2 * fs/ext4/extents_status.c
4 * Written by Yongqiang Yang <xiaoqiangnk@gmail.com>
6 * Allison Henderson <achender@linux.vnet.ibm.com>
7 * Hugh Dickins <hughd@google.com>
8 * Zheng Liu <wenqing.lz@taobao.com>
10 * Ext4 extents status tree core functions.
12 #include <linux/rbtree.h>
14 #include "extents_status.h"
15 #include "ext4_extents.h"
17 #include <trace/events/ext4.h>
20 * According to previous discussion in Ext4 Developer Workshop, we
21 * will introduce a new structure called io tree to track all extent
22 * status in order to solve some problems that we have met
23 * (e.g. Reservation space warning), and provide extent-level locking.
24 * Delay extent tree is the first step to achieve this goal. It is
25 * original built by Yongqiang Yang. At that time it is called delay
26 * extent tree, whose goal is only track delayed extents in memory to
27 * simplify the implementation of fiemap and bigalloc, and introduce
28 * lseek SEEK_DATA/SEEK_HOLE support. That is why it is still called
29 * delay extent tree at the first commit. But for better understand
30 * what it does, it has been rename to extent status tree.
33 * Currently the first step has been done. All delayed extents are
34 * tracked in the tree. It maintains the delayed extent when a delayed
35 * allocation is issued, and the delayed extent is written out or
36 * invalidated. Therefore the implementation of fiemap and bigalloc
37 * are simplified, and SEEK_DATA/SEEK_HOLE are introduced.
39 * The following comment describes the implemenmtation of extent
40 * status tree and future works.
43 * In this step all extent status are tracked by extent status tree.
44 * Thus, we can first try to lookup a block mapping in this tree before
45 * finding it in extent tree. Hence, single extent cache can be removed
46 * because extent status tree can do a better job. Extents in status
47 * tree are loaded on-demand. Therefore, the extent status tree may not
48 * contain all of the extents in a file. Meanwhile we define a shrinker
49 * to reclaim memory from extent status tree because fragmented extent
50 * tree will make status tree cost too much memory. written/unwritten/-
51 * hole extents in the tree will be reclaimed by this shrinker when we
52 * are under high memory pressure. Delayed extents will not be
53 * reclimed because fiemap, bigalloc, and seek_data/hole need it.
57 * Extent status tree implementation for ext4.
60 * ==========================================================================
61 * Extent status tree tracks all extent status.
63 * 1. Why we need to implement extent status tree?
65 * Without extent status tree, ext4 identifies a delayed extent by looking
66 * up page cache, this has several deficiencies - complicated, buggy,
67 * and inefficient code.
69 * FIEMAP, SEEK_HOLE/DATA, bigalloc, and writeout all need to know if a
70 * block or a range of blocks are belonged to a delayed extent.
72 * Let us have a look at how they do without extent status tree.
74 * FIEMAP looks up page cache to identify delayed allocations from holes.
77 * SEEK_HOLE/DATA has the same problem as FIEMAP.
80 * bigalloc looks up page cache to figure out if a block is
81 * already under delayed allocation or not to determine whether
82 * quota reserving is needed for the cluster.
85 * Writeout looks up whole page cache to see if a buffer is
86 * mapped, If there are not very many delayed buffers, then it is
89 * With extent status tree implementation, FIEMAP, SEEK_HOLE/DATA,
90 * bigalloc and writeout can figure out if a block or a range of
91 * blocks is under delayed allocation(belonged to a delayed extent) or
92 * not by searching the extent tree.
95 * ==========================================================================
96 * 2. Ext4 extent status tree impelmentation
99 * A extent is a range of blocks which are contiguous logically and
100 * physically. Unlike extent in extent tree, this extent in ext4 is
101 * a in-memory struct, there is no corresponding on-disk data. There
102 * is no limit on length of extent, so an extent can contain as many
103 * blocks as they are contiguous logically and physically.
105 * -- extent status tree
106 * Every inode has an extent status tree and all allocation blocks
107 * are added to the tree with different status. The extent in the
108 * tree are ordered by logical block no.
110 * -- operations on a extent status tree
111 * There are three important operations on a delayed extent tree: find
112 * next extent, adding a extent(a range of blocks) and removing a extent.
114 * -- race on a extent status tree
115 * Extent status tree is protected by inode->i_es_lock.
117 * -- memory consumption
118 * Fragmented extent tree will make extent status tree cost too much
119 * memory. Hence, we will reclaim written/unwritten/hole extents from
120 * the tree under a heavy memory pressure.
123 * ==========================================================================
124 * 3. Performance analysis
127 * 1. There is a cache extent for write access, so if writes are
128 * not very random, adding space operaions are in O(1) time.
131 * 2. Code is much simpler, more readable, more maintainable and
135 * ==========================================================================
138 * -- Refactor delayed space reservation
140 * -- Extent-level locking
143 static struct kmem_cache
*ext4_es_cachep
;
145 static int __es_insert_extent(struct inode
*inode
, struct extent_status
*newes
);
146 static int __es_remove_extent(struct inode
*inode
, ext4_lblk_t lblk
,
148 static int __es_try_to_reclaim_extents(struct ext4_inode_info
*ei
,
150 static int ext4_es_reclaim_extents_count(struct super_block
*sb
);
152 int __init
ext4_init_es(void)
154 ext4_es_cachep
= KMEM_CACHE(extent_status
, SLAB_RECLAIM_ACCOUNT
);
155 if (ext4_es_cachep
== NULL
)
160 void ext4_exit_es(void)
163 kmem_cache_destroy(ext4_es_cachep
);
166 void ext4_es_init_tree(struct ext4_es_tree
*tree
)
168 tree
->root
= RB_ROOT
;
169 tree
->cache_es
= NULL
;
173 static void ext4_es_print_tree(struct inode
*inode
)
175 struct ext4_es_tree
*tree
;
176 struct rb_node
*node
;
178 printk(KERN_DEBUG
"status extents for inode %lu:", inode
->i_ino
);
179 tree
= &EXT4_I(inode
)->i_es_tree
;
180 node
= rb_first(&tree
->root
);
182 struct extent_status
*es
;
183 es
= rb_entry(node
, struct extent_status
, rb_node
);
184 printk(KERN_DEBUG
" [%u/%u) %llu %llx",
185 es
->es_lblk
, es
->es_len
,
186 ext4_es_pblock(es
), ext4_es_status(es
));
187 node
= rb_next(node
);
189 printk(KERN_DEBUG
"\n");
192 #define ext4_es_print_tree(inode)
195 static inline ext4_lblk_t
ext4_es_end(struct extent_status
*es
)
197 BUG_ON(es
->es_lblk
+ es
->es_len
< es
->es_lblk
);
198 return es
->es_lblk
+ es
->es_len
- 1;
202 * search through the tree for an delayed extent with a given offset. If
203 * it can't be found, try to find next extent.
205 static struct extent_status
*__es_tree_search(struct rb_root
*root
,
208 struct rb_node
*node
= root
->rb_node
;
209 struct extent_status
*es
= NULL
;
212 es
= rb_entry(node
, struct extent_status
, rb_node
);
213 if (lblk
< es
->es_lblk
)
214 node
= node
->rb_left
;
215 else if (lblk
> ext4_es_end(es
))
216 node
= node
->rb_right
;
221 if (es
&& lblk
< es
->es_lblk
)
224 if (es
&& lblk
> ext4_es_end(es
)) {
225 node
= rb_next(&es
->rb_node
);
226 return node
? rb_entry(node
, struct extent_status
, rb_node
) :
234 * ext4_es_find_delayed_extent: find the 1st delayed extent covering @es->lblk
235 * if it exists, otherwise, the next extent after @es->lblk.
237 * @inode: the inode which owns delayed extents
238 * @lblk: the offset where we start to search
239 * @es: delayed extent that we found
241 void ext4_es_find_delayed_extent(struct inode
*inode
, ext4_lblk_t lblk
,
242 struct extent_status
*es
)
244 struct ext4_es_tree
*tree
= NULL
;
245 struct extent_status
*es1
= NULL
;
246 struct rb_node
*node
;
249 trace_ext4_es_find_delayed_extent_enter(inode
, lblk
);
251 read_lock(&EXT4_I(inode
)->i_es_lock
);
252 tree
= &EXT4_I(inode
)->i_es_tree
;
254 /* find extent in cache firstly */
255 es
->es_lblk
= es
->es_len
= es
->es_pblk
= 0;
256 if (tree
->cache_es
) {
257 es1
= tree
->cache_es
;
258 if (in_range(lblk
, es1
->es_lblk
, es1
->es_len
)) {
259 es_debug("%u cached by [%u/%u) %llu %llx\n",
260 lblk
, es1
->es_lblk
, es1
->es_len
,
261 ext4_es_pblock(es1
), ext4_es_status(es1
));
266 es1
= __es_tree_search(&tree
->root
, lblk
);
269 if (es1
&& !ext4_es_is_delayed(es1
)) {
270 while ((node
= rb_next(&es1
->rb_node
)) != NULL
) {
271 es1
= rb_entry(node
, struct extent_status
, rb_node
);
272 if (ext4_es_is_delayed(es1
))
277 if (es1
&& ext4_es_is_delayed(es1
)) {
278 tree
->cache_es
= es1
;
279 es
->es_lblk
= es1
->es_lblk
;
280 es
->es_len
= es1
->es_len
;
281 es
->es_pblk
= es1
->es_pblk
;
284 read_unlock(&EXT4_I(inode
)->i_es_lock
);
286 ext4_es_lru_add(inode
);
287 trace_ext4_es_find_delayed_extent_exit(inode
, es
);
290 static struct extent_status
*
291 ext4_es_alloc_extent(struct inode
*inode
, ext4_lblk_t lblk
, ext4_lblk_t len
,
294 struct extent_status
*es
;
295 es
= kmem_cache_alloc(ext4_es_cachep
, GFP_ATOMIC
);
303 * We don't count delayed extent because we never try to reclaim them
305 if (!ext4_es_is_delayed(es
))
306 EXT4_I(inode
)->i_es_lru_nr
++;
311 static void ext4_es_free_extent(struct inode
*inode
, struct extent_status
*es
)
313 /* Decrease the lru counter when this es is not delayed */
314 if (!ext4_es_is_delayed(es
)) {
315 BUG_ON(EXT4_I(inode
)->i_es_lru_nr
== 0);
316 EXT4_I(inode
)->i_es_lru_nr
--;
319 kmem_cache_free(ext4_es_cachep
, es
);
323 * Check whether or not two extents can be merged
325 * - logical block number is contiguous
326 * - physical block number is contiguous
329 static int ext4_es_can_be_merged(struct extent_status
*es1
,
330 struct extent_status
*es2
)
332 if (es1
->es_lblk
+ es1
->es_len
!= es2
->es_lblk
)
335 if (ext4_es_status(es1
) != ext4_es_status(es2
))
338 if ((ext4_es_is_written(es1
) || ext4_es_is_unwritten(es1
)) &&
339 (ext4_es_pblock(es1
) + es1
->es_len
!= ext4_es_pblock(es2
)))
345 static struct extent_status
*
346 ext4_es_try_to_merge_left(struct inode
*inode
, struct extent_status
*es
)
348 struct ext4_es_tree
*tree
= &EXT4_I(inode
)->i_es_tree
;
349 struct extent_status
*es1
;
350 struct rb_node
*node
;
352 node
= rb_prev(&es
->rb_node
);
356 es1
= rb_entry(node
, struct extent_status
, rb_node
);
357 if (ext4_es_can_be_merged(es1
, es
)) {
358 es1
->es_len
+= es
->es_len
;
359 rb_erase(&es
->rb_node
, &tree
->root
);
360 ext4_es_free_extent(inode
, es
);
367 static struct extent_status
*
368 ext4_es_try_to_merge_right(struct inode
*inode
, struct extent_status
*es
)
370 struct ext4_es_tree
*tree
= &EXT4_I(inode
)->i_es_tree
;
371 struct extent_status
*es1
;
372 struct rb_node
*node
;
374 node
= rb_next(&es
->rb_node
);
378 es1
= rb_entry(node
, struct extent_status
, rb_node
);
379 if (ext4_es_can_be_merged(es
, es1
)) {
380 es
->es_len
+= es1
->es_len
;
381 rb_erase(node
, &tree
->root
);
382 ext4_es_free_extent(inode
, es1
);
388 static int __es_insert_extent(struct inode
*inode
, struct extent_status
*newes
)
390 struct ext4_es_tree
*tree
= &EXT4_I(inode
)->i_es_tree
;
391 struct rb_node
**p
= &tree
->root
.rb_node
;
392 struct rb_node
*parent
= NULL
;
393 struct extent_status
*es
;
397 es
= rb_entry(parent
, struct extent_status
, rb_node
);
399 if (newes
->es_lblk
< es
->es_lblk
) {
400 if (ext4_es_can_be_merged(newes
, es
)) {
402 * Here we can modify es_lblk directly
403 * because it isn't overlapped.
405 es
->es_lblk
= newes
->es_lblk
;
406 es
->es_len
+= newes
->es_len
;
407 if (ext4_es_is_written(es
) ||
408 ext4_es_is_unwritten(es
))
409 ext4_es_store_pblock(es
,
411 es
= ext4_es_try_to_merge_left(inode
, es
);
415 } else if (newes
->es_lblk
> ext4_es_end(es
)) {
416 if (ext4_es_can_be_merged(es
, newes
)) {
417 es
->es_len
+= newes
->es_len
;
418 es
= ext4_es_try_to_merge_right(inode
, es
);
428 es
= ext4_es_alloc_extent(inode
, newes
->es_lblk
, newes
->es_len
,
432 rb_link_node(&es
->rb_node
, parent
, p
);
433 rb_insert_color(&es
->rb_node
, &tree
->root
);
441 * ext4_es_insert_extent() adds a space to a extent status tree.
443 * ext4_es_insert_extent is called by ext4_da_write_begin and
444 * ext4_es_remove_extent.
446 * Return 0 on success, error code on failure.
448 int ext4_es_insert_extent(struct inode
*inode
, ext4_lblk_t lblk
,
449 ext4_lblk_t len
, ext4_fsblk_t pblk
,
450 unsigned long long status
)
452 struct extent_status newes
;
453 ext4_lblk_t end
= lblk
+ len
- 1;
456 es_debug("add [%u/%u) %llu %llx to extent status tree of inode %lu\n",
457 lblk
, len
, pblk
, status
, inode
->i_ino
);
464 newes
.es_lblk
= lblk
;
466 ext4_es_store_pblock(&newes
, pblk
);
467 ext4_es_store_status(&newes
, status
);
468 trace_ext4_es_insert_extent(inode
, &newes
);
470 write_lock(&EXT4_I(inode
)->i_es_lock
);
471 err
= __es_remove_extent(inode
, lblk
, end
);
474 err
= __es_insert_extent(inode
, &newes
);
477 write_unlock(&EXT4_I(inode
)->i_es_lock
);
479 ext4_es_lru_add(inode
);
480 ext4_es_print_tree(inode
);
486 * ext4_es_lookup_extent() looks up an extent in extent status tree.
488 * ext4_es_lookup_extent is called by ext4_map_blocks/ext4_da_map_blocks.
490 * Return: 1 on found, 0 on not
492 int ext4_es_lookup_extent(struct inode
*inode
, ext4_lblk_t lblk
,
493 struct extent_status
*es
)
495 struct ext4_es_tree
*tree
;
496 struct extent_status
*es1
= NULL
;
497 struct rb_node
*node
;
500 trace_ext4_es_lookup_extent_enter(inode
, lblk
);
501 es_debug("lookup extent in block %u\n", lblk
);
503 tree
= &EXT4_I(inode
)->i_es_tree
;
504 read_lock(&EXT4_I(inode
)->i_es_lock
);
506 /* find extent in cache firstly */
507 es
->es_lblk
= es
->es_len
= es
->es_pblk
= 0;
508 if (tree
->cache_es
) {
509 es1
= tree
->cache_es
;
510 if (in_range(lblk
, es1
->es_lblk
, es1
->es_len
)) {
511 es_debug("%u cached by [%u/%u)\n",
512 lblk
, es1
->es_lblk
, es1
->es_len
);
518 node
= tree
->root
.rb_node
;
520 es1
= rb_entry(node
, struct extent_status
, rb_node
);
521 if (lblk
< es1
->es_lblk
)
522 node
= node
->rb_left
;
523 else if (lblk
> ext4_es_end(es1
))
524 node
= node
->rb_right
;
534 es
->es_lblk
= es1
->es_lblk
;
535 es
->es_len
= es1
->es_len
;
536 es
->es_pblk
= es1
->es_pblk
;
539 read_unlock(&EXT4_I(inode
)->i_es_lock
);
541 ext4_es_lru_add(inode
);
542 trace_ext4_es_lookup_extent_exit(inode
, es
, found
);
546 static int __es_remove_extent(struct inode
*inode
, ext4_lblk_t lblk
,
549 struct ext4_es_tree
*tree
= &EXT4_I(inode
)->i_es_tree
;
550 struct rb_node
*node
;
551 struct extent_status
*es
;
552 struct extent_status orig_es
;
553 ext4_lblk_t len1
, len2
;
557 es
= __es_tree_search(&tree
->root
, lblk
);
560 if (es
->es_lblk
> end
)
563 /* Simply invalidate cache_es. */
564 tree
->cache_es
= NULL
;
566 orig_es
.es_lblk
= es
->es_lblk
;
567 orig_es
.es_len
= es
->es_len
;
568 orig_es
.es_pblk
= es
->es_pblk
;
570 len1
= lblk
> es
->es_lblk
? lblk
- es
->es_lblk
: 0;
571 len2
= ext4_es_end(es
) > end
? ext4_es_end(es
) - end
: 0;
576 struct extent_status newes
;
578 newes
.es_lblk
= end
+ 1;
580 if (ext4_es_is_written(&orig_es
) ||
581 ext4_es_is_unwritten(&orig_es
)) {
582 block
= ext4_es_pblock(&orig_es
) +
583 orig_es
.es_len
- len2
;
584 ext4_es_store_pblock(&newes
, block
);
586 ext4_es_store_status(&newes
, ext4_es_status(&orig_es
));
587 err
= __es_insert_extent(inode
, &newes
);
589 es
->es_lblk
= orig_es
.es_lblk
;
590 es
->es_len
= orig_es
.es_len
;
594 es
->es_lblk
= end
+ 1;
596 if (ext4_es_is_written(es
) ||
597 ext4_es_is_unwritten(es
)) {
598 block
= orig_es
.es_pblk
+ orig_es
.es_len
- len2
;
599 ext4_es_store_pblock(es
, block
);
606 node
= rb_next(&es
->rb_node
);
608 es
= rb_entry(node
, struct extent_status
, rb_node
);
613 while (es
&& ext4_es_end(es
) <= end
) {
614 node
= rb_next(&es
->rb_node
);
615 rb_erase(&es
->rb_node
, &tree
->root
);
616 ext4_es_free_extent(inode
, es
);
621 es
= rb_entry(node
, struct extent_status
, rb_node
);
624 if (es
&& es
->es_lblk
< end
+ 1) {
625 ext4_lblk_t orig_len
= es
->es_len
;
627 len1
= ext4_es_end(es
) - end
;
628 es
->es_lblk
= end
+ 1;
630 if (ext4_es_is_written(es
) || ext4_es_is_unwritten(es
)) {
631 block
= es
->es_pblk
+ orig_len
- len1
;
632 ext4_es_store_pblock(es
, block
);
641 * ext4_es_remove_extent() removes a space from a extent status tree.
643 * Return 0 on success, error code on failure.
645 int ext4_es_remove_extent(struct inode
*inode
, ext4_lblk_t lblk
,
651 trace_ext4_es_remove_extent(inode
, lblk
, len
);
652 es_debug("remove [%u/%u) from extent status tree of inode %lu\n",
653 lblk
, len
, inode
->i_ino
);
658 end
= lblk
+ len
- 1;
661 write_lock(&EXT4_I(inode
)->i_es_lock
);
662 err
= __es_remove_extent(inode
, lblk
, end
);
663 write_unlock(&EXT4_I(inode
)->i_es_lock
);
664 ext4_es_print_tree(inode
);
668 static int ext4_es_shrink(struct shrinker
*shrink
, struct shrink_control
*sc
)
670 struct ext4_sb_info
*sbi
= container_of(shrink
,
671 struct ext4_sb_info
, s_es_shrinker
);
672 struct ext4_inode_info
*ei
;
673 struct list_head
*cur
, *tmp
, scanned
;
674 int nr_to_scan
= sc
->nr_to_scan
;
675 int ret
, nr_shrunk
= 0;
677 trace_ext4_es_shrink_enter(sbi
->s_sb
, nr_to_scan
);
680 return ext4_es_reclaim_extents_count(sbi
->s_sb
);
682 INIT_LIST_HEAD(&scanned
);
684 spin_lock(&sbi
->s_es_lru_lock
);
685 list_for_each_safe(cur
, tmp
, &sbi
->s_es_lru
) {
686 list_move_tail(cur
, &scanned
);
688 ei
= list_entry(cur
, struct ext4_inode_info
, i_es_lru
);
690 read_lock(&ei
->i_es_lock
);
691 if (ei
->i_es_lru_nr
== 0) {
692 read_unlock(&ei
->i_es_lock
);
695 read_unlock(&ei
->i_es_lock
);
697 write_lock(&ei
->i_es_lock
);
698 ret
= __es_try_to_reclaim_extents(ei
, nr_to_scan
);
699 write_unlock(&ei
->i_es_lock
);
706 list_splice_tail(&scanned
, &sbi
->s_es_lru
);
707 spin_unlock(&sbi
->s_es_lru_lock
);
708 trace_ext4_es_shrink_exit(sbi
->s_sb
, nr_shrunk
);
710 return ext4_es_reclaim_extents_count(sbi
->s_sb
);
713 void ext4_es_register_shrinker(struct super_block
*sb
)
715 struct ext4_sb_info
*sbi
;
718 INIT_LIST_HEAD(&sbi
->s_es_lru
);
719 spin_lock_init(&sbi
->s_es_lru_lock
);
720 sbi
->s_es_shrinker
.shrink
= ext4_es_shrink
;
721 sbi
->s_es_shrinker
.seeks
= DEFAULT_SEEKS
;
722 register_shrinker(&sbi
->s_es_shrinker
);
725 void ext4_es_unregister_shrinker(struct super_block
*sb
)
727 unregister_shrinker(&EXT4_SB(sb
)->s_es_shrinker
);
730 void ext4_es_lru_add(struct inode
*inode
)
732 struct ext4_inode_info
*ei
= EXT4_I(inode
);
733 struct ext4_sb_info
*sbi
= EXT4_SB(inode
->i_sb
);
735 spin_lock(&sbi
->s_es_lru_lock
);
736 if (list_empty(&ei
->i_es_lru
))
737 list_add_tail(&ei
->i_es_lru
, &sbi
->s_es_lru
);
739 list_move_tail(&ei
->i_es_lru
, &sbi
->s_es_lru
);
740 spin_unlock(&sbi
->s_es_lru_lock
);
743 void ext4_es_lru_del(struct inode
*inode
)
745 struct ext4_inode_info
*ei
= EXT4_I(inode
);
746 struct ext4_sb_info
*sbi
= EXT4_SB(inode
->i_sb
);
748 spin_lock(&sbi
->s_es_lru_lock
);
749 if (!list_empty(&ei
->i_es_lru
))
750 list_del_init(&ei
->i_es_lru
);
751 spin_unlock(&sbi
->s_es_lru_lock
);
754 static int ext4_es_reclaim_extents_count(struct super_block
*sb
)
756 struct ext4_sb_info
*sbi
= EXT4_SB(sb
);
757 struct ext4_inode_info
*ei
;
758 struct list_head
*cur
;
761 spin_lock(&sbi
->s_es_lru_lock
);
762 list_for_each(cur
, &sbi
->s_es_lru
) {
763 ei
= list_entry(cur
, struct ext4_inode_info
, i_es_lru
);
764 read_lock(&ei
->i_es_lock
);
765 nr_cached
+= ei
->i_es_lru_nr
;
766 read_unlock(&ei
->i_es_lock
);
768 spin_unlock(&sbi
->s_es_lru_lock
);
769 trace_ext4_es_reclaim_extents_count(sb
, nr_cached
);
773 static int __es_try_to_reclaim_extents(struct ext4_inode_info
*ei
,
776 struct inode
*inode
= &ei
->vfs_inode
;
777 struct ext4_es_tree
*tree
= &ei
->i_es_tree
;
778 struct rb_node
*node
;
779 struct extent_status
*es
;
782 if (ei
->i_es_lru_nr
== 0)
785 node
= rb_first(&tree
->root
);
786 while (node
!= NULL
) {
787 es
= rb_entry(node
, struct extent_status
, rb_node
);
788 node
= rb_next(&es
->rb_node
);
790 * We can't reclaim delayed extent from status tree because
791 * fiemap, bigallic, and seek_data/hole need to use it.
793 if (!ext4_es_is_delayed(es
)) {
794 rb_erase(&es
->rb_node
, &tree
->root
);
795 ext4_es_free_extent(inode
, es
);
797 if (--nr_to_scan
== 0)
801 tree
->cache_es
= NULL
;