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1/*
2 * fs/ext4/extents_status.c
3 *
4 * Written by Yongqiang Yang <xiaoqiangnk@gmail.com>
5 * Modified by
6 * Allison Henderson <achender@linux.vnet.ibm.com>
7 * Hugh Dickins <hughd@google.com>
8 * Zheng Liu <wenqing.lz@taobao.com>
9 *
10 * Ext4 extents status tree core functions.
11 */
12#include <linux/rbtree.h>
13#include <linux/list_sort.h>
14#include "ext4.h"
15#include "extents_status.h"
16
17#include <trace/events/ext4.h>
18
19/*
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.
31 *
32 * Step1:
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.
38 *
39 * The following comment describes the implemenmtation of extent
40 * status tree and future works.
41 *
42 * Step2:
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.
54 */
55
56/*
57 * Extent status tree implementation for ext4.
58 *
59 *
60 * ==========================================================================
61 * Extent status tree tracks all extent status.
62 *
63 * 1. Why we need to implement extent status tree?
64 *
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.
68 *
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.
71 *
72 * Let us have a look at how they do without extent status tree.
73 * -- FIEMAP
74 * FIEMAP looks up page cache to identify delayed allocations from holes.
75 *
76 * -- SEEK_HOLE/DATA
77 * SEEK_HOLE/DATA has the same problem as FIEMAP.
78 *
79 * -- bigalloc
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.
83 *
84 * -- writeout
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
87 * time comsuming.
88 *
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.
93 *
94 *
95 * ==========================================================================
96 * 2. Ext4 extent status tree impelmentation
97 *
98 * -- extent
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.
104 *
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.
109 *
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.
113 *
114 * -- race on a extent status tree
115 * Extent status tree is protected by inode->i_es_lock.
116 *
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.
121 *
122 *
123 * ==========================================================================
124 * 3. Performance analysis
125 *
126 * -- overhead
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.
129 *
130 * -- gain
131 * 2. Code is much simpler, more readable, more maintainable and
132 * more efficient.
133 *
134 *
135 * ==========================================================================
136 * 4. TODO list
137 *
138 * -- Refactor delayed space reservation
139 *
140 * -- Extent-level locking
141 */
142
143static struct kmem_cache *ext4_es_cachep;
144
145static int __es_insert_extent(struct inode *inode, struct extent_status *newes);
146static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
147 ext4_lblk_t end);
148static int __es_try_to_reclaim_extents(struct ext4_inode_info *ei,
149 int nr_to_scan);
150static int __ext4_es_shrink(struct ext4_sb_info *sbi, int nr_to_scan,
151 struct ext4_inode_info *locked_ei);
152
153int __init ext4_init_es(void)
154{
155 ext4_es_cachep = kmem_cache_create("ext4_extent_status",
156 sizeof(struct extent_status),
157 0, (SLAB_RECLAIM_ACCOUNT), NULL);
158 if (ext4_es_cachep == NULL)
159 return -ENOMEM;
160 return 0;
161}
162
163void ext4_exit_es(void)
164{
165 if (ext4_es_cachep)
166 kmem_cache_destroy(ext4_es_cachep);
167}
168
169void ext4_es_init_tree(struct ext4_es_tree *tree)
170{
171 tree->root = RB_ROOT;
172 tree->cache_es = NULL;
173}
174
175#ifdef ES_DEBUG__
176static void ext4_es_print_tree(struct inode *inode)
177{
178 struct ext4_es_tree *tree;
179 struct rb_node *node;
180
181 printk(KERN_DEBUG "status extents for inode %lu:", inode->i_ino);
182 tree = &EXT4_I(inode)->i_es_tree;
183 node = rb_first(&tree->root);
184 while (node) {
185 struct extent_status *es;
186 es = rb_entry(node, struct extent_status, rb_node);
187 printk(KERN_DEBUG " [%u/%u) %llu %x",
188 es->es_lblk, es->es_len,
189 ext4_es_pblock(es), ext4_es_status(es));
190 node = rb_next(node);
191 }
192 printk(KERN_DEBUG "\n");
193}
194#else
195#define ext4_es_print_tree(inode)
196#endif
197
198static inline ext4_lblk_t ext4_es_end(struct extent_status *es)
199{
200 BUG_ON(es->es_lblk + es->es_len < es->es_lblk);
201 return es->es_lblk + es->es_len - 1;
202}
203
204/*
205 * search through the tree for an delayed extent with a given offset. If
206 * it can't be found, try to find next extent.
207 */
208static struct extent_status *__es_tree_search(struct rb_root *root,
209 ext4_lblk_t lblk)
210{
211 struct rb_node *node = root->rb_node;
212 struct extent_status *es = NULL;
213
214 while (node) {
215 es = rb_entry(node, struct extent_status, rb_node);
216 if (lblk < es->es_lblk)
217 node = node->rb_left;
218 else if (lblk > ext4_es_end(es))
219 node = node->rb_right;
220 else
221 return es;
222 }
223
224 if (es && lblk < es->es_lblk)
225 return es;
226
227 if (es && lblk > ext4_es_end(es)) {
228 node = rb_next(&es->rb_node);
229 return node ? rb_entry(node, struct extent_status, rb_node) :
230 NULL;
231 }
232
233 return NULL;
234}
235
236/*
237 * ext4_es_find_delayed_extent_range: find the 1st delayed extent covering
238 * @es->lblk if it exists, otherwise, the next extent after @es->lblk.
239 *
240 * @inode: the inode which owns delayed extents
241 * @lblk: the offset where we start to search
242 * @end: the offset where we stop to search
243 * @es: delayed extent that we found
244 */
245void ext4_es_find_delayed_extent_range(struct inode *inode,
246 ext4_lblk_t lblk, ext4_lblk_t end,
247 struct extent_status *es)
248{
249 struct ext4_es_tree *tree = NULL;
250 struct extent_status *es1 = NULL;
251 struct rb_node *node;
252
253 BUG_ON(es == NULL);
254 BUG_ON(end < lblk);
255 trace_ext4_es_find_delayed_extent_range_enter(inode, lblk);
256
257 read_lock(&EXT4_I(inode)->i_es_lock);
258 tree = &EXT4_I(inode)->i_es_tree;
259
260 /* find extent in cache firstly */
261 es->es_lblk = es->es_len = es->es_pblk = 0;
262 if (tree->cache_es) {
263 es1 = tree->cache_es;
264 if (in_range(lblk, es1->es_lblk, es1->es_len)) {
265 es_debug("%u cached by [%u/%u) %llu %x\n",
266 lblk, es1->es_lblk, es1->es_len,
267 ext4_es_pblock(es1), ext4_es_status(es1));
268 goto out;
269 }
270 }
271
272 es1 = __es_tree_search(&tree->root, lblk);
273
274out:
275 if (es1 && !ext4_es_is_delayed(es1)) {
276 while ((node = rb_next(&es1->rb_node)) != NULL) {
277 es1 = rb_entry(node, struct extent_status, rb_node);
278 if (es1->es_lblk > end) {
279 es1 = NULL;
280 break;
281 }
282 if (ext4_es_is_delayed(es1))
283 break;
284 }
285 }
286
287 if (es1 && ext4_es_is_delayed(es1)) {
288 tree->cache_es = es1;
289 es->es_lblk = es1->es_lblk;
290 es->es_len = es1->es_len;
291 es->es_pblk = es1->es_pblk;
292 }
293
294 read_unlock(&EXT4_I(inode)->i_es_lock);
295
296 trace_ext4_es_find_delayed_extent_range_exit(inode, es);
297}
298
299static struct extent_status *
300ext4_es_alloc_extent(struct inode *inode, ext4_lblk_t lblk, ext4_lblk_t len,
301 ext4_fsblk_t pblk)
302{
303 struct extent_status *es;
304 es = kmem_cache_alloc(ext4_es_cachep, GFP_ATOMIC);
305 if (es == NULL)
306 return NULL;
307 es->es_lblk = lblk;
308 es->es_len = len;
309 es->es_pblk = pblk;
310
311 /*
312 * We don't count delayed extent because we never try to reclaim them
313 */
314 if (!ext4_es_is_delayed(es)) {
315 EXT4_I(inode)->i_es_lru_nr++;
316 percpu_counter_inc(&EXT4_SB(inode->i_sb)->s_extent_cache_cnt);
317 }
318
319 return es;
320}
321
322static void ext4_es_free_extent(struct inode *inode, struct extent_status *es)
323{
324 /* Decrease the lru counter when this es is not delayed */
325 if (!ext4_es_is_delayed(es)) {
326 BUG_ON(EXT4_I(inode)->i_es_lru_nr == 0);
327 EXT4_I(inode)->i_es_lru_nr--;
328 percpu_counter_dec(&EXT4_SB(inode->i_sb)->s_extent_cache_cnt);
329 }
330
331 kmem_cache_free(ext4_es_cachep, es);
332}
333
334/*
335 * Check whether or not two extents can be merged
336 * Condition:
337 * - logical block number is contiguous
338 * - physical block number is contiguous
339 * - status is equal
340 */
341static int ext4_es_can_be_merged(struct extent_status *es1,
342 struct extent_status *es2)
343{
344 if (ext4_es_status(es1) != ext4_es_status(es2))
345 return 0;
346
347 if (((__u64) es1->es_len) + es2->es_len > 0xFFFFFFFFULL)
348 return 0;
349
350 if (((__u64) es1->es_lblk) + es1->es_len != es2->es_lblk)
351 return 0;
352
353 if ((ext4_es_is_written(es1) || ext4_es_is_unwritten(es1)) &&
354 (ext4_es_pblock(es1) + es1->es_len == ext4_es_pblock(es2)))
355 return 1;
356
357 if (ext4_es_is_hole(es1))
358 return 1;
359
360 /* we need to check delayed extent is without unwritten status */
361 if (ext4_es_is_delayed(es1) && !ext4_es_is_unwritten(es1))
362 return 1;
363
364 return 0;
365}
366
367static struct extent_status *
368ext4_es_try_to_merge_left(struct inode *inode, struct extent_status *es)
369{
370 struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
371 struct extent_status *es1;
372 struct rb_node *node;
373
374 node = rb_prev(&es->rb_node);
375 if (!node)
376 return es;
377
378 es1 = rb_entry(node, struct extent_status, rb_node);
379 if (ext4_es_can_be_merged(es1, es)) {
380 es1->es_len += es->es_len;
381 rb_erase(&es->rb_node, &tree->root);
382 ext4_es_free_extent(inode, es);
383 es = es1;
384 }
385
386 return es;
387}
388
389static struct extent_status *
390ext4_es_try_to_merge_right(struct inode *inode, struct extent_status *es)
391{
392 struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
393 struct extent_status *es1;
394 struct rb_node *node;
395
396 node = rb_next(&es->rb_node);
397 if (!node)
398 return es;
399
400 es1 = rb_entry(node, struct extent_status, rb_node);
401 if (ext4_es_can_be_merged(es, es1)) {
402 es->es_len += es1->es_len;
403 rb_erase(node, &tree->root);
404 ext4_es_free_extent(inode, es1);
405 }
406
407 return es;
408}
409
410#ifdef ES_AGGRESSIVE_TEST
411#include "ext4_extents.h" /* Needed when ES_AGGRESSIVE_TEST is defined */
412
413static void ext4_es_insert_extent_ext_check(struct inode *inode,
414 struct extent_status *es)
415{
416 struct ext4_ext_path *path = NULL;
417 struct ext4_extent *ex;
418 ext4_lblk_t ee_block;
419 ext4_fsblk_t ee_start;
420 unsigned short ee_len;
421 int depth, ee_status, es_status;
422
423 path = ext4_ext_find_extent(inode, es->es_lblk, NULL, EXT4_EX_NOCACHE);
424 if (IS_ERR(path))
425 return;
426
427 depth = ext_depth(inode);
428 ex = path[depth].p_ext;
429
430 if (ex) {
431
432 ee_block = le32_to_cpu(ex->ee_block);
433 ee_start = ext4_ext_pblock(ex);
434 ee_len = ext4_ext_get_actual_len(ex);
435
436 ee_status = ext4_ext_is_uninitialized(ex) ? 1 : 0;
437 es_status = ext4_es_is_unwritten(es) ? 1 : 0;
438
439 /*
440 * Make sure ex and es are not overlap when we try to insert
441 * a delayed/hole extent.
442 */
443 if (!ext4_es_is_written(es) && !ext4_es_is_unwritten(es)) {
444 if (in_range(es->es_lblk, ee_block, ee_len)) {
445 pr_warn("ES insert assertion failed for "
446 "inode: %lu we can find an extent "
447 "at block [%d/%d/%llu/%c], but we "
448 "want to add a delayed/hole extent "
449 "[%d/%d/%llu/%x]\n",
450 inode->i_ino, ee_block, ee_len,
451 ee_start, ee_status ? 'u' : 'w',
452 es->es_lblk, es->es_len,
453 ext4_es_pblock(es), ext4_es_status(es));
454 }
455 goto out;
456 }
457
458 /*
459 * We don't check ee_block == es->es_lblk, etc. because es
460 * might be a part of whole extent, vice versa.
461 */
462 if (es->es_lblk < ee_block ||
463 ext4_es_pblock(es) != ee_start + es->es_lblk - ee_block) {
464 pr_warn("ES insert assertion failed for inode: %lu "
465 "ex_status [%d/%d/%llu/%c] != "
466 "es_status [%d/%d/%llu/%c]\n", inode->i_ino,
467 ee_block, ee_len, ee_start,
468 ee_status ? 'u' : 'w', es->es_lblk, es->es_len,
469 ext4_es_pblock(es), es_status ? 'u' : 'w');
470 goto out;
471 }
472
473 if (ee_status ^ es_status) {
474 pr_warn("ES insert assertion failed for inode: %lu "
475 "ex_status [%d/%d/%llu/%c] != "
476 "es_status [%d/%d/%llu/%c]\n", inode->i_ino,
477 ee_block, ee_len, ee_start,
478 ee_status ? 'u' : 'w', es->es_lblk, es->es_len,
479 ext4_es_pblock(es), es_status ? 'u' : 'w');
480 }
481 } else {
482 /*
483 * We can't find an extent on disk. So we need to make sure
484 * that we don't want to add an written/unwritten extent.
485 */
486 if (!ext4_es_is_delayed(es) && !ext4_es_is_hole(es)) {
487 pr_warn("ES insert assertion failed for inode: %lu "
488 "can't find an extent at block %d but we want "
489 "to add a written/unwritten extent "
490 "[%d/%d/%llu/%x]\n", inode->i_ino,
491 es->es_lblk, es->es_lblk, es->es_len,
492 ext4_es_pblock(es), ext4_es_status(es));
493 }
494 }
495out:
496 if (path) {
497 ext4_ext_drop_refs(path);
498 kfree(path);
499 }
500}
501
502static void ext4_es_insert_extent_ind_check(struct inode *inode,
503 struct extent_status *es)
504{
505 struct ext4_map_blocks map;
506 int retval;
507
508 /*
509 * Here we call ext4_ind_map_blocks to lookup a block mapping because
510 * 'Indirect' structure is defined in indirect.c. So we couldn't
511 * access direct/indirect tree from outside. It is too dirty to define
512 * this function in indirect.c file.
513 */
514
515 map.m_lblk = es->es_lblk;
516 map.m_len = es->es_len;
517
518 retval = ext4_ind_map_blocks(NULL, inode, &map, 0);
519 if (retval > 0) {
520 if (ext4_es_is_delayed(es) || ext4_es_is_hole(es)) {
521 /*
522 * We want to add a delayed/hole extent but this
523 * block has been allocated.
524 */
525 pr_warn("ES insert assertion failed for inode: %lu "
526 "We can find blocks but we want to add a "
527 "delayed/hole extent [%d/%d/%llu/%x]\n",
528 inode->i_ino, es->es_lblk, es->es_len,
529 ext4_es_pblock(es), ext4_es_status(es));
530 return;
531 } else if (ext4_es_is_written(es)) {
532 if (retval != es->es_len) {
533 pr_warn("ES insert assertion failed for "
534 "inode: %lu retval %d != es_len %d\n",
535 inode->i_ino, retval, es->es_len);
536 return;
537 }
538 if (map.m_pblk != ext4_es_pblock(es)) {
539 pr_warn("ES insert assertion failed for "
540 "inode: %lu m_pblk %llu != "
541 "es_pblk %llu\n",
542 inode->i_ino, map.m_pblk,
543 ext4_es_pblock(es));
544 return;
545 }
546 } else {
547 /*
548 * We don't need to check unwritten extent because
549 * indirect-based file doesn't have it.
550 */
551 BUG_ON(1);
552 }
553 } else if (retval == 0) {
554 if (ext4_es_is_written(es)) {
555 pr_warn("ES insert assertion failed for inode: %lu "
556 "We can't find the block but we want to add "
557 "a written extent [%d/%d/%llu/%x]\n",
558 inode->i_ino, es->es_lblk, es->es_len,
559 ext4_es_pblock(es), ext4_es_status(es));
560 return;
561 }
562 }
563}
564
565static inline void ext4_es_insert_extent_check(struct inode *inode,
566 struct extent_status *es)
567{
568 /*
569 * We don't need to worry about the race condition because
570 * caller takes i_data_sem locking.
571 */
572 BUG_ON(!rwsem_is_locked(&EXT4_I(inode)->i_data_sem));
573 if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
574 ext4_es_insert_extent_ext_check(inode, es);
575 else
576 ext4_es_insert_extent_ind_check(inode, es);
577}
578#else
579static inline void ext4_es_insert_extent_check(struct inode *inode,
580 struct extent_status *es)
581{
582}
583#endif
584
585static int __es_insert_extent(struct inode *inode, struct extent_status *newes)
586{
587 struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
588 struct rb_node **p = &tree->root.rb_node;
589 struct rb_node *parent = NULL;
590 struct extent_status *es;
591
592 while (*p) {
593 parent = *p;
594 es = rb_entry(parent, struct extent_status, rb_node);
595
596 if (newes->es_lblk < es->es_lblk) {
597 if (ext4_es_can_be_merged(newes, es)) {
598 /*
599 * Here we can modify es_lblk directly
600 * because it isn't overlapped.
601 */
602 es->es_lblk = newes->es_lblk;
603 es->es_len += newes->es_len;
604 if (ext4_es_is_written(es) ||
605 ext4_es_is_unwritten(es))
606 ext4_es_store_pblock(es,
607 newes->es_pblk);
608 es = ext4_es_try_to_merge_left(inode, es);
609 goto out;
610 }
611 p = &(*p)->rb_left;
612 } else if (newes->es_lblk > ext4_es_end(es)) {
613 if (ext4_es_can_be_merged(es, newes)) {
614 es->es_len += newes->es_len;
615 es = ext4_es_try_to_merge_right(inode, es);
616 goto out;
617 }
618 p = &(*p)->rb_right;
619 } else {
620 BUG_ON(1);
621 return -EINVAL;
622 }
623 }
624
625 es = ext4_es_alloc_extent(inode, newes->es_lblk, newes->es_len,
626 newes->es_pblk);
627 if (!es)
628 return -ENOMEM;
629 rb_link_node(&es->rb_node, parent, p);
630 rb_insert_color(&es->rb_node, &tree->root);
631
632out:
633 tree->cache_es = es;
634 return 0;
635}
636
637/*
638 * ext4_es_insert_extent() adds information to an inode's extent
639 * status tree.
640 *
641 * Return 0 on success, error code on failure.
642 */
643int ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
644 ext4_lblk_t len, ext4_fsblk_t pblk,
645 unsigned int status)
646{
647 struct extent_status newes;
648 ext4_lblk_t end = lblk + len - 1;
649 int err = 0;
650
651 es_debug("add [%u/%u) %llu %x to extent status tree of inode %lu\n",
652 lblk, len, pblk, status, inode->i_ino);
653
654 if (!len)
655 return 0;
656
657 BUG_ON(end < lblk);
658
659 newes.es_lblk = lblk;
660 newes.es_len = len;
661 ext4_es_store_pblock_status(&newes, pblk, status);
662 trace_ext4_es_insert_extent(inode, &newes);
663
664 ext4_es_insert_extent_check(inode, &newes);
665
666 write_lock(&EXT4_I(inode)->i_es_lock);
667 err = __es_remove_extent(inode, lblk, end);
668 if (err != 0)
669 goto error;
670retry:
671 err = __es_insert_extent(inode, &newes);
672 if (err == -ENOMEM && __ext4_es_shrink(EXT4_SB(inode->i_sb), 1,
673 EXT4_I(inode)))
674 goto retry;
675 if (err == -ENOMEM && !ext4_es_is_delayed(&newes))
676 err = 0;
677
678error:
679 write_unlock(&EXT4_I(inode)->i_es_lock);
680
681 ext4_es_print_tree(inode);
682
683 return err;
684}
685
686/*
687 * ext4_es_cache_extent() inserts information into the extent status
688 * tree if and only if there isn't information about the range in
689 * question already.
690 */
691void ext4_es_cache_extent(struct inode *inode, ext4_lblk_t lblk,
692 ext4_lblk_t len, ext4_fsblk_t pblk,
693 unsigned int status)
694{
695 struct extent_status *es;
696 struct extent_status newes;
697 ext4_lblk_t end = lblk + len - 1;
698
699 newes.es_lblk = lblk;
700 newes.es_len = len;
701 ext4_es_store_pblock_status(&newes, pblk, status);
702 trace_ext4_es_cache_extent(inode, &newes);
703
704 if (!len)
705 return;
706
707 BUG_ON(end < lblk);
708
709 write_lock(&EXT4_I(inode)->i_es_lock);
710
711 es = __es_tree_search(&EXT4_I(inode)->i_es_tree.root, lblk);
712 if (!es || es->es_lblk > end)
713 __es_insert_extent(inode, &newes);
714 write_unlock(&EXT4_I(inode)->i_es_lock);
715}
716
717/*
718 * ext4_es_lookup_extent() looks up an extent in extent status tree.
719 *
720 * ext4_es_lookup_extent is called by ext4_map_blocks/ext4_da_map_blocks.
721 *
722 * Return: 1 on found, 0 on not
723 */
724int ext4_es_lookup_extent(struct inode *inode, ext4_lblk_t lblk,
725 struct extent_status *es)
726{
727 struct ext4_es_tree *tree;
728 struct extent_status *es1 = NULL;
729 struct rb_node *node;
730 int found = 0;
731
732 trace_ext4_es_lookup_extent_enter(inode, lblk);
733 es_debug("lookup extent in block %u\n", lblk);
734
735 tree = &EXT4_I(inode)->i_es_tree;
736 read_lock(&EXT4_I(inode)->i_es_lock);
737
738 /* find extent in cache firstly */
739 es->es_lblk = es->es_len = es->es_pblk = 0;
740 if (tree->cache_es) {
741 es1 = tree->cache_es;
742 if (in_range(lblk, es1->es_lblk, es1->es_len)) {
743 es_debug("%u cached by [%u/%u)\n",
744 lblk, es1->es_lblk, es1->es_len);
745 found = 1;
746 goto out;
747 }
748 }
749
750 node = tree->root.rb_node;
751 while (node) {
752 es1 = rb_entry(node, struct extent_status, rb_node);
753 if (lblk < es1->es_lblk)
754 node = node->rb_left;
755 else if (lblk > ext4_es_end(es1))
756 node = node->rb_right;
757 else {
758 found = 1;
759 break;
760 }
761 }
762
763out:
764 if (found) {
765 BUG_ON(!es1);
766 es->es_lblk = es1->es_lblk;
767 es->es_len = es1->es_len;
768 es->es_pblk = es1->es_pblk;
769 }
770
771 read_unlock(&EXT4_I(inode)->i_es_lock);
772
773 trace_ext4_es_lookup_extent_exit(inode, es, found);
774 return found;
775}
776
777static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
778 ext4_lblk_t end)
779{
780 struct ext4_es_tree *tree = &EXT4_I(inode)->i_es_tree;
781 struct rb_node *node;
782 struct extent_status *es;
783 struct extent_status orig_es;
784 ext4_lblk_t len1, len2;
785 ext4_fsblk_t block;
786 int err;
787
788retry:
789 err = 0;
790 es = __es_tree_search(&tree->root, lblk);
791 if (!es)
792 goto out;
793 if (es->es_lblk > end)
794 goto out;
795
796 /* Simply invalidate cache_es. */
797 tree->cache_es = NULL;
798
799 orig_es.es_lblk = es->es_lblk;
800 orig_es.es_len = es->es_len;
801 orig_es.es_pblk = es->es_pblk;
802
803 len1 = lblk > es->es_lblk ? lblk - es->es_lblk : 0;
804 len2 = ext4_es_end(es) > end ? ext4_es_end(es) - end : 0;
805 if (len1 > 0)
806 es->es_len = len1;
807 if (len2 > 0) {
808 if (len1 > 0) {
809 struct extent_status newes;
810
811 newes.es_lblk = end + 1;
812 newes.es_len = len2;
813 block = 0x7FDEADBEEFULL;
814 if (ext4_es_is_written(&orig_es) ||
815 ext4_es_is_unwritten(&orig_es))
816 block = ext4_es_pblock(&orig_es) +
817 orig_es.es_len - len2;
818 ext4_es_store_pblock_status(&newes, block,
819 ext4_es_status(&orig_es));
820 err = __es_insert_extent(inode, &newes);
821 if (err) {
822 es->es_lblk = orig_es.es_lblk;
823 es->es_len = orig_es.es_len;
824 if ((err == -ENOMEM) &&
825 __ext4_es_shrink(EXT4_SB(inode->i_sb), 1,
826 EXT4_I(inode)))
827 goto retry;
828 goto out;
829 }
830 } else {
831 es->es_lblk = end + 1;
832 es->es_len = len2;
833 if (ext4_es_is_written(es) ||
834 ext4_es_is_unwritten(es)) {
835 block = orig_es.es_pblk + orig_es.es_len - len2;
836 ext4_es_store_pblock(es, block);
837 }
838 }
839 goto out;
840 }
841
842 if (len1 > 0) {
843 node = rb_next(&es->rb_node);
844 if (node)
845 es = rb_entry(node, struct extent_status, rb_node);
846 else
847 es = NULL;
848 }
849
850 while (es && ext4_es_end(es) <= end) {
851 node = rb_next(&es->rb_node);
852 rb_erase(&es->rb_node, &tree->root);
853 ext4_es_free_extent(inode, es);
854 if (!node) {
855 es = NULL;
856 break;
857 }
858 es = rb_entry(node, struct extent_status, rb_node);
859 }
860
861 if (es && es->es_lblk < end + 1) {
862 ext4_lblk_t orig_len = es->es_len;
863
864 len1 = ext4_es_end(es) - end;
865 es->es_lblk = end + 1;
866 es->es_len = len1;
867 if (ext4_es_is_written(es) || ext4_es_is_unwritten(es)) {
868 block = es->es_pblk + orig_len - len1;
869 ext4_es_store_pblock(es, block);
870 }
871 }
872
873out:
874 return err;
875}
876
877/*
878 * ext4_es_remove_extent() removes a space from a extent status tree.
879 *
880 * Return 0 on success, error code on failure.
881 */
882int ext4_es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
883 ext4_lblk_t len)
884{
885 ext4_lblk_t end;
886 int err = 0;
887
888 trace_ext4_es_remove_extent(inode, lblk, len);
889 es_debug("remove [%u/%u) from extent status tree of inode %lu\n",
890 lblk, len, inode->i_ino);
891
892 if (!len)
893 return err;
894
895 end = lblk + len - 1;
896 BUG_ON(end < lblk);
897
898 write_lock(&EXT4_I(inode)->i_es_lock);
899 err = __es_remove_extent(inode, lblk, end);
900 write_unlock(&EXT4_I(inode)->i_es_lock);
901 ext4_es_print_tree(inode);
902 return err;
903}
904
905static int ext4_inode_touch_time_cmp(void *priv, struct list_head *a,
906 struct list_head *b)
907{
908 struct ext4_inode_info *eia, *eib;
909 eia = list_entry(a, struct ext4_inode_info, i_es_lru);
910 eib = list_entry(b, struct ext4_inode_info, i_es_lru);
911
912 if (ext4_test_inode_state(&eia->vfs_inode, EXT4_STATE_EXT_PRECACHED) &&
913 !ext4_test_inode_state(&eib->vfs_inode, EXT4_STATE_EXT_PRECACHED))
914 return 1;
915 if (!ext4_test_inode_state(&eia->vfs_inode, EXT4_STATE_EXT_PRECACHED) &&
916 ext4_test_inode_state(&eib->vfs_inode, EXT4_STATE_EXT_PRECACHED))
917 return -1;
918 if (eia->i_touch_when == eib->i_touch_when)
919 return 0;
920 if (time_after(eia->i_touch_when, eib->i_touch_when))
921 return 1;
922 else
923 return -1;
924}
925
926static int __ext4_es_shrink(struct ext4_sb_info *sbi, int nr_to_scan,
927 struct ext4_inode_info *locked_ei)
928{
929 struct ext4_inode_info *ei;
930 struct list_head *cur, *tmp;
931 LIST_HEAD(skipped);
932 int nr_shrunk = 0;
933 int retried = 0, skip_precached = 1, nr_skipped = 0;
934
935 spin_lock(&sbi->s_es_lru_lock);
936
937retry:
938 list_for_each_safe(cur, tmp, &sbi->s_es_lru) {
939 int shrunk;
940
941 /*
942 * If we have already reclaimed all extents from extent
943 * status tree, just stop the loop immediately.
944 */
945 if (percpu_counter_read_positive(&sbi->s_extent_cache_cnt) == 0)
946 break;
947
948 ei = list_entry(cur, struct ext4_inode_info, i_es_lru);
949
950 /*
951 * Skip the inode that is newer than the last_sorted
952 * time. Normally we try hard to avoid shrinking
953 * precached inodes, but we will as a last resort.
954 */
955 if ((sbi->s_es_last_sorted < ei->i_touch_when) ||
956 (skip_precached && ext4_test_inode_state(&ei->vfs_inode,
957 EXT4_STATE_EXT_PRECACHED))) {
958 nr_skipped++;
959 list_move_tail(cur, &skipped);
960 continue;
961 }
962
963 if (ei->i_es_lru_nr == 0 || ei == locked_ei)
964 continue;
965
966 write_lock(&ei->i_es_lock);
967 shrunk = __es_try_to_reclaim_extents(ei, nr_to_scan);
968 if (ei->i_es_lru_nr == 0)
969 list_del_init(&ei->i_es_lru);
970 write_unlock(&ei->i_es_lock);
971
972 nr_shrunk += shrunk;
973 nr_to_scan -= shrunk;
974 if (nr_to_scan == 0)
975 break;
976 }
977
978 /* Move the newer inodes into the tail of the LRU list. */
979 list_splice_tail(&skipped, &sbi->s_es_lru);
980 INIT_LIST_HEAD(&skipped);
981
982 /*
983 * If we skipped any inodes, and we weren't able to make any
984 * forward progress, sort the list and try again.
985 */
986 if ((nr_shrunk == 0) && nr_skipped && !retried) {
987 retried++;
988 list_sort(NULL, &sbi->s_es_lru, ext4_inode_touch_time_cmp);
989 sbi->s_es_last_sorted = jiffies;
990 ei = list_first_entry(&sbi->s_es_lru, struct ext4_inode_info,
991 i_es_lru);
992 /*
993 * If there are no non-precached inodes left on the
994 * list, start releasing precached extents.
995 */
996 if (ext4_test_inode_state(&ei->vfs_inode,
997 EXT4_STATE_EXT_PRECACHED))
998 skip_precached = 0;
999 goto retry;
1000 }
1001
1002 spin_unlock(&sbi->s_es_lru_lock);
1003
1004 if (locked_ei && nr_shrunk == 0)
1005 nr_shrunk = __es_try_to_reclaim_extents(locked_ei, nr_to_scan);
1006
1007 return nr_shrunk;
1008}
1009
1010static unsigned long ext4_es_count(struct shrinker *shrink,
1011 struct shrink_control *sc)
1012{
1013 unsigned long nr;
1014 struct ext4_sb_info *sbi;
1015
1016 sbi = container_of(shrink, struct ext4_sb_info, s_es_shrinker);
1017 nr = percpu_counter_read_positive(&sbi->s_extent_cache_cnt);
1018 trace_ext4_es_shrink_enter(sbi->s_sb, sc->nr_to_scan, nr);
1019 return nr;
1020}
1021
1022static unsigned long ext4_es_scan(struct shrinker *shrink,
1023 struct shrink_control *sc)
1024{
1025 struct ext4_sb_info *sbi = container_of(shrink,
1026 struct ext4_sb_info, s_es_shrinker);
1027 int nr_to_scan = sc->nr_to_scan;
1028 int ret, nr_shrunk;
1029
1030 ret = percpu_counter_read_positive(&sbi->s_extent_cache_cnt);
1031 trace_ext4_es_shrink_enter(sbi->s_sb, nr_to_scan, ret);
1032
1033 if (!nr_to_scan)
1034 return ret;
1035
1036 nr_shrunk = __ext4_es_shrink(sbi, nr_to_scan, NULL);
1037
1038 trace_ext4_es_shrink_exit(sbi->s_sb, nr_shrunk, ret);
1039 return nr_shrunk;
1040}
1041
1042void ext4_es_register_shrinker(struct ext4_sb_info *sbi)
1043{
1044 INIT_LIST_HEAD(&sbi->s_es_lru);
1045 spin_lock_init(&sbi->s_es_lru_lock);
1046 sbi->s_es_last_sorted = 0;
1047 sbi->s_es_shrinker.scan_objects = ext4_es_scan;
1048 sbi->s_es_shrinker.count_objects = ext4_es_count;
1049 sbi->s_es_shrinker.seeks = DEFAULT_SEEKS;
1050 register_shrinker(&sbi->s_es_shrinker);
1051}
1052
1053void ext4_es_unregister_shrinker(struct ext4_sb_info *sbi)
1054{
1055 unregister_shrinker(&sbi->s_es_shrinker);
1056}
1057
1058void ext4_es_lru_add(struct inode *inode)
1059{
1060 struct ext4_inode_info *ei = EXT4_I(inode);
1061 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1062
1063 ei->i_touch_when = jiffies;
1064
1065 if (!list_empty(&ei->i_es_lru))
1066 return;
1067
1068 spin_lock(&sbi->s_es_lru_lock);
1069 if (list_empty(&ei->i_es_lru))
1070 list_add_tail(&ei->i_es_lru, &sbi->s_es_lru);
1071 spin_unlock(&sbi->s_es_lru_lock);
1072}
1073
1074void ext4_es_lru_del(struct inode *inode)
1075{
1076 struct ext4_inode_info *ei = EXT4_I(inode);
1077 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1078
1079 spin_lock(&sbi->s_es_lru_lock);
1080 if (!list_empty(&ei->i_es_lru))
1081 list_del_init(&ei->i_es_lru);
1082 spin_unlock(&sbi->s_es_lru_lock);
1083}
1084
1085static int __es_try_to_reclaim_extents(struct ext4_inode_info *ei,
1086 int nr_to_scan)
1087{
1088 struct inode *inode = &ei->vfs_inode;
1089 struct ext4_es_tree *tree = &ei->i_es_tree;
1090 struct rb_node *node;
1091 struct extent_status *es;
1092 unsigned long nr_shrunk = 0;
1093 static DEFINE_RATELIMIT_STATE(_rs, DEFAULT_RATELIMIT_INTERVAL,
1094 DEFAULT_RATELIMIT_BURST);
1095
1096 if (ei->i_es_lru_nr == 0)
1097 return 0;
1098
1099 if (ext4_test_inode_state(inode, EXT4_STATE_EXT_PRECACHED) &&
1100 __ratelimit(&_rs))
1101 ext4_warning(inode->i_sb, "forced shrink of precached extents");
1102
1103 node = rb_first(&tree->root);
1104 while (node != NULL) {
1105 es = rb_entry(node, struct extent_status, rb_node);
1106 node = rb_next(&es->rb_node);
1107 /*
1108 * We can't reclaim delayed extent from status tree because
1109 * fiemap, bigallic, and seek_data/hole need to use it.
1110 */
1111 if (!ext4_es_is_delayed(es)) {
1112 rb_erase(&es->rb_node, &tree->root);
1113 ext4_es_free_extent(inode, es);
1114 nr_shrunk++;
1115 if (--nr_to_scan == 0)
1116 break;
1117 }
1118 }
1119 tree->cache_es = NULL;
1120 return nr_shrunk;
1121}