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