXTENT_DATA_KEY ||
334                     key.objectid != inode->i_ino) {
335                         goto out;
336                 }
337                 if (recow) {
338                         search_start = max(key.offset, start);
339                         continue;
340                 }
341                 if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY) {
342                         extent = btrfs_item_ptr(leaf, slot,
343                                                 struct btrfs_file_extent_item);
344                         found_type = btrfs_file_extent_type(leaf, extent);
345                         compression = btrfs_file_extent_compression(leaf,
346                                                                     extent);
347                         encryption = btrfs_file_extent_encryption(leaf,
348                                                                   extent);
349                         other_encoding = btrfs_file_extent_other_encoding(leaf,
350                                                                   extent);
351                         if (found_type == BTRFS_FILE_EXTENT_REG ||
352                             found_type == BTRFS_FILE_EXTENT_PREALLOC) {
353                                 extent_end =
354                                      btrfs_file_extent_disk_bytenr(leaf,
355                                                                    extent);
356                                 if (extent_end)
357                                         *hint_byte = extent_end;
358
359                                 extent_end = key.offset +
360                                      btrfs_file_extent_num_bytes(leaf, extent);
361                                 ram_bytes = btrfs_file_extent_ram_bytes(leaf,
362                                                                 extent);
363                                 found_extent = 1;
364                         } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
365                                 found_inline = 1;
366                                 extent_end = key.offset +
367                                      btrfs_file_extent_inline_len(leaf, extent);
368                         }
369                 } else {
370                         extent_end = search_start;
371                 }
372
373                 /* we found nothing we can drop */
374                 if ((!found_extent && !found_inline) ||
375                     search_start >= extent_end) {
376                         int nextret;
377                         u32 nritems;
378                         nritems = btrfs_header_nritems(leaf);
379                         if (slot >= nritems - 1) {
380                                 nextret = btrfs_next_leaf(root, path);
381                                 if (nextret)
382                                         goto out;
383                                 recow = 1;
384                         } else {
385                                 path->slots[0]++;
386                         }
387                         goto next_slot;
388                 }
389
390                 if (end <= extent_end && start >= key.offset && found_inline)
391                         *hint_byte = EXTENT_MAP_INLINE;
392
393                 if (found_extent) {
394                         read_extent_buffer(leaf, &old, (unsigned long)extent,
395                                            sizeof(old));
396                 }
397
398                 if (end < extent_end && end >= key.offset) {
399                         bookend = 1;
400                         if (found_inline && start <= key.offset)
401                                 keep = 1;
402                 }
403
404                 if (bookend && found_extent) {
405                         if (locked_end < extent_end) {
406                                 ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
407                                                 locked_end, extent_end - 1,
408                                                 GFP_NOFS);
409                                 if (!ret) {
410                                         btrfs_release_path(root, path);
411                                         lock_extent(&BTRFS_I(inode)->io_tree,
412                                                 locked_end, extent_end - 1,
413                                                 GFP_NOFS);
414                                         locked_end = extent_end;
415                                         continue;
416                                 }
417                                 locked_end = extent_end;
418                         }
419                         disk_bytenr = le64_to_cpu(old.disk_bytenr);
420                         if (disk_bytenr != 0) {
421                                 ret = btrfs_inc_extent_ref(trans, root,
422                                            disk_bytenr,
423                                            le64_to_cpu(old.disk_num_bytes), 0,
424                                            root->root_key.objectid,
425                                            key.objectid, key.offset -
426                                            le64_to_cpu(old.offset));
427                                 BUG_ON(ret);
428                         }
429                 }
430
431                 if (found_inline) {
432                         u64 mask = root->sectorsize - 1;
433                         search_start = (extent_end + mask) & ~mask;
434                 } else
435                         search_start = extent_end;
436
437                 /* truncate existing extent */
438                 if (start > key.offset) {
439                         u64 new_num;
440                         u64 old_num;
441                         keep = 1;
442                         WARN_ON(start & (root->sectorsize - 1));
443                         if (found_extent) {
444                                 new_num = start - key.offset;
445                                 old_num = btrfs_file_extent_num_bytes(leaf,
446                                                                       extent);
447                                 *hint_byte =
448                                         btrfs_file_extent_disk_bytenr(leaf,
449                                                                       extent);
450                                 if (btrfs_file_extent_disk_bytenr(leaf,
451                                                                   extent)) {
452                                         inode_sub_bytes(inode, old_num -
453                                                         new_num);
454                                 }
455                                 btrfs_set_file_extent_num_bytes(leaf,
456                                                         extent, new_num);
457                                 btrfs_mark_buffer_dirty(leaf);
458                         } else if (key.offset < inline_limit &&
459                                    (end > extent_end) &&
460                                    (inline_limit < extent_end)) {
461                                 u32 new_size;
462                                 new_size = btrfs_file_extent_calc_inline_size(
463                                                    inline_limit - key.offset);
464                                 inode_sub_bytes(inode, extent_end -
465                                                 inline_limit);
466                                 btrfs_set_file_extent_ram_bytes(leaf, extent,
467                                                         new_size);
468                                 if (!compression && !encryption) {
469                                         btrfs_truncate_item(trans, root, path,
470                                                             new_size, 1);
471                                 }
472                         }
473                 }
474                 /* delete the entire extent */
475                 if (!keep) {
476                         if (found_inline)
477                                 inode_sub_bytes(inode, extent_end -
478                                                 key.offset);
479                         ret = btrfs_del_item(trans, root, path);
480                         /* TODO update progress marker and return */
481                         BUG_ON(ret);
482                         extent = NULL;
483                         btrfs_release_path(root, path);
484                         /* the extent will be freed later */
485                 }
486                 if (bookend && found_inline && start <= key.offset) {
487                         u32 new_size;
488                         new_size = btrfs_file_extent_calc_inline_size(
489                                                    extent_end - end);
490                         inode_sub_bytes(inode, end - key.offset);
491                         btrfs_set_file_extent_ram_bytes(leaf, extent,
492                                                         new_size);
493                         if (!compression && !encryption)
494                                 ret = btrfs_truncate_item(trans, root, path,
495                                                           new_size, 0);
496                         BUG_ON(ret);
497                 }
498                 /* create bookend, splitting the extent in two */
499                 if (bookend && found_extent) {
500                         struct btrfs_key ins;
501                         ins.objectid = inode->i_ino;
502                         ins.offset = end;
503                         btrfs_set_key_type(&ins, BTRFS_EXTENT_DATA_KEY);
504
505                         btrfs_release_path(root, path);
506                         path->leave_spinning = 1;
507                         ret = btrfs_insert_empty_item(trans, root, path, &ins,
508                                                       sizeof(*extent));
509                         BUG_ON(ret);
510
511                         leaf = path->nodes[0];
512                         extent = btrfs_item_ptr(leaf, path->slots[0],
513                                                 struct btrfs_file_extent_item);
514                         write_extent_buffer(leaf, &old,
515                                             (unsigned long)extent, sizeof(old));
516
517                         btrfs_set_file_extent_compression(leaf, extent,
518                                                           compression);
519                         btrfs_set_file_extent_encryption(leaf, extent,
520                                                          encryption);
521                         btrfs_set_file_extent_other_encoding(leaf, extent,
522                                                              other_encoding);
523                         btrfs_set_file_extent_offset(leaf, extent,
524                                     le64_to_cpu(old.offset) + end - key.offset);
525                         WARN_ON(le64_to_cpu(old.num_bytes) <
526                                 (extent_end - end));
527                         btrfs_set_file_extent_num_bytes(leaf, extent,
528                                                         extent_end - end);
529
530                         /*
531                          * set the ram bytes to the size of the full extent
532                          * before splitting.  This is a worst case flag,
533                          * but its the best we can do because we don't know
534                          * how splitting affects compression
535                          */
536                         btrfs_set_file_extent_ram_bytes(leaf, extent,
537                                                         ram_bytes);
538                         btrfs_set_file_extent_type(leaf, extent, found_type);
539
540                         btrfs_unlock_up_safe(path, 1);
541                         btrfs_mark_buffer_dirty(path->nodes[0]);
542                         btrfs_set_lock_blocking(path->nodes[0]);
543
544                         path->leave_spinning = 0;
545                         btrfs_release_path(root, path);
546                         if (disk_bytenr != 0)
547                                 inode_add_bytes(inode, extent_end - end);
548                 }
549
550                 if (found_extent && !keep) {
551                         u64 old_disk_bytenr = le64_to_cpu(old.disk_bytenr);
552
553                         if (old_disk_bytenr != 0) {
554                                 inode_sub_bytes(inode,
555                                                 le64_to_cpu(old.num_bytes));
556                                 ret = btrfs_free_extent(trans, root,
557                                                 old_disk_bytenr,
558                                                 le64_to_cpu(old.disk_num_bytes),
559                                                 0, root->root_key.objectid,
560                                                 key.objectid, key.offset -
561                                                 le64_to_cpu(old.offset));
562                                 BUG_ON(ret);
563                                 *hint_byte = old_disk_bytenr;
564                         }
565                 }
566
567                 if (search_start >= end) {
568                         ret = 0;
569                         goto out;
570                 }
571         }
572 out:
573         btrfs_free_path(path);
574         if (locked_end > orig_locked_end) {
575                 unlock_extent(&BTRFS_I(inode)->io_tree, orig_locked_end,
576                               locked_end - 1, GFP_NOFS);
577         }
578         return ret;
579 }
580
581 static int extent_mergeable(struct extent_buffer *leaf, int slot,
582                             u64 objectid, u64 bytenr, u64 *start, u64 *end)
583 {
584         struct btrfs_file_extent_item *fi;
585         struct btrfs_key key;
586         u64 extent_end;
587
588         if (slot < 0 || slot >= btrfs_header_nritems(leaf))
589                 return 0;
590
591         btrfs_item_key_to_cpu(leaf, &key, slot);
592         if (key.objectid != objectid || key.type != BTRFS_EXTENT_DATA_KEY)
593                 return 0;
594
595         fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
596         if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG ||
597             btrfs_file_extent_disk_bytenr(leaf, fi) != bytenr ||
598             btrfs_file_extent_compression(leaf, fi) ||
599             btrfs_file_extent_encryption(leaf, fi) ||
600             btrfs_file_extent_other_encoding(leaf, fi))
601                 return 0;
602
603         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
604         if ((*start && *start != key.offset) || (*end && *end != extent_end))
605                 return 0;
606
607         *start = key.offset;
608         *end = extent_end;
609         return 1;
610 }
611
612 /*
613  * Mark extent in the range start - end as written.
614  *
615  * This changes extent type from 'pre-allocated' to 'regular'. If only
616  * part of extent is marked as written, the extent will be split into
617  * two or three.
618  */
619 int btrfs_mark_extent_written(struct btrfs_trans_handle *trans,
620                               struct btrfs_root *root,
621                               struct inode *inode, u64 start, u64 end)
622 {
623         struct extent_buffer *leaf;
624         struct btrfs_path *path;
625         struct btrfs_file_extent_item *fi;
626         struct btrfs_key key;
627         u64 bytenr;
628         u64 num_bytes;
629         u64 extent_end;
630         u64 orig_offset;
631         u64 other_start;
632         u64 other_end;
633         u64 split = start;
634         u64 locked_end = end;
635         int extent_type;
636         int split_end = 1;
637         int ret;
638
639         btrfs_drop_extent_cache(inode, start, end - 1, 0);
640
641         path = btrfs_alloc_path();
642         BUG_ON(!path);
643 again:
644         key.objectid = inode->i_ino;
645         key.type = BTRFS_EXTENT_DATA_KEY;
646         if (split == start)
647                 key.offset = split;
648         else
649                 key.offset = split - 1;
650
651         ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
652         if (ret > 0 && path->slots[0] > 0)
653                 path->slots[0]--;
654
655         leaf = path->nodes[0];
656         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
657         BUG_ON(key.objectid != inode->i_ino ||
658                key.type != BTRFS_EXTENT_DATA_KEY);
659         fi = btrfs_item_ptr(leaf, path->slots[0],
660                             struct btrfs_file_extent_item);
661         extent_type = btrfs_file_extent_type(leaf, fi);
662         BUG_ON(extent_type != BTRFS_FILE_EXTENT_PREALLOC);
663         extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi);
664         BUG_ON(key.offset > start || extent_end < end);
665
666         bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
667         num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
668         orig_offset = key.offset - btrfs_file_extent_offset(leaf, fi);
669
670         if (key.offset == start)
671                 split = end;
672
673         if (key.offset == start && extent_end == end) {
674                 int del_nr = 0;
675                 int del_slot = 0;
676                 other_start = end;
677                 other_end = 0;
678                 if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
679                                      bytenr, &other_start, &other_end)) {
680                         extent_end = other_end;
681                         del_slot = path->slots[0] + 1;
682                         del_nr++;
683                         ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
684                                                 0, root->root_key.objectid,
685                                                 inode->i_ino, orig_offset);
686                         BUG_ON(ret);
687                 }
688                 other_start = 0;
689                 other_end = start;
690                 if (extent_mergeable(leaf, path->slots[0] - 1, inode->i_ino,
691                                      bytenr, &other_start, &other_end)) {
692                         key.offset = other_start;
693                         del_slot = path->slots[0];
694                         del_nr++;
695                         ret = btrfs_free_extent(trans, root, bytenr, num_bytes,
696                                                 0, root->root_key.objectid,
697                                                 inode->i_ino, orig_offset);
698                         BUG_ON(ret);
699                 }
700                 split_end = 0;
701                 if (del_nr == 0) {
702                         btrfs_set_file_extent_type(leaf, fi,
703                                                    BTRFS_FILE_EXTENT_REG);
704                         goto done;
705                 }
706
707                 fi = btrfs_item_ptr(leaf, del_slot - 1,
708                                     struct btrfs_file_extent_item);
709                 btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG);
710                 btrfs_set_file_extent_num_bytes(leaf, fi,
711                                                 extent_end - key.offset);
712                 btrfs_mark_buffer_dirty(leaf);
713
714                 ret = btrfs_del_items(trans, root, path, del_slot, del_nr);
715                 BUG_ON(ret);
716                 goto release;
717         } else if (split == start) {
718                 if (locked_end < extent_end) {
719                         ret = try_lock_extent(&BTRFS_I(inode)->io_tree,
720                                         locked_end, extent_end - 1, GFP_NOFS);
721                         if (!ret) {
722                                 btrfs_release_path(root, path);
723                                 lock_extent(&BTRFS_I(inode)->io_tree,
724                                         locked_end, extent_end - 1, GFP_NOFS);
725                                 locked_end = extent_end;
726                                 goto again;
727                         }
728                         locked_end = extent_end;
729                 }
730                 btrfs_set_file_extent_num_bytes(leaf, fi, split - key.offset);
731         } else  {
732                 BUG_ON(key.offset != start);
733                 key.offset = split;
734                 btrfs_set_file_extent_offset(leaf, fi, key.offset -
735                                              orig_offset);
736                 btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - split);
737                 btrfs_set_item_key_safe(trans, root, path, &key);
738                 extent_end = split;
739         }
740
741         if (extent_end == end) {
742                 split_end = 0;
743                 extent_type = BTRFS_FILE_EXTENT_REG;
744         }
745         if (extent_end == end && split == start) {
746                 other_start = end;
747                 other_end = 0;
748                 if (extent_mergeable(leaf, path->slots[0] + 1, inode->i_ino,
749                                      bytenr, &other_start, &other_end)) {
750                         path->slots[0]++;
751                         fi = btrfs_item_ptr(leaf, path->slots[0],
752                                             struct btrfs_file_extent_item);
753                         key.offset = split;
754                         btrfs_set_item_key_safe(trans, root, path, &key);
755                         btrfs_set_file_extent_offset(leaf, fi, key.offset -
756                                                      orig_offset);
757                         btrfs_set_file_extent_num_bytes(leaf, fi,
758                                                         other_end - split);
759                         goto done;
760                 }
761         }
762         if (extent_end == end && split == end) {
763                 other_start = 0;
764                 other_end = start;
765                 if (extent_mergeable(leaf, path->slots[0] - 1 , inode->i_ino,
766                                      bytenr, &other_start, &other_end)) {
767                         path->slots[0]--;
768                         fi = btrfs_item_ptr(leaf, path->slots[0],
769                                             struct btrfs_file_extent_item);
770                         btrfs_set_file_extent_num_bytes(leaf, fi, extent_end -
771                                                         other_start);
772                         goto done;
773                 }
774         }
775
776         btrfs_mark_buffer_dirty(leaf);
777
778         ret = btrfs_inc_extent_ref(trans, root, bytenr, num_bytes, 0,
779                                    root->root_key.objectid,
780                                    inode->i_ino, orig_offset);
781         BUG_ON(ret);
782         btrfs_release_path(root, path);
783
784         key.offset = start;
785         ret = btrfs_insert_empty_item(trans, root, path, &key, sizeof(*fi));
786         BUG_ON(ret);
787
788         leaf = path->nodes[0];
789         fi = btrfs_item_ptr(leaf, path->slots[0],
790                             struct btrfs_file_extent_item);
791         btrfs_set_file_extent_generation(leaf, fi, trans->transid);
792         btrfs_set_file_extent_type(leaf, fi, extent_type);
793         btrfs_set_file_extent_disk_bytenr(leaf, fi, bytenr);
794         btrfs_set_file_extent_disk_num_bytes(leaf, fi, num_bytes);
795         btrfs_set_file_extent_offset(leaf, fi, key.offset - orig_offset);
796         btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - key.offset);
797         btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes);
798         btrfs_set_file_extent_compression(leaf, fi, 0);
799         btrfs_set_file_extent_encryption(leaf, fi, 0);
800         btrfs_set_file_extent_other_encoding(leaf, fi, 0);
801 done:
802         btrfs_mark_buffer_dirty(leaf);
803
804 release:
805         btrfs_release_path(root, path);
806         if (split_end && split == start) {
807                 split = end;
808                 goto again;
809         }
810         if (locked_end > end) {
811                 unlock_extent(&BTRFS_I(inode)->io_tree, end, locked_end - 1,
812                               GFP_NOFS);
813         }
814         btrfs_free_path(path);
815         return 0;
816 }
817
818 /*
819  * this gets pages into the page cache and locks them down, it also properly
820  * waits for data=ordered extents to finish before allowing the pages to be
821  * modified.
822  */
823 static noinline int prepare_pages(struct btrfs_root *root, struct file *file,
824                          struct page **pages, size_t num_pages,
825                          loff_t pos, unsigned long first_index,
826                          unsigned long last_index, size_t write_bytes)
827 {
828         int i;
829         unsigned long index = pos >> PAGE_CACHE_SHIFT;
830         struct inode *inode = fdentry(file)->d_inode;
831         int err = 0;
832         u64 start_pos;
833         u64 last_pos;
834
835         start_pos = pos & ~((u64)root->sectorsize - 1);
836         last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
837
838         if (start_pos > inode->i_size) {
839                 err = btrfs_cont_expand(inode, start_pos);
840                 if (err)
841                         return err;
842         }
843
844         memset(pages, 0, num_pages * sizeof(struct page *));
845 again:
846         for (i = 0; i < num_pages; i++) {
847                 pages[i] = grab_cache_page(inode->i_mapping, index + i);
848                 if (!pages[i]) {
849                         err = -ENOMEM;
850                         BUG_ON(1);
851                 }
852                 wait_on_page_writeback(pages[i]);
853         }
854         if (start_pos < inode->i_size) {
855                 struct btrfs_ordered_extent *ordered;
856                 lock_extent(&BTRFS_I(inode)->io_tree,
857                             start_pos, last_pos - 1, GFP_NOFS);
858                 ordered = btrfs_lookup_first_ordered_extent(inode,
859                                                             last_pos - 1);
860                 if (ordered &&
861                     ordered->file_offset + ordered->len > start_pos &&
862                     ordered->file_offset < last_pos) {
863                         btrfs_put_ordered_extent(ordered);
864                         unlock_extent(&BTRFS_I(inode)->io_tree,
865                                       start_pos, last_pos - 1, GFP_NOFS);
866                         for (i = 0; i < num_pages; i++) {
867                                 unlock_page(pages[i]);
868                                 page_cache_release(pages[i]);
869                         }
870                         btrfs_wait_ordered_range(inode, start_pos,
871                                                  last_pos - start_pos);
872                         goto again;
873                 }
874                 if (ordered)
875                         btrfs_put_ordered_extent(ordered);
876
877                 clear_extent_bits(&BTRFS_I(inode)->io_tree, start_pos,
878                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC,
879                                   GFP_NOFS);
880                 unlock_extent(&BTRFS_I(inode)->io_tree,
881                               start_pos, last_pos - 1, GFP_NOFS);
882         }
883         for (i = 0; i < num_pages; i++) {
884                 clear_page_dirty_for_io(pages[i]);
885                 set_page_extent_mapped(pages[i]);
886                 WARN_ON(!PageLocked(pages[i]));
887         }
888         return 0;
889 }
890
891 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
892                                 size_t count, loff_t *ppos)
893 {
894         loff_t pos;
895         loff_t start_pos;
896         ssize_t num_written = 0;
897         ssize_t err = 0;
898         int ret = 0;
899         struct inode *inode = fdentry(file)->d_inode;
900         struct btrfs_root *root = BTRFS_I(inode)->root;
901         struct page **pages = NULL;
902         int nrptrs;
903         struct page *pinned[2];
904         unsigned long first_index;
905         unsigned long last_index;
906         int will_write;
907
908         will_write = ((file->f_flags & O_SYNC) || IS_SYNC(inode) ||
909                       (file->f_flags & O_DIRECT));
910
911         nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,
912                      PAGE_CACHE_SIZE / (sizeof(struct page *)));
913         pinned[0] = NULL;
914         pinned[1] = NULL;
915
916         pos = *ppos;
917         start_pos = pos;
918
919         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
920         current->backing_dev_info = inode->i_mapping->backing_dev_info;
921         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
922         if (err)
923                 goto out_nolock;
924         if (count == 0)
925                 goto out_nolock;
926
927         err = file_remove_suid(file);
928         if (err)
929                 goto out_nolock;
930         file_update_time(file);
931
932         pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
933
934         mutex_lock(&inode->i_mutex);
935         BTRFS_I(inode)->sequence++;
936         first_index = pos >> PAGE_CACHE_SHIFT;
937         last_index = (pos + count) >> PAGE_CACHE_SHIFT;
938
939         /*
940          * there are lots of better ways to do this, but this code
941          * makes sure the first and last page in the file range are
942          * up to date and ready for cow
943          */
944         if ((pos & (PAGE_CACHE_SIZE - 1))) {
945                 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
946                 if (!PageUptodate(pinned[0])) {
947                         ret = btrfs_readpage(NULL, pinned[0]);
948                         BUG_ON(ret);
949                         wait_on_page_locked(pinned[0]);
950                 } else {
951                         unlock_page(pinned[0]);
952                 }
953         }
954         if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
955                 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
956                 if (!PageUptodate(pinned[1])) {
957                         ret = btrfs_readpage(NULL, pinned[1]);
958                         BUG_ON(ret);
959                         wait_on_page_locked(pinned[1]);
960                 } else {
961                         unlock_page(pinned[1]);
962                 }
963         }
964
965         while (count > 0) {
966                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
967                 size_t write_bytes = min(count, nrptrs *
968                                         (size_t)PAGE_CACHE_SIZE -
969                                          offset);
970                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
971                                         PAGE_CACHE_SHIFT;
972
973                 WARN_ON(num_pages > nrptrs);
974                 memset(pages, 0, sizeof(struct page *) * nrptrs);
975
976                 ret = btrfs_check_data_free_space(root, inode, write_bytes);
977                 if (ret)
978                         goto out;
979
980                 ret = prepare_pages(root, file, pages, num_pages,
981                                     pos, first_index, last_index,
982                                     write_bytes);
983                 if (ret) {
984                         btrfs_free_reserved_data_space(root, inode,
985                                                        write_bytes);
986                         goto out;
987                 }
988
989                 ret = btrfs_copy_from_user(pos, num_pages,
990                                            write_bytes, pages, buf);
991                 if (ret) {
992                         btrfs_free_reserved_data_space(root, inode,
993                                                        write_bytes);
994                         btrfs_drop_pages(pages, num_pages);
995                         goto out;
996                 }
997
998                 ret = dirty_and_release_pages(NULL, root, file, pages,
999                                               num_pages, pos, write_bytes);
1000                 btrfs_drop_pages(pages, num_pages);
1001                 if (ret) {
1002                         btrfs_free_reserved_data_space(root, inode,
1003                                                        write_bytes);
1004                         goto out;
1005                 }
1006
1007                 if (will_write) {
1008                         btrfs_fdatawrite_range(inode->i_mapping, pos,
1009                                                pos + write_bytes - 1,
1010                                                WB_SYNC_ALL);
1011                 } else {
1012                         balance_dirty_pages_ratelimited_nr(inode->i_mapping,
1013                                                            num_pages);
1014                         if (num_pages <
1015                             (root->leafsize >> PAGE_CACHE_SHIFT) + 1)
1016                                 btrfs_btree_balance_dirty(root, 1);
1017                         btrfs_throttle(root);
1018                 }
1019
1020                 buf += write_bytes;
1021                 count -= write_bytes;
1022                 pos += write_bytes;
1023                 num_written += write_bytes;
1024
1025                 cond_resched();
1026         }
1027 out:
1028         mutex_unlock(&inode->i_mutex);
1029         if (ret)
1030                 err = ret;
1031
1032 out_nolock:
1033         kfree(pages);
1034         if (pinned[0])
1035                 page_cache_release(pinned[0]);
1036         if (pinned[1])
1037                 page_cache_release(pinned[1]);
1038         *ppos = pos;
1039
1040         /*
1041          * we want to make sure fsync finds this change
1042          * but we haven't joined a transaction running right now.
1043          *
1044          * Later on, someone is sure to update the inode and get the
1045          * real transid recorded.
1046          *
1047          * We set last_trans now to the fs_info generation + 1,
1048          * this will either be one more than the running transaction
1049          * or the generation used for the next transaction if there isn't
1050          * one running right now.
1051          */
1052         BTRFS_I(inode)->last_trans = root->fs_info->generation + 1;
1053
1054         if (num_written > 0 && will_write) {
1055                 struct btrfs_trans_handle *trans;
1056
1057                 err = btrfs_wait_ordered_range(inode, start_pos, num_written);
1058                 if (err)
1059                         num_written = err;
1060
1061                 if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
1062                         trans = btrfs_start_transaction(root, 1);
1063                         ret = btrfs_log_dentry_safe(trans, root,
1064                                                     file->f_dentry);
1065                         if (ret == 0) {
1066                                 ret = btrfs_sync_log(trans, root);
1067                                 if (ret == 0)
1068                                         btrfs_end_transaction(trans, root);
1069                                 else
1070                                         btrfs_commit_transaction(trans, root);
1071                         } else {
1072                                 btrfs_commit_transaction(trans, root);
1073                         }
1074                 }
1075                 if (file->f_flags & O_DIRECT) {
1076                         invalidate_mapping_pages(inode->i_mapping,
1077                               start_pos >> PAGE_CACHE_SHIFT,
1078                              (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);
1079                 }
1080         }
1081         current->backing_dev_info = NULL;
1082         return num_written ? num_written : err;
1083 }
1084
1085 int btrfs_release_file(struct inode *inode, struct file *filp)
1086 {
1087         /*
1088          * ordered_data_close is set by settattr when we are about to truncate
1089          * a file from a non-zero size to a zero size.  This tries to
1090          * flush down new bytes that may have been written if the
1091          * application were using truncate to replace a file in place.
1092          */
1093         if (BTRFS_I(inode)->ordered_data_close) {
1094                 BTRFS_I(inode)->ordered_data_close = 0;
1095                 btrfs_add_ordered_operation(NULL, BTRFS_I(inode)->root, inode);
1096                 if (inode->i_size > BTRFS_ORDERED_OPERATIONS_FLUSH_LIMIT)
1097                         filemap_flush(inode->i_mapping);
1098         }
1099         if (filp->private_data)
1100                 btrfs_ioctl_trans_end(filp);
1101         return 0;
1102 }
1103
1104 /*
1105  * fsync call for both files and directories.  This logs the inode into
1106  * the tree log instead of forcing full commits whenever possible.
1107  *
1108  * It needs to call filemap_fdatawait so that all ordered extent updates are
1109  * in the metadata btree are up to date for copying to the log.
1110  *
1111  * It drops the inode mutex before doing the tree log commit.  This is an
1112  * important optimization for directories because holding the mutex prevents
1113  * new operations on the dir while we write to disk.
1114  */
1115 int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
1116 {
1117         struct inode *inode = dentry->d_inode;
1118         struct btrfs_root *root = BTRFS_I(inode)->root;
1119         int ret = 0;
1120         struct btrfs_trans_handle *trans;
1121
1122         /*
1123          * check the transaction that last modified this inode
1124          * and see if its already been committed
1125          */
1126         if (!BTRFS_I(inode)->last_trans)
1127                 goto out;
1128
1129         mutex_lock(&root->fs_info->trans_mutex);
1130         if (BTRFS_I(inode)->last_trans <=
1131             root->fs_info->last_trans_committed) {
1132                 BTRFS_I(inode)->last_trans = 0;
1133                 mutex_unlock(&root->fs_info->trans_mutex);
1134                 goto out;
1135         }
1136         mutex_unlock(&root->fs_info->trans_mutex);
1137
1138         root->log_batch++;
1139         filemap_fdatawrite(inode->i_mapping);
1140         btrfs_wait_ordered_range(inode, 0, (u64)-1);
1141         root->log_batch++;
1142
1143         if (datasync && !(inode->i_state & I_DIRTY_PAGES))
1144                 goto out;
1145         /*
1146          * ok we haven't committed the transaction yet, lets do a commit
1147          */
1148         if (file && file->private_data)
1149                 btrfs_ioctl_trans_end(file);
1150
1151         trans = btrfs_start_transaction(root, 1);
1152         if (!trans) {
1153                 ret = -ENOMEM;
1154                 goto out;
1155         }
1156
1157         ret = btrfs_log_dentry_safe(trans, root, dentry);
1158         if (ret < 0)
1159                 goto out;
1160
1161         /* we've logged all the items and now have a consistent
1162          * version of the file in the log.  It is possible that
1163          * someone will come in and modify the file, but that's
1164          * fine because the log is consistent on disk, and we
1165          * have references to all of the file's extents
1166          *
1167          * It is possible that someone will come in and log the
1168          * file again, but that will end up using the synchronization
1169          * inside btrfs_sync_log to keep things safe.
1170          */
1171         mutex_unlock(&dentry->d_inode->i_mutex);
1172
1173         if (ret > 0) {
1174                 ret = btrfs_commit_transaction(trans, root);
1175         } else {
1176                 ret = btrfs_sync_log(trans, root);
1177                 if (ret == 0)
1178                         ret = btrfs_end_transaction(trans, root);
1179                 else
1180                         ret = btrfs_commit_transaction(trans, root);
1181         }
1182         mutex_lock(&dentry->d_inode->i_mutex);
1183 out:
1184         return ret > 0 ? EIO : ret;
1185 }
1186
1187 static const struct vm_operations_struct btrfs_file_vm_ops = {
1188         .fault          = filemap_fault,
1189         .page_mkwrite   = btrfs_page_mkwrite,
1190 };
1191
1192 static int btrfs_file_mmap(struct file  *filp, struct vm_area_struct *vma)
1193 {
1194         vma->vm_ops = &btrfs_file_vm_ops;
1195         file_accessed(filp);
1196         return 0;
1197 }
1198
1199 struct file_operations btrfs_file_operations = {
1200         .llseek         = generic_file_llseek,
1201         .read           = do_sync_read,
1202         .aio_read       = generic_file_aio_read,
1203         .splice_read    = generic_file_splice_read,
1204         .write          = btrfs_file_write,
1205         .mmap           = btrfs_file_mmap,
1206         .open           = generic_file_open,
1207         .release        = btrfs_release_file,
1208         .fsync          = btrfs_sync_file,
1209         .unlocked_ioctl = btrfs_ioctl,
1210 #ifdef CONFIG_COMPAT
1211         .compat_ioctl   = btrfs_ioctl,
1212 #endif
1213 };