ext4: enable "punch hole" functionality
[pandora-kernel.git] / fs / ext4 / extents.c
1 /*
2  * Copyright (c) 2003-2006, Cluster File Systems, Inc, info@clusterfs.com
3  * Written by Alex Tomas <alex@clusterfs.com>
4  *
5  * Architecture independence:
6  *   Copyright (c) 2005, Bull S.A.
7  *   Written by Pierre Peiffer <pierre.peiffer@bull.net>
8  *
9  * This program is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License version 2 as
11  * published by the Free Software Foundation.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16  * GNU General Public License for more details.
17  *
18  * You should have received a copy of the GNU General Public Licens
19  * along with this program; if not, write to the Free Software
20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
21  */
22
23 /*
24  * Extents support for EXT4
25  *
26  * TODO:
27  *   - ext4*_error() should be used in some situations
28  *   - analyze all BUG()/BUG_ON(), use -EIO where appropriate
29  *   - smart tree reduction
30  */
31
32 #include <linux/module.h>
33 #include <linux/fs.h>
34 #include <linux/time.h>
35 #include <linux/jbd2.h>
36 #include <linux/highuid.h>
37 #include <linux/pagemap.h>
38 #include <linux/quotaops.h>
39 #include <linux/string.h>
40 #include <linux/slab.h>
41 #include <linux/falloc.h>
42 #include <asm/uaccess.h>
43 #include <linux/fiemap.h>
44 #include "ext4_jbd2.h"
45 #include "ext4_extents.h"
46
47 #include <trace/events/ext4.h>
48
49 static int ext4_split_extent(handle_t *handle,
50                                 struct inode *inode,
51                                 struct ext4_ext_path *path,
52                                 struct ext4_map_blocks *map,
53                                 int split_flag,
54                                 int flags);
55
56 static int ext4_ext_truncate_extend_restart(handle_t *handle,
57                                             struct inode *inode,
58                                             int needed)
59 {
60         int err;
61
62         if (!ext4_handle_valid(handle))
63                 return 0;
64         if (handle->h_buffer_credits > needed)
65                 return 0;
66         err = ext4_journal_extend(handle, needed);
67         if (err <= 0)
68                 return err;
69         err = ext4_truncate_restart_trans(handle, inode, needed);
70         if (err == 0)
71                 err = -EAGAIN;
72
73         return err;
74 }
75
76 /*
77  * could return:
78  *  - EROFS
79  *  - ENOMEM
80  */
81 static int ext4_ext_get_access(handle_t *handle, struct inode *inode,
82                                 struct ext4_ext_path *path)
83 {
84         if (path->p_bh) {
85                 /* path points to block */
86                 return ext4_journal_get_write_access(handle, path->p_bh);
87         }
88         /* path points to leaf/index in inode body */
89         /* we use in-core data, no need to protect them */
90         return 0;
91 }
92
93 /*
94  * could return:
95  *  - EROFS
96  *  - ENOMEM
97  *  - EIO
98  */
99 static int ext4_ext_dirty(handle_t *handle, struct inode *inode,
100                                 struct ext4_ext_path *path)
101 {
102         int err;
103         if (path->p_bh) {
104                 /* path points to block */
105                 err = ext4_handle_dirty_metadata(handle, inode, path->p_bh);
106         } else {
107                 /* path points to leaf/index in inode body */
108                 err = ext4_mark_inode_dirty(handle, inode);
109         }
110         return err;
111 }
112
113 static ext4_fsblk_t ext4_ext_find_goal(struct inode *inode,
114                               struct ext4_ext_path *path,
115                               ext4_lblk_t block)
116 {
117         struct ext4_inode_info *ei = EXT4_I(inode);
118         ext4_fsblk_t bg_start;
119         ext4_fsblk_t last_block;
120         ext4_grpblk_t colour;
121         ext4_group_t block_group;
122         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
123         int depth;
124
125         if (path) {
126                 struct ext4_extent *ex;
127                 depth = path->p_depth;
128
129                 /*
130                  * Try to predict block placement assuming that we are
131                  * filling in a file which will eventually be
132                  * non-sparse --- i.e., in the case of libbfd writing
133                  * an ELF object sections out-of-order but in a way
134                  * the eventually results in a contiguous object or
135                  * executable file, or some database extending a table
136                  * space file.  However, this is actually somewhat
137                  * non-ideal if we are writing a sparse file such as
138                  * qemu or KVM writing a raw image file that is going
139                  * to stay fairly sparse, since it will end up
140                  * fragmenting the file system's free space.  Maybe we
141                  * should have some hueristics or some way to allow
142                  * userspace to pass a hint to file system,
143                  * especially if the latter case turns out to be
144                  * common.
145                  */
146                 ex = path[depth].p_ext;
147                 if (ex) {
148                         ext4_fsblk_t ext_pblk = ext4_ext_pblock(ex);
149                         ext4_lblk_t ext_block = le32_to_cpu(ex->ee_block);
150
151                         if (block > ext_block)
152                                 return ext_pblk + (block - ext_block);
153                         else
154                                 return ext_pblk - (ext_block - block);
155                 }
156
157                 /* it looks like index is empty;
158                  * try to find starting block from index itself */
159                 if (path[depth].p_bh)
160                         return path[depth].p_bh->b_blocknr;
161         }
162
163         /* OK. use inode's group */
164         block_group = ei->i_block_group;
165         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
166                 /*
167                  * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
168                  * block groups per flexgroup, reserve the first block
169                  * group for directories and special files.  Regular
170                  * files will start at the second block group.  This
171                  * tends to speed up directory access and improves
172                  * fsck times.
173                  */
174                 block_group &= ~(flex_size-1);
175                 if (S_ISREG(inode->i_mode))
176                         block_group++;
177         }
178         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
179         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
180
181         /*
182          * If we are doing delayed allocation, we don't need take
183          * colour into account.
184          */
185         if (test_opt(inode->i_sb, DELALLOC))
186                 return bg_start;
187
188         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
189                 colour = (current->pid % 16) *
190                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
191         else
192                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
193         return bg_start + colour + block;
194 }
195
196 /*
197  * Allocation for a meta data block
198  */
199 static ext4_fsblk_t
200 ext4_ext_new_meta_block(handle_t *handle, struct inode *inode,
201                         struct ext4_ext_path *path,
202                         struct ext4_extent *ex, int *err, unsigned int flags)
203 {
204         ext4_fsblk_t goal, newblock;
205
206         goal = ext4_ext_find_goal(inode, path, le32_to_cpu(ex->ee_block));
207         newblock = ext4_new_meta_blocks(handle, inode, goal, flags,
208                                         NULL, err);
209         return newblock;
210 }
211
212 static inline int ext4_ext_space_block(struct inode *inode, int check)
213 {
214         int size;
215
216         size = (inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
217                         / sizeof(struct ext4_extent);
218         if (!check) {
219 #ifdef AGGRESSIVE_TEST
220                 if (size > 6)
221                         size = 6;
222 #endif
223         }
224         return size;
225 }
226
227 static inline int ext4_ext_space_block_idx(struct inode *inode, int check)
228 {
229         int size;
230
231         size = (inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
232                         / sizeof(struct ext4_extent_idx);
233         if (!check) {
234 #ifdef AGGRESSIVE_TEST
235                 if (size > 5)
236                         size = 5;
237 #endif
238         }
239         return size;
240 }
241
242 static inline int ext4_ext_space_root(struct inode *inode, int check)
243 {
244         int size;
245
246         size = sizeof(EXT4_I(inode)->i_data);
247         size -= sizeof(struct ext4_extent_header);
248         size /= sizeof(struct ext4_extent);
249         if (!check) {
250 #ifdef AGGRESSIVE_TEST
251                 if (size > 3)
252                         size = 3;
253 #endif
254         }
255         return size;
256 }
257
258 static inline int ext4_ext_space_root_idx(struct inode *inode, int check)
259 {
260         int size;
261
262         size = sizeof(EXT4_I(inode)->i_data);
263         size -= sizeof(struct ext4_extent_header);
264         size /= sizeof(struct ext4_extent_idx);
265         if (!check) {
266 #ifdef AGGRESSIVE_TEST
267                 if (size > 4)
268                         size = 4;
269 #endif
270         }
271         return size;
272 }
273
274 /*
275  * Calculate the number of metadata blocks needed
276  * to allocate @blocks
277  * Worse case is one block per extent
278  */
279 int ext4_ext_calc_metadata_amount(struct inode *inode, ext4_lblk_t lblock)
280 {
281         struct ext4_inode_info *ei = EXT4_I(inode);
282         int idxs, num = 0;
283
284         idxs = ((inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
285                 / sizeof(struct ext4_extent_idx));
286
287         /*
288          * If the new delayed allocation block is contiguous with the
289          * previous da block, it can share index blocks with the
290          * previous block, so we only need to allocate a new index
291          * block every idxs leaf blocks.  At ldxs**2 blocks, we need
292          * an additional index block, and at ldxs**3 blocks, yet
293          * another index blocks.
294          */
295         if (ei->i_da_metadata_calc_len &&
296             ei->i_da_metadata_calc_last_lblock+1 == lblock) {
297                 if ((ei->i_da_metadata_calc_len % idxs) == 0)
298                         num++;
299                 if ((ei->i_da_metadata_calc_len % (idxs*idxs)) == 0)
300                         num++;
301                 if ((ei->i_da_metadata_calc_len % (idxs*idxs*idxs)) == 0) {
302                         num++;
303                         ei->i_da_metadata_calc_len = 0;
304                 } else
305                         ei->i_da_metadata_calc_len++;
306                 ei->i_da_metadata_calc_last_lblock++;
307                 return num;
308         }
309
310         /*
311          * In the worst case we need a new set of index blocks at
312          * every level of the inode's extent tree.
313          */
314         ei->i_da_metadata_calc_len = 1;
315         ei->i_da_metadata_calc_last_lblock = lblock;
316         return ext_depth(inode) + 1;
317 }
318
319 static int
320 ext4_ext_max_entries(struct inode *inode, int depth)
321 {
322         int max;
323
324         if (depth == ext_depth(inode)) {
325                 if (depth == 0)
326                         max = ext4_ext_space_root(inode, 1);
327                 else
328                         max = ext4_ext_space_root_idx(inode, 1);
329         } else {
330                 if (depth == 0)
331                         max = ext4_ext_space_block(inode, 1);
332                 else
333                         max = ext4_ext_space_block_idx(inode, 1);
334         }
335
336         return max;
337 }
338
339 static int ext4_valid_extent(struct inode *inode, struct ext4_extent *ext)
340 {
341         ext4_fsblk_t block = ext4_ext_pblock(ext);
342         int len = ext4_ext_get_actual_len(ext);
343
344         return ext4_data_block_valid(EXT4_SB(inode->i_sb), block, len);
345 }
346
347 static int ext4_valid_extent_idx(struct inode *inode,
348                                 struct ext4_extent_idx *ext_idx)
349 {
350         ext4_fsblk_t block = ext4_idx_pblock(ext_idx);
351
352         return ext4_data_block_valid(EXT4_SB(inode->i_sb), block, 1);
353 }
354
355 static int ext4_valid_extent_entries(struct inode *inode,
356                                 struct ext4_extent_header *eh,
357                                 int depth)
358 {
359         struct ext4_extent *ext;
360         struct ext4_extent_idx *ext_idx;
361         unsigned short entries;
362         if (eh->eh_entries == 0)
363                 return 1;
364
365         entries = le16_to_cpu(eh->eh_entries);
366
367         if (depth == 0) {
368                 /* leaf entries */
369                 ext = EXT_FIRST_EXTENT(eh);
370                 while (entries) {
371                         if (!ext4_valid_extent(inode, ext))
372                                 return 0;
373                         ext++;
374                         entries--;
375                 }
376         } else {
377                 ext_idx = EXT_FIRST_INDEX(eh);
378                 while (entries) {
379                         if (!ext4_valid_extent_idx(inode, ext_idx))
380                                 return 0;
381                         ext_idx++;
382                         entries--;
383                 }
384         }
385         return 1;
386 }
387
388 static int __ext4_ext_check(const char *function, unsigned int line,
389                             struct inode *inode, struct ext4_extent_header *eh,
390                             int depth)
391 {
392         const char *error_msg;
393         int max = 0;
394
395         if (unlikely(eh->eh_magic != EXT4_EXT_MAGIC)) {
396                 error_msg = "invalid magic";
397                 goto corrupted;
398         }
399         if (unlikely(le16_to_cpu(eh->eh_depth) != depth)) {
400                 error_msg = "unexpected eh_depth";
401                 goto corrupted;
402         }
403         if (unlikely(eh->eh_max == 0)) {
404                 error_msg = "invalid eh_max";
405                 goto corrupted;
406         }
407         max = ext4_ext_max_entries(inode, depth);
408         if (unlikely(le16_to_cpu(eh->eh_max) > max)) {
409                 error_msg = "too large eh_max";
410                 goto corrupted;
411         }
412         if (unlikely(le16_to_cpu(eh->eh_entries) > le16_to_cpu(eh->eh_max))) {
413                 error_msg = "invalid eh_entries";
414                 goto corrupted;
415         }
416         if (!ext4_valid_extent_entries(inode, eh, depth)) {
417                 error_msg = "invalid extent entries";
418                 goto corrupted;
419         }
420         return 0;
421
422 corrupted:
423         ext4_error_inode(inode, function, line, 0,
424                         "bad header/extent: %s - magic %x, "
425                         "entries %u, max %u(%u), depth %u(%u)",
426                         error_msg, le16_to_cpu(eh->eh_magic),
427                         le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max),
428                         max, le16_to_cpu(eh->eh_depth), depth);
429
430         return -EIO;
431 }
432
433 #define ext4_ext_check(inode, eh, depth)        \
434         __ext4_ext_check(__func__, __LINE__, inode, eh, depth)
435
436 int ext4_ext_check_inode(struct inode *inode)
437 {
438         return ext4_ext_check(inode, ext_inode_hdr(inode), ext_depth(inode));
439 }
440
441 #ifdef EXT_DEBUG
442 static void ext4_ext_show_path(struct inode *inode, struct ext4_ext_path *path)
443 {
444         int k, l = path->p_depth;
445
446         ext_debug("path:");
447         for (k = 0; k <= l; k++, path++) {
448                 if (path->p_idx) {
449                   ext_debug("  %d->%llu", le32_to_cpu(path->p_idx->ei_block),
450                             ext4_idx_pblock(path->p_idx));
451                 } else if (path->p_ext) {
452                         ext_debug("  %d:[%d]%d:%llu ",
453                                   le32_to_cpu(path->p_ext->ee_block),
454                                   ext4_ext_is_uninitialized(path->p_ext),
455                                   ext4_ext_get_actual_len(path->p_ext),
456                                   ext4_ext_pblock(path->p_ext));
457                 } else
458                         ext_debug("  []");
459         }
460         ext_debug("\n");
461 }
462
463 static void ext4_ext_show_leaf(struct inode *inode, struct ext4_ext_path *path)
464 {
465         int depth = ext_depth(inode);
466         struct ext4_extent_header *eh;
467         struct ext4_extent *ex;
468         int i;
469
470         if (!path)
471                 return;
472
473         eh = path[depth].p_hdr;
474         ex = EXT_FIRST_EXTENT(eh);
475
476         ext_debug("Displaying leaf extents for inode %lu\n", inode->i_ino);
477
478         for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ex++) {
479                 ext_debug("%d:[%d]%d:%llu ", le32_to_cpu(ex->ee_block),
480                           ext4_ext_is_uninitialized(ex),
481                           ext4_ext_get_actual_len(ex), ext4_ext_pblock(ex));
482         }
483         ext_debug("\n");
484 }
485 #else
486 #define ext4_ext_show_path(inode, path)
487 #define ext4_ext_show_leaf(inode, path)
488 #endif
489
490 void ext4_ext_drop_refs(struct ext4_ext_path *path)
491 {
492         int depth = path->p_depth;
493         int i;
494
495         for (i = 0; i <= depth; i++, path++)
496                 if (path->p_bh) {
497                         brelse(path->p_bh);
498                         path->p_bh = NULL;
499                 }
500 }
501
502 /*
503  * ext4_ext_binsearch_idx:
504  * binary search for the closest index of the given block
505  * the header must be checked before calling this
506  */
507 static void
508 ext4_ext_binsearch_idx(struct inode *inode,
509                         struct ext4_ext_path *path, ext4_lblk_t block)
510 {
511         struct ext4_extent_header *eh = path->p_hdr;
512         struct ext4_extent_idx *r, *l, *m;
513
514
515         ext_debug("binsearch for %u(idx):  ", block);
516
517         l = EXT_FIRST_INDEX(eh) + 1;
518         r = EXT_LAST_INDEX(eh);
519         while (l <= r) {
520                 m = l + (r - l) / 2;
521                 if (block < le32_to_cpu(m->ei_block))
522                         r = m - 1;
523                 else
524                         l = m + 1;
525                 ext_debug("%p(%u):%p(%u):%p(%u) ", l, le32_to_cpu(l->ei_block),
526                                 m, le32_to_cpu(m->ei_block),
527                                 r, le32_to_cpu(r->ei_block));
528         }
529
530         path->p_idx = l - 1;
531         ext_debug("  -> %d->%lld ", le32_to_cpu(path->p_idx->ei_block),
532                   ext4_idx_pblock(path->p_idx));
533
534 #ifdef CHECK_BINSEARCH
535         {
536                 struct ext4_extent_idx *chix, *ix;
537                 int k;
538
539                 chix = ix = EXT_FIRST_INDEX(eh);
540                 for (k = 0; k < le16_to_cpu(eh->eh_entries); k++, ix++) {
541                   if (k != 0 &&
542                       le32_to_cpu(ix->ei_block) <= le32_to_cpu(ix[-1].ei_block)) {
543                                 printk(KERN_DEBUG "k=%d, ix=0x%p, "
544                                        "first=0x%p\n", k,
545                                        ix, EXT_FIRST_INDEX(eh));
546                                 printk(KERN_DEBUG "%u <= %u\n",
547                                        le32_to_cpu(ix->ei_block),
548                                        le32_to_cpu(ix[-1].ei_block));
549                         }
550                         BUG_ON(k && le32_to_cpu(ix->ei_block)
551                                            <= le32_to_cpu(ix[-1].ei_block));
552                         if (block < le32_to_cpu(ix->ei_block))
553                                 break;
554                         chix = ix;
555                 }
556                 BUG_ON(chix != path->p_idx);
557         }
558 #endif
559
560 }
561
562 /*
563  * ext4_ext_binsearch:
564  * binary search for closest extent of the given block
565  * the header must be checked before calling this
566  */
567 static void
568 ext4_ext_binsearch(struct inode *inode,
569                 struct ext4_ext_path *path, ext4_lblk_t block)
570 {
571         struct ext4_extent_header *eh = path->p_hdr;
572         struct ext4_extent *r, *l, *m;
573
574         if (eh->eh_entries == 0) {
575                 /*
576                  * this leaf is empty:
577                  * we get such a leaf in split/add case
578                  */
579                 return;
580         }
581
582         ext_debug("binsearch for %u:  ", block);
583
584         l = EXT_FIRST_EXTENT(eh) + 1;
585         r = EXT_LAST_EXTENT(eh);
586
587         while (l <= r) {
588                 m = l + (r - l) / 2;
589                 if (block < le32_to_cpu(m->ee_block))
590                         r = m - 1;
591                 else
592                         l = m + 1;
593                 ext_debug("%p(%u):%p(%u):%p(%u) ", l, le32_to_cpu(l->ee_block),
594                                 m, le32_to_cpu(m->ee_block),
595                                 r, le32_to_cpu(r->ee_block));
596         }
597
598         path->p_ext = l - 1;
599         ext_debug("  -> %d:%llu:[%d]%d ",
600                         le32_to_cpu(path->p_ext->ee_block),
601                         ext4_ext_pblock(path->p_ext),
602                         ext4_ext_is_uninitialized(path->p_ext),
603                         ext4_ext_get_actual_len(path->p_ext));
604
605 #ifdef CHECK_BINSEARCH
606         {
607                 struct ext4_extent *chex, *ex;
608                 int k;
609
610                 chex = ex = EXT_FIRST_EXTENT(eh);
611                 for (k = 0; k < le16_to_cpu(eh->eh_entries); k++, ex++) {
612                         BUG_ON(k && le32_to_cpu(ex->ee_block)
613                                           <= le32_to_cpu(ex[-1].ee_block));
614                         if (block < le32_to_cpu(ex->ee_block))
615                                 break;
616                         chex = ex;
617                 }
618                 BUG_ON(chex != path->p_ext);
619         }
620 #endif
621
622 }
623
624 int ext4_ext_tree_init(handle_t *handle, struct inode *inode)
625 {
626         struct ext4_extent_header *eh;
627
628         eh = ext_inode_hdr(inode);
629         eh->eh_depth = 0;
630         eh->eh_entries = 0;
631         eh->eh_magic = EXT4_EXT_MAGIC;
632         eh->eh_max = cpu_to_le16(ext4_ext_space_root(inode, 0));
633         ext4_mark_inode_dirty(handle, inode);
634         ext4_ext_invalidate_cache(inode);
635         return 0;
636 }
637
638 struct ext4_ext_path *
639 ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
640                                         struct ext4_ext_path *path)
641 {
642         struct ext4_extent_header *eh;
643         struct buffer_head *bh;
644         short int depth, i, ppos = 0, alloc = 0;
645
646         eh = ext_inode_hdr(inode);
647         depth = ext_depth(inode);
648
649         /* account possible depth increase */
650         if (!path) {
651                 path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 2),
652                                 GFP_NOFS);
653                 if (!path)
654                         return ERR_PTR(-ENOMEM);
655                 alloc = 1;
656         }
657         path[0].p_hdr = eh;
658         path[0].p_bh = NULL;
659
660         i = depth;
661         /* walk through the tree */
662         while (i) {
663                 int need_to_validate = 0;
664
665                 ext_debug("depth %d: num %d, max %d\n",
666                           ppos, le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));
667
668                 ext4_ext_binsearch_idx(inode, path + ppos, block);
669                 path[ppos].p_block = ext4_idx_pblock(path[ppos].p_idx);
670                 path[ppos].p_depth = i;
671                 path[ppos].p_ext = NULL;
672
673                 bh = sb_getblk(inode->i_sb, path[ppos].p_block);
674                 if (unlikely(!bh))
675                         goto err;
676                 if (!bh_uptodate_or_lock(bh)) {
677                         trace_ext4_ext_load_extent(inode, block,
678                                                 path[ppos].p_block);
679                         if (bh_submit_read(bh) < 0) {
680                                 put_bh(bh);
681                                 goto err;
682                         }
683                         /* validate the extent entries */
684                         need_to_validate = 1;
685                 }
686                 eh = ext_block_hdr(bh);
687                 ppos++;
688                 if (unlikely(ppos > depth)) {
689                         put_bh(bh);
690                         EXT4_ERROR_INODE(inode,
691                                          "ppos %d > depth %d", ppos, depth);
692                         goto err;
693                 }
694                 path[ppos].p_bh = bh;
695                 path[ppos].p_hdr = eh;
696                 i--;
697
698                 if (need_to_validate && ext4_ext_check(inode, eh, i))
699                         goto err;
700         }
701
702         path[ppos].p_depth = i;
703         path[ppos].p_ext = NULL;
704         path[ppos].p_idx = NULL;
705
706         /* find extent */
707         ext4_ext_binsearch(inode, path + ppos, block);
708         /* if not an empty leaf */
709         if (path[ppos].p_ext)
710                 path[ppos].p_block = ext4_ext_pblock(path[ppos].p_ext);
711
712         ext4_ext_show_path(inode, path);
713
714         return path;
715
716 err:
717         ext4_ext_drop_refs(path);
718         if (alloc)
719                 kfree(path);
720         return ERR_PTR(-EIO);
721 }
722
723 /*
724  * ext4_ext_insert_index:
725  * insert new index [@logical;@ptr] into the block at @curp;
726  * check where to insert: before @curp or after @curp
727  */
728 static int ext4_ext_insert_index(handle_t *handle, struct inode *inode,
729                                  struct ext4_ext_path *curp,
730                                  int logical, ext4_fsblk_t ptr)
731 {
732         struct ext4_extent_idx *ix;
733         int len, err;
734
735         err = ext4_ext_get_access(handle, inode, curp);
736         if (err)
737                 return err;
738
739         if (unlikely(logical == le32_to_cpu(curp->p_idx->ei_block))) {
740                 EXT4_ERROR_INODE(inode,
741                                  "logical %d == ei_block %d!",
742                                  logical, le32_to_cpu(curp->p_idx->ei_block));
743                 return -EIO;
744         }
745         len = EXT_MAX_INDEX(curp->p_hdr) - curp->p_idx;
746         if (logical > le32_to_cpu(curp->p_idx->ei_block)) {
747                 /* insert after */
748                 if (curp->p_idx != EXT_LAST_INDEX(curp->p_hdr)) {
749                         len = (len - 1) * sizeof(struct ext4_extent_idx);
750                         len = len < 0 ? 0 : len;
751                         ext_debug("insert new index %d after: %llu. "
752                                         "move %d from 0x%p to 0x%p\n",
753                                         logical, ptr, len,
754                                         (curp->p_idx + 1), (curp->p_idx + 2));
755                         memmove(curp->p_idx + 2, curp->p_idx + 1, len);
756                 }
757                 ix = curp->p_idx + 1;
758         } else {
759                 /* insert before */
760                 len = len * sizeof(struct ext4_extent_idx);
761                 len = len < 0 ? 0 : len;
762                 ext_debug("insert new index %d before: %llu. "
763                                 "move %d from 0x%p to 0x%p\n",
764                                 logical, ptr, len,
765                                 curp->p_idx, (curp->p_idx + 1));
766                 memmove(curp->p_idx + 1, curp->p_idx, len);
767                 ix = curp->p_idx;
768         }
769
770         ix->ei_block = cpu_to_le32(logical);
771         ext4_idx_store_pblock(ix, ptr);
772         le16_add_cpu(&curp->p_hdr->eh_entries, 1);
773
774         if (unlikely(le16_to_cpu(curp->p_hdr->eh_entries)
775                              > le16_to_cpu(curp->p_hdr->eh_max))) {
776                 EXT4_ERROR_INODE(inode,
777                                  "logical %d == ei_block %d!",
778                                  logical, le32_to_cpu(curp->p_idx->ei_block));
779                 return -EIO;
780         }
781         if (unlikely(ix > EXT_LAST_INDEX(curp->p_hdr))) {
782                 EXT4_ERROR_INODE(inode, "ix > EXT_LAST_INDEX!");
783                 return -EIO;
784         }
785
786         err = ext4_ext_dirty(handle, inode, curp);
787         ext4_std_error(inode->i_sb, err);
788
789         return err;
790 }
791
792 /*
793  * ext4_ext_split:
794  * inserts new subtree into the path, using free index entry
795  * at depth @at:
796  * - allocates all needed blocks (new leaf and all intermediate index blocks)
797  * - makes decision where to split
798  * - moves remaining extents and index entries (right to the split point)
799  *   into the newly allocated blocks
800  * - initializes subtree
801  */
802 static int ext4_ext_split(handle_t *handle, struct inode *inode,
803                           unsigned int flags,
804                           struct ext4_ext_path *path,
805                           struct ext4_extent *newext, int at)
806 {
807         struct buffer_head *bh = NULL;
808         int depth = ext_depth(inode);
809         struct ext4_extent_header *neh;
810         struct ext4_extent_idx *fidx;
811         struct ext4_extent *ex;
812         int i = at, k, m, a;
813         ext4_fsblk_t newblock, oldblock;
814         __le32 border;
815         ext4_fsblk_t *ablocks = NULL; /* array of allocated blocks */
816         int err = 0;
817
818         /* make decision: where to split? */
819         /* FIXME: now decision is simplest: at current extent */
820
821         /* if current leaf will be split, then we should use
822          * border from split point */
823         if (unlikely(path[depth].p_ext > EXT_MAX_EXTENT(path[depth].p_hdr))) {
824                 EXT4_ERROR_INODE(inode, "p_ext > EXT_MAX_EXTENT!");
825                 return -EIO;
826         }
827         if (path[depth].p_ext != EXT_MAX_EXTENT(path[depth].p_hdr)) {
828                 border = path[depth].p_ext[1].ee_block;
829                 ext_debug("leaf will be split."
830                                 " next leaf starts at %d\n",
831                                   le32_to_cpu(border));
832         } else {
833                 border = newext->ee_block;
834                 ext_debug("leaf will be added."
835                                 " next leaf starts at %d\n",
836                                 le32_to_cpu(border));
837         }
838
839         /*
840          * If error occurs, then we break processing
841          * and mark filesystem read-only. index won't
842          * be inserted and tree will be in consistent
843          * state. Next mount will repair buffers too.
844          */
845
846         /*
847          * Get array to track all allocated blocks.
848          * We need this to handle errors and free blocks
849          * upon them.
850          */
851         ablocks = kzalloc(sizeof(ext4_fsblk_t) * depth, GFP_NOFS);
852         if (!ablocks)
853                 return -ENOMEM;
854
855         /* allocate all needed blocks */
856         ext_debug("allocate %d blocks for indexes/leaf\n", depth - at);
857         for (a = 0; a < depth - at; a++) {
858                 newblock = ext4_ext_new_meta_block(handle, inode, path,
859                                                    newext, &err, flags);
860                 if (newblock == 0)
861                         goto cleanup;
862                 ablocks[a] = newblock;
863         }
864
865         /* initialize new leaf */
866         newblock = ablocks[--a];
867         if (unlikely(newblock == 0)) {
868                 EXT4_ERROR_INODE(inode, "newblock == 0!");
869                 err = -EIO;
870                 goto cleanup;
871         }
872         bh = sb_getblk(inode->i_sb, newblock);
873         if (!bh) {
874                 err = -EIO;
875                 goto cleanup;
876         }
877         lock_buffer(bh);
878
879         err = ext4_journal_get_create_access(handle, bh);
880         if (err)
881                 goto cleanup;
882
883         neh = ext_block_hdr(bh);
884         neh->eh_entries = 0;
885         neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode, 0));
886         neh->eh_magic = EXT4_EXT_MAGIC;
887         neh->eh_depth = 0;
888         ex = EXT_FIRST_EXTENT(neh);
889
890         /* move remainder of path[depth] to the new leaf */
891         if (unlikely(path[depth].p_hdr->eh_entries !=
892                      path[depth].p_hdr->eh_max)) {
893                 EXT4_ERROR_INODE(inode, "eh_entries %d != eh_max %d!",
894                                  path[depth].p_hdr->eh_entries,
895                                  path[depth].p_hdr->eh_max);
896                 err = -EIO;
897                 goto cleanup;
898         }
899         /* start copy from next extent */
900         /* TODO: we could do it by single memmove */
901         m = 0;
902         path[depth].p_ext++;
903         while (path[depth].p_ext <=
904                         EXT_MAX_EXTENT(path[depth].p_hdr)) {
905                 ext_debug("move %d:%llu:[%d]%d in new leaf %llu\n",
906                                 le32_to_cpu(path[depth].p_ext->ee_block),
907                                 ext4_ext_pblock(path[depth].p_ext),
908                                 ext4_ext_is_uninitialized(path[depth].p_ext),
909                                 ext4_ext_get_actual_len(path[depth].p_ext),
910                                 newblock);
911                 /*memmove(ex++, path[depth].p_ext++,
912                                 sizeof(struct ext4_extent));
913                 neh->eh_entries++;*/
914                 path[depth].p_ext++;
915                 m++;
916         }
917         if (m) {
918                 memmove(ex, path[depth].p_ext-m, sizeof(struct ext4_extent)*m);
919                 le16_add_cpu(&neh->eh_entries, m);
920         }
921
922         set_buffer_uptodate(bh);
923         unlock_buffer(bh);
924
925         err = ext4_handle_dirty_metadata(handle, inode, bh);
926         if (err)
927                 goto cleanup;
928         brelse(bh);
929         bh = NULL;
930
931         /* correct old leaf */
932         if (m) {
933                 err = ext4_ext_get_access(handle, inode, path + depth);
934                 if (err)
935                         goto cleanup;
936                 le16_add_cpu(&path[depth].p_hdr->eh_entries, -m);
937                 err = ext4_ext_dirty(handle, inode, path + depth);
938                 if (err)
939                         goto cleanup;
940
941         }
942
943         /* create intermediate indexes */
944         k = depth - at - 1;
945         if (unlikely(k < 0)) {
946                 EXT4_ERROR_INODE(inode, "k %d < 0!", k);
947                 err = -EIO;
948                 goto cleanup;
949         }
950         if (k)
951                 ext_debug("create %d intermediate indices\n", k);
952         /* insert new index into current index block */
953         /* current depth stored in i var */
954         i = depth - 1;
955         while (k--) {
956                 oldblock = newblock;
957                 newblock = ablocks[--a];
958                 bh = sb_getblk(inode->i_sb, newblock);
959                 if (!bh) {
960                         err = -EIO;
961                         goto cleanup;
962                 }
963                 lock_buffer(bh);
964
965                 err = ext4_journal_get_create_access(handle, bh);
966                 if (err)
967                         goto cleanup;
968
969                 neh = ext_block_hdr(bh);
970                 neh->eh_entries = cpu_to_le16(1);
971                 neh->eh_magic = EXT4_EXT_MAGIC;
972                 neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode, 0));
973                 neh->eh_depth = cpu_to_le16(depth - i);
974                 fidx = EXT_FIRST_INDEX(neh);
975                 fidx->ei_block = border;
976                 ext4_idx_store_pblock(fidx, oldblock);
977
978                 ext_debug("int.index at %d (block %llu): %u -> %llu\n",
979                                 i, newblock, le32_to_cpu(border), oldblock);
980                 /* copy indexes */
981                 m = 0;
982                 path[i].p_idx++;
983
984                 ext_debug("cur 0x%p, last 0x%p\n", path[i].p_idx,
985                                 EXT_MAX_INDEX(path[i].p_hdr));
986                 if (unlikely(EXT_MAX_INDEX(path[i].p_hdr) !=
987                                         EXT_LAST_INDEX(path[i].p_hdr))) {
988                         EXT4_ERROR_INODE(inode,
989                                          "EXT_MAX_INDEX != EXT_LAST_INDEX ee_block %d!",
990                                          le32_to_cpu(path[i].p_ext->ee_block));
991                         err = -EIO;
992                         goto cleanup;
993                 }
994                 while (path[i].p_idx <= EXT_MAX_INDEX(path[i].p_hdr)) {
995                         ext_debug("%d: move %d:%llu in new index %llu\n", i,
996                                         le32_to_cpu(path[i].p_idx->ei_block),
997                                         ext4_idx_pblock(path[i].p_idx),
998                                         newblock);
999                         /*memmove(++fidx, path[i].p_idx++,
1000                                         sizeof(struct ext4_extent_idx));
1001                         neh->eh_entries++;
1002                         BUG_ON(neh->eh_entries > neh->eh_max);*/
1003                         path[i].p_idx++;
1004                         m++;
1005                 }
1006                 if (m) {
1007                         memmove(++fidx, path[i].p_idx - m,
1008                                 sizeof(struct ext4_extent_idx) * m);
1009                         le16_add_cpu(&neh->eh_entries, m);
1010                 }
1011                 set_buffer_uptodate(bh);
1012                 unlock_buffer(bh);
1013
1014                 err = ext4_handle_dirty_metadata(handle, inode, bh);
1015                 if (err)
1016                         goto cleanup;
1017                 brelse(bh);
1018                 bh = NULL;
1019
1020                 /* correct old index */
1021                 if (m) {
1022                         err = ext4_ext_get_access(handle, inode, path + i);
1023                         if (err)
1024                                 goto cleanup;
1025                         le16_add_cpu(&path[i].p_hdr->eh_entries, -m);
1026                         err = ext4_ext_dirty(handle, inode, path + i);
1027                         if (err)
1028                                 goto cleanup;
1029                 }
1030
1031                 i--;
1032         }
1033
1034         /* insert new index */
1035         err = ext4_ext_insert_index(handle, inode, path + at,
1036                                     le32_to_cpu(border), newblock);
1037
1038 cleanup:
1039         if (bh) {
1040                 if (buffer_locked(bh))
1041                         unlock_buffer(bh);
1042                 brelse(bh);
1043         }
1044
1045         if (err) {
1046                 /* free all allocated blocks in error case */
1047                 for (i = 0; i < depth; i++) {
1048                         if (!ablocks[i])
1049                                 continue;
1050                         ext4_free_blocks(handle, inode, NULL, ablocks[i], 1,
1051                                          EXT4_FREE_BLOCKS_METADATA);
1052                 }
1053         }
1054         kfree(ablocks);
1055
1056         return err;
1057 }
1058
1059 /*
1060  * ext4_ext_grow_indepth:
1061  * implements tree growing procedure:
1062  * - allocates new block
1063  * - moves top-level data (index block or leaf) into the new block
1064  * - initializes new top-level, creating index that points to the
1065  *   just created block
1066  */
1067 static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode,
1068                                  unsigned int flags,
1069                                  struct ext4_ext_path *path,
1070                                  struct ext4_extent *newext)
1071 {
1072         struct ext4_ext_path *curp = path;
1073         struct ext4_extent_header *neh;
1074         struct buffer_head *bh;
1075         ext4_fsblk_t newblock;
1076         int err = 0;
1077
1078         newblock = ext4_ext_new_meta_block(handle, inode, path,
1079                 newext, &err, flags);
1080         if (newblock == 0)
1081                 return err;
1082
1083         bh = sb_getblk(inode->i_sb, newblock);
1084         if (!bh) {
1085                 err = -EIO;
1086                 ext4_std_error(inode->i_sb, err);
1087                 return err;
1088         }
1089         lock_buffer(bh);
1090
1091         err = ext4_journal_get_create_access(handle, bh);
1092         if (err) {
1093                 unlock_buffer(bh);
1094                 goto out;
1095         }
1096
1097         /* move top-level index/leaf into new block */
1098         memmove(bh->b_data, curp->p_hdr, sizeof(EXT4_I(inode)->i_data));
1099
1100         /* set size of new block */
1101         neh = ext_block_hdr(bh);
1102         /* old root could have indexes or leaves
1103          * so calculate e_max right way */
1104         if (ext_depth(inode))
1105                 neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode, 0));
1106         else
1107                 neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode, 0));
1108         neh->eh_magic = EXT4_EXT_MAGIC;
1109         set_buffer_uptodate(bh);
1110         unlock_buffer(bh);
1111
1112         err = ext4_handle_dirty_metadata(handle, inode, bh);
1113         if (err)
1114                 goto out;
1115
1116         /* create index in new top-level index: num,max,pointer */
1117         err = ext4_ext_get_access(handle, inode, curp);
1118         if (err)
1119                 goto out;
1120
1121         curp->p_hdr->eh_magic = EXT4_EXT_MAGIC;
1122         curp->p_hdr->eh_max = cpu_to_le16(ext4_ext_space_root_idx(inode, 0));
1123         curp->p_hdr->eh_entries = cpu_to_le16(1);
1124         curp->p_idx = EXT_FIRST_INDEX(curp->p_hdr);
1125
1126         if (path[0].p_hdr->eh_depth)
1127                 curp->p_idx->ei_block =
1128                         EXT_FIRST_INDEX(path[0].p_hdr)->ei_block;
1129         else
1130                 curp->p_idx->ei_block =
1131                         EXT_FIRST_EXTENT(path[0].p_hdr)->ee_block;
1132         ext4_idx_store_pblock(curp->p_idx, newblock);
1133
1134         neh = ext_inode_hdr(inode);
1135         ext_debug("new root: num %d(%d), lblock %d, ptr %llu\n",
1136                   le16_to_cpu(neh->eh_entries), le16_to_cpu(neh->eh_max),
1137                   le32_to_cpu(EXT_FIRST_INDEX(neh)->ei_block),
1138                   ext4_idx_pblock(EXT_FIRST_INDEX(neh)));
1139
1140         neh->eh_depth = cpu_to_le16(path->p_depth + 1);
1141         err = ext4_ext_dirty(handle, inode, curp);
1142 out:
1143         brelse(bh);
1144
1145         return err;
1146 }
1147
1148 /*
1149  * ext4_ext_create_new_leaf:
1150  * finds empty index and adds new leaf.
1151  * if no free index is found, then it requests in-depth growing.
1152  */
1153 static int ext4_ext_create_new_leaf(handle_t *handle, struct inode *inode,
1154                                     unsigned int flags,
1155                                     struct ext4_ext_path *path,
1156                                     struct ext4_extent *newext)
1157 {
1158         struct ext4_ext_path *curp;
1159         int depth, i, err = 0;
1160
1161 repeat:
1162         i = depth = ext_depth(inode);
1163
1164         /* walk up to the tree and look for free index entry */
1165         curp = path + depth;
1166         while (i > 0 && !EXT_HAS_FREE_INDEX(curp)) {
1167                 i--;
1168                 curp--;
1169         }
1170
1171         /* we use already allocated block for index block,
1172          * so subsequent data blocks should be contiguous */
1173         if (EXT_HAS_FREE_INDEX(curp)) {
1174                 /* if we found index with free entry, then use that
1175                  * entry: create all needed subtree and add new leaf */
1176                 err = ext4_ext_split(handle, inode, flags, path, newext, i);
1177                 if (err)
1178                         goto out;
1179
1180                 /* refill path */
1181                 ext4_ext_drop_refs(path);
1182                 path = ext4_ext_find_extent(inode,
1183                                     (ext4_lblk_t)le32_to_cpu(newext->ee_block),
1184                                     path);
1185                 if (IS_ERR(path))
1186                         err = PTR_ERR(path);
1187         } else {
1188                 /* tree is full, time to grow in depth */
1189                 err = ext4_ext_grow_indepth(handle, inode, flags,
1190                                             path, newext);
1191                 if (err)
1192                         goto out;
1193
1194                 /* refill path */
1195                 ext4_ext_drop_refs(path);
1196                 path = ext4_ext_find_extent(inode,
1197                                    (ext4_lblk_t)le32_to_cpu(newext->ee_block),
1198                                     path);
1199                 if (IS_ERR(path)) {
1200                         err = PTR_ERR(path);
1201                         goto out;
1202                 }
1203
1204                 /*
1205                  * only first (depth 0 -> 1) produces free space;
1206                  * in all other cases we have to split the grown tree
1207                  */
1208                 depth = ext_depth(inode);
1209                 if (path[depth].p_hdr->eh_entries == path[depth].p_hdr->eh_max) {
1210                         /* now we need to split */
1211                         goto repeat;
1212                 }
1213         }
1214
1215 out:
1216         return err;
1217 }
1218
1219 /*
1220  * search the closest allocated block to the left for *logical
1221  * and returns it at @logical + it's physical address at @phys
1222  * if *logical is the smallest allocated block, the function
1223  * returns 0 at @phys
1224  * return value contains 0 (success) or error code
1225  */
1226 static int ext4_ext_search_left(struct inode *inode,
1227                                 struct ext4_ext_path *path,
1228                                 ext4_lblk_t *logical, ext4_fsblk_t *phys)
1229 {
1230         struct ext4_extent_idx *ix;
1231         struct ext4_extent *ex;
1232         int depth, ee_len;
1233
1234         if (unlikely(path == NULL)) {
1235                 EXT4_ERROR_INODE(inode, "path == NULL *logical %d!", *logical);
1236                 return -EIO;
1237         }
1238         depth = path->p_depth;
1239         *phys = 0;
1240
1241         if (depth == 0 && path->p_ext == NULL)
1242                 return 0;
1243
1244         /* usually extent in the path covers blocks smaller
1245          * then *logical, but it can be that extent is the
1246          * first one in the file */
1247
1248         ex = path[depth].p_ext;
1249         ee_len = ext4_ext_get_actual_len(ex);
1250         if (*logical < le32_to_cpu(ex->ee_block)) {
1251                 if (unlikely(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex)) {
1252                         EXT4_ERROR_INODE(inode,
1253                                          "EXT_FIRST_EXTENT != ex *logical %d ee_block %d!",
1254                                          *logical, le32_to_cpu(ex->ee_block));
1255                         return -EIO;
1256                 }
1257                 while (--depth >= 0) {
1258                         ix = path[depth].p_idx;
1259                         if (unlikely(ix != EXT_FIRST_INDEX(path[depth].p_hdr))) {
1260                                 EXT4_ERROR_INODE(inode,
1261                                   "ix (%d) != EXT_FIRST_INDEX (%d) (depth %d)!",
1262                                   ix != NULL ? ix->ei_block : 0,
1263                                   EXT_FIRST_INDEX(path[depth].p_hdr) != NULL ?
1264                                     EXT_FIRST_INDEX(path[depth].p_hdr)->ei_block : 0,
1265                                   depth);
1266                                 return -EIO;
1267                         }
1268                 }
1269                 return 0;
1270         }
1271
1272         if (unlikely(*logical < (le32_to_cpu(ex->ee_block) + ee_len))) {
1273                 EXT4_ERROR_INODE(inode,
1274                                  "logical %d < ee_block %d + ee_len %d!",
1275                                  *logical, le32_to_cpu(ex->ee_block), ee_len);
1276                 return -EIO;
1277         }
1278
1279         *logical = le32_to_cpu(ex->ee_block) + ee_len - 1;
1280         *phys = ext4_ext_pblock(ex) + ee_len - 1;
1281         return 0;
1282 }
1283
1284 /*
1285  * search the closest allocated block to the right for *logical
1286  * and returns it at @logical + it's physical address at @phys
1287  * if *logical is the smallest allocated block, the function
1288  * returns 0 at @phys
1289  * return value contains 0 (success) or error code
1290  */
1291 static int ext4_ext_search_right(struct inode *inode,
1292                                  struct ext4_ext_path *path,
1293                                  ext4_lblk_t *logical, ext4_fsblk_t *phys)
1294 {
1295         struct buffer_head *bh = NULL;
1296         struct ext4_extent_header *eh;
1297         struct ext4_extent_idx *ix;
1298         struct ext4_extent *ex;
1299         ext4_fsblk_t block;
1300         int depth;      /* Note, NOT eh_depth; depth from top of tree */
1301         int ee_len;
1302
1303         if (unlikely(path == NULL)) {
1304                 EXT4_ERROR_INODE(inode, "path == NULL *logical %d!", *logical);
1305                 return -EIO;
1306         }
1307         depth = path->p_depth;
1308         *phys = 0;
1309
1310         if (depth == 0 && path->p_ext == NULL)
1311                 return 0;
1312
1313         /* usually extent in the path covers blocks smaller
1314          * then *logical, but it can be that extent is the
1315          * first one in the file */
1316
1317         ex = path[depth].p_ext;
1318         ee_len = ext4_ext_get_actual_len(ex);
1319         if (*logical < le32_to_cpu(ex->ee_block)) {
1320                 if (unlikely(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex)) {
1321                         EXT4_ERROR_INODE(inode,
1322                                          "first_extent(path[%d].p_hdr) != ex",
1323                                          depth);
1324                         return -EIO;
1325                 }
1326                 while (--depth >= 0) {
1327                         ix = path[depth].p_idx;
1328                         if (unlikely(ix != EXT_FIRST_INDEX(path[depth].p_hdr))) {
1329                                 EXT4_ERROR_INODE(inode,
1330                                                  "ix != EXT_FIRST_INDEX *logical %d!",
1331                                                  *logical);
1332                                 return -EIO;
1333                         }
1334                 }
1335                 *logical = le32_to_cpu(ex->ee_block);
1336                 *phys = ext4_ext_pblock(ex);
1337                 return 0;
1338         }
1339
1340         if (unlikely(*logical < (le32_to_cpu(ex->ee_block) + ee_len))) {
1341                 EXT4_ERROR_INODE(inode,
1342                                  "logical %d < ee_block %d + ee_len %d!",
1343                                  *logical, le32_to_cpu(ex->ee_block), ee_len);
1344                 return -EIO;
1345         }
1346
1347         if (ex != EXT_LAST_EXTENT(path[depth].p_hdr)) {
1348                 /* next allocated block in this leaf */
1349                 ex++;
1350                 *logical = le32_to_cpu(ex->ee_block);
1351                 *phys = ext4_ext_pblock(ex);
1352                 return 0;
1353         }
1354
1355         /* go up and search for index to the right */
1356         while (--depth >= 0) {
1357                 ix = path[depth].p_idx;
1358                 if (ix != EXT_LAST_INDEX(path[depth].p_hdr))
1359                         goto got_index;
1360         }
1361
1362         /* we've gone up to the root and found no index to the right */
1363         return 0;
1364
1365 got_index:
1366         /* we've found index to the right, let's
1367          * follow it and find the closest allocated
1368          * block to the right */
1369         ix++;
1370         block = ext4_idx_pblock(ix);
1371         while (++depth < path->p_depth) {
1372                 bh = sb_bread(inode->i_sb, block);
1373                 if (bh == NULL)
1374                         return -EIO;
1375                 eh = ext_block_hdr(bh);
1376                 /* subtract from p_depth to get proper eh_depth */
1377                 if (ext4_ext_check(inode, eh, path->p_depth - depth)) {
1378                         put_bh(bh);
1379                         return -EIO;
1380                 }
1381                 ix = EXT_FIRST_INDEX(eh);
1382                 block = ext4_idx_pblock(ix);
1383                 put_bh(bh);
1384         }
1385
1386         bh = sb_bread(inode->i_sb, block);
1387         if (bh == NULL)
1388                 return -EIO;
1389         eh = ext_block_hdr(bh);
1390         if (ext4_ext_check(inode, eh, path->p_depth - depth)) {
1391                 put_bh(bh);
1392                 return -EIO;
1393         }
1394         ex = EXT_FIRST_EXTENT(eh);
1395         *logical = le32_to_cpu(ex->ee_block);
1396         *phys = ext4_ext_pblock(ex);
1397         put_bh(bh);
1398         return 0;
1399 }
1400
1401 /*
1402  * ext4_ext_next_allocated_block:
1403  * returns allocated block in subsequent extent or EXT_MAX_BLOCK.
1404  * NOTE: it considers block number from index entry as
1405  * allocated block. Thus, index entries have to be consistent
1406  * with leaves.
1407  */
1408 static ext4_lblk_t
1409 ext4_ext_next_allocated_block(struct ext4_ext_path *path)
1410 {
1411         int depth;
1412
1413         BUG_ON(path == NULL);
1414         depth = path->p_depth;
1415
1416         if (depth == 0 && path->p_ext == NULL)
1417                 return EXT_MAX_BLOCK;
1418
1419         while (depth >= 0) {
1420                 if (depth == path->p_depth) {
1421                         /* leaf */
1422                         if (path[depth].p_ext !=
1423                                         EXT_LAST_EXTENT(path[depth].p_hdr))
1424                           return le32_to_cpu(path[depth].p_ext[1].ee_block);
1425                 } else {
1426                         /* index */
1427                         if (path[depth].p_idx !=
1428                                         EXT_LAST_INDEX(path[depth].p_hdr))
1429                           return le32_to_cpu(path[depth].p_idx[1].ei_block);
1430                 }
1431                 depth--;
1432         }
1433
1434         return EXT_MAX_BLOCK;
1435 }
1436
1437 /*
1438  * ext4_ext_next_leaf_block:
1439  * returns first allocated block from next leaf or EXT_MAX_BLOCK
1440  */
1441 static ext4_lblk_t ext4_ext_next_leaf_block(struct inode *inode,
1442                                         struct ext4_ext_path *path)
1443 {
1444         int depth;
1445
1446         BUG_ON(path == NULL);
1447         depth = path->p_depth;
1448
1449         /* zero-tree has no leaf blocks at all */
1450         if (depth == 0)
1451                 return EXT_MAX_BLOCK;
1452
1453         /* go to index block */
1454         depth--;
1455
1456         while (depth >= 0) {
1457                 if (path[depth].p_idx !=
1458                                 EXT_LAST_INDEX(path[depth].p_hdr))
1459                         return (ext4_lblk_t)
1460                                 le32_to_cpu(path[depth].p_idx[1].ei_block);
1461                 depth--;
1462         }
1463
1464         return EXT_MAX_BLOCK;
1465 }
1466
1467 /*
1468  * ext4_ext_correct_indexes:
1469  * if leaf gets modified and modified extent is first in the leaf,
1470  * then we have to correct all indexes above.
1471  * TODO: do we need to correct tree in all cases?
1472  */
1473 static int ext4_ext_correct_indexes(handle_t *handle, struct inode *inode,
1474                                 struct ext4_ext_path *path)
1475 {
1476         struct ext4_extent_header *eh;
1477         int depth = ext_depth(inode);
1478         struct ext4_extent *ex;
1479         __le32 border;
1480         int k, err = 0;
1481
1482         eh = path[depth].p_hdr;
1483         ex = path[depth].p_ext;
1484
1485         if (unlikely(ex == NULL || eh == NULL)) {
1486                 EXT4_ERROR_INODE(inode,
1487                                  "ex %p == NULL or eh %p == NULL", ex, eh);
1488                 return -EIO;
1489         }
1490
1491         if (depth == 0) {
1492                 /* there is no tree at all */
1493                 return 0;
1494         }
1495
1496         if (ex != EXT_FIRST_EXTENT(eh)) {
1497                 /* we correct tree if first leaf got modified only */
1498                 return 0;
1499         }
1500
1501         /*
1502          * TODO: we need correction if border is smaller than current one
1503          */
1504         k = depth - 1;
1505         border = path[depth].p_ext->ee_block;
1506         err = ext4_ext_get_access(handle, inode, path + k);
1507         if (err)
1508                 return err;
1509         path[k].p_idx->ei_block = border;
1510         err = ext4_ext_dirty(handle, inode, path + k);
1511         if (err)
1512                 return err;
1513
1514         while (k--) {
1515                 /* change all left-side indexes */
1516                 if (path[k+1].p_idx != EXT_FIRST_INDEX(path[k+1].p_hdr))
1517                         break;
1518                 err = ext4_ext_get_access(handle, inode, path + k);
1519                 if (err)
1520                         break;
1521                 path[k].p_idx->ei_block = border;
1522                 err = ext4_ext_dirty(handle, inode, path + k);
1523                 if (err)
1524                         break;
1525         }
1526
1527         return err;
1528 }
1529
1530 int
1531 ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
1532                                 struct ext4_extent *ex2)
1533 {
1534         unsigned short ext1_ee_len, ext2_ee_len, max_len;
1535
1536         /*
1537          * Make sure that either both extents are uninitialized, or
1538          * both are _not_.
1539          */
1540         if (ext4_ext_is_uninitialized(ex1) ^ ext4_ext_is_uninitialized(ex2))
1541                 return 0;
1542
1543         if (ext4_ext_is_uninitialized(ex1))
1544                 max_len = EXT_UNINIT_MAX_LEN;
1545         else
1546                 max_len = EXT_INIT_MAX_LEN;
1547
1548         ext1_ee_len = ext4_ext_get_actual_len(ex1);
1549         ext2_ee_len = ext4_ext_get_actual_len(ex2);
1550
1551         if (le32_to_cpu(ex1->ee_block) + ext1_ee_len !=
1552                         le32_to_cpu(ex2->ee_block))
1553                 return 0;
1554
1555         /*
1556          * To allow future support for preallocated extents to be added
1557          * as an RO_COMPAT feature, refuse to merge to extents if
1558          * this can result in the top bit of ee_len being set.
1559          */
1560         if (ext1_ee_len + ext2_ee_len > max_len)
1561                 return 0;
1562 #ifdef AGGRESSIVE_TEST
1563         if (ext1_ee_len >= 4)
1564                 return 0;
1565 #endif
1566
1567         if (ext4_ext_pblock(ex1) + ext1_ee_len == ext4_ext_pblock(ex2))
1568                 return 1;
1569         return 0;
1570 }
1571
1572 /*
1573  * This function tries to merge the "ex" extent to the next extent in the tree.
1574  * It always tries to merge towards right. If you want to merge towards
1575  * left, pass "ex - 1" as argument instead of "ex".
1576  * Returns 0 if the extents (ex and ex+1) were _not_ merged and returns
1577  * 1 if they got merged.
1578  */
1579 static int ext4_ext_try_to_merge_right(struct inode *inode,
1580                                  struct ext4_ext_path *path,
1581                                  struct ext4_extent *ex)
1582 {
1583         struct ext4_extent_header *eh;
1584         unsigned int depth, len;
1585         int merge_done = 0;
1586         int uninitialized = 0;
1587
1588         depth = ext_depth(inode);
1589         BUG_ON(path[depth].p_hdr == NULL);
1590         eh = path[depth].p_hdr;
1591
1592         while (ex < EXT_LAST_EXTENT(eh)) {
1593                 if (!ext4_can_extents_be_merged(inode, ex, ex + 1))
1594                         break;
1595                 /* merge with next extent! */
1596                 if (ext4_ext_is_uninitialized(ex))
1597                         uninitialized = 1;
1598                 ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
1599                                 + ext4_ext_get_actual_len(ex + 1));
1600                 if (uninitialized)
1601                         ext4_ext_mark_uninitialized(ex);
1602
1603                 if (ex + 1 < EXT_LAST_EXTENT(eh)) {
1604                         len = (EXT_LAST_EXTENT(eh) - ex - 1)
1605                                 * sizeof(struct ext4_extent);
1606                         memmove(ex + 1, ex + 2, len);
1607                 }
1608                 le16_add_cpu(&eh->eh_entries, -1);
1609                 merge_done = 1;
1610                 WARN_ON(eh->eh_entries == 0);
1611                 if (!eh->eh_entries)
1612                         EXT4_ERROR_INODE(inode, "eh->eh_entries = 0!");
1613         }
1614
1615         return merge_done;
1616 }
1617
1618 /*
1619  * This function tries to merge the @ex extent to neighbours in the tree.
1620  * return 1 if merge left else 0.
1621  */
1622 static int ext4_ext_try_to_merge(struct inode *inode,
1623                                   struct ext4_ext_path *path,
1624                                   struct ext4_extent *ex) {
1625         struct ext4_extent_header *eh;
1626         unsigned int depth;
1627         int merge_done = 0;
1628         int ret = 0;
1629
1630         depth = ext_depth(inode);
1631         BUG_ON(path[depth].p_hdr == NULL);
1632         eh = path[depth].p_hdr;
1633
1634         if (ex > EXT_FIRST_EXTENT(eh))
1635                 merge_done = ext4_ext_try_to_merge_right(inode, path, ex - 1);
1636
1637         if (!merge_done)
1638                 ret = ext4_ext_try_to_merge_right(inode, path, ex);
1639
1640         return ret;
1641 }
1642
1643 /*
1644  * check if a portion of the "newext" extent overlaps with an
1645  * existing extent.
1646  *
1647  * If there is an overlap discovered, it updates the length of the newext
1648  * such that there will be no overlap, and then returns 1.
1649  * If there is no overlap found, it returns 0.
1650  */
1651 static unsigned int ext4_ext_check_overlap(struct inode *inode,
1652                                            struct ext4_extent *newext,
1653                                            struct ext4_ext_path *path)
1654 {
1655         ext4_lblk_t b1, b2;
1656         unsigned int depth, len1;
1657         unsigned int ret = 0;
1658
1659         b1 = le32_to_cpu(newext->ee_block);
1660         len1 = ext4_ext_get_actual_len(newext);
1661         depth = ext_depth(inode);
1662         if (!path[depth].p_ext)
1663                 goto out;
1664         b2 = le32_to_cpu(path[depth].p_ext->ee_block);
1665
1666         /*
1667          * get the next allocated block if the extent in the path
1668          * is before the requested block(s)
1669          */
1670         if (b2 < b1) {
1671                 b2 = ext4_ext_next_allocated_block(path);
1672                 if (b2 == EXT_MAX_BLOCK)
1673                         goto out;
1674         }
1675
1676         /* check for wrap through zero on extent logical start block*/
1677         if (b1 + len1 < b1) {
1678                 len1 = EXT_MAX_BLOCK - b1;
1679                 newext->ee_len = cpu_to_le16(len1);
1680                 ret = 1;
1681         }
1682
1683         /* check for overlap */
1684         if (b1 + len1 > b2) {
1685                 newext->ee_len = cpu_to_le16(b2 - b1);
1686                 ret = 1;
1687         }
1688 out:
1689         return ret;
1690 }
1691
1692 /*
1693  * ext4_ext_insert_extent:
1694  * tries to merge requsted extent into the existing extent or
1695  * inserts requested extent as new one into the tree,
1696  * creating new leaf in the no-space case.
1697  */
1698 int ext4_ext_insert_extent(handle_t *handle, struct inode *inode,
1699                                 struct ext4_ext_path *path,
1700                                 struct ext4_extent *newext, int flag)
1701 {
1702         struct ext4_extent_header *eh;
1703         struct ext4_extent *ex, *fex;
1704         struct ext4_extent *nearex; /* nearest extent */
1705         struct ext4_ext_path *npath = NULL;
1706         int depth, len, err;
1707         ext4_lblk_t next;
1708         unsigned uninitialized = 0;
1709         int flags = 0;
1710
1711         if (unlikely(ext4_ext_get_actual_len(newext) == 0)) {
1712                 EXT4_ERROR_INODE(inode, "ext4_ext_get_actual_len(newext) == 0");
1713                 return -EIO;
1714         }
1715         depth = ext_depth(inode);
1716         ex = path[depth].p_ext;
1717         if (unlikely(path[depth].p_hdr == NULL)) {
1718                 EXT4_ERROR_INODE(inode, "path[%d].p_hdr == NULL", depth);
1719                 return -EIO;
1720         }
1721
1722         /* try to insert block into found extent and return */
1723         if (ex && !(flag & EXT4_GET_BLOCKS_PRE_IO)
1724                 && ext4_can_extents_be_merged(inode, ex, newext)) {
1725                 ext_debug("append [%d]%d block to %d:[%d]%d (from %llu)\n",
1726                           ext4_ext_is_uninitialized(newext),
1727                           ext4_ext_get_actual_len(newext),
1728                           le32_to_cpu(ex->ee_block),
1729                           ext4_ext_is_uninitialized(ex),
1730                           ext4_ext_get_actual_len(ex),
1731                           ext4_ext_pblock(ex));
1732                 err = ext4_ext_get_access(handle, inode, path + depth);
1733                 if (err)
1734                         return err;
1735
1736                 /*
1737                  * ext4_can_extents_be_merged should have checked that either
1738                  * both extents are uninitialized, or both aren't. Thus we
1739                  * need to check only one of them here.
1740                  */
1741                 if (ext4_ext_is_uninitialized(ex))
1742                         uninitialized = 1;
1743                 ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
1744                                         + ext4_ext_get_actual_len(newext));
1745                 if (uninitialized)
1746                         ext4_ext_mark_uninitialized(ex);
1747                 eh = path[depth].p_hdr;
1748                 nearex = ex;
1749                 goto merge;
1750         }
1751
1752 repeat:
1753         depth = ext_depth(inode);
1754         eh = path[depth].p_hdr;
1755         if (le16_to_cpu(eh->eh_entries) < le16_to_cpu(eh->eh_max))
1756                 goto has_space;
1757
1758         /* probably next leaf has space for us? */
1759         fex = EXT_LAST_EXTENT(eh);
1760         next = ext4_ext_next_leaf_block(inode, path);
1761         if (le32_to_cpu(newext->ee_block) > le32_to_cpu(fex->ee_block)
1762             && next != EXT_MAX_BLOCK) {
1763                 ext_debug("next leaf block - %d\n", next);
1764                 BUG_ON(npath != NULL);
1765                 npath = ext4_ext_find_extent(inode, next, NULL);
1766                 if (IS_ERR(npath))
1767                         return PTR_ERR(npath);
1768                 BUG_ON(npath->p_depth != path->p_depth);
1769                 eh = npath[depth].p_hdr;
1770                 if (le16_to_cpu(eh->eh_entries) < le16_to_cpu(eh->eh_max)) {
1771                         ext_debug("next leaf isn't full(%d)\n",
1772                                   le16_to_cpu(eh->eh_entries));
1773                         path = npath;
1774                         goto repeat;
1775                 }
1776                 ext_debug("next leaf has no free space(%d,%d)\n",
1777                           le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));
1778         }
1779
1780         /*
1781          * There is no free space in the found leaf.
1782          * We're gonna add a new leaf in the tree.
1783          */
1784         if (flag & EXT4_GET_BLOCKS_PUNCH_OUT_EXT)
1785                 flags = EXT4_MB_USE_ROOT_BLOCKS;
1786         err = ext4_ext_create_new_leaf(handle, inode, flags, path, newext);
1787         if (err)
1788                 goto cleanup;
1789         depth = ext_depth(inode);
1790         eh = path[depth].p_hdr;
1791
1792 has_space:
1793         nearex = path[depth].p_ext;
1794
1795         err = ext4_ext_get_access(handle, inode, path + depth);
1796         if (err)
1797                 goto cleanup;
1798
1799         if (!nearex) {
1800                 /* there is no extent in this leaf, create first one */
1801                 ext_debug("first extent in the leaf: %d:%llu:[%d]%d\n",
1802                                 le32_to_cpu(newext->ee_block),
1803                                 ext4_ext_pblock(newext),
1804                                 ext4_ext_is_uninitialized(newext),
1805                                 ext4_ext_get_actual_len(newext));
1806                 path[depth].p_ext = EXT_FIRST_EXTENT(eh);
1807         } else if (le32_to_cpu(newext->ee_block)
1808                            > le32_to_cpu(nearex->ee_block)) {
1809 /*              BUG_ON(newext->ee_block == nearex->ee_block); */
1810                 if (nearex != EXT_LAST_EXTENT(eh)) {
1811                         len = EXT_MAX_EXTENT(eh) - nearex;
1812                         len = (len - 1) * sizeof(struct ext4_extent);
1813                         len = len < 0 ? 0 : len;
1814                         ext_debug("insert %d:%llu:[%d]%d after: nearest 0x%p, "
1815                                         "move %d from 0x%p to 0x%p\n",
1816                                         le32_to_cpu(newext->ee_block),
1817                                         ext4_ext_pblock(newext),
1818                                         ext4_ext_is_uninitialized(newext),
1819                                         ext4_ext_get_actual_len(newext),
1820                                         nearex, len, nearex + 1, nearex + 2);
1821                         memmove(nearex + 2, nearex + 1, len);
1822                 }
1823                 path[depth].p_ext = nearex + 1;
1824         } else {
1825                 BUG_ON(newext->ee_block == nearex->ee_block);
1826                 len = (EXT_MAX_EXTENT(eh) - nearex) * sizeof(struct ext4_extent);
1827                 len = len < 0 ? 0 : len;
1828                 ext_debug("insert %d:%llu:[%d]%d before: nearest 0x%p, "
1829                                 "move %d from 0x%p to 0x%p\n",
1830                                 le32_to_cpu(newext->ee_block),
1831                                 ext4_ext_pblock(newext),
1832                                 ext4_ext_is_uninitialized(newext),
1833                                 ext4_ext_get_actual_len(newext),
1834                                 nearex, len, nearex + 1, nearex + 2);
1835                 memmove(nearex + 1, nearex, len);
1836                 path[depth].p_ext = nearex;
1837         }
1838
1839         le16_add_cpu(&eh->eh_entries, 1);
1840         nearex = path[depth].p_ext;
1841         nearex->ee_block = newext->ee_block;
1842         ext4_ext_store_pblock(nearex, ext4_ext_pblock(newext));
1843         nearex->ee_len = newext->ee_len;
1844
1845 merge:
1846         /* try to merge extents to the right */
1847         if (!(flag & EXT4_GET_BLOCKS_PRE_IO))
1848                 ext4_ext_try_to_merge(inode, path, nearex);
1849
1850         /* try to merge extents to the left */
1851
1852         /* time to correct all indexes above */
1853         err = ext4_ext_correct_indexes(handle, inode, path);
1854         if (err)
1855                 goto cleanup;
1856
1857         err = ext4_ext_dirty(handle, inode, path + depth);
1858
1859 cleanup:
1860         if (npath) {
1861                 ext4_ext_drop_refs(npath);
1862                 kfree(npath);
1863         }
1864         ext4_ext_invalidate_cache(inode);
1865         return err;
1866 }
1867
1868 static int ext4_ext_walk_space(struct inode *inode, ext4_lblk_t block,
1869                                ext4_lblk_t num, ext_prepare_callback func,
1870                                void *cbdata)
1871 {
1872         struct ext4_ext_path *path = NULL;
1873         struct ext4_ext_cache cbex;
1874         struct ext4_extent *ex;
1875         ext4_lblk_t next, start = 0, end = 0;
1876         ext4_lblk_t last = block + num;
1877         int depth, exists, err = 0;
1878
1879         BUG_ON(func == NULL);
1880         BUG_ON(inode == NULL);
1881
1882         while (block < last && block != EXT_MAX_BLOCK) {
1883                 num = last - block;
1884                 /* find extent for this block */
1885                 down_read(&EXT4_I(inode)->i_data_sem);
1886                 path = ext4_ext_find_extent(inode, block, path);
1887                 up_read(&EXT4_I(inode)->i_data_sem);
1888                 if (IS_ERR(path)) {
1889                         err = PTR_ERR(path);
1890                         path = NULL;
1891                         break;
1892                 }
1893
1894                 depth = ext_depth(inode);
1895                 if (unlikely(path[depth].p_hdr == NULL)) {
1896                         EXT4_ERROR_INODE(inode, "path[%d].p_hdr == NULL", depth);
1897                         err = -EIO;
1898                         break;
1899                 }
1900                 ex = path[depth].p_ext;
1901                 next = ext4_ext_next_allocated_block(path);
1902
1903                 exists = 0;
1904                 if (!ex) {
1905                         /* there is no extent yet, so try to allocate
1906                          * all requested space */
1907                         start = block;
1908                         end = block + num;
1909                 } else if (le32_to_cpu(ex->ee_block) > block) {
1910                         /* need to allocate space before found extent */
1911                         start = block;
1912                         end = le32_to_cpu(ex->ee_block);
1913                         if (block + num < end)
1914                                 end = block + num;
1915                 } else if (block >= le32_to_cpu(ex->ee_block)
1916                                         + ext4_ext_get_actual_len(ex)) {
1917                         /* need to allocate space after found extent */
1918                         start = block;
1919                         end = block + num;
1920                         if (end >= next)
1921                                 end = next;
1922                 } else if (block >= le32_to_cpu(ex->ee_block)) {
1923                         /*
1924                          * some part of requested space is covered
1925                          * by found extent
1926                          */
1927                         start = block;
1928                         end = le32_to_cpu(ex->ee_block)
1929                                 + ext4_ext_get_actual_len(ex);
1930                         if (block + num < end)
1931                                 end = block + num;
1932                         exists = 1;
1933                 } else {
1934                         BUG();
1935                 }
1936                 BUG_ON(end <= start);
1937
1938                 if (!exists) {
1939                         cbex.ec_block = start;
1940                         cbex.ec_len = end - start;
1941                         cbex.ec_start = 0;
1942                 } else {
1943                         cbex.ec_block = le32_to_cpu(ex->ee_block);
1944                         cbex.ec_len = ext4_ext_get_actual_len(ex);
1945                         cbex.ec_start = ext4_ext_pblock(ex);
1946                 }
1947
1948                 if (unlikely(cbex.ec_len == 0)) {
1949                         EXT4_ERROR_INODE(inode, "cbex.ec_len == 0");
1950                         err = -EIO;
1951                         break;
1952                 }
1953                 err = func(inode, path, &cbex, ex, cbdata);
1954                 ext4_ext_drop_refs(path);
1955
1956                 if (err < 0)
1957                         break;
1958
1959                 if (err == EXT_REPEAT)
1960                         continue;
1961                 else if (err == EXT_BREAK) {
1962                         err = 0;
1963                         break;
1964                 }
1965
1966                 if (ext_depth(inode) != depth) {
1967                         /* depth was changed. we have to realloc path */
1968                         kfree(path);
1969                         path = NULL;
1970                 }
1971
1972                 block = cbex.ec_block + cbex.ec_len;
1973         }
1974
1975         if (path) {
1976                 ext4_ext_drop_refs(path);
1977                 kfree(path);
1978         }
1979
1980         return err;
1981 }
1982
1983 static void
1984 ext4_ext_put_in_cache(struct inode *inode, ext4_lblk_t block,
1985                         __u32 len, ext4_fsblk_t start)
1986 {
1987         struct ext4_ext_cache *cex;
1988         BUG_ON(len == 0);
1989         spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1990         cex = &EXT4_I(inode)->i_cached_extent;
1991         cex->ec_block = block;
1992         cex->ec_len = len;
1993         cex->ec_start = start;
1994         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1995 }
1996
1997 /*
1998  * ext4_ext_put_gap_in_cache:
1999  * calculate boundaries of the gap that the requested block fits into
2000  * and cache this gap
2001  */
2002 static void
2003 ext4_ext_put_gap_in_cache(struct inode *inode, struct ext4_ext_path *path,
2004                                 ext4_lblk_t block)
2005 {
2006         int depth = ext_depth(inode);
2007         unsigned long len;
2008         ext4_lblk_t lblock;
2009         struct ext4_extent *ex;
2010
2011         ex = path[depth].p_ext;
2012         if (ex == NULL) {
2013                 /* there is no extent yet, so gap is [0;-] */
2014                 lblock = 0;
2015                 len = EXT_MAX_BLOCK;
2016                 ext_debug("cache gap(whole file):");
2017         } else if (block < le32_to_cpu(ex->ee_block)) {
2018                 lblock = block;
2019                 len = le32_to_cpu(ex->ee_block) - block;
2020                 ext_debug("cache gap(before): %u [%u:%u]",
2021                                 block,
2022                                 le32_to_cpu(ex->ee_block),
2023                                  ext4_ext_get_actual_len(ex));
2024         } else if (block >= le32_to_cpu(ex->ee_block)
2025                         + ext4_ext_get_actual_len(ex)) {
2026                 ext4_lblk_t next;
2027                 lblock = le32_to_cpu(ex->ee_block)
2028                         + ext4_ext_get_actual_len(ex);
2029
2030                 next = ext4_ext_next_allocated_block(path);
2031                 ext_debug("cache gap(after): [%u:%u] %u",
2032                                 le32_to_cpu(ex->ee_block),
2033                                 ext4_ext_get_actual_len(ex),
2034                                 block);
2035                 BUG_ON(next == lblock);
2036                 len = next - lblock;
2037         } else {
2038                 lblock = len = 0;
2039                 BUG();
2040         }
2041
2042         ext_debug(" -> %u:%lu\n", lblock, len);
2043         ext4_ext_put_in_cache(inode, lblock, len, 0);
2044 }
2045
2046 /*
2047  * ext4_ext_in_cache()
2048  * Checks to see if the given block is in the cache.
2049  * If it is, the cached extent is stored in the given
2050  * cache extent pointer.  If the cached extent is a hole,
2051  * this routine should be used instead of
2052  * ext4_ext_in_cache if the calling function needs to
2053  * know the size of the hole.
2054  *
2055  * @inode: The files inode
2056  * @block: The block to look for in the cache
2057  * @ex:    Pointer where the cached extent will be stored
2058  *         if it contains block
2059  *
2060  * Return 0 if cache is invalid; 1 if the cache is valid
2061  */
2062 static int ext4_ext_check_cache(struct inode *inode, ext4_lblk_t block,
2063         struct ext4_ext_cache *ex){
2064         struct ext4_ext_cache *cex;
2065         struct ext4_sb_info *sbi;
2066         int ret = 0;
2067
2068         /*
2069          * We borrow i_block_reservation_lock to protect i_cached_extent
2070          */
2071         spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
2072         cex = &EXT4_I(inode)->i_cached_extent;
2073         sbi = EXT4_SB(inode->i_sb);
2074
2075         /* has cache valid data? */
2076         if (cex->ec_len == 0)
2077                 goto errout;
2078
2079         if (in_range(block, cex->ec_block, cex->ec_len)) {
2080                 memcpy(ex, cex, sizeof(struct ext4_ext_cache));
2081                 ext_debug("%u cached by %u:%u:%llu\n",
2082                                 block,
2083                                 cex->ec_block, cex->ec_len, cex->ec_start);
2084                 ret = 1;
2085         }
2086 errout:
2087         if (!ret)
2088                 sbi->extent_cache_misses++;
2089         else
2090                 sbi->extent_cache_hits++;
2091         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
2092         return ret;
2093 }
2094
2095 /*
2096  * ext4_ext_in_cache()
2097  * Checks to see if the given block is in the cache.
2098  * If it is, the cached extent is stored in the given
2099  * extent pointer.
2100  *
2101  * @inode: The files inode
2102  * @block: The block to look for in the cache
2103  * @ex:    Pointer where the cached extent will be stored
2104  *         if it contains block
2105  *
2106  * Return 0 if cache is invalid; 1 if the cache is valid
2107  */
2108 static int
2109 ext4_ext_in_cache(struct inode *inode, ext4_lblk_t block,
2110                         struct ext4_extent *ex)
2111 {
2112         struct ext4_ext_cache cex;
2113         int ret = 0;
2114
2115         if (ext4_ext_check_cache(inode, block, &cex)) {
2116                 ex->ee_block = cpu_to_le32(cex.ec_block);
2117                 ext4_ext_store_pblock(ex, cex.ec_start);
2118                 ex->ee_len = cpu_to_le16(cex.ec_len);
2119                 ret = 1;
2120         }
2121
2122         return ret;
2123 }
2124
2125
2126 /*
2127  * ext4_ext_rm_idx:
2128  * removes index from the index block.
2129  * It's used in truncate case only, thus all requests are for
2130  * last index in the block only.
2131  */
2132 static int ext4_ext_rm_idx(handle_t *handle, struct inode *inode,
2133                         struct ext4_ext_path *path)
2134 {
2135         int err;
2136         ext4_fsblk_t leaf;
2137
2138         /* free index block */
2139         path--;
2140         leaf = ext4_idx_pblock(path->p_idx);
2141         if (unlikely(path->p_hdr->eh_entries == 0)) {
2142                 EXT4_ERROR_INODE(inode, "path->p_hdr->eh_entries == 0");
2143                 return -EIO;
2144         }
2145         err = ext4_ext_get_access(handle, inode, path);
2146         if (err)
2147                 return err;
2148         le16_add_cpu(&path->p_hdr->eh_entries, -1);
2149         err = ext4_ext_dirty(handle, inode, path);
2150         if (err)
2151                 return err;
2152         ext_debug("index is empty, remove it, free block %llu\n", leaf);
2153         ext4_free_blocks(handle, inode, NULL, leaf, 1,
2154                          EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
2155         return err;
2156 }
2157
2158 /*
2159  * ext4_ext_calc_credits_for_single_extent:
2160  * This routine returns max. credits that needed to insert an extent
2161  * to the extent tree.
2162  * When pass the actual path, the caller should calculate credits
2163  * under i_data_sem.
2164  */
2165 int ext4_ext_calc_credits_for_single_extent(struct inode *inode, int nrblocks,
2166                                                 struct ext4_ext_path *path)
2167 {
2168         if (path) {
2169                 int depth = ext_depth(inode);
2170                 int ret = 0;
2171
2172                 /* probably there is space in leaf? */
2173                 if (le16_to_cpu(path[depth].p_hdr->eh_entries)
2174                                 < le16_to_cpu(path[depth].p_hdr->eh_max)) {
2175
2176                         /*
2177                          *  There are some space in the leaf tree, no
2178                          *  need to account for leaf block credit
2179                          *
2180                          *  bitmaps and block group descriptor blocks
2181                          *  and other metadat blocks still need to be
2182                          *  accounted.
2183                          */
2184                         /* 1 bitmap, 1 block group descriptor */
2185                         ret = 2 + EXT4_META_TRANS_BLOCKS(inode->i_sb);
2186                         return ret;
2187                 }
2188         }
2189
2190         return ext4_chunk_trans_blocks(inode, nrblocks);
2191 }
2192
2193 /*
2194  * How many index/leaf blocks need to change/allocate to modify nrblocks?
2195  *
2196  * if nrblocks are fit in a single extent (chunk flag is 1), then
2197  * in the worse case, each tree level index/leaf need to be changed
2198  * if the tree split due to insert a new extent, then the old tree
2199  * index/leaf need to be updated too
2200  *
2201  * If the nrblocks are discontiguous, they could cause
2202  * the whole tree split more than once, but this is really rare.
2203  */
2204 int ext4_ext_index_trans_blocks(struct inode *inode, int nrblocks, int chunk)
2205 {
2206         int index;
2207         int depth = ext_depth(inode);
2208
2209         if (chunk)
2210                 index = depth * 2;
2211         else
2212                 index = depth * 3;
2213
2214         return index;
2215 }
2216
2217 static int ext4_remove_blocks(handle_t *handle, struct inode *inode,
2218                                 struct ext4_extent *ex,
2219                                 ext4_lblk_t from, ext4_lblk_t to)
2220 {
2221         unsigned short ee_len =  ext4_ext_get_actual_len(ex);
2222         int flags = EXT4_FREE_BLOCKS_FORGET;
2223
2224         if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
2225                 flags |= EXT4_FREE_BLOCKS_METADATA;
2226 #ifdef EXTENTS_STATS
2227         {
2228                 struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
2229                 spin_lock(&sbi->s_ext_stats_lock);
2230                 sbi->s_ext_blocks += ee_len;
2231                 sbi->s_ext_extents++;
2232                 if (ee_len < sbi->s_ext_min)
2233                         sbi->s_ext_min = ee_len;
2234                 if (ee_len > sbi->s_ext_max)
2235                         sbi->s_ext_max = ee_len;
2236                 if (ext_depth(inode) > sbi->s_depth_max)
2237                         sbi->s_depth_max = ext_depth(inode);
2238                 spin_unlock(&sbi->s_ext_stats_lock);
2239         }
2240 #endif
2241         if (from >= le32_to_cpu(ex->ee_block)
2242             && to == le32_to_cpu(ex->ee_block) + ee_len - 1) {
2243                 /* tail removal */
2244                 ext4_lblk_t num;
2245                 ext4_fsblk_t start;
2246
2247                 num = le32_to_cpu(ex->ee_block) + ee_len - from;
2248                 start = ext4_ext_pblock(ex) + ee_len - num;
2249                 ext_debug("free last %u blocks starting %llu\n", num, start);
2250                 ext4_free_blocks(handle, inode, NULL, start, num, flags);
2251         } else if (from == le32_to_cpu(ex->ee_block)
2252                    && to <= le32_to_cpu(ex->ee_block) + ee_len - 1) {
2253                 /* head removal */
2254                 ext4_lblk_t num;
2255                 ext4_fsblk_t start;
2256
2257                 num = to - from;
2258                 start = ext4_ext_pblock(ex);
2259
2260                 ext_debug("free first %u blocks starting %llu\n", num, start);
2261                 ext4_free_blocks(handle, inode, 0, start, num, flags);
2262
2263         } else {
2264                 printk(KERN_INFO "strange request: removal(2) "
2265                                 "%u-%u from %u:%u\n",
2266                                 from, to, le32_to_cpu(ex->ee_block), ee_len);
2267         }
2268         return 0;
2269 }
2270
2271
2272 /*
2273  * ext4_ext_rm_leaf() Removes the extents associated with the
2274  * blocks appearing between "start" and "end", and splits the extents
2275  * if "start" and "end" appear in the same extent
2276  *
2277  * @handle: The journal handle
2278  * @inode:  The files inode
2279  * @path:   The path to the leaf
2280  * @start:  The first block to remove
2281  * @end:   The last block to remove
2282  */
2283 static int
2284 ext4_ext_rm_leaf(handle_t *handle, struct inode *inode,
2285                 struct ext4_ext_path *path, ext4_lblk_t start,
2286                 ext4_lblk_t end)
2287 {
2288         int err = 0, correct_index = 0;
2289         int depth = ext_depth(inode), credits;
2290         struct ext4_extent_header *eh;
2291         ext4_lblk_t a, b, block;
2292         unsigned num;
2293         ext4_lblk_t ex_ee_block;
2294         unsigned short ex_ee_len;
2295         unsigned uninitialized = 0;
2296         struct ext4_extent *ex;
2297         struct ext4_map_blocks map;
2298
2299         /* the header must be checked already in ext4_ext_remove_space() */
2300         ext_debug("truncate since %u in leaf\n", start);
2301         if (!path[depth].p_hdr)
2302                 path[depth].p_hdr = ext_block_hdr(path[depth].p_bh);
2303         eh = path[depth].p_hdr;
2304         if (unlikely(path[depth].p_hdr == NULL)) {
2305                 EXT4_ERROR_INODE(inode, "path[%d].p_hdr == NULL", depth);
2306                 return -EIO;
2307         }
2308         /* find where to start removing */
2309         ex = EXT_LAST_EXTENT(eh);
2310
2311         ex_ee_block = le32_to_cpu(ex->ee_block);
2312         ex_ee_len = ext4_ext_get_actual_len(ex);
2313
2314         while (ex >= EXT_FIRST_EXTENT(eh) &&
2315                         ex_ee_block + ex_ee_len > start) {
2316
2317                 if (ext4_ext_is_uninitialized(ex))
2318                         uninitialized = 1;
2319                 else
2320                         uninitialized = 0;
2321
2322                 ext_debug("remove ext %u:[%d]%d\n", ex_ee_block,
2323                          uninitialized, ex_ee_len);
2324                 path[depth].p_ext = ex;
2325
2326                 a = ex_ee_block > start ? ex_ee_block : start;
2327                 b = ex_ee_block+ex_ee_len - 1 < end ?
2328                         ex_ee_block+ex_ee_len - 1 : end;
2329
2330                 ext_debug("  border %u:%u\n", a, b);
2331
2332                 /* If this extent is beyond the end of the hole, skip it */
2333                 if (end <= ex_ee_block) {
2334                         ex--;
2335                         ex_ee_block = le32_to_cpu(ex->ee_block);
2336                         ex_ee_len = ext4_ext_get_actual_len(ex);
2337                         continue;
2338                 } else if (a != ex_ee_block &&
2339                         b != ex_ee_block + ex_ee_len - 1) {
2340                         /*
2341                          * If this is a truncate, then this condition should
2342                          * never happen because at least one of the end points
2343                          * needs to be on the edge of the extent.
2344                          */
2345                         if (end == EXT_MAX_BLOCK) {
2346                                 ext_debug("  bad truncate %u:%u\n",
2347                                                 start, end);
2348                                 block = 0;
2349                                 num = 0;
2350                                 err = -EIO;
2351                                 goto out;
2352                         }
2353                         /*
2354                          * else this is a hole punch, so the extent needs to
2355                          * be split since neither edge of the hole is on the
2356                          * extent edge
2357                          */
2358                         else{
2359                                 map.m_pblk = ext4_ext_pblock(ex);
2360                                 map.m_lblk = ex_ee_block;
2361                                 map.m_len = b - ex_ee_block;
2362
2363                                 err = ext4_split_extent(handle,
2364                                         inode, path, &map, 0,
2365                                         EXT4_GET_BLOCKS_PUNCH_OUT_EXT |
2366                                         EXT4_GET_BLOCKS_PRE_IO);
2367
2368                                 if (err < 0)
2369                                         goto out;
2370
2371                                 ex_ee_len = ext4_ext_get_actual_len(ex);
2372
2373                                 b = ex_ee_block+ex_ee_len - 1 < end ?
2374                                         ex_ee_block+ex_ee_len - 1 : end;
2375
2376                                 /* Then remove tail of this extent */
2377                                 block = ex_ee_block;
2378                                 num = a - block;
2379                         }
2380                 } else if (a != ex_ee_block) {
2381                         /* remove tail of the extent */
2382                         block = ex_ee_block;
2383                         num = a - block;
2384                 } else if (b != ex_ee_block + ex_ee_len - 1) {
2385                         /* remove head of the extent */
2386                         block = b;
2387                         num =  ex_ee_block + ex_ee_len - b;
2388
2389                         /*
2390                          * If this is a truncate, this condition
2391                          * should never happen
2392                          */
2393                         if (end == EXT_MAX_BLOCK) {
2394                                 ext_debug("  bad truncate %u:%u\n",
2395                                         start, end);
2396                                 err = -EIO;
2397                                 goto out;
2398                         }
2399                 } else {
2400                         /* remove whole extent: excellent! */
2401                         block = ex_ee_block;
2402                         num = 0;
2403                         if (a != ex_ee_block) {
2404                                 ext_debug("  bad truncate %u:%u\n",
2405                                         start, end);
2406                                 err = -EIO;
2407                                 goto out;
2408                         }
2409
2410                         if (b != ex_ee_block + ex_ee_len - 1) {
2411                                 ext_debug("  bad truncate %u:%u\n",
2412                                         start, end);
2413                                 err = -EIO;
2414                                 goto out;
2415                         }
2416                 }
2417
2418                 /*
2419                  * 3 for leaf, sb, and inode plus 2 (bmap and group
2420                  * descriptor) for each block group; assume two block
2421                  * groups plus ex_ee_len/blocks_per_block_group for
2422                  * the worst case
2423                  */
2424                 credits = 7 + 2*(ex_ee_len/EXT4_BLOCKS_PER_GROUP(inode->i_sb));
2425                 if (ex == EXT_FIRST_EXTENT(eh)) {
2426                         correct_index = 1;
2427                         credits += (ext_depth(inode)) + 1;
2428                 }
2429                 credits += EXT4_MAXQUOTAS_TRANS_BLOCKS(inode->i_sb);
2430
2431                 err = ext4_ext_truncate_extend_restart(handle, inode, credits);
2432                 if (err)
2433                         goto out;
2434
2435                 err = ext4_ext_get_access(handle, inode, path + depth);
2436                 if (err)
2437                         goto out;
2438
2439                 err = ext4_remove_blocks(handle, inode, ex, a, b);
2440                 if (err)
2441                         goto out;
2442
2443                 if (num == 0) {
2444                         /* this extent is removed; mark slot entirely unused */
2445                         ext4_ext_store_pblock(ex, 0);
2446                 } else if (block != ex_ee_block) {
2447                         /*
2448                          * If this was a head removal, then we need to update
2449                          * the physical block since it is now at a different
2450                          * location
2451                          */
2452                         ext4_ext_store_pblock(ex, ext4_ext_pblock(ex) + (b-a));
2453                 }
2454
2455                 ex->ee_block = cpu_to_le32(block);
2456                 ex->ee_len = cpu_to_le16(num);
2457                 /*
2458                  * Do not mark uninitialized if all the blocks in the
2459                  * extent have been removed.
2460                  */
2461                 if (uninitialized && num)
2462                         ext4_ext_mark_uninitialized(ex);
2463
2464                 err = ext4_ext_dirty(handle, inode, path + depth);
2465                 if (err)
2466                         goto out;
2467
2468                 /*
2469                  * If the extent was completely released,
2470                  * we need to remove it from the leaf
2471                  */
2472                 if (num == 0) {
2473                         if (end != EXT_MAX_BLOCK) {
2474                                 /*
2475                                  * For hole punching, we need to scoot all the
2476                                  * extents up when an extent is removed so that
2477                                  * we dont have blank extents in the middle
2478                                  */
2479                                 memmove(ex, ex+1, (EXT_LAST_EXTENT(eh) - ex) *
2480                                         sizeof(struct ext4_extent));
2481
2482                                 /* Now get rid of the one at the end */
2483                                 memset(EXT_LAST_EXTENT(eh), 0,
2484                                         sizeof(struct ext4_extent));
2485                         }
2486                         le16_add_cpu(&eh->eh_entries, -1);
2487                 }
2488
2489                 ext_debug("new extent: %u:%u:%llu\n", block, num,
2490                                 ext4_ext_pblock(ex));
2491                 ex--;
2492                 ex_ee_block = le32_to_cpu(ex->ee_block);
2493                 ex_ee_len = ext4_ext_get_actual_len(ex);
2494         }
2495
2496         if (correct_index && eh->eh_entries)
2497                 err = ext4_ext_correct_indexes(handle, inode, path);
2498
2499         /* if this leaf is free, then we should
2500          * remove it from index block above */
2501         if (err == 0 && eh->eh_entries == 0 && path[depth].p_bh != NULL)
2502                 err = ext4_ext_rm_idx(handle, inode, path + depth);
2503
2504 out:
2505         return err;
2506 }
2507
2508 /*
2509  * ext4_ext_more_to_rm:
2510  * returns 1 if current index has to be freed (even partial)
2511  */
2512 static int
2513 ext4_ext_more_to_rm(struct ext4_ext_path *path)
2514 {
2515         BUG_ON(path->p_idx == NULL);
2516
2517         if (path->p_idx < EXT_FIRST_INDEX(path->p_hdr))
2518                 return 0;
2519
2520         /*
2521          * if truncate on deeper level happened, it wasn't partial,
2522          * so we have to consider current index for truncation
2523          */
2524         if (le16_to_cpu(path->p_hdr->eh_entries) == path->p_block)
2525                 return 0;
2526         return 1;
2527 }
2528
2529 static int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start,
2530                                 ext4_lblk_t end)
2531 {
2532         struct super_block *sb = inode->i_sb;
2533         int depth = ext_depth(inode);
2534         struct ext4_ext_path *path;
2535         handle_t *handle;
2536         int i, err;
2537
2538         ext_debug("truncate since %u\n", start);
2539
2540         /* probably first extent we're gonna free will be last in block */
2541         handle = ext4_journal_start(inode, depth + 1);
2542         if (IS_ERR(handle))
2543                 return PTR_ERR(handle);
2544
2545 again:
2546         ext4_ext_invalidate_cache(inode);
2547
2548         /*
2549          * We start scanning from right side, freeing all the blocks
2550          * after i_size and walking into the tree depth-wise.
2551          */
2552         depth = ext_depth(inode);
2553         path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 1), GFP_NOFS);
2554         if (path == NULL) {
2555                 ext4_journal_stop(handle);
2556                 return -ENOMEM;
2557         }
2558         path[0].p_depth = depth;
2559         path[0].p_hdr = ext_inode_hdr(inode);
2560         if (ext4_ext_check(inode, path[0].p_hdr, depth)) {
2561                 err = -EIO;
2562                 goto out;
2563         }
2564         i = err = 0;
2565
2566         while (i >= 0 && err == 0) {
2567                 if (i == depth) {
2568                         /* this is leaf block */
2569                         err = ext4_ext_rm_leaf(handle, inode, path,
2570                                         start, end);
2571                         /* root level has p_bh == NULL, brelse() eats this */
2572                         brelse(path[i].p_bh);
2573                         path[i].p_bh = NULL;
2574                         i--;
2575                         continue;
2576                 }
2577
2578                 /* this is index block */
2579                 if (!path[i].p_hdr) {
2580                         ext_debug("initialize header\n");
2581                         path[i].p_hdr = ext_block_hdr(path[i].p_bh);
2582                 }
2583
2584                 if (!path[i].p_idx) {
2585                         /* this level hasn't been touched yet */
2586                         path[i].p_idx = EXT_LAST_INDEX(path[i].p_hdr);
2587                         path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries)+1;
2588                         ext_debug("init index ptr: hdr 0x%p, num %d\n",
2589                                   path[i].p_hdr,
2590                                   le16_to_cpu(path[i].p_hdr->eh_entries));
2591                 } else {
2592                         /* we were already here, see at next index */
2593                         path[i].p_idx--;
2594                 }
2595
2596                 ext_debug("level %d - index, first 0x%p, cur 0x%p\n",
2597                                 i, EXT_FIRST_INDEX(path[i].p_hdr),
2598                                 path[i].p_idx);
2599                 if (ext4_ext_more_to_rm(path + i)) {
2600                         struct buffer_head *bh;
2601                         /* go to the next level */
2602                         ext_debug("move to level %d (block %llu)\n",
2603                                   i + 1, ext4_idx_pblock(path[i].p_idx));
2604                         memset(path + i + 1, 0, sizeof(*path));
2605                         bh = sb_bread(sb, ext4_idx_pblock(path[i].p_idx));
2606                         if (!bh) {
2607                                 /* should we reset i_size? */
2608                                 err = -EIO;
2609                                 break;
2610                         }
2611                         if (WARN_ON(i + 1 > depth)) {
2612                                 err = -EIO;
2613                                 break;
2614                         }
2615                         if (ext4_ext_check(inode, ext_block_hdr(bh),
2616                                                         depth - i - 1)) {
2617                                 err = -EIO;
2618                                 break;
2619                         }
2620                         path[i + 1].p_bh = bh;
2621
2622                         /* save actual number of indexes since this
2623                          * number is changed at the next iteration */
2624                         path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries);
2625                         i++;
2626                 } else {
2627                         /* we finished processing this index, go up */
2628                         if (path[i].p_hdr->eh_entries == 0 && i > 0) {
2629                                 /* index is empty, remove it;
2630                                  * handle must be already prepared by the
2631                                  * truncatei_leaf() */
2632                                 err = ext4_ext_rm_idx(handle, inode, path + i);
2633                         }
2634                         /* root level has p_bh == NULL, brelse() eats this */
2635                         brelse(path[i].p_bh);
2636                         path[i].p_bh = NULL;
2637                         i--;
2638                         ext_debug("return to level %d\n", i);
2639                 }
2640         }
2641
2642         /* TODO: flexible tree reduction should be here */
2643         if (path->p_hdr->eh_entries == 0) {
2644                 /*
2645                  * truncate to zero freed all the tree,
2646                  * so we need to correct eh_depth
2647                  */
2648                 err = ext4_ext_get_access(handle, inode, path);
2649                 if (err == 0) {
2650                         ext_inode_hdr(inode)->eh_depth = 0;
2651                         ext_inode_hdr(inode)->eh_max =
2652                                 cpu_to_le16(ext4_ext_space_root(inode, 0));
2653                         err = ext4_ext_dirty(handle, inode, path);
2654                 }
2655         }
2656 out:
2657         ext4_ext_drop_refs(path);
2658         kfree(path);
2659         if (err == -EAGAIN)
2660                 goto again;
2661         ext4_journal_stop(handle);
2662
2663         return err;
2664 }
2665
2666 /*
2667  * called at mount time
2668  */
2669 void ext4_ext_init(struct super_block *sb)
2670 {
2671         /*
2672          * possible initialization would be here
2673          */
2674
2675         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS)) {
2676 #if defined(AGGRESSIVE_TEST) || defined(CHECK_BINSEARCH) || defined(EXTENTS_STATS)
2677                 printk(KERN_INFO "EXT4-fs: file extents enabled");
2678 #ifdef AGGRESSIVE_TEST
2679                 printk(", aggressive tests");
2680 #endif
2681 #ifdef CHECK_BINSEARCH
2682                 printk(", check binsearch");
2683 #endif
2684 #ifdef EXTENTS_STATS
2685                 printk(", stats");
2686 #endif
2687                 printk("\n");
2688 #endif
2689 #ifdef EXTENTS_STATS
2690                 spin_lock_init(&EXT4_SB(sb)->s_ext_stats_lock);
2691                 EXT4_SB(sb)->s_ext_min = 1 << 30;
2692                 EXT4_SB(sb)->s_ext_max = 0;
2693 #endif
2694         }
2695 }
2696
2697 /*
2698  * called at umount time
2699  */
2700 void ext4_ext_release(struct super_block *sb)
2701 {
2702         if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS))
2703                 return;
2704
2705 #ifdef EXTENTS_STATS
2706         if (EXT4_SB(sb)->s_ext_blocks && EXT4_SB(sb)->s_ext_extents) {
2707                 struct ext4_sb_info *sbi = EXT4_SB(sb);
2708                 printk(KERN_ERR "EXT4-fs: %lu blocks in %lu extents (%lu ave)\n",
2709                         sbi->s_ext_blocks, sbi->s_ext_extents,
2710                         sbi->s_ext_blocks / sbi->s_ext_extents);
2711                 printk(KERN_ERR "EXT4-fs: extents: %lu min, %lu max, max depth %lu\n",
2712                         sbi->s_ext_min, sbi->s_ext_max, sbi->s_depth_max);
2713         }
2714 #endif
2715 }
2716
2717 /* FIXME!! we need to try to merge to left or right after zero-out  */
2718 static int ext4_ext_zeroout(struct inode *inode, struct ext4_extent *ex)
2719 {
2720         ext4_fsblk_t ee_pblock;
2721         unsigned int ee_len;
2722         int ret;
2723
2724         ee_len    = ext4_ext_get_actual_len(ex);
2725         ee_pblock = ext4_ext_pblock(ex);
2726
2727         ret = sb_issue_zeroout(inode->i_sb, ee_pblock, ee_len, GFP_NOFS);
2728         if (ret > 0)
2729                 ret = 0;
2730
2731         return ret;
2732 }
2733
2734 /*
2735  * used by extent splitting.
2736  */
2737 #define EXT4_EXT_MAY_ZEROOUT    0x1  /* safe to zeroout if split fails \
2738                                         due to ENOSPC */
2739 #define EXT4_EXT_MARK_UNINIT1   0x2  /* mark first half uninitialized */
2740 #define EXT4_EXT_MARK_UNINIT2   0x4  /* mark second half uninitialized */
2741
2742 /*
2743  * ext4_split_extent_at() splits an extent at given block.
2744  *
2745  * @handle: the journal handle
2746  * @inode: the file inode
2747  * @path: the path to the extent
2748  * @split: the logical block where the extent is splitted.
2749  * @split_flags: indicates if the extent could be zeroout if split fails, and
2750  *               the states(init or uninit) of new extents.
2751  * @flags: flags used to insert new extent to extent tree.
2752  *
2753  *
2754  * Splits extent [a, b] into two extents [a, @split) and [@split, b], states
2755  * of which are deterimined by split_flag.
2756  *
2757  * There are two cases:
2758  *  a> the extent are splitted into two extent.
2759  *  b> split is not needed, and just mark the extent.
2760  *
2761  * return 0 on success.
2762  */
2763 static int ext4_split_extent_at(handle_t *handle,
2764                              struct inode *inode,
2765                              struct ext4_ext_path *path,
2766                              ext4_lblk_t split,
2767                              int split_flag,
2768                              int flags)
2769 {
2770         ext4_fsblk_t newblock;
2771         ext4_lblk_t ee_block;
2772         struct ext4_extent *ex, newex, orig_ex;
2773         struct ext4_extent *ex2 = NULL;
2774         unsigned int ee_len, depth;
2775         int err = 0;
2776
2777         ext_debug("ext4_split_extents_at: inode %lu, logical"
2778                 "block %llu\n", inode->i_ino, (unsigned long long)split);
2779
2780         ext4_ext_show_leaf(inode, path);
2781
2782         depth = ext_depth(inode);
2783         ex = path[depth].p_ext;
2784         ee_block = le32_to_cpu(ex->ee_block);
2785         ee_len = ext4_ext_get_actual_len(ex);
2786         newblock = split - ee_block + ext4_ext_pblock(ex);
2787
2788         BUG_ON(split < ee_block || split >= (ee_block + ee_len));
2789
2790         err = ext4_ext_get_access(handle, inode, path + depth);
2791         if (err)
2792                 goto out;
2793
2794         if (split == ee_block) {
2795                 /*
2796                  * case b: block @split is the block that the extent begins with
2797                  * then we just change the state of the extent, and splitting
2798                  * is not needed.
2799                  */
2800                 if (split_flag & EXT4_EXT_MARK_UNINIT2)
2801                         ext4_ext_mark_uninitialized(ex);
2802                 else
2803                         ext4_ext_mark_initialized(ex);
2804
2805                 if (!(flags & EXT4_GET_BLOCKS_PRE_IO))
2806                         ext4_ext_try_to_merge(inode, path, ex);
2807
2808                 err = ext4_ext_dirty(handle, inode, path + depth);
2809                 goto out;
2810         }
2811
2812         /* case a */
2813         memcpy(&orig_ex, ex, sizeof(orig_ex));
2814         ex->ee_len = cpu_to_le16(split - ee_block);
2815         if (split_flag & EXT4_EXT_MARK_UNINIT1)
2816                 ext4_ext_mark_uninitialized(ex);
2817
2818         /*
2819          * path may lead to new leaf, not to original leaf any more
2820          * after ext4_ext_insert_extent() returns,
2821          */
2822         err = ext4_ext_dirty(handle, inode, path + depth);
2823         if (err)
2824                 goto fix_extent_len;
2825
2826         ex2 = &newex;
2827         ex2->ee_block = cpu_to_le32(split);
2828         ex2->ee_len   = cpu_to_le16(ee_len - (split - ee_block));
2829         ext4_ext_store_pblock(ex2, newblock);
2830         if (split_flag & EXT4_EXT_MARK_UNINIT2)
2831                 ext4_ext_mark_uninitialized(ex2);
2832
2833         err = ext4_ext_insert_extent(handle, inode, path, &newex, flags);
2834         if (err == -ENOSPC && (EXT4_EXT_MAY_ZEROOUT & split_flag)) {
2835                 err = ext4_ext_zeroout(inode, &orig_ex);
2836                 if (err)
2837                         goto fix_extent_len;
2838                 /* update the extent length and mark as initialized */
2839                 ex->ee_len = cpu_to_le32(ee_len);
2840                 ext4_ext_try_to_merge(inode, path, ex);
2841                 err = ext4_ext_dirty(handle, inode, path + depth);
2842                 goto out;
2843         } else if (err)
2844                 goto fix_extent_len;
2845
2846 out:
2847         ext4_ext_show_leaf(inode, path);
2848         return err;
2849
2850 fix_extent_len:
2851         ex->ee_len = orig_ex.ee_len;
2852         ext4_ext_dirty(handle, inode, path + depth);
2853         return err;
2854 }
2855
2856 /*
2857  * ext4_split_extents() splits an extent and mark extent which is covered
2858  * by @map as split_flags indicates
2859  *
2860  * It may result in splitting the extent into multiple extents (upto three)
2861  * There are three possibilities:
2862  *   a> There is no split required
2863  *   b> Splits in two extents: Split is happening at either end of the extent
2864  *   c> Splits in three extents: Somone is splitting in middle of the extent
2865  *
2866  */
2867 static int ext4_split_extent(handle_t *handle,
2868                               struct inode *inode,
2869                               struct ext4_ext_path *path,
2870                               struct ext4_map_blocks *map,
2871                               int split_flag,
2872                               int flags)
2873 {
2874         ext4_lblk_t ee_block;
2875         struct ext4_extent *ex;
2876         unsigned int ee_len, depth;
2877         int err = 0;
2878         int uninitialized;
2879         int split_flag1, flags1;
2880
2881         depth = ext_depth(inode);
2882         ex = path[depth].p_ext;
2883         ee_block = le32_to_cpu(ex->ee_block);
2884         ee_len = ext4_ext_get_actual_len(ex);
2885         uninitialized = ext4_ext_is_uninitialized(ex);
2886
2887         if (map->m_lblk + map->m_len < ee_block + ee_len) {
2888                 split_flag1 = split_flag & EXT4_EXT_MAY_ZEROOUT ?
2889                               EXT4_EXT_MAY_ZEROOUT : 0;
2890                 flags1 = flags | EXT4_GET_BLOCKS_PRE_IO;
2891                 if (uninitialized)
2892                         split_flag1 |= EXT4_EXT_MARK_UNINIT1 |
2893                                        EXT4_EXT_MARK_UNINIT2;
2894                 err = ext4_split_extent_at(handle, inode, path,
2895                                 map->m_lblk + map->m_len, split_flag1, flags1);
2896                 if (err)
2897                         goto out;
2898         }
2899
2900         ext4_ext_drop_refs(path);
2901         path = ext4_ext_find_extent(inode, map->m_lblk, path);
2902         if (IS_ERR(path))
2903                 return PTR_ERR(path);
2904
2905         if (map->m_lblk >= ee_block) {
2906                 split_flag1 = split_flag & EXT4_EXT_MAY_ZEROOUT ?
2907                               EXT4_EXT_MAY_ZEROOUT : 0;
2908                 if (uninitialized)
2909                         split_flag1 |= EXT4_EXT_MARK_UNINIT1;
2910                 if (split_flag & EXT4_EXT_MARK_UNINIT2)
2911                         split_flag1 |= EXT4_EXT_MARK_UNINIT2;
2912                 err = ext4_split_extent_at(handle, inode, path,
2913                                 map->m_lblk, split_flag1, flags);
2914                 if (err)
2915                         goto out;
2916         }
2917
2918         ext4_ext_show_leaf(inode, path);
2919 out:
2920         return err ? err : map->m_len;
2921 }
2922
2923 #define EXT4_EXT_ZERO_LEN 7
2924 /*
2925  * This function is called by ext4_ext_map_blocks() if someone tries to write
2926  * to an uninitialized extent. It may result in splitting the uninitialized
2927  * extent into multiple extents (up to three - one initialized and two
2928  * uninitialized).
2929  * There are three possibilities:
2930  *   a> There is no split required: Entire extent should be initialized
2931  *   b> Splits in two extents: Write is happening at either end of the extent
2932  *   c> Splits in three extents: Somone is writing in middle of the extent
2933  */
2934 static int ext4_ext_convert_to_initialized(handle_t *handle,
2935                                            struct inode *inode,
2936                                            struct ext4_map_blocks *map,
2937                                            struct ext4_ext_path *path)
2938 {
2939         struct ext4_map_blocks split_map;
2940         struct ext4_extent zero_ex;
2941         struct ext4_extent *ex;
2942         ext4_lblk_t ee_block, eof_block;
2943         unsigned int allocated, ee_len, depth;
2944         int err = 0;
2945         int split_flag = 0;
2946
2947         ext_debug("ext4_ext_convert_to_initialized: inode %lu, logical"
2948                 "block %llu, max_blocks %u\n", inode->i_ino,
2949                 (unsigned long long)map->m_lblk, map->m_len);
2950
2951         eof_block = (inode->i_size + inode->i_sb->s_blocksize - 1) >>
2952                 inode->i_sb->s_blocksize_bits;
2953         if (eof_block < map->m_lblk + map->m_len)
2954                 eof_block = map->m_lblk + map->m_len;
2955
2956         depth = ext_depth(inode);
2957         ex = path[depth].p_ext;
2958         ee_block = le32_to_cpu(ex->ee_block);
2959         ee_len = ext4_ext_get_actual_len(ex);
2960         allocated = ee_len - (map->m_lblk - ee_block);
2961
2962         WARN_ON(map->m_lblk < ee_block);
2963         /*
2964          * It is safe to convert extent to initialized via explicit
2965          * zeroout only if extent is fully insde i_size or new_size.
2966          */
2967         split_flag |= ee_block + ee_len <= eof_block ? EXT4_EXT_MAY_ZEROOUT : 0;
2968
2969         /* If extent has less than 2*EXT4_EXT_ZERO_LEN zerout directly */
2970         if (ee_len <= 2*EXT4_EXT_ZERO_LEN &&
2971             (EXT4_EXT_MAY_ZEROOUT & split_flag)) {
2972                 err = ext4_ext_zeroout(inode, ex);
2973                 if (err)
2974                         goto out;
2975
2976                 err = ext4_ext_get_access(handle, inode, path + depth);
2977                 if (err)
2978                         goto out;
2979                 ext4_ext_mark_initialized(ex);
2980                 ext4_ext_try_to_merge(inode, path, ex);
2981                 err = ext4_ext_dirty(handle, inode, path + depth);
2982                 goto out;
2983         }
2984
2985         /*
2986          * four cases:
2987          * 1. split the extent into three extents.
2988          * 2. split the extent into two extents, zeroout the first half.
2989          * 3. split the extent into two extents, zeroout the second half.
2990          * 4. split the extent into two extents with out zeroout.
2991          */
2992         split_map.m_lblk = map->m_lblk;
2993         split_map.m_len = map->m_len;
2994
2995         if (allocated > map->m_len) {
2996                 if (allocated <= EXT4_EXT_ZERO_LEN &&
2997                     (EXT4_EXT_MAY_ZEROOUT & split_flag)) {
2998                         /* case 3 */
2999                         zero_ex.ee_block =
3000                                          cpu_to_le32(map->m_lblk);
3001                         zero_ex.ee_len = cpu_to_le16(allocated);
3002                         ext4_ext_store_pblock(&zero_ex,
3003                                 ext4_ext_pblock(ex) + map->m_lblk - ee_block);
3004                         err = ext4_ext_zeroout(inode, &zero_ex);
3005                         if (err)
3006                                 goto out;
3007                         split_map.m_lblk = map->m_lblk;
3008                         split_map.m_len = allocated;
3009                 } else if ((map->m_lblk - ee_block + map->m_len <
3010                            EXT4_EXT_ZERO_LEN) &&
3011                            (EXT4_EXT_MAY_ZEROOUT & split_flag)) {
3012                         /* case 2 */
3013                         if (map->m_lblk != ee_block) {
3014                                 zero_ex.ee_block = ex->ee_block;
3015                                 zero_ex.ee_len = cpu_to_le16(map->m_lblk -
3016                                                         ee_block);
3017                                 ext4_ext_store_pblock(&zero_ex,
3018                                                       ext4_ext_pblock(ex));
3019                                 err = ext4_ext_zeroout(inode, &zero_ex);
3020                                 if (err)
3021                                         goto out;
3022                         }
3023
3024                         split_map.m_lblk = ee_block;
3025                         split_map.m_len = map->m_lblk - ee_block + map->m_len;
3026                         allocated = map->m_len;
3027                 }
3028         }
3029
3030         allocated = ext4_split_extent(handle, inode, path,
3031                                        &split_map, split_flag, 0);
3032         if (allocated < 0)
3033                 err = allocated;
3034
3035 out:
3036         return err ? err : allocated;
3037 }
3038
3039 /*
3040  * This function is called by ext4_ext_map_blocks() from
3041  * ext4_get_blocks_dio_write() when DIO to write
3042  * to an uninitialized extent.
3043  *
3044  * Writing to an uninitialized extent may result in splitting the uninitialized
3045  * extent into multiple /initialized uninitialized extents (up to three)
3046  * There are three possibilities:
3047  *   a> There is no split required: Entire extent should be uninitialized
3048  *   b> Splits in two extents: Write is happening at either end of the extent
3049  *   c> Splits in three extents: Somone is writing in middle of the extent
3050  *
3051  * One of more index blocks maybe needed if the extent tree grow after
3052  * the uninitialized extent split. To prevent ENOSPC occur at the IO
3053  * complete, we need to split the uninitialized extent before DIO submit
3054  * the IO. The uninitialized extent called at this time will be split
3055  * into three uninitialized extent(at most). After IO complete, the part
3056  * being filled will be convert to initialized by the end_io callback function
3057  * via ext4_convert_unwritten_extents().
3058  *
3059  * Returns the size of uninitialized extent to be written on success.
3060  */
3061 static int ext4_split_unwritten_extents(handle_t *handle,
3062                                         struct inode *inode,
3063                                         struct ext4_map_blocks *map,
3064                                         struct ext4_ext_path *path,
3065                                         int flags)
3066 {
3067         ext4_lblk_t eof_block;
3068         ext4_lblk_t ee_block;
3069         struct ext4_extent *ex;
3070         unsigned int ee_len;
3071         int split_flag = 0, depth;
3072
3073         ext_debug("ext4_split_unwritten_extents: inode %lu, logical"
3074                 "block %llu, max_blocks %u\n", inode->i_ino,
3075                 (unsigned long long)map->m_lblk, map->m_len);
3076
3077         eof_block = (inode->i_size + inode->i_sb->s_blocksize - 1) >>
3078                 inode->i_sb->s_blocksize_bits;
3079         if (eof_block < map->m_lblk + map->m_len)
3080                 eof_block = map->m_lblk + map->m_len;
3081         /*
3082          * It is safe to convert extent to initialized via explicit
3083          * zeroout only if extent is fully insde i_size or new_size.
3084          */
3085         depth = ext_depth(inode);
3086         ex = path[depth].p_ext;
3087         ee_block = le32_to_cpu(ex->ee_block);
3088         ee_len = ext4_ext_get_actual_len(ex);
3089
3090         split_flag |= ee_block + ee_len <= eof_block ? EXT4_EXT_MAY_ZEROOUT : 0;
3091         split_flag |= EXT4_EXT_MARK_UNINIT2;