Root/fs/btrfs/ordered-data.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/slab.h>
20#include <linux/blkdev.h>
21#include <linux/writeback.h>
22#include <linux/pagevec.h>
23#include "ctree.h"
24#include "transaction.h"
25#include "btrfs_inode.h"
26#include "extent_io.h"
27
28static u64 entry_end(struct btrfs_ordered_extent *entry)
29{
30    if (entry->file_offset + entry->len < entry->file_offset)
31        return (u64)-1;
32    return entry->file_offset + entry->len;
33}
34
35/* returns NULL if the insertion worked, or it returns the node it did find
36 * in the tree
37 */
38static struct rb_node *tree_insert(struct rb_root *root, u64 file_offset,
39                   struct rb_node *node)
40{
41    struct rb_node **p = &root->rb_node;
42    struct rb_node *parent = NULL;
43    struct btrfs_ordered_extent *entry;
44
45    while (*p) {
46        parent = *p;
47        entry = rb_entry(parent, struct btrfs_ordered_extent, rb_node);
48
49        if (file_offset < entry->file_offset)
50            p = &(*p)->rb_left;
51        else if (file_offset >= entry_end(entry))
52            p = &(*p)->rb_right;
53        else
54            return parent;
55    }
56
57    rb_link_node(node, parent, p);
58    rb_insert_color(node, root);
59    return NULL;
60}
61
62/*
63 * look for a given offset in the tree, and if it can't be found return the
64 * first lesser offset
65 */
66static struct rb_node *__tree_search(struct rb_root *root, u64 file_offset,
67                     struct rb_node **prev_ret)
68{
69    struct rb_node *n = root->rb_node;
70    struct rb_node *prev = NULL;
71    struct rb_node *test;
72    struct btrfs_ordered_extent *entry;
73    struct btrfs_ordered_extent *prev_entry = NULL;
74
75    while (n) {
76        entry = rb_entry(n, struct btrfs_ordered_extent, rb_node);
77        prev = n;
78        prev_entry = entry;
79
80        if (file_offset < entry->file_offset)
81            n = n->rb_left;
82        else if (file_offset >= entry_end(entry))
83            n = n->rb_right;
84        else
85            return n;
86    }
87    if (!prev_ret)
88        return NULL;
89
90    while (prev && file_offset >= entry_end(prev_entry)) {
91        test = rb_next(prev);
92        if (!test)
93            break;
94        prev_entry = rb_entry(test, struct btrfs_ordered_extent,
95                      rb_node);
96        if (file_offset < entry_end(prev_entry))
97            break;
98
99        prev = test;
100    }
101    if (prev)
102        prev_entry = rb_entry(prev, struct btrfs_ordered_extent,
103                      rb_node);
104    while (prev && file_offset < entry_end(prev_entry)) {
105        test = rb_prev(prev);
106        if (!test)
107            break;
108        prev_entry = rb_entry(test, struct btrfs_ordered_extent,
109                      rb_node);
110        prev = test;
111    }
112    *prev_ret = prev;
113    return NULL;
114}
115
116/*
117 * helper to check if a given offset is inside a given entry
118 */
119static int offset_in_entry(struct btrfs_ordered_extent *entry, u64 file_offset)
120{
121    if (file_offset < entry->file_offset ||
122        entry->file_offset + entry->len <= file_offset)
123        return 0;
124    return 1;
125}
126
127/*
128 * look find the first ordered struct that has this offset, otherwise
129 * the first one less than this offset
130 */
131static inline struct rb_node *tree_search(struct btrfs_ordered_inode_tree *tree,
132                      u64 file_offset)
133{
134    struct rb_root *root = &tree->tree;
135    struct rb_node *prev;
136    struct rb_node *ret;
137    struct btrfs_ordered_extent *entry;
138
139    if (tree->last) {
140        entry = rb_entry(tree->last, struct btrfs_ordered_extent,
141                 rb_node);
142        if (offset_in_entry(entry, file_offset))
143            return tree->last;
144    }
145    ret = __tree_search(root, file_offset, &prev);
146    if (!ret)
147        ret = prev;
148    if (ret)
149        tree->last = ret;
150    return ret;
151}
152
153/* allocate and add a new ordered_extent into the per-inode tree.
154 * file_offset is the logical offset in the file
155 *
156 * start is the disk block number of an extent already reserved in the
157 * extent allocation tree
158 *
159 * len is the length of the extent
160 *
161 * The tree is given a single reference on the ordered extent that was
162 * inserted.
163 */
164int btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
165                 u64 start, u64 len, u64 disk_len, int type)
166{
167    struct btrfs_ordered_inode_tree *tree;
168    struct rb_node *node;
169    struct btrfs_ordered_extent *entry;
170
171    tree = &BTRFS_I(inode)->ordered_tree;
172    entry = kzalloc(sizeof(*entry), GFP_NOFS);
173    if (!entry)
174        return -ENOMEM;
175
176    entry->file_offset = file_offset;
177    entry->start = start;
178    entry->len = len;
179    entry->disk_len = disk_len;
180    entry->bytes_left = len;
181    entry->inode = inode;
182    if (type != BTRFS_ORDERED_IO_DONE && type != BTRFS_ORDERED_COMPLETE)
183        set_bit(type, &entry->flags);
184
185    /* one ref for the tree */
186    atomic_set(&entry->refs, 1);
187    init_waitqueue_head(&entry->wait);
188    INIT_LIST_HEAD(&entry->list);
189    INIT_LIST_HEAD(&entry->root_extent_list);
190
191    spin_lock(&tree->lock);
192    node = tree_insert(&tree->tree, file_offset,
193               &entry->rb_node);
194    BUG_ON(node);
195    spin_unlock(&tree->lock);
196
197    spin_lock(&BTRFS_I(inode)->root->fs_info->ordered_extent_lock);
198    list_add_tail(&entry->root_extent_list,
199              &BTRFS_I(inode)->root->fs_info->ordered_extents);
200    spin_unlock(&BTRFS_I(inode)->root->fs_info->ordered_extent_lock);
201
202    BUG_ON(node);
203    return 0;
204}
205
206/*
207 * Add a struct btrfs_ordered_sum into the list of checksums to be inserted
208 * when an ordered extent is finished. If the list covers more than one
209 * ordered extent, it is split across multiples.
210 */
211int btrfs_add_ordered_sum(struct inode *inode,
212              struct btrfs_ordered_extent *entry,
213              struct btrfs_ordered_sum *sum)
214{
215    struct btrfs_ordered_inode_tree *tree;
216
217    tree = &BTRFS_I(inode)->ordered_tree;
218    spin_lock(&tree->lock);
219    list_add_tail(&sum->list, &entry->list);
220    spin_unlock(&tree->lock);
221    return 0;
222}
223
224/*
225 * this is used to account for finished IO across a given range
226 * of the file. The IO should not span ordered extents. If
227 * a given ordered_extent is completely done, 1 is returned, otherwise
228 * 0.
229 *
230 * test_and_set_bit on a flag in the struct btrfs_ordered_extent is used
231 * to make sure this function only returns 1 once for a given ordered extent.
232 */
233int btrfs_dec_test_ordered_pending(struct inode *inode,
234                   struct btrfs_ordered_extent **cached,
235                   u64 file_offset, u64 io_size)
236{
237    struct btrfs_ordered_inode_tree *tree;
238    struct rb_node *node;
239    struct btrfs_ordered_extent *entry = NULL;
240    int ret;
241
242    tree = &BTRFS_I(inode)->ordered_tree;
243    spin_lock(&tree->lock);
244    node = tree_search(tree, file_offset);
245    if (!node) {
246        ret = 1;
247        goto out;
248    }
249
250    entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
251    if (!offset_in_entry(entry, file_offset)) {
252        ret = 1;
253        goto out;
254    }
255
256    if (io_size > entry->bytes_left) {
257        printk(KERN_CRIT "bad ordered accounting left %llu size %llu\n",
258               (unsigned long long)entry->bytes_left,
259               (unsigned long long)io_size);
260    }
261    entry->bytes_left -= io_size;
262    if (entry->bytes_left == 0)
263        ret = test_and_set_bit(BTRFS_ORDERED_IO_DONE, &entry->flags);
264    else
265        ret = 1;
266out:
267    if (!ret && cached && entry) {
268        *cached = entry;
269        atomic_inc(&entry->refs);
270    }
271    spin_unlock(&tree->lock);
272    return ret == 0;
273}
274
275/*
276 * used to drop a reference on an ordered extent. This will free
277 * the extent if the last reference is dropped
278 */
279int btrfs_put_ordered_extent(struct btrfs_ordered_extent *entry)
280{
281    struct list_head *cur;
282    struct btrfs_ordered_sum *sum;
283
284    if (atomic_dec_and_test(&entry->refs)) {
285        while (!list_empty(&entry->list)) {
286            cur = entry->list.next;
287            sum = list_entry(cur, struct btrfs_ordered_sum, list);
288            list_del(&sum->list);
289            kfree(sum);
290        }
291        kfree(entry);
292    }
293    return 0;
294}
295
296/*
297 * remove an ordered extent from the tree. No references are dropped
298 * and you must wake_up entry->wait. You must hold the tree lock
299 * while you call this function.
300 */
301static int __btrfs_remove_ordered_extent(struct inode *inode,
302                struct btrfs_ordered_extent *entry)
303{
304    struct btrfs_ordered_inode_tree *tree;
305    struct btrfs_root *root = BTRFS_I(inode)->root;
306    struct rb_node *node;
307
308    tree = &BTRFS_I(inode)->ordered_tree;
309    node = &entry->rb_node;
310    rb_erase(node, &tree->tree);
311    tree->last = NULL;
312    set_bit(BTRFS_ORDERED_COMPLETE, &entry->flags);
313
314    spin_lock(&BTRFS_I(inode)->accounting_lock);
315    WARN_ON(!BTRFS_I(inode)->outstanding_extents);
316    BTRFS_I(inode)->outstanding_extents--;
317    spin_unlock(&BTRFS_I(inode)->accounting_lock);
318    btrfs_unreserve_metadata_for_delalloc(BTRFS_I(inode)->root,
319                          inode, 1);
320
321    spin_lock(&root->fs_info->ordered_extent_lock);
322    list_del_init(&entry->root_extent_list);
323
324    /*
325     * we have no more ordered extents for this inode and
326     * no dirty pages. We can safely remove it from the
327     * list of ordered extents
328     */
329    if (RB_EMPTY_ROOT(&tree->tree) &&
330        !mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) {
331        list_del_init(&BTRFS_I(inode)->ordered_operations);
332    }
333    spin_unlock(&root->fs_info->ordered_extent_lock);
334
335    return 0;
336}
337
338/*
339 * remove an ordered extent from the tree. No references are dropped
340 * but any waiters are woken.
341 */
342int btrfs_remove_ordered_extent(struct inode *inode,
343                struct btrfs_ordered_extent *entry)
344{
345    struct btrfs_ordered_inode_tree *tree;
346    int ret;
347
348    tree = &BTRFS_I(inode)->ordered_tree;
349    spin_lock(&tree->lock);
350    ret = __btrfs_remove_ordered_extent(inode, entry);
351    spin_unlock(&tree->lock);
352    wake_up(&entry->wait);
353
354    return ret;
355}
356
357/*
358 * wait for all the ordered extents in a root. This is done when balancing
359 * space between drives.
360 */
361int btrfs_wait_ordered_extents(struct btrfs_root *root,
362                   int nocow_only, int delay_iput)
363{
364    struct list_head splice;
365    struct list_head *cur;
366    struct btrfs_ordered_extent *ordered;
367    struct inode *inode;
368
369    INIT_LIST_HEAD(&splice);
370
371    spin_lock(&root->fs_info->ordered_extent_lock);
372    list_splice_init(&root->fs_info->ordered_extents, &splice);
373    while (!list_empty(&splice)) {
374        cur = splice.next;
375        ordered = list_entry(cur, struct btrfs_ordered_extent,
376                     root_extent_list);
377        if (nocow_only &&
378            !test_bit(BTRFS_ORDERED_NOCOW, &ordered->flags) &&
379            !test_bit(BTRFS_ORDERED_PREALLOC, &ordered->flags)) {
380            list_move(&ordered->root_extent_list,
381                  &root->fs_info->ordered_extents);
382            cond_resched_lock(&root->fs_info->ordered_extent_lock);
383            continue;
384        }
385
386        list_del_init(&ordered->root_extent_list);
387        atomic_inc(&ordered->refs);
388
389        /*
390         * the inode may be getting freed (in sys_unlink path).
391         */
392        inode = igrab(ordered->inode);
393
394        spin_unlock(&root->fs_info->ordered_extent_lock);
395
396        if (inode) {
397            btrfs_start_ordered_extent(inode, ordered, 1);
398            btrfs_put_ordered_extent(ordered);
399            if (delay_iput)
400                btrfs_add_delayed_iput(inode);
401            else
402                iput(inode);
403        } else {
404            btrfs_put_ordered_extent(ordered);
405        }
406
407        spin_lock(&root->fs_info->ordered_extent_lock);
408    }
409    spin_unlock(&root->fs_info->ordered_extent_lock);
410    return 0;
411}
412
413/*
414 * this is used during transaction commit to write all the inodes
415 * added to the ordered operation list. These files must be fully on
416 * disk before the transaction commits.
417 *
418 * we have two modes here, one is to just start the IO via filemap_flush
419 * and the other is to wait for all the io. When we wait, we have an
420 * extra check to make sure the ordered operation list really is empty
421 * before we return
422 */
423int btrfs_run_ordered_operations(struct btrfs_root *root, int wait)
424{
425    struct btrfs_inode *btrfs_inode;
426    struct inode *inode;
427    struct list_head splice;
428
429    INIT_LIST_HEAD(&splice);
430
431    mutex_lock(&root->fs_info->ordered_operations_mutex);
432    spin_lock(&root->fs_info->ordered_extent_lock);
433again:
434    list_splice_init(&root->fs_info->ordered_operations, &splice);
435
436    while (!list_empty(&splice)) {
437        btrfs_inode = list_entry(splice.next, struct btrfs_inode,
438                   ordered_operations);
439
440        inode = &btrfs_inode->vfs_inode;
441
442        list_del_init(&btrfs_inode->ordered_operations);
443
444        /*
445         * the inode may be getting freed (in sys_unlink path).
446         */
447        inode = igrab(inode);
448
449        if (!wait && inode) {
450            list_add_tail(&BTRFS_I(inode)->ordered_operations,
451                  &root->fs_info->ordered_operations);
452        }
453        spin_unlock(&root->fs_info->ordered_extent_lock);
454
455        if (inode) {
456            if (wait)
457                btrfs_wait_ordered_range(inode, 0, (u64)-1);
458            else
459                filemap_flush(inode->i_mapping);
460            btrfs_add_delayed_iput(inode);
461        }
462
463        cond_resched();
464        spin_lock(&root->fs_info->ordered_extent_lock);
465    }
466    if (wait && !list_empty(&root->fs_info->ordered_operations))
467        goto again;
468
469    spin_unlock(&root->fs_info->ordered_extent_lock);
470    mutex_unlock(&root->fs_info->ordered_operations_mutex);
471
472    return 0;
473}
474
475/*
476 * Used to start IO or wait for a given ordered extent to finish.
477 *
478 * If wait is one, this effectively waits on page writeback for all the pages
479 * in the extent, and it waits on the io completion code to insert
480 * metadata into the btree corresponding to the extent
481 */
482void btrfs_start_ordered_extent(struct inode *inode,
483                       struct btrfs_ordered_extent *entry,
484                       int wait)
485{
486    u64 start = entry->file_offset;
487    u64 end = start + entry->len - 1;
488
489    /*
490     * pages in the range can be dirty, clean or writeback. We
491     * start IO on any dirty ones so the wait doesn't stall waiting
492     * for pdflush to find them
493     */
494    filemap_fdatawrite_range(inode->i_mapping, start, end);
495    if (wait) {
496        wait_event(entry->wait, test_bit(BTRFS_ORDERED_COMPLETE,
497                         &entry->flags));
498    }
499}
500
501/*
502 * Used to wait on ordered extents across a large range of bytes.
503 */
504int btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len)
505{
506    u64 end;
507    u64 orig_end;
508    u64 wait_end;
509    struct btrfs_ordered_extent *ordered;
510    int found;
511
512    if (start + len < start) {
513        orig_end = INT_LIMIT(loff_t);
514    } else {
515        orig_end = start + len - 1;
516        if (orig_end > INT_LIMIT(loff_t))
517            orig_end = INT_LIMIT(loff_t);
518    }
519    wait_end = orig_end;
520again:
521    /* start IO across the range first to instantiate any delalloc
522     * extents
523     */
524    filemap_fdatawrite_range(inode->i_mapping, start, orig_end);
525
526    /* The compression code will leave pages locked but return from
527     * writepage without setting the page writeback. Starting again
528     * with WB_SYNC_ALL will end up waiting for the IO to actually start.
529     */
530    filemap_fdatawrite_range(inode->i_mapping, start, orig_end);
531
532    filemap_fdatawait_range(inode->i_mapping, start, orig_end);
533
534    end = orig_end;
535    found = 0;
536    while (1) {
537        ordered = btrfs_lookup_first_ordered_extent(inode, end);
538        if (!ordered)
539            break;
540        if (ordered->file_offset > orig_end) {
541            btrfs_put_ordered_extent(ordered);
542            break;
543        }
544        if (ordered->file_offset + ordered->len < start) {
545            btrfs_put_ordered_extent(ordered);
546            break;
547        }
548        found++;
549        btrfs_start_ordered_extent(inode, ordered, 1);
550        end = ordered->file_offset;
551        btrfs_put_ordered_extent(ordered);
552        if (end == 0 || end == start)
553            break;
554        end--;
555    }
556    if (found || test_range_bit(&BTRFS_I(inode)->io_tree, start, orig_end,
557               EXTENT_DELALLOC, 0, NULL)) {
558        schedule_timeout(1);
559        goto again;
560    }
561    return 0;
562}
563
564/*
565 * find an ordered extent corresponding to file_offset. return NULL if
566 * nothing is found, otherwise take a reference on the extent and return it
567 */
568struct btrfs_ordered_extent *btrfs_lookup_ordered_extent(struct inode *inode,
569                             u64 file_offset)
570{
571    struct btrfs_ordered_inode_tree *tree;
572    struct rb_node *node;
573    struct btrfs_ordered_extent *entry = NULL;
574
575    tree = &BTRFS_I(inode)->ordered_tree;
576    spin_lock(&tree->lock);
577    node = tree_search(tree, file_offset);
578    if (!node)
579        goto out;
580
581    entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
582    if (!offset_in_entry(entry, file_offset))
583        entry = NULL;
584    if (entry)
585        atomic_inc(&entry->refs);
586out:
587    spin_unlock(&tree->lock);
588    return entry;
589}
590
591/*
592 * lookup and return any extent before 'file_offset'. NULL is returned
593 * if none is found
594 */
595struct btrfs_ordered_extent *
596btrfs_lookup_first_ordered_extent(struct inode *inode, u64 file_offset)
597{
598    struct btrfs_ordered_inode_tree *tree;
599    struct rb_node *node;
600    struct btrfs_ordered_extent *entry = NULL;
601
602    tree = &BTRFS_I(inode)->ordered_tree;
603    spin_lock(&tree->lock);
604    node = tree_search(tree, file_offset);
605    if (!node)
606        goto out;
607
608    entry = rb_entry(node, struct btrfs_ordered_extent, rb_node);
609    atomic_inc(&entry->refs);
610out:
611    spin_unlock(&tree->lock);
612    return entry;
613}
614
615/*
616 * After an extent is done, call this to conditionally update the on disk
617 * i_size. i_size is updated to cover any fully written part of the file.
618 */
619int btrfs_ordered_update_i_size(struct inode *inode, u64 offset,
620                struct btrfs_ordered_extent *ordered)
621{
622    struct btrfs_ordered_inode_tree *tree = &BTRFS_I(inode)->ordered_tree;
623    struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
624    u64 disk_i_size;
625    u64 new_i_size;
626    u64 i_size_test;
627    u64 i_size = i_size_read(inode);
628    struct rb_node *node;
629    struct rb_node *prev = NULL;
630    struct btrfs_ordered_extent *test;
631    int ret = 1;
632
633    if (ordered)
634        offset = entry_end(ordered);
635    else
636        offset = ALIGN(offset, BTRFS_I(inode)->root->sectorsize);
637
638    spin_lock(&tree->lock);
639    disk_i_size = BTRFS_I(inode)->disk_i_size;
640
641    /* truncate file */
642    if (disk_i_size > i_size) {
643        BTRFS_I(inode)->disk_i_size = i_size;
644        ret = 0;
645        goto out;
646    }
647
648    /*
649     * if the disk i_size is already at the inode->i_size, or
650     * this ordered extent is inside the disk i_size, we're done
651     */
652    if (disk_i_size == i_size || offset <= disk_i_size) {
653        goto out;
654    }
655
656    /*
657     * we can't update the disk_isize if there are delalloc bytes
658     * between disk_i_size and this ordered extent
659     */
660    if (test_range_bit(io_tree, disk_i_size, offset - 1,
661               EXTENT_DELALLOC, 0, NULL)) {
662        goto out;
663    }
664    /*
665     * walk backward from this ordered extent to disk_i_size.
666     * if we find an ordered extent then we can't update disk i_size
667     * yet
668     */
669    if (ordered) {
670        node = rb_prev(&ordered->rb_node);
671    } else {
672        prev = tree_search(tree, offset);
673        /*
674         * we insert file extents without involving ordered struct,
675         * so there should be no ordered struct cover this offset
676         */
677        if (prev) {
678            test = rb_entry(prev, struct btrfs_ordered_extent,
679                    rb_node);
680            BUG_ON(offset_in_entry(test, offset));
681        }
682        node = prev;
683    }
684    while (node) {
685        test = rb_entry(node, struct btrfs_ordered_extent, rb_node);
686        if (test->file_offset + test->len <= disk_i_size)
687            break;
688        if (test->file_offset >= i_size)
689            break;
690        if (test->file_offset >= disk_i_size)
691            goto out;
692        node = rb_prev(node);
693    }
694    new_i_size = min_t(u64, offset, i_size);
695
696    /*
697     * at this point, we know we can safely update i_size to at least
698     * the offset from this ordered extent. But, we need to
699     * walk forward and see if ios from higher up in the file have
700     * finished.
701     */
702    if (ordered) {
703        node = rb_next(&ordered->rb_node);
704    } else {
705        if (prev)
706            node = rb_next(prev);
707        else
708            node = rb_first(&tree->tree);
709    }
710    i_size_test = 0;
711    if (node) {
712        /*
713         * do we have an area where IO might have finished
714         * between our ordered extent and the next one.
715         */
716        test = rb_entry(node, struct btrfs_ordered_extent, rb_node);
717        if (test->file_offset > offset)
718            i_size_test = test->file_offset;
719    } else {
720        i_size_test = i_size;
721    }
722
723    /*
724     * i_size_test is the end of a region after this ordered
725     * extent where there are no ordered extents. As long as there
726     * are no delalloc bytes in this area, it is safe to update
727     * disk_i_size to the end of the region.
728     */
729    if (i_size_test > offset &&
730        !test_range_bit(io_tree, offset, i_size_test - 1,
731                EXTENT_DELALLOC, 0, NULL)) {
732        new_i_size = min_t(u64, i_size_test, i_size);
733    }
734    BTRFS_I(inode)->disk_i_size = new_i_size;
735    ret = 0;
736out:
737    /*
738     * we need to remove the ordered extent with the tree lock held
739     * so that other people calling this function don't find our fully
740     * processed ordered entry and skip updating the i_size
741     */
742    if (ordered)
743        __btrfs_remove_ordered_extent(inode, ordered);
744    spin_unlock(&tree->lock);
745    if (ordered)
746        wake_up(&ordered->wait);
747    return ret;
748}
749
750/*
751 * search the ordered extents for one corresponding to 'offset' and
752 * try to find a checksum. This is used because we allow pages to
753 * be reclaimed before their checksum is actually put into the btree
754 */
755int btrfs_find_ordered_sum(struct inode *inode, u64 offset, u64 disk_bytenr,
756               u32 *sum)
757{
758    struct btrfs_ordered_sum *ordered_sum;
759    struct btrfs_sector_sum *sector_sums;
760    struct btrfs_ordered_extent *ordered;
761    struct btrfs_ordered_inode_tree *tree = &BTRFS_I(inode)->ordered_tree;
762    unsigned long num_sectors;
763    unsigned long i;
764    u32 sectorsize = BTRFS_I(inode)->root->sectorsize;
765    int ret = 1;
766
767    ordered = btrfs_lookup_ordered_extent(inode, offset);
768    if (!ordered)
769        return 1;
770
771    spin_lock(&tree->lock);
772    list_for_each_entry_reverse(ordered_sum, &ordered->list, list) {
773        if (disk_bytenr >= ordered_sum->bytenr) {
774            num_sectors = ordered_sum->len / sectorsize;
775            sector_sums = ordered_sum->sums;
776            for (i = 0; i < num_sectors; i++) {
777                if (sector_sums[i].bytenr == disk_bytenr) {
778                    *sum = sector_sums[i].sum;
779                    ret = 0;
780                    goto out;
781                }
782            }
783        }
784    }
785out:
786    spin_unlock(&tree->lock);
787    btrfs_put_ordered_extent(ordered);
788    return ret;
789}
790
791
792/*
793 * add a given inode to the list of inodes that must be fully on
794 * disk before a transaction commit finishes.
795 *
796 * This basically gives us the ext3 style data=ordered mode, and it is mostly
797 * used to make sure renamed files are fully on disk.
798 *
799 * It is a noop if the inode is already fully on disk.
800 *
801 * If trans is not null, we'll do a friendly check for a transaction that
802 * is already flushing things and force the IO down ourselves.
803 */
804int btrfs_add_ordered_operation(struct btrfs_trans_handle *trans,
805                struct btrfs_root *root,
806                struct inode *inode)
807{
808    u64 last_mod;
809
810    last_mod = max(BTRFS_I(inode)->generation, BTRFS_I(inode)->last_trans);
811
812    /*
813     * if this file hasn't been changed since the last transaction
814     * commit, we can safely return without doing anything
815     */
816    if (last_mod < root->fs_info->last_trans_committed)
817        return 0;
818
819    /*
820     * the transaction is already committing. Just start the IO and
821     * don't bother with all of this list nonsense
822     */
823    if (trans && root->fs_info->running_transaction->blocked) {
824        btrfs_wait_ordered_range(inode, 0, (u64)-1);
825        return 0;
826    }
827
828    spin_lock(&root->fs_info->ordered_extent_lock);
829    if (list_empty(&BTRFS_I(inode)->ordered_operations)) {
830        list_add_tail(&BTRFS_I(inode)->ordered_operations,
831                  &root->fs_info->ordered_operations);
832    }
833    spin_unlock(&root->fs_info->ordered_extent_lock);
834
835    return 0;
836}
837

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