ext4: fix memory leakage in mext_check_coverage
[linux-3.10.git] / fs / ext4 / move_extent.c
1 /*
2  * Copyright (c) 2008,2009 NEC Software Tohoku, Ltd.
3  * Written by Takashi Sato <t-sato@yk.jp.nec.com>
4  *            Akira Fujita <a-fujita@rs.jp.nec.com>
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of version 2.1 of the GNU Lesser General Public License
8  * as published by the Free Software Foundation.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13  * GNU General Public License for more details.
14  */
15
16 #include <linux/fs.h>
17 #include <linux/quotaops.h>
18 #include <linux/slab.h>
19 #include "ext4_jbd2.h"
20 #include "ext4.h"
21 #include "ext4_extents.h"
22
23 /**
24  * get_ext_path - Find an extent path for designated logical block number.
25  *
26  * @inode:      an inode which is searched
27  * @lblock:     logical block number to find an extent path
28  * @path:       pointer to an extent path pointer (for output)
29  *
30  * ext4_ext_find_extent wrapper. Return 0 on success, or a negative error value
31  * on failure.
32  */
33 static inline int
34 get_ext_path(struct inode *inode, ext4_lblk_t lblock,
35                 struct ext4_ext_path **orig_path)
36 {
37         int ret = 0;
38         struct ext4_ext_path *path;
39
40         path = ext4_ext_find_extent(inode, lblock, *orig_path);
41         if (IS_ERR(path))
42                 ret = PTR_ERR(path);
43         else if (path[ext_depth(inode)].p_ext == NULL)
44                 ret = -ENODATA;
45         else
46                 *orig_path = path;
47
48         return ret;
49 }
50
51 /**
52  * copy_extent_status - Copy the extent's initialization status
53  *
54  * @src:        an extent for getting initialize status
55  * @dest:       an extent to be set the status
56  */
57 static void
58 copy_extent_status(struct ext4_extent *src, struct ext4_extent *dest)
59 {
60         if (ext4_ext_is_uninitialized(src))
61                 ext4_ext_mark_uninitialized(dest);
62         else
63                 dest->ee_len = cpu_to_le16(ext4_ext_get_actual_len(dest));
64 }
65
66 /**
67  * mext_next_extent - Search for the next extent and set it to "extent"
68  *
69  * @inode:      inode which is searched
70  * @path:       this will obtain data for the next extent
71  * @extent:     pointer to the next extent we have just gotten
72  *
73  * Search the next extent in the array of ext4_ext_path structure (@path)
74  * and set it to ext4_extent structure (@extent). In addition, the member of
75  * @path (->p_ext) also points the next extent. Return 0 on success, 1 if
76  * ext4_ext_path structure refers to the last extent, or a negative error
77  * value on failure.
78  */
79 static int
80 mext_next_extent(struct inode *inode, struct ext4_ext_path *path,
81                       struct ext4_extent **extent)
82 {
83         struct ext4_extent_header *eh;
84         int ppos, leaf_ppos = path->p_depth;
85
86         ppos = leaf_ppos;
87         if (EXT_LAST_EXTENT(path[ppos].p_hdr) > path[ppos].p_ext) {
88                 /* leaf block */
89                 *extent = ++path[ppos].p_ext;
90                 path[ppos].p_block = ext4_ext_pblock(path[ppos].p_ext);
91                 return 0;
92         }
93
94         while (--ppos >= 0) {
95                 if (EXT_LAST_INDEX(path[ppos].p_hdr) >
96                     path[ppos].p_idx) {
97                         int cur_ppos = ppos;
98
99                         /* index block */
100                         path[ppos].p_idx++;
101                         path[ppos].p_block = ext4_idx_pblock(path[ppos].p_idx);
102                         if (path[ppos+1].p_bh)
103                                 brelse(path[ppos+1].p_bh);
104                         path[ppos+1].p_bh =
105                                 sb_bread(inode->i_sb, path[ppos].p_block);
106                         if (!path[ppos+1].p_bh)
107                                 return -EIO;
108                         path[ppos+1].p_hdr =
109                                 ext_block_hdr(path[ppos+1].p_bh);
110
111                         /* Halfway index block */
112                         while (++cur_ppos < leaf_ppos) {
113                                 path[cur_ppos].p_idx =
114                                         EXT_FIRST_INDEX(path[cur_ppos].p_hdr);
115                                 path[cur_ppos].p_block =
116                                         ext4_idx_pblock(path[cur_ppos].p_idx);
117                                 if (path[cur_ppos+1].p_bh)
118                                         brelse(path[cur_ppos+1].p_bh);
119                                 path[cur_ppos+1].p_bh = sb_bread(inode->i_sb,
120                                         path[cur_ppos].p_block);
121                                 if (!path[cur_ppos+1].p_bh)
122                                         return -EIO;
123                                 path[cur_ppos+1].p_hdr =
124                                         ext_block_hdr(path[cur_ppos+1].p_bh);
125                         }
126
127                         path[leaf_ppos].p_ext = *extent = NULL;
128
129                         eh = path[leaf_ppos].p_hdr;
130                         if (le16_to_cpu(eh->eh_entries) == 0)
131                                 /* empty leaf is found */
132                                 return -ENODATA;
133
134                         /* leaf block */
135                         path[leaf_ppos].p_ext = *extent =
136                                 EXT_FIRST_EXTENT(path[leaf_ppos].p_hdr);
137                         path[leaf_ppos].p_block =
138                                         ext4_ext_pblock(path[leaf_ppos].p_ext);
139                         return 0;
140                 }
141         }
142         /* We found the last extent */
143         return 1;
144 }
145
146 /**
147  * double_down_write_data_sem - Acquire two inodes' write lock of i_data_sem
148  *
149  * Acquire write lock of i_data_sem of the two inodes
150  */
151 static void
152 double_down_write_data_sem(struct inode *first, struct inode *second)
153 {
154         if (first < second) {
155                 down_write(&EXT4_I(first)->i_data_sem);
156                 down_write_nested(&EXT4_I(second)->i_data_sem, SINGLE_DEPTH_NESTING);
157         } else {
158                 down_write(&EXT4_I(second)->i_data_sem);
159                 down_write_nested(&EXT4_I(first)->i_data_sem, SINGLE_DEPTH_NESTING);
160
161         }
162 }
163
164 /**
165  * double_up_write_data_sem - Release two inodes' write lock of i_data_sem
166  *
167  * @orig_inode:         original inode structure to be released its lock first
168  * @donor_inode:        donor inode structure to be released its lock second
169  * Release write lock of i_data_sem of two inodes (orig and donor).
170  */
171 static void
172 double_up_write_data_sem(struct inode *orig_inode, struct inode *donor_inode)
173 {
174         up_write(&EXT4_I(orig_inode)->i_data_sem);
175         up_write(&EXT4_I(donor_inode)->i_data_sem);
176 }
177
178 /**
179  * mext_insert_across_blocks - Insert extents across leaf block
180  *
181  * @handle:             journal handle
182  * @orig_inode:         original inode
183  * @o_start:            first original extent to be changed
184  * @o_end:              last original extent to be changed
185  * @start_ext:          first new extent to be inserted
186  * @new_ext:            middle of new extent to be inserted
187  * @end_ext:            last new extent to be inserted
188  *
189  * Allocate a new leaf block and insert extents into it. Return 0 on success,
190  * or a negative error value on failure.
191  */
192 static int
193 mext_insert_across_blocks(handle_t *handle, struct inode *orig_inode,
194                 struct ext4_extent *o_start, struct ext4_extent *o_end,
195                 struct ext4_extent *start_ext, struct ext4_extent *new_ext,
196                 struct ext4_extent *end_ext)
197 {
198         struct ext4_ext_path *orig_path = NULL;
199         ext4_lblk_t eblock = 0;
200         int new_flag = 0;
201         int end_flag = 0;
202         int err = 0;
203
204         if (start_ext->ee_len && new_ext->ee_len && end_ext->ee_len) {
205                 if (o_start == o_end) {
206
207                         /*       start_ext   new_ext    end_ext
208                          * donor |---------|-----------|--------|
209                          * orig  |------------------------------|
210                          */
211                         end_flag = 1;
212                 } else {
213
214                         /*       start_ext   new_ext   end_ext
215                          * donor |---------|----------|---------|
216                          * orig  |---------------|--------------|
217                          */
218                         o_end->ee_block = end_ext->ee_block;
219                         o_end->ee_len = end_ext->ee_len;
220                         ext4_ext_store_pblock(o_end, ext4_ext_pblock(end_ext));
221                 }
222
223                 o_start->ee_len = start_ext->ee_len;
224                 eblock = le32_to_cpu(start_ext->ee_block);
225                 new_flag = 1;
226
227         } else if (start_ext->ee_len && new_ext->ee_len &&
228                    !end_ext->ee_len && o_start == o_end) {
229
230                 /*       start_ext      new_ext
231                  * donor |--------------|---------------|
232                  * orig  |------------------------------|
233                  */
234                 o_start->ee_len = start_ext->ee_len;
235                 eblock = le32_to_cpu(start_ext->ee_block);
236                 new_flag = 1;
237
238         } else if (!start_ext->ee_len && new_ext->ee_len &&
239                    end_ext->ee_len && o_start == o_end) {
240
241                 /*        new_ext       end_ext
242                  * donor |--------------|---------------|
243                  * orig  |------------------------------|
244                  */
245                 o_end->ee_block = end_ext->ee_block;
246                 o_end->ee_len = end_ext->ee_len;
247                 ext4_ext_store_pblock(o_end, ext4_ext_pblock(end_ext));
248
249                 /*
250                  * Set 0 to the extent block if new_ext was
251                  * the first block.
252                  */
253                 if (new_ext->ee_block)
254                         eblock = le32_to_cpu(new_ext->ee_block);
255
256                 new_flag = 1;
257         } else {
258                 ext4_debug("ext4 move extent: Unexpected insert case\n");
259                 return -EIO;
260         }
261
262         if (new_flag) {
263                 err = get_ext_path(orig_inode, eblock, &orig_path);
264                 if (err)
265                         goto out;
266
267                 if (ext4_ext_insert_extent(handle, orig_inode,
268                                         orig_path, new_ext, 0))
269                         goto out;
270         }
271
272         if (end_flag) {
273                 err = get_ext_path(orig_inode,
274                                 le32_to_cpu(end_ext->ee_block) - 1, &orig_path);
275                 if (err)
276                         goto out;
277
278                 if (ext4_ext_insert_extent(handle, orig_inode,
279                                            orig_path, end_ext, 0))
280                         goto out;
281         }
282 out:
283         if (orig_path) {
284                 ext4_ext_drop_refs(orig_path);
285                 kfree(orig_path);
286         }
287
288         return err;
289
290 }
291
292 /**
293  * mext_insert_inside_block - Insert new extent to the extent block
294  *
295  * @o_start:            first original extent to be moved
296  * @o_end:              last original extent to be moved
297  * @start_ext:          first new extent to be inserted
298  * @new_ext:            middle of new extent to be inserted
299  * @end_ext:            last new extent to be inserted
300  * @eh:                 extent header of target leaf block
301  * @range_to_move:      used to decide how to insert extent
302  *
303  * Insert extents into the leaf block. The extent (@o_start) is overwritten
304  * by inserted extents.
305  */
306 static void
307 mext_insert_inside_block(struct ext4_extent *o_start,
308                               struct ext4_extent *o_end,
309                               struct ext4_extent *start_ext,
310                               struct ext4_extent *new_ext,
311                               struct ext4_extent *end_ext,
312                               struct ext4_extent_header *eh,
313                               int range_to_move)
314 {
315         int i = 0;
316         unsigned long len;
317
318         /* Move the existing extents */
319         if (range_to_move && o_end < EXT_LAST_EXTENT(eh)) {
320                 len = (unsigned long)(EXT_LAST_EXTENT(eh) + 1) -
321                         (unsigned long)(o_end + 1);
322                 memmove(o_end + 1 + range_to_move, o_end + 1, len);
323         }
324
325         /* Insert start entry */
326         if (start_ext->ee_len)
327                 o_start[i++].ee_len = start_ext->ee_len;
328
329         /* Insert new entry */
330         if (new_ext->ee_len) {
331                 o_start[i] = *new_ext;
332                 ext4_ext_store_pblock(&o_start[i++], ext4_ext_pblock(new_ext));
333         }
334
335         /* Insert end entry */
336         if (end_ext->ee_len)
337                 o_start[i] = *end_ext;
338
339         /* Increment the total entries counter on the extent block */
340         le16_add_cpu(&eh->eh_entries, range_to_move);
341 }
342
343 /**
344  * mext_insert_extents - Insert new extent
345  *
346  * @handle:     journal handle
347  * @orig_inode: original inode
348  * @orig_path:  path indicates first extent to be changed
349  * @o_start:    first original extent to be changed
350  * @o_end:      last original extent to be changed
351  * @start_ext:  first new extent to be inserted
352  * @new_ext:    middle of new extent to be inserted
353  * @end_ext:    last new extent to be inserted
354  *
355  * Call the function to insert extents. If we cannot add more extents into
356  * the leaf block, we call mext_insert_across_blocks() to create a
357  * new leaf block. Otherwise call mext_insert_inside_block(). Return 0
358  * on success, or a negative error value on failure.
359  */
360 static int
361 mext_insert_extents(handle_t *handle, struct inode *orig_inode,
362                          struct ext4_ext_path *orig_path,
363                          struct ext4_extent *o_start,
364                          struct ext4_extent *o_end,
365                          struct ext4_extent *start_ext,
366                          struct ext4_extent *new_ext,
367                          struct ext4_extent *end_ext)
368 {
369         struct  ext4_extent_header *eh;
370         unsigned long need_slots, slots_range;
371         int     range_to_move, depth, ret;
372
373         /*
374          * The extents need to be inserted
375          * start_extent + new_extent + end_extent.
376          */
377         need_slots = (start_ext->ee_len ? 1 : 0) + (end_ext->ee_len ? 1 : 0) +
378                 (new_ext->ee_len ? 1 : 0);
379
380         /* The number of slots between start and end */
381         slots_range = ((unsigned long)(o_end + 1) - (unsigned long)o_start + 1)
382                 / sizeof(struct ext4_extent);
383
384         /* Range to move the end of extent */
385         range_to_move = need_slots - slots_range;
386         depth = orig_path->p_depth;
387         orig_path += depth;
388         eh = orig_path->p_hdr;
389
390         if (depth) {
391                 /* Register to journal */
392                 ret = ext4_journal_get_write_access(handle, orig_path->p_bh);
393                 if (ret)
394                         return ret;
395         }
396
397         /* Expansion */
398         if (range_to_move > 0 &&
399                 (range_to_move > le16_to_cpu(eh->eh_max)
400                         - le16_to_cpu(eh->eh_entries))) {
401
402                 ret = mext_insert_across_blocks(handle, orig_inode, o_start,
403                                         o_end, start_ext, new_ext, end_ext);
404                 if (ret < 0)
405                         return ret;
406         } else
407                 mext_insert_inside_block(o_start, o_end, start_ext, new_ext,
408                                                 end_ext, eh, range_to_move);
409
410         if (depth) {
411                 ret = ext4_handle_dirty_metadata(handle, orig_inode,
412                                                  orig_path->p_bh);
413                 if (ret)
414                         return ret;
415         } else {
416                 ret = ext4_mark_inode_dirty(handle, orig_inode);
417                 if (ret < 0)
418                         return ret;
419         }
420
421         return 0;
422 }
423
424 /**
425  * mext_leaf_block - Move one leaf extent block into the inode.
426  *
427  * @handle:             journal handle
428  * @orig_inode:         original inode
429  * @orig_path:          path indicates first extent to be changed
430  * @dext:               donor extent
431  * @from:               start offset on the target file
432  *
433  * In order to insert extents into the leaf block, we must divide the extent
434  * in the leaf block into three extents. The one is located to be inserted
435  * extents, and the others are located around it.
436  *
437  * Therefore, this function creates structures to save extents of the leaf
438  * block, and inserts extents by calling mext_insert_extents() with
439  * created extents. Return 0 on success, or a negative error value on failure.
440  */
441 static int
442 mext_leaf_block(handle_t *handle, struct inode *orig_inode,
443                      struct ext4_ext_path *orig_path, struct ext4_extent *dext,
444                      ext4_lblk_t *from)
445 {
446         struct ext4_extent *oext, *o_start, *o_end, *prev_ext;
447         struct ext4_extent new_ext, start_ext, end_ext;
448         ext4_lblk_t new_ext_end;
449         int oext_alen, new_ext_alen, end_ext_alen;
450         int depth = ext_depth(orig_inode);
451         int ret;
452
453         start_ext.ee_block = end_ext.ee_block = 0;
454         o_start = o_end = oext = orig_path[depth].p_ext;
455         oext_alen = ext4_ext_get_actual_len(oext);
456         start_ext.ee_len = end_ext.ee_len = 0;
457
458         new_ext.ee_block = cpu_to_le32(*from);
459         ext4_ext_store_pblock(&new_ext, ext4_ext_pblock(dext));
460         new_ext.ee_len = dext->ee_len;
461         new_ext_alen = ext4_ext_get_actual_len(&new_ext);
462         new_ext_end = le32_to_cpu(new_ext.ee_block) + new_ext_alen - 1;
463
464         /*
465          * Case: original extent is first
466          * oext      |--------|
467          * new_ext      |--|
468          * start_ext |--|
469          */
470         if (le32_to_cpu(oext->ee_block) < le32_to_cpu(new_ext.ee_block) &&
471                 le32_to_cpu(new_ext.ee_block) <
472                 le32_to_cpu(oext->ee_block) + oext_alen) {
473                 start_ext.ee_len = cpu_to_le16(le32_to_cpu(new_ext.ee_block) -
474                                                le32_to_cpu(oext->ee_block));
475                 start_ext.ee_block = oext->ee_block;
476                 copy_extent_status(oext, &start_ext);
477         } else if (oext > EXT_FIRST_EXTENT(orig_path[depth].p_hdr)) {
478                 prev_ext = oext - 1;
479                 /*
480                  * We can merge new_ext into previous extent,
481                  * if these are contiguous and same extent type.
482                  */
483                 if (ext4_can_extents_be_merged(orig_inode, prev_ext,
484                                                &new_ext)) {
485                         o_start = prev_ext;
486                         start_ext.ee_len = cpu_to_le16(
487                                 ext4_ext_get_actual_len(prev_ext) +
488                                 new_ext_alen);
489                         start_ext.ee_block = oext->ee_block;
490                         copy_extent_status(prev_ext, &start_ext);
491                         new_ext.ee_len = 0;
492                 }
493         }
494
495         /*
496          * Case: new_ext_end must be less than oext
497          * oext      |-----------|
498          * new_ext       |-------|
499          */
500         if (le32_to_cpu(oext->ee_block) + oext_alen - 1 < new_ext_end) {
501                 EXT4_ERROR_INODE(orig_inode,
502                         "new_ext_end(%u) should be less than or equal to "
503                         "oext->ee_block(%u) + oext_alen(%d) - 1",
504                         new_ext_end, le32_to_cpu(oext->ee_block),
505                         oext_alen);
506                 ret = -EIO;
507                 goto out;
508         }
509
510         /*
511          * Case: new_ext is smaller than original extent
512          * oext    |---------------|
513          * new_ext |-----------|
514          * end_ext             |---|
515          */
516         if (le32_to_cpu(oext->ee_block) <= new_ext_end &&
517                 new_ext_end < le32_to_cpu(oext->ee_block) + oext_alen - 1) {
518                 end_ext.ee_len =
519                         cpu_to_le16(le32_to_cpu(oext->ee_block) +
520                         oext_alen - 1 - new_ext_end);
521                 copy_extent_status(oext, &end_ext);
522                 end_ext_alen = ext4_ext_get_actual_len(&end_ext);
523                 ext4_ext_store_pblock(&end_ext,
524                         (ext4_ext_pblock(o_end) + oext_alen - end_ext_alen));
525                 end_ext.ee_block =
526                         cpu_to_le32(le32_to_cpu(o_end->ee_block) +
527                         oext_alen - end_ext_alen);
528         }
529
530         ret = mext_insert_extents(handle, orig_inode, orig_path, o_start,
531                                 o_end, &start_ext, &new_ext, &end_ext);
532 out:
533         return ret;
534 }
535
536 /**
537  * mext_calc_swap_extents - Calculate extents for extent swapping.
538  *
539  * @tmp_dext:           the extent that will belong to the original inode
540  * @tmp_oext:           the extent that will belong to the donor inode
541  * @orig_off:           block offset of original inode
542  * @donor_off:          block offset of donor inode
543  * @max_count:          the maximum length of extents
544  *
545  * Return 0 on success, or a negative error value on failure.
546  */
547 static int
548 mext_calc_swap_extents(struct ext4_extent *tmp_dext,
549                               struct ext4_extent *tmp_oext,
550                               ext4_lblk_t orig_off, ext4_lblk_t donor_off,
551                               ext4_lblk_t max_count)
552 {
553         ext4_lblk_t diff, orig_diff;
554         struct ext4_extent dext_old, oext_old;
555
556         BUG_ON(orig_off != donor_off);
557
558         /* original and donor extents have to cover the same block offset */
559         if (orig_off < le32_to_cpu(tmp_oext->ee_block) ||
560             le32_to_cpu(tmp_oext->ee_block) +
561                         ext4_ext_get_actual_len(tmp_oext) - 1 < orig_off)
562                 return -ENODATA;
563
564         if (orig_off < le32_to_cpu(tmp_dext->ee_block) ||
565             le32_to_cpu(tmp_dext->ee_block) +
566                         ext4_ext_get_actual_len(tmp_dext) - 1 < orig_off)
567                 return -ENODATA;
568
569         dext_old = *tmp_dext;
570         oext_old = *tmp_oext;
571
572         /* When tmp_dext is too large, pick up the target range. */
573         diff = donor_off - le32_to_cpu(tmp_dext->ee_block);
574
575         ext4_ext_store_pblock(tmp_dext, ext4_ext_pblock(tmp_dext) + diff);
576         le32_add_cpu(&tmp_dext->ee_block, diff);
577         le16_add_cpu(&tmp_dext->ee_len, -diff);
578
579         if (max_count < ext4_ext_get_actual_len(tmp_dext))
580                 tmp_dext->ee_len = cpu_to_le16(max_count);
581
582         orig_diff = orig_off - le32_to_cpu(tmp_oext->ee_block);
583         ext4_ext_store_pblock(tmp_oext, ext4_ext_pblock(tmp_oext) + orig_diff);
584
585         /* Adjust extent length if donor extent is larger than orig */
586         if (ext4_ext_get_actual_len(tmp_dext) >
587             ext4_ext_get_actual_len(tmp_oext) - orig_diff)
588                 tmp_dext->ee_len = cpu_to_le16(le16_to_cpu(tmp_oext->ee_len) -
589                                                 orig_diff);
590
591         tmp_oext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(tmp_dext));
592
593         copy_extent_status(&oext_old, tmp_dext);
594         copy_extent_status(&dext_old, tmp_oext);
595
596         return 0;
597 }
598
599 /**
600  * mext_check_coverage - Check that all extents in range has the same type
601  *
602  * @inode:              inode in question
603  * @from:               block offset of inode
604  * @count:              block count to be checked
605  * @uninit:             extents expected to be uninitialized
606  * @err:                pointer to save error value
607  *
608  * Return 1 if all extents in range has expected type, and zero otherwise.
609  */
610 static int
611 mext_check_coverage(struct inode *inode, ext4_lblk_t from, ext4_lblk_t count,
612                           int uninit, int *err)
613 {
614         struct ext4_ext_path *path = NULL;
615         struct ext4_extent *ext;
616         int ret = 0;
617         ext4_lblk_t last = from + count;
618         while (from < last) {
619                 *err = get_ext_path(inode, from, &path);
620                 if (*err)
621                         goto out;
622                 ext = path[ext_depth(inode)].p_ext;
623                 if (uninit != ext4_ext_is_uninitialized(ext))
624                         goto out;
625                 from += ext4_ext_get_actual_len(ext);
626                 ext4_ext_drop_refs(path);
627         }
628         ret = 1;
629 out:
630         if (path) {
631                 ext4_ext_drop_refs(path);
632                 kfree(path);
633         }
634         return ret;
635 }
636
637 /**
638  * mext_replace_branches - Replace original extents with new extents
639  *
640  * @handle:             journal handle
641  * @orig_inode:         original inode
642  * @donor_inode:        donor inode
643  * @from:               block offset of orig_inode
644  * @count:              block count to be replaced
645  * @err:                pointer to save return value
646  *
647  * Replace original inode extents and donor inode extents page by page.
648  * We implement this replacement in the following three steps:
649  * 1. Save the block information of original and donor inodes into
650  *    dummy extents.
651  * 2. Change the block information of original inode to point at the
652  *    donor inode blocks.
653  * 3. Change the block information of donor inode to point at the saved
654  *    original inode blocks in the dummy extents.
655  *
656  * Return replaced block count.
657  */
658 static int
659 mext_replace_branches(handle_t *handle, struct inode *orig_inode,
660                            struct inode *donor_inode, ext4_lblk_t from,
661                            ext4_lblk_t count, int *err)
662 {
663         struct ext4_ext_path *orig_path = NULL;
664         struct ext4_ext_path *donor_path = NULL;
665         struct ext4_extent *oext, *dext;
666         struct ext4_extent tmp_dext, tmp_oext;
667         ext4_lblk_t orig_off = from, donor_off = from;
668         int depth;
669         int replaced_count = 0;
670         int dext_alen;
671
672         *err = ext4_es_remove_extent(orig_inode, from, count);
673         if (*err)
674                 goto out;
675
676         *err = ext4_es_remove_extent(donor_inode, from, count);
677         if (*err)
678                 goto out;
679
680         /* Get the original extent for the block "orig_off" */
681         *err = get_ext_path(orig_inode, orig_off, &orig_path);
682         if (*err)
683                 goto out;
684
685         /* Get the donor extent for the head */
686         *err = get_ext_path(donor_inode, donor_off, &donor_path);
687         if (*err)
688                 goto out;
689         depth = ext_depth(orig_inode);
690         oext = orig_path[depth].p_ext;
691         tmp_oext = *oext;
692
693         depth = ext_depth(donor_inode);
694         dext = donor_path[depth].p_ext;
695         if (unlikely(!dext))
696                 goto missing_donor_extent;
697         tmp_dext = *dext;
698
699         *err = mext_calc_swap_extents(&tmp_dext, &tmp_oext, orig_off,
700                                       donor_off, count);
701         if (*err)
702                 goto out;
703
704         /* Loop for the donor extents */
705         while (1) {
706                 /* The extent for donor must be found. */
707                 if (unlikely(!dext)) {
708                 missing_donor_extent:
709                         EXT4_ERROR_INODE(donor_inode,
710                                    "The extent for donor must be found");
711                         *err = -EIO;
712                         goto out;
713                 } else if (donor_off != le32_to_cpu(tmp_dext.ee_block)) {
714                         EXT4_ERROR_INODE(donor_inode,
715                                 "Donor offset(%u) and the first block of donor "
716                                 "extent(%u) should be equal",
717                                 donor_off,
718                                 le32_to_cpu(tmp_dext.ee_block));
719                         *err = -EIO;
720                         goto out;
721                 }
722
723                 /* Set donor extent to orig extent */
724                 *err = mext_leaf_block(handle, orig_inode,
725                                            orig_path, &tmp_dext, &orig_off);
726                 if (*err)
727                         goto out;
728
729                 /* Set orig extent to donor extent */
730                 *err = mext_leaf_block(handle, donor_inode,
731                                            donor_path, &tmp_oext, &donor_off);
732                 if (*err)
733                         goto out;
734
735                 dext_alen = ext4_ext_get_actual_len(&tmp_dext);
736                 replaced_count += dext_alen;
737                 donor_off += dext_alen;
738                 orig_off += dext_alen;
739
740                 /* Already moved the expected blocks */
741                 if (replaced_count >= count)
742                         break;
743
744                 if (orig_path)
745                         ext4_ext_drop_refs(orig_path);
746                 *err = get_ext_path(orig_inode, orig_off, &orig_path);
747                 if (*err)
748                         goto out;
749                 depth = ext_depth(orig_inode);
750                 oext = orig_path[depth].p_ext;
751                 tmp_oext = *oext;
752
753                 if (donor_path)
754                         ext4_ext_drop_refs(donor_path);
755                 *err = get_ext_path(donor_inode, donor_off, &donor_path);
756                 if (*err)
757                         goto out;
758                 depth = ext_depth(donor_inode);
759                 dext = donor_path[depth].p_ext;
760                 tmp_dext = *dext;
761
762                 *err = mext_calc_swap_extents(&tmp_dext, &tmp_oext, orig_off,
763                                            donor_off, count - replaced_count);
764                 if (*err)
765                         goto out;
766         }
767
768 out:
769         if (orig_path) {
770                 ext4_ext_drop_refs(orig_path);
771                 kfree(orig_path);
772         }
773         if (donor_path) {
774                 ext4_ext_drop_refs(donor_path);
775                 kfree(donor_path);
776         }
777
778         return replaced_count;
779 }
780
781 /**
782  * mext_page_double_lock - Grab and lock pages on both @inode1 and @inode2
783  *
784  * @inode1:     the inode structure
785  * @inode2:     the inode structure
786  * @index:      page index
787  * @page:       result page vector
788  *
789  * Grab two locked pages for inode's by inode order
790  */
791 static int
792 mext_page_double_lock(struct inode *inode1, struct inode *inode2,
793                       pgoff_t index, struct page *page[2])
794 {
795         struct address_space *mapping[2];
796         unsigned fl = AOP_FLAG_NOFS;
797
798         BUG_ON(!inode1 || !inode2);
799         if (inode1 < inode2) {
800                 mapping[0] = inode1->i_mapping;
801                 mapping[1] = inode2->i_mapping;
802         } else {
803                 mapping[0] = inode2->i_mapping;
804                 mapping[1] = inode1->i_mapping;
805         }
806
807         page[0] = grab_cache_page_write_begin(mapping[0], index, fl);
808         if (!page[0])
809                 return -ENOMEM;
810
811         page[1] = grab_cache_page_write_begin(mapping[1], index, fl);
812         if (!page[1]) {
813                 unlock_page(page[0]);
814                 page_cache_release(page[0]);
815                 return -ENOMEM;
816         }
817
818         if (inode1 > inode2) {
819                 struct page *tmp;
820                 tmp = page[0];
821                 page[0] = page[1];
822                 page[1] = tmp;
823         }
824         return 0;
825 }
826
827 /* Force page buffers uptodate w/o dropping page's lock */
828 static int
829 mext_page_mkuptodate(struct page *page, unsigned from, unsigned to)
830 {
831         struct inode *inode = page->mapping->host;
832         sector_t block;
833         struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
834         unsigned int blocksize, block_start, block_end;
835         int i, err,  nr = 0, partial = 0;
836         BUG_ON(!PageLocked(page));
837         BUG_ON(PageWriteback(page));
838
839         if (PageUptodate(page))
840                 return 0;
841
842         blocksize = 1 << inode->i_blkbits;
843         if (!page_has_buffers(page))
844                 create_empty_buffers(page, blocksize, 0);
845
846         head = page_buffers(page);
847         block = (sector_t)page->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
848         for (bh = head, block_start = 0; bh != head || !block_start;
849              block++, block_start = block_end, bh = bh->b_this_page) {
850                 block_end = block_start + blocksize;
851                 if (block_end <= from || block_start >= to) {
852                         if (!buffer_uptodate(bh))
853                                 partial = 1;
854                         continue;
855                 }
856                 if (buffer_uptodate(bh))
857                         continue;
858                 if (!buffer_mapped(bh)) {
859                         int err = 0;
860                         err = ext4_get_block(inode, block, bh, 0);
861                         if (err) {
862                                 SetPageError(page);
863                                 return err;
864                         }
865                         if (!buffer_mapped(bh)) {
866                                 zero_user(page, block_start, blocksize);
867                                 if (!err)
868                                         set_buffer_uptodate(bh);
869                                 continue;
870                         }
871                 }
872                 BUG_ON(nr >= MAX_BUF_PER_PAGE);
873                 arr[nr++] = bh;
874         }
875         /* No io required */
876         if (!nr)
877                 goto out;
878
879         for (i = 0; i < nr; i++) {
880                 bh = arr[i];
881                 if (!bh_uptodate_or_lock(bh)) {
882                         err = bh_submit_read(bh);
883                         if (err)
884                                 return err;
885                 }
886         }
887 out:
888         if (!partial)
889                 SetPageUptodate(page);
890         return 0;
891 }
892
893 /**
894  * move_extent_per_page - Move extent data per page
895  *
896  * @o_filp:                     file structure of original file
897  * @donor_inode:                donor inode
898  * @orig_page_offset:           page index on original file
899  * @data_offset_in_page:        block index where data swapping starts
900  * @block_len_in_page:          the number of blocks to be swapped
901  * @uninit:                     orig extent is uninitialized or not
902  * @err:                        pointer to save return value
903  *
904  * Save the data in original inode blocks and replace original inode extents
905  * with donor inode extents by calling mext_replace_branches().
906  * Finally, write out the saved data in new original inode blocks. Return
907  * replaced block count.
908  */
909 static int
910 move_extent_per_page(struct file *o_filp, struct inode *donor_inode,
911                   pgoff_t orig_page_offset, int data_offset_in_page,
912                   int block_len_in_page, int uninit, int *err)
913 {
914         struct inode *orig_inode = o_filp->f_dentry->d_inode;
915         struct page *pagep[2] = {NULL, NULL};
916         handle_t *handle;
917         ext4_lblk_t orig_blk_offset;
918         long long offs = orig_page_offset << PAGE_CACHE_SHIFT;
919         unsigned long blocksize = orig_inode->i_sb->s_blocksize;
920         unsigned int w_flags = 0;
921         unsigned int tmp_data_size, data_size, replaced_size;
922         int err2, jblocks, retries = 0;
923         int replaced_count = 0;
924         int from = data_offset_in_page << orig_inode->i_blkbits;
925         int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits;
926
927         /*
928          * It needs twice the amount of ordinary journal buffers because
929          * inode and donor_inode may change each different metadata blocks.
930          */
931 again:
932         *err = 0;
933         jblocks = ext4_writepage_trans_blocks(orig_inode) * 2;
934         handle = ext4_journal_start(orig_inode, EXT4_HT_MOVE_EXTENTS, jblocks);
935         if (IS_ERR(handle)) {
936                 *err = PTR_ERR(handle);
937                 return 0;
938         }
939
940         if (segment_eq(get_fs(), KERNEL_DS))
941                 w_flags |= AOP_FLAG_UNINTERRUPTIBLE;
942
943         orig_blk_offset = orig_page_offset * blocks_per_page +
944                 data_offset_in_page;
945
946         offs = (long long)orig_blk_offset << orig_inode->i_blkbits;
947
948         /* Calculate data_size */
949         if ((orig_blk_offset + block_len_in_page - 1) ==
950             ((orig_inode->i_size - 1) >> orig_inode->i_blkbits)) {
951                 /* Replace the last block */
952                 tmp_data_size = orig_inode->i_size & (blocksize - 1);
953                 /*
954                  * If data_size equal zero, it shows data_size is multiples of
955                  * blocksize. So we set appropriate value.
956                  */
957                 if (tmp_data_size == 0)
958                         tmp_data_size = blocksize;
959
960                 data_size = tmp_data_size +
961                         ((block_len_in_page - 1) << orig_inode->i_blkbits);
962         } else
963                 data_size = block_len_in_page << orig_inode->i_blkbits;
964
965         replaced_size = data_size;
966
967         *err = mext_page_double_lock(orig_inode, donor_inode, orig_page_offset,
968                                      pagep);
969         if (unlikely(*err < 0))
970                 goto stop_journal;
971         /*
972          * If orig extent was uninitialized it can become initialized
973          * at any time after i_data_sem was dropped, in order to
974          * serialize with delalloc we have recheck extent while we
975          * hold page's lock, if it is still the case data copy is not
976          * necessary, just swap data blocks between orig and donor.
977          */
978         if (uninit) {
979                 double_down_write_data_sem(orig_inode, donor_inode);
980                 /* If any of extents in range became initialized we have to
981                  * fallback to data copying */
982                 uninit = mext_check_coverage(orig_inode, orig_blk_offset,
983                                              block_len_in_page, 1, err);
984                 if (*err)
985                         goto drop_data_sem;
986
987                 uninit &= mext_check_coverage(donor_inode, orig_blk_offset,
988                                               block_len_in_page, 1, err);
989                 if (*err)
990                         goto drop_data_sem;
991
992                 if (!uninit) {
993                         double_up_write_data_sem(orig_inode, donor_inode);
994                         goto data_copy;
995                 }
996                 if ((page_has_private(pagep[0]) &&
997                      !try_to_release_page(pagep[0], 0)) ||
998                     (page_has_private(pagep[1]) &&
999                      !try_to_release_page(pagep[1], 0))) {
1000                         *err = -EBUSY;
1001                         goto drop_data_sem;
1002                 }
1003                 replaced_count = mext_replace_branches(handle, orig_inode,
1004                                                 donor_inode, orig_blk_offset,
1005                                                 block_len_in_page, err);
1006         drop_data_sem:
1007                 double_up_write_data_sem(orig_inode, donor_inode);
1008                 goto unlock_pages;
1009         }
1010 data_copy:
1011         *err = mext_page_mkuptodate(pagep[0], from, from + replaced_size);
1012         if (*err)
1013                 goto unlock_pages;
1014
1015         /* At this point all buffers in range are uptodate, old mapping layout
1016          * is no longer required, try to drop it now. */
1017         if ((page_has_private(pagep[0]) && !try_to_release_page(pagep[0], 0)) ||
1018             (page_has_private(pagep[1]) && !try_to_release_page(pagep[1], 0))) {
1019                 *err = -EBUSY;
1020                 goto unlock_pages;
1021         }
1022
1023         replaced_count = mext_replace_branches(handle, orig_inode, donor_inode,
1024                                                orig_blk_offset,
1025                                                block_len_in_page, err);
1026         if (*err) {
1027                 if (replaced_count) {
1028                         block_len_in_page = replaced_count;
1029                         replaced_size =
1030                                 block_len_in_page << orig_inode->i_blkbits;
1031                 } else
1032                         goto unlock_pages;
1033         }
1034         /* Perform all necessary steps similar write_begin()/write_end()
1035          * but keeping in mind that i_size will not change */
1036         *err = __block_write_begin(pagep[0], from, from + replaced_size,
1037                                    ext4_get_block);
1038         if (!*err)
1039                 *err = block_commit_write(pagep[0], from, from + replaced_size);
1040
1041         if (unlikely(*err < 0))
1042                 goto repair_branches;
1043
1044         /* Even in case of data=writeback it is reasonable to pin
1045          * inode to transaction, to prevent unexpected data loss */
1046         *err = ext4_jbd2_file_inode(handle, orig_inode);
1047
1048 unlock_pages:
1049         unlock_page(pagep[0]);
1050         page_cache_release(pagep[0]);
1051         unlock_page(pagep[1]);
1052         page_cache_release(pagep[1]);
1053 stop_journal:
1054         ext4_journal_stop(handle);
1055         /* Buffer was busy because probably is pinned to journal transaction,
1056          * force transaction commit may help to free it. */
1057         if (*err == -EBUSY && ext4_should_retry_alloc(orig_inode->i_sb,
1058                                                       &retries))
1059                 goto again;
1060         return replaced_count;
1061
1062 repair_branches:
1063         /*
1064          * This should never ever happen!
1065          * Extents are swapped already, but we are not able to copy data.
1066          * Try to swap extents to it's original places
1067          */
1068         double_down_write_data_sem(orig_inode, donor_inode);
1069         replaced_count = mext_replace_branches(handle, donor_inode, orig_inode,
1070                                                orig_blk_offset,
1071                                                block_len_in_page, &err2);
1072         double_up_write_data_sem(orig_inode, donor_inode);
1073         if (replaced_count != block_len_in_page) {
1074                 EXT4_ERROR_INODE_BLOCK(orig_inode, (sector_t)(orig_blk_offset),
1075                                        "Unable to copy data block,"
1076                                        " data will be lost.");
1077                 *err = -EIO;
1078         }
1079         replaced_count = 0;
1080         goto unlock_pages;
1081 }
1082
1083 /**
1084  * mext_check_arguments - Check whether move extent can be done
1085  *
1086  * @orig_inode:         original inode
1087  * @donor_inode:        donor inode
1088  * @orig_start:         logical start offset in block for orig
1089  * @donor_start:        logical start offset in block for donor
1090  * @len:                the number of blocks to be moved
1091  *
1092  * Check the arguments of ext4_move_extents() whether the files can be
1093  * exchanged with each other.
1094  * Return 0 on success, or a negative error value on failure.
1095  */
1096 static int
1097 mext_check_arguments(struct inode *orig_inode,
1098                      struct inode *donor_inode, __u64 orig_start,
1099                      __u64 donor_start, __u64 *len)
1100 {
1101         ext4_lblk_t orig_blocks, donor_blocks;
1102         unsigned int blkbits = orig_inode->i_blkbits;
1103         unsigned int blocksize = 1 << blkbits;
1104
1105         if (donor_inode->i_mode & (S_ISUID|S_ISGID)) {
1106                 ext4_debug("ext4 move extent: suid or sgid is set"
1107                            " to donor file [ino:orig %lu, donor %lu]\n",
1108                            orig_inode->i_ino, donor_inode->i_ino);
1109                 return -EINVAL;
1110         }
1111
1112         if (IS_IMMUTABLE(donor_inode) || IS_APPEND(donor_inode))
1113                 return -EPERM;
1114
1115         /* Ext4 move extent does not support swapfile */
1116         if (IS_SWAPFILE(orig_inode) || IS_SWAPFILE(donor_inode)) {
1117                 ext4_debug("ext4 move extent: The argument files should "
1118                         "not be swapfile [ino:orig %lu, donor %lu]\n",
1119                         orig_inode->i_ino, donor_inode->i_ino);
1120                 return -EINVAL;
1121         }
1122
1123         /* Ext4 move extent supports only extent based file */
1124         if (!(ext4_test_inode_flag(orig_inode, EXT4_INODE_EXTENTS))) {
1125                 ext4_debug("ext4 move extent: orig file is not extents "
1126                         "based file [ino:orig %lu]\n", orig_inode->i_ino);
1127                 return -EOPNOTSUPP;
1128         } else if (!(ext4_test_inode_flag(donor_inode, EXT4_INODE_EXTENTS))) {
1129                 ext4_debug("ext4 move extent: donor file is not extents "
1130                         "based file [ino:donor %lu]\n", donor_inode->i_ino);
1131                 return -EOPNOTSUPP;
1132         }
1133
1134         if ((!orig_inode->i_size) || (!donor_inode->i_size)) {
1135                 ext4_debug("ext4 move extent: File size is 0 byte\n");
1136                 return -EINVAL;
1137         }
1138
1139         /* Start offset should be same */
1140         if (orig_start != donor_start) {
1141                 ext4_debug("ext4 move extent: orig and donor's start "
1142                         "offset are not same [ino:orig %lu, donor %lu]\n",
1143                         orig_inode->i_ino, donor_inode->i_ino);
1144                 return -EINVAL;
1145         }
1146
1147         if ((orig_start >= EXT_MAX_BLOCKS) ||
1148             (*len > EXT_MAX_BLOCKS) ||
1149             (orig_start + *len >= EXT_MAX_BLOCKS))  {
1150                 ext4_debug("ext4 move extent: Can't handle over [%u] blocks "
1151                         "[ino:orig %lu, donor %lu]\n", EXT_MAX_BLOCKS,
1152                         orig_inode->i_ino, donor_inode->i_ino);
1153                 return -EINVAL;
1154         }
1155
1156         if (orig_inode->i_size > donor_inode->i_size) {
1157                 donor_blocks = (donor_inode->i_size + blocksize - 1) >> blkbits;
1158                 /* TODO: eliminate this artificial restriction */
1159                 if (orig_start >= donor_blocks) {
1160                         ext4_debug("ext4 move extent: orig start offset "
1161                         "[%llu] should be less than donor file blocks "
1162                         "[%u] [ino:orig %lu, donor %lu]\n",
1163                         orig_start, donor_blocks,
1164                         orig_inode->i_ino, donor_inode->i_ino);
1165                         return -EINVAL;
1166                 }
1167
1168                 /* TODO: eliminate this artificial restriction */
1169                 if (orig_start + *len > donor_blocks) {
1170                         ext4_debug("ext4 move extent: End offset [%llu] should "
1171                                 "be less than donor file blocks [%u]."
1172                                 "So adjust length from %llu to %llu "
1173                                 "[ino:orig %lu, donor %lu]\n",
1174                                 orig_start + *len, donor_blocks,
1175                                 *len, donor_blocks - orig_start,
1176                                 orig_inode->i_ino, donor_inode->i_ino);
1177                         *len = donor_blocks - orig_start;
1178                 }
1179         } else {
1180                 orig_blocks = (orig_inode->i_size + blocksize - 1) >> blkbits;
1181                 if (orig_start >= orig_blocks) {
1182                         ext4_debug("ext4 move extent: start offset [%llu] "
1183                                 "should be less than original file blocks "
1184                                 "[%u] [ino:orig %lu, donor %lu]\n",
1185                                  orig_start, orig_blocks,
1186                                 orig_inode->i_ino, donor_inode->i_ino);
1187                         return -EINVAL;
1188                 }
1189
1190                 if (orig_start + *len > orig_blocks) {
1191                         ext4_debug("ext4 move extent: Adjust length "
1192                                 "from %llu to %llu. Because it should be "
1193                                 "less than original file blocks "
1194                                 "[ino:orig %lu, donor %lu]\n",
1195                                 *len, orig_blocks - orig_start,
1196                                 orig_inode->i_ino, donor_inode->i_ino);
1197                         *len = orig_blocks - orig_start;
1198                 }
1199         }
1200
1201         if (!*len) {
1202                 ext4_debug("ext4 move extent: len should not be 0 "
1203                         "[ino:orig %lu, donor %lu]\n", orig_inode->i_ino,
1204                         donor_inode->i_ino);
1205                 return -EINVAL;
1206         }
1207
1208         return 0;
1209 }
1210
1211 /**
1212  * mext_inode_double_lock - Lock i_mutex on both @inode1 and @inode2
1213  *
1214  * @inode1:     the inode structure
1215  * @inode2:     the inode structure
1216  *
1217  * Lock two inodes' i_mutex
1218  */
1219 static void
1220 mext_inode_double_lock(struct inode *inode1, struct inode *inode2)
1221 {
1222         BUG_ON(inode1 == inode2);
1223         if (inode1 < inode2) {
1224                 mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);
1225                 mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD);
1226         } else {
1227                 mutex_lock_nested(&inode2->i_mutex, I_MUTEX_PARENT);
1228                 mutex_lock_nested(&inode1->i_mutex, I_MUTEX_CHILD);
1229         }
1230 }
1231
1232 /**
1233  * mext_inode_double_unlock - Release i_mutex on both @inode1 and @inode2
1234  *
1235  * @inode1:     the inode that is released first
1236  * @inode2:     the inode that is released second
1237  *
1238  */
1239
1240 static void
1241 mext_inode_double_unlock(struct inode *inode1, struct inode *inode2)
1242 {
1243         mutex_unlock(&inode1->i_mutex);
1244         mutex_unlock(&inode2->i_mutex);
1245 }
1246
1247 /**
1248  * ext4_move_extents - Exchange the specified range of a file
1249  *
1250  * @o_filp:             file structure of the original file
1251  * @d_filp:             file structure of the donor file
1252  * @orig_start:         start offset in block for orig
1253  * @donor_start:        start offset in block for donor
1254  * @len:                the number of blocks to be moved
1255  * @moved_len:          moved block length
1256  *
1257  * This function returns 0 and moved block length is set in moved_len
1258  * if succeed, otherwise returns error value.
1259  *
1260  * Note: ext4_move_extents() proceeds the following order.
1261  * 1:ext4_move_extents() calculates the last block number of moving extent
1262  *   function by the start block number (orig_start) and the number of blocks
1263  *   to be moved (len) specified as arguments.
1264  *   If the {orig, donor}_start points a hole, the extent's start offset
1265  *   pointed by ext_cur (current extent), holecheck_path, orig_path are set
1266  *   after hole behind.
1267  * 2:Continue step 3 to step 5, until the holecheck_path points to last_extent
1268  *   or the ext_cur exceeds the block_end which is last logical block number.
1269  * 3:To get the length of continues area, call mext_next_extent()
1270  *   specified with the ext_cur (initial value is holecheck_path) re-cursive,
1271  *   until find un-continuous extent, the start logical block number exceeds
1272  *   the block_end or the extent points to the last extent.
1273  * 4:Exchange the original inode data with donor inode data
1274  *   from orig_page_offset to seq_end_page.
1275  *   The start indexes of data are specified as arguments.
1276  *   That of the original inode is orig_page_offset,
1277  *   and the donor inode is also orig_page_offset
1278  *   (To easily handle blocksize != pagesize case, the offset for the
1279  *   donor inode is block unit).
1280  * 5:Update holecheck_path and orig_path to points a next proceeding extent,
1281  *   then returns to step 2.
1282  * 6:Release holecheck_path, orig_path and set the len to moved_len
1283  *   which shows the number of moved blocks.
1284  *   The moved_len is useful for the command to calculate the file offset
1285  *   for starting next move extent ioctl.
1286  * 7:Return 0 on success, or a negative error value on failure.
1287  */
1288 int
1289 ext4_move_extents(struct file *o_filp, struct file *d_filp,
1290                  __u64 orig_start, __u64 donor_start, __u64 len,
1291                  __u64 *moved_len)
1292 {
1293         struct inode *orig_inode = o_filp->f_dentry->d_inode;
1294         struct inode *donor_inode = d_filp->f_dentry->d_inode;
1295         struct ext4_ext_path *orig_path = NULL, *holecheck_path = NULL;
1296         struct ext4_extent *ext_prev, *ext_cur, *ext_dummy;
1297         ext4_lblk_t block_start = orig_start;
1298         ext4_lblk_t block_end, seq_start, add_blocks, file_end, seq_blocks = 0;
1299         ext4_lblk_t rest_blocks;
1300         pgoff_t orig_page_offset = 0, seq_end_page;
1301         int ret, depth, last_extent = 0;
1302         int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits;
1303         int data_offset_in_page;
1304         int block_len_in_page;
1305         int uninit;
1306
1307         if (orig_inode->i_sb != donor_inode->i_sb) {
1308                 ext4_debug("ext4 move extent: The argument files "
1309                         "should be in same FS [ino:orig %lu, donor %lu]\n",
1310                         orig_inode->i_ino, donor_inode->i_ino);
1311                 return -EINVAL;
1312         }
1313
1314         /* orig and donor should be different inodes */
1315         if (orig_inode == donor_inode) {
1316                 ext4_debug("ext4 move extent: The argument files should not "
1317                         "be same inode [ino:orig %lu, donor %lu]\n",
1318                         orig_inode->i_ino, donor_inode->i_ino);
1319                 return -EINVAL;
1320         }
1321
1322         /* Regular file check */
1323         if (!S_ISREG(orig_inode->i_mode) || !S_ISREG(donor_inode->i_mode)) {
1324                 ext4_debug("ext4 move extent: The argument files should be "
1325                         "regular file [ino:orig %lu, donor %lu]\n",
1326                         orig_inode->i_ino, donor_inode->i_ino);
1327                 return -EINVAL;
1328         }
1329         /* TODO: This is non obvious task to swap blocks for inodes with full
1330            jornaling enabled */
1331         if (ext4_should_journal_data(orig_inode) ||
1332             ext4_should_journal_data(donor_inode)) {
1333                 return -EINVAL;
1334         }
1335         /* Protect orig and donor inodes against a truncate */
1336         mext_inode_double_lock(orig_inode, donor_inode);
1337
1338         /* Wait for all existing dio workers */
1339         ext4_inode_block_unlocked_dio(orig_inode);
1340         ext4_inode_block_unlocked_dio(donor_inode);
1341         inode_dio_wait(orig_inode);
1342         inode_dio_wait(donor_inode);
1343
1344         /* Protect extent tree against block allocations via delalloc */
1345         double_down_write_data_sem(orig_inode, donor_inode);
1346         /* Check the filesystem environment whether move_extent can be done */
1347         ret = mext_check_arguments(orig_inode, donor_inode, orig_start,
1348                                     donor_start, &len);
1349         if (ret)
1350                 goto out;
1351
1352         file_end = (i_size_read(orig_inode) - 1) >> orig_inode->i_blkbits;
1353         block_end = block_start + len - 1;
1354         if (file_end < block_end)
1355                 len -= block_end - file_end;
1356
1357         ret = get_ext_path(orig_inode, block_start, &orig_path);
1358         if (ret)
1359                 goto out;
1360
1361         /* Get path structure to check the hole */
1362         ret = get_ext_path(orig_inode, block_start, &holecheck_path);
1363         if (ret)
1364                 goto out;
1365
1366         depth = ext_depth(orig_inode);
1367         ext_cur = holecheck_path[depth].p_ext;
1368
1369         /*
1370          * Get proper starting location of block replacement if block_start was
1371          * within the hole.
1372          */
1373         if (le32_to_cpu(ext_cur->ee_block) +
1374                 ext4_ext_get_actual_len(ext_cur) - 1 < block_start) {
1375                 /*
1376                  * The hole exists between extents or the tail of
1377                  * original file.
1378                  */
1379                 last_extent = mext_next_extent(orig_inode,
1380                                         holecheck_path, &ext_cur);
1381                 if (last_extent < 0) {
1382                         ret = last_extent;
1383                         goto out;
1384                 }
1385                 last_extent = mext_next_extent(orig_inode, orig_path,
1386                                                         &ext_dummy);
1387                 if (last_extent < 0) {
1388                         ret = last_extent;
1389                         goto out;
1390                 }
1391                 seq_start = le32_to_cpu(ext_cur->ee_block);
1392         } else if (le32_to_cpu(ext_cur->ee_block) > block_start)
1393                 /* The hole exists at the beginning of original file. */
1394                 seq_start = le32_to_cpu(ext_cur->ee_block);
1395         else
1396                 seq_start = block_start;
1397
1398         /* No blocks within the specified range. */
1399         if (le32_to_cpu(ext_cur->ee_block) > block_end) {
1400                 ext4_debug("ext4 move extent: The specified range of file "
1401                                                         "may be the hole\n");
1402                 ret = -EINVAL;
1403                 goto out;
1404         }
1405
1406         /* Adjust start blocks */
1407         add_blocks = min(le32_to_cpu(ext_cur->ee_block) +
1408                          ext4_ext_get_actual_len(ext_cur), block_end + 1) -
1409                      max(le32_to_cpu(ext_cur->ee_block), block_start);
1410
1411         while (!last_extent && le32_to_cpu(ext_cur->ee_block) <= block_end) {
1412                 seq_blocks += add_blocks;
1413
1414                 /* Adjust tail blocks */
1415                 if (seq_start + seq_blocks - 1 > block_end)
1416                         seq_blocks = block_end - seq_start + 1;
1417
1418                 ext_prev = ext_cur;
1419                 last_extent = mext_next_extent(orig_inode, holecheck_path,
1420                                                 &ext_cur);
1421                 if (last_extent < 0) {
1422                         ret = last_extent;
1423                         break;
1424                 }
1425                 add_blocks = ext4_ext_get_actual_len(ext_cur);
1426
1427                 /*
1428                  * Extend the length of contiguous block (seq_blocks)
1429                  * if extents are contiguous.
1430                  */
1431                 if (ext4_can_extents_be_merged(orig_inode,
1432                                                ext_prev, ext_cur) &&
1433                     block_end >= le32_to_cpu(ext_cur->ee_block) &&
1434                     !last_extent)
1435                         continue;
1436
1437                 /* Is original extent is uninitialized */
1438                 uninit = ext4_ext_is_uninitialized(ext_prev);
1439
1440                 data_offset_in_page = seq_start % blocks_per_page;
1441
1442                 /*
1443                  * Calculate data blocks count that should be swapped
1444                  * at the first page.
1445                  */
1446                 if (data_offset_in_page + seq_blocks > blocks_per_page) {
1447                         /* Swapped blocks are across pages */
1448                         block_len_in_page =
1449                                         blocks_per_page - data_offset_in_page;
1450                 } else {
1451                         /* Swapped blocks are in a page */
1452                         block_len_in_page = seq_blocks;
1453                 }
1454
1455                 orig_page_offset = seq_start >>
1456                                 (PAGE_CACHE_SHIFT - orig_inode->i_blkbits);
1457                 seq_end_page = (seq_start + seq_blocks - 1) >>
1458                                 (PAGE_CACHE_SHIFT - orig_inode->i_blkbits);
1459                 seq_start = le32_to_cpu(ext_cur->ee_block);
1460                 rest_blocks = seq_blocks;
1461
1462                 /*
1463                  * Up semaphore to avoid following problems:
1464                  * a. transaction deadlock among ext4_journal_start,
1465                  *    ->write_begin via pagefault, and jbd2_journal_commit
1466                  * b. racing with ->readpage, ->write_begin, and ext4_get_block
1467                  *    in move_extent_per_page
1468                  */
1469                 double_up_write_data_sem(orig_inode, donor_inode);
1470
1471                 while (orig_page_offset <= seq_end_page) {
1472
1473                         /* Swap original branches with new branches */
1474                         block_len_in_page = move_extent_per_page(
1475                                                 o_filp, donor_inode,
1476                                                 orig_page_offset,
1477                                                 data_offset_in_page,
1478                                                 block_len_in_page, uninit,
1479                                                 &ret);
1480
1481                         /* Count how many blocks we have exchanged */
1482                         *moved_len += block_len_in_page;
1483                         if (ret < 0)
1484                                 break;
1485                         if (*moved_len > len) {
1486                                 EXT4_ERROR_INODE(orig_inode,
1487                                         "We replaced blocks too much! "
1488                                         "sum of replaced: %llu requested: %llu",
1489                                         *moved_len, len);
1490                                 ret = -EIO;
1491                                 break;
1492                         }
1493
1494                         orig_page_offset++;
1495                         data_offset_in_page = 0;
1496                         rest_blocks -= block_len_in_page;
1497                         if (rest_blocks > blocks_per_page)
1498                                 block_len_in_page = blocks_per_page;
1499                         else
1500                                 block_len_in_page = rest_blocks;
1501                 }
1502
1503                 double_down_write_data_sem(orig_inode, donor_inode);
1504                 if (ret < 0)
1505                         break;
1506
1507                 /* Decrease buffer counter */
1508                 if (holecheck_path)
1509                         ext4_ext_drop_refs(holecheck_path);
1510                 ret = get_ext_path(orig_inode, seq_start, &holecheck_path);
1511                 if (ret)
1512                         break;
1513                 depth = holecheck_path->p_depth;
1514
1515                 /* Decrease buffer counter */
1516                 if (orig_path)
1517                         ext4_ext_drop_refs(orig_path);
1518                 ret = get_ext_path(orig_inode, seq_start, &orig_path);
1519                 if (ret)
1520                         break;
1521
1522                 ext_cur = holecheck_path[depth].p_ext;
1523                 add_blocks = ext4_ext_get_actual_len(ext_cur);
1524                 seq_blocks = 0;
1525
1526         }
1527 out:
1528         if (*moved_len) {
1529                 ext4_discard_preallocations(orig_inode);
1530                 ext4_discard_preallocations(donor_inode);
1531         }
1532
1533         if (orig_path) {
1534                 ext4_ext_drop_refs(orig_path);
1535                 kfree(orig_path);
1536         }
1537         if (holecheck_path) {
1538                 ext4_ext_drop_refs(holecheck_path);
1539                 kfree(holecheck_path);
1540         }
1541         double_up_write_data_sem(orig_inode, donor_inode);
1542         ext4_inode_resume_unlocked_dio(orig_inode);
1543         ext4_inode_resume_unlocked_dio(donor_inode);
1544         mext_inode_double_unlock(orig_inode, donor_inode);
1545
1546         return ret;
1547 }