ext4: Implement range_cyclic in ext4_da_writepages instead of write_cache_pages
[sfrench/cifs-2.6.git] / fs / ext4 / migrate.c
1 /*
2  * Copyright IBM Corporation, 2007
3  * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
4  *
5  * This program is free software; you can redistribute it and/or modify it
6  * under the terms of version 2.1 of the GNU Lesser General Public License
7  * as published by the Free Software Foundation.
8  *
9  * This program is distributed in the hope that it would be useful, but
10  * WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
12  *
13  */
14
15 #include <linux/module.h>
16 #include "ext4_jbd2.h"
17 #include "ext4_extents.h"
18
19 /*
20  * The contiguous blocks details which can be
21  * represented by a single extent
22  */
23 struct list_blocks_struct {
24         ext4_lblk_t first_block, last_block;
25         ext4_fsblk_t first_pblock, last_pblock;
26 };
27
28 static int finish_range(handle_t *handle, struct inode *inode,
29                                 struct list_blocks_struct *lb)
30
31 {
32         int retval = 0, needed;
33         struct ext4_extent newext;
34         struct ext4_ext_path *path;
35         if (lb->first_pblock == 0)
36                 return 0;
37
38         /* Add the extent to temp inode*/
39         newext.ee_block = cpu_to_le32(lb->first_block);
40         newext.ee_len   = cpu_to_le16(lb->last_block - lb->first_block + 1);
41         ext4_ext_store_pblock(&newext, lb->first_pblock);
42         path = ext4_ext_find_extent(inode, lb->first_block, NULL);
43
44         if (IS_ERR(path)) {
45                 retval = PTR_ERR(path);
46                 path = NULL;
47                 goto err_out;
48         }
49
50         /*
51          * Calculate the credit needed to inserting this extent
52          * Since we are doing this in loop we may accumalate extra
53          * credit. But below we try to not accumalate too much
54          * of them by restarting the journal.
55          */
56         needed = ext4_ext_calc_credits_for_single_extent(inode,
57                     lb->last_block - lb->first_block + 1, path);
58
59         /*
60          * Make sure the credit we accumalated is not really high
61          */
62         if (needed && ext4_handle_has_enough_credits(handle,
63                                                 EXT4_RESERVE_TRANS_BLOCKS)) {
64                 retval = ext4_journal_restart(handle, needed);
65                 if (retval)
66                         goto err_out;
67         } else if (needed) {
68                 retval = ext4_journal_extend(handle, needed);
69                 if (retval) {
70                         /*
71                          * IF not able to extend the journal restart the journal
72                          */
73                         retval = ext4_journal_restart(handle, needed);
74                         if (retval)
75                                 goto err_out;
76                 }
77         }
78         retval = ext4_ext_insert_extent(handle, inode, path, &newext);
79 err_out:
80         if (path) {
81                 ext4_ext_drop_refs(path);
82                 kfree(path);
83         }
84         lb->first_pblock = 0;
85         return retval;
86 }
87
88 static int update_extent_range(handle_t *handle, struct inode *inode,
89                                 ext4_fsblk_t pblock, ext4_lblk_t blk_num,
90                                 struct list_blocks_struct *lb)
91 {
92         int retval;
93         /*
94          * See if we can add on to the existing range (if it exists)
95          */
96         if (lb->first_pblock &&
97                 (lb->last_pblock+1 == pblock) &&
98                 (lb->last_block+1 == blk_num)) {
99                 lb->last_pblock = pblock;
100                 lb->last_block = blk_num;
101                 return 0;
102         }
103         /*
104          * Start a new range.
105          */
106         retval = finish_range(handle, inode, lb);
107         lb->first_pblock = lb->last_pblock = pblock;
108         lb->first_block = lb->last_block = blk_num;
109
110         return retval;
111 }
112
113 static int update_ind_extent_range(handle_t *handle, struct inode *inode,
114                                    ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
115                                    struct list_blocks_struct *lb)
116 {
117         struct buffer_head *bh;
118         __le32 *i_data;
119         int i, retval = 0;
120         ext4_lblk_t blk_count = *blk_nump;
121         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
122
123         if (!pblock) {
124                 /* Only update the file block number */
125                 *blk_nump += max_entries;
126                 return 0;
127         }
128
129         bh = sb_bread(inode->i_sb, pblock);
130         if (!bh)
131                 return -EIO;
132
133         i_data = (__le32 *)bh->b_data;
134         for (i = 0; i < max_entries; i++, blk_count++) {
135                 if (i_data[i]) {
136                         retval = update_extent_range(handle, inode,
137                                                 le32_to_cpu(i_data[i]),
138                                                 blk_count, lb);
139                         if (retval)
140                                 break;
141                 }
142         }
143
144         /* Update the file block number */
145         *blk_nump = blk_count;
146         put_bh(bh);
147         return retval;
148
149 }
150
151 static int update_dind_extent_range(handle_t *handle, struct inode *inode,
152                                     ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
153                                     struct list_blocks_struct *lb)
154 {
155         struct buffer_head *bh;
156         __le32 *i_data;
157         int i, retval = 0;
158         ext4_lblk_t blk_count = *blk_nump;
159         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
160
161         if (!pblock) {
162                 /* Only update the file block number */
163                 *blk_nump += max_entries * max_entries;
164                 return 0;
165         }
166         bh = sb_bread(inode->i_sb, pblock);
167         if (!bh)
168                 return -EIO;
169
170         i_data = (__le32 *)bh->b_data;
171         for (i = 0; i < max_entries; i++) {
172                 if (i_data[i]) {
173                         retval = update_ind_extent_range(handle, inode,
174                                                 le32_to_cpu(i_data[i]),
175                                                 &blk_count, lb);
176                         if (retval)
177                                 break;
178                 } else {
179                         /* Only update the file block number */
180                         blk_count += max_entries;
181                 }
182         }
183
184         /* Update the file block number */
185         *blk_nump = blk_count;
186         put_bh(bh);
187         return retval;
188
189 }
190
191 static int update_tind_extent_range(handle_t *handle, struct inode *inode,
192                                      ext4_fsblk_t pblock, ext4_lblk_t *blk_nump,
193                                      struct list_blocks_struct *lb)
194 {
195         struct buffer_head *bh;
196         __le32 *i_data;
197         int i, retval = 0;
198         ext4_lblk_t blk_count = *blk_nump;
199         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
200
201         if (!pblock) {
202                 /* Only update the file block number */
203                 *blk_nump += max_entries * max_entries * max_entries;
204                 return 0;
205         }
206         bh = sb_bread(inode->i_sb, pblock);
207         if (!bh)
208                 return -EIO;
209
210         i_data = (__le32 *)bh->b_data;
211         for (i = 0; i < max_entries; i++) {
212                 if (i_data[i]) {
213                         retval = update_dind_extent_range(handle, inode,
214                                                 le32_to_cpu(i_data[i]),
215                                                 &blk_count, lb);
216                         if (retval)
217                                 break;
218                 } else
219                         /* Only update the file block number */
220                         blk_count += max_entries * max_entries;
221         }
222         /* Update the file block number */
223         *blk_nump = blk_count;
224         put_bh(bh);
225         return retval;
226
227 }
228
229 static int extend_credit_for_blkdel(handle_t *handle, struct inode *inode)
230 {
231         int retval = 0, needed;
232
233         if (ext4_handle_has_enough_credits(handle, EXT4_RESERVE_TRANS_BLOCKS+1))
234                 return 0;
235         /*
236          * We are freeing a blocks. During this we touch
237          * superblock, group descriptor and block bitmap.
238          * So allocate a credit of 3. We may update
239          * quota (user and group).
240          */
241         needed = 3 + 2*EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb);
242
243         if (ext4_journal_extend(handle, needed) != 0)
244                 retval = ext4_journal_restart(handle, needed);
245
246         return retval;
247 }
248
249 static int free_dind_blocks(handle_t *handle,
250                                 struct inode *inode, __le32 i_data)
251 {
252         int i;
253         __le32 *tmp_idata;
254         struct buffer_head *bh;
255         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
256
257         bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
258         if (!bh)
259                 return -EIO;
260
261         tmp_idata = (__le32 *)bh->b_data;
262         for (i = 0; i < max_entries; i++) {
263                 if (tmp_idata[i]) {
264                         extend_credit_for_blkdel(handle, inode);
265                         ext4_free_blocks(handle, inode,
266                                         le32_to_cpu(tmp_idata[i]), 1, 1);
267                 }
268         }
269         put_bh(bh);
270         extend_credit_for_blkdel(handle, inode);
271         ext4_free_blocks(handle, inode, le32_to_cpu(i_data), 1, 1);
272         return 0;
273 }
274
275 static int free_tind_blocks(handle_t *handle,
276                                 struct inode *inode, __le32 i_data)
277 {
278         int i, retval = 0;
279         __le32 *tmp_idata;
280         struct buffer_head *bh;
281         unsigned long max_entries = inode->i_sb->s_blocksize >> 2;
282
283         bh = sb_bread(inode->i_sb, le32_to_cpu(i_data));
284         if (!bh)
285                 return -EIO;
286
287         tmp_idata = (__le32 *)bh->b_data;
288         for (i = 0; i < max_entries; i++) {
289                 if (tmp_idata[i]) {
290                         retval = free_dind_blocks(handle,
291                                         inode, tmp_idata[i]);
292                         if (retval) {
293                                 put_bh(bh);
294                                 return retval;
295                         }
296                 }
297         }
298         put_bh(bh);
299         extend_credit_for_blkdel(handle, inode);
300         ext4_free_blocks(handle, inode, le32_to_cpu(i_data), 1, 1);
301         return 0;
302 }
303
304 static int free_ind_block(handle_t *handle, struct inode *inode, __le32 *i_data)
305 {
306         int retval;
307
308         /* ei->i_data[EXT4_IND_BLOCK] */
309         if (i_data[0]) {
310                 extend_credit_for_blkdel(handle, inode);
311                 ext4_free_blocks(handle, inode,
312                                 le32_to_cpu(i_data[0]), 1, 1);
313         }
314
315         /* ei->i_data[EXT4_DIND_BLOCK] */
316         if (i_data[1]) {
317                 retval = free_dind_blocks(handle, inode, i_data[1]);
318                 if (retval)
319                         return retval;
320         }
321
322         /* ei->i_data[EXT4_TIND_BLOCK] */
323         if (i_data[2]) {
324                 retval = free_tind_blocks(handle, inode, i_data[2]);
325                 if (retval)
326                         return retval;
327         }
328         return 0;
329 }
330
331 static int ext4_ext_swap_inode_data(handle_t *handle, struct inode *inode,
332                                                 struct inode *tmp_inode)
333 {
334         int retval;
335         __le32  i_data[3];
336         struct ext4_inode_info *ei = EXT4_I(inode);
337         struct ext4_inode_info *tmp_ei = EXT4_I(tmp_inode);
338
339         /*
340          * One credit accounted for writing the
341          * i_data field of the original inode
342          */
343         retval = ext4_journal_extend(handle, 1);
344         if (retval) {
345                 retval = ext4_journal_restart(handle, 1);
346                 if (retval)
347                         goto err_out;
348         }
349
350         i_data[0] = ei->i_data[EXT4_IND_BLOCK];
351         i_data[1] = ei->i_data[EXT4_DIND_BLOCK];
352         i_data[2] = ei->i_data[EXT4_TIND_BLOCK];
353
354         down_write(&EXT4_I(inode)->i_data_sem);
355         /*
356          * if EXT4_EXT_MIGRATE is cleared a block allocation
357          * happened after we started the migrate. We need to
358          * fail the migrate
359          */
360         if (!(EXT4_I(inode)->i_flags & EXT4_EXT_MIGRATE)) {
361                 retval = -EAGAIN;
362                 up_write(&EXT4_I(inode)->i_data_sem);
363                 goto err_out;
364         } else
365                 EXT4_I(inode)->i_flags = EXT4_I(inode)->i_flags &
366                                                         ~EXT4_EXT_MIGRATE;
367         /*
368          * We have the extent map build with the tmp inode.
369          * Now copy the i_data across
370          */
371         ei->i_flags |= EXT4_EXTENTS_FL;
372         memcpy(ei->i_data, tmp_ei->i_data, sizeof(ei->i_data));
373
374         /*
375          * Update i_blocks with the new blocks that got
376          * allocated while adding extents for extent index
377          * blocks.
378          *
379          * While converting to extents we need not
380          * update the orignal inode i_blocks for extent blocks
381          * via quota APIs. The quota update happened via tmp_inode already.
382          */
383         spin_lock(&inode->i_lock);
384         inode->i_blocks += tmp_inode->i_blocks;
385         spin_unlock(&inode->i_lock);
386         up_write(&EXT4_I(inode)->i_data_sem);
387
388         /*
389          * We mark the inode dirty after, because we decrement the
390          * i_blocks when freeing the indirect meta-data blocks
391          */
392         retval = free_ind_block(handle, inode, i_data);
393         ext4_mark_inode_dirty(handle, inode);
394
395 err_out:
396         return retval;
397 }
398
399 static int free_ext_idx(handle_t *handle, struct inode *inode,
400                                         struct ext4_extent_idx *ix)
401 {
402         int i, retval = 0;
403         ext4_fsblk_t block;
404         struct buffer_head *bh;
405         struct ext4_extent_header *eh;
406
407         block = idx_pblock(ix);
408         bh = sb_bread(inode->i_sb, block);
409         if (!bh)
410                 return -EIO;
411
412         eh = (struct ext4_extent_header *)bh->b_data;
413         if (eh->eh_depth != 0) {
414                 ix = EXT_FIRST_INDEX(eh);
415                 for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
416                         retval = free_ext_idx(handle, inode, ix);
417                         if (retval)
418                                 break;
419                 }
420         }
421         put_bh(bh);
422         extend_credit_for_blkdel(handle, inode);
423         ext4_free_blocks(handle, inode, block, 1, 1);
424         return retval;
425 }
426
427 /*
428  * Free the extent meta data blocks only
429  */
430 static int free_ext_block(handle_t *handle, struct inode *inode)
431 {
432         int i, retval = 0;
433         struct ext4_inode_info *ei = EXT4_I(inode);
434         struct ext4_extent_header *eh = (struct ext4_extent_header *)ei->i_data;
435         struct ext4_extent_idx *ix;
436         if (eh->eh_depth == 0)
437                 /*
438                  * No extra blocks allocated for extent meta data
439                  */
440                 return 0;
441         ix = EXT_FIRST_INDEX(eh);
442         for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ix++) {
443                 retval = free_ext_idx(handle, inode, ix);
444                 if (retval)
445                         return retval;
446         }
447         return retval;
448
449 }
450
451 int ext4_ext_migrate(struct inode *inode)
452 {
453         handle_t *handle;
454         int retval = 0, i;
455         __le32 *i_data;
456         ext4_lblk_t blk_count = 0;
457         struct ext4_inode_info *ei;
458         struct inode *tmp_inode = NULL;
459         struct list_blocks_struct lb;
460         unsigned long max_entries;
461
462         /*
463          * If the filesystem does not support extents, or the inode
464          * already is extent-based, error out.
465          */
466         if (!EXT4_HAS_INCOMPAT_FEATURE(inode->i_sb,
467                                        EXT4_FEATURE_INCOMPAT_EXTENTS) ||
468             (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
469                 return -EINVAL;
470
471         if (S_ISLNK(inode->i_mode) && inode->i_blocks == 0)
472                 /*
473                  * don't migrate fast symlink
474                  */
475                 return retval;
476
477         handle = ext4_journal_start(inode,
478                                         EXT4_DATA_TRANS_BLOCKS(inode->i_sb) +
479                                         EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3 +
480                                         2 * EXT4_QUOTA_INIT_BLOCKS(inode->i_sb)
481                                         + 1);
482         if (IS_ERR(handle)) {
483                 retval = PTR_ERR(handle);
484                 goto err_out;
485         }
486         tmp_inode = ext4_new_inode(handle,
487                                 inode->i_sb->s_root->d_inode,
488                                 S_IFREG);
489         if (IS_ERR(tmp_inode)) {
490                 retval = -ENOMEM;
491                 ext4_journal_stop(handle);
492                 tmp_inode = NULL;
493                 goto err_out;
494         }
495         i_size_write(tmp_inode, i_size_read(inode));
496         /*
497          * We don't want the inode to be reclaimed
498          * if we got interrupted in between. We have
499          * this tmp inode carrying reference to the
500          * data blocks of the original file. We set
501          * the i_nlink to zero at the last stage after
502          * switching the original file to extent format
503          */
504         tmp_inode->i_nlink = 1;
505
506         ext4_ext_tree_init(handle, tmp_inode);
507         ext4_orphan_add(handle, tmp_inode);
508         ext4_journal_stop(handle);
509
510         /*
511          * start with one credit accounted for
512          * superblock modification.
513          *
514          * For the tmp_inode we already have commited the
515          * trascation that created the inode. Later as and
516          * when we add extents we extent the journal
517          */
518         /*
519          * Even though we take i_mutex we can still cause block allocation
520          * via mmap write to holes. If we have allocated new blocks we fail
521          * migrate.  New block allocation will clear EXT4_EXT_MIGRATE flag.
522          * The flag is updated with i_data_sem held to prevent racing with
523          * block allocation.
524          */
525         down_read((&EXT4_I(inode)->i_data_sem));
526         EXT4_I(inode)->i_flags = EXT4_I(inode)->i_flags | EXT4_EXT_MIGRATE;
527         up_read((&EXT4_I(inode)->i_data_sem));
528
529         handle = ext4_journal_start(inode, 1);
530
531         ei = EXT4_I(inode);
532         i_data = ei->i_data;
533         memset(&lb, 0, sizeof(lb));
534
535         /* 32 bit block address 4 bytes */
536         max_entries = inode->i_sb->s_blocksize >> 2;
537         for (i = 0; i < EXT4_NDIR_BLOCKS; i++, blk_count++) {
538                 if (i_data[i]) {
539                         retval = update_extent_range(handle, tmp_inode,
540                                                 le32_to_cpu(i_data[i]),
541                                                 blk_count, &lb);
542                         if (retval)
543                                 goto err_out;
544                 }
545         }
546         if (i_data[EXT4_IND_BLOCK]) {
547                 retval = update_ind_extent_range(handle, tmp_inode,
548                                         le32_to_cpu(i_data[EXT4_IND_BLOCK]),
549                                         &blk_count, &lb);
550                         if (retval)
551                                 goto err_out;
552         } else
553                 blk_count +=  max_entries;
554         if (i_data[EXT4_DIND_BLOCK]) {
555                 retval = update_dind_extent_range(handle, tmp_inode,
556                                         le32_to_cpu(i_data[EXT4_DIND_BLOCK]),
557                                         &blk_count, &lb);
558                         if (retval)
559                                 goto err_out;
560         } else
561                 blk_count += max_entries * max_entries;
562         if (i_data[EXT4_TIND_BLOCK]) {
563                 retval = update_tind_extent_range(handle, tmp_inode,
564                                         le32_to_cpu(i_data[EXT4_TIND_BLOCK]),
565                                         &blk_count, &lb);
566                         if (retval)
567                                 goto err_out;
568         }
569         /*
570          * Build the last extent
571          */
572         retval = finish_range(handle, tmp_inode, &lb);
573 err_out:
574         if (retval)
575                 /*
576                  * Failure case delete the extent information with the
577                  * tmp_inode
578                  */
579                 free_ext_block(handle, tmp_inode);
580         else {
581                 retval = ext4_ext_swap_inode_data(handle, inode, tmp_inode);
582                 if (retval)
583                         /*
584                          * if we fail to swap inode data free the extent
585                          * details of the tmp inode
586                          */
587                         free_ext_block(handle, tmp_inode);
588         }
589
590         /* We mark the tmp_inode dirty via ext4_ext_tree_init. */
591         if (ext4_journal_extend(handle, 1) != 0)
592                 ext4_journal_restart(handle, 1);
593
594         /*
595          * Mark the tmp_inode as of size zero
596          */
597         i_size_write(tmp_inode, 0);
598
599         /*
600          * set the  i_blocks count to zero
601          * so that the ext4_delete_inode does the
602          * right job
603          *
604          * We don't need to take the i_lock because
605          * the inode is not visible to user space.
606          */
607         tmp_inode->i_blocks = 0;
608
609         /* Reset the extent details */
610         ext4_ext_tree_init(handle, tmp_inode);
611
612         /*
613          * Set the i_nlink to zero so that
614          * generic_drop_inode really deletes the
615          * inode
616          */
617         tmp_inode->i_nlink = 0;
618
619         ext4_journal_stop(handle);
620
621         if (tmp_inode)
622                 iput(tmp_inode);
623
624         return retval;
625 }