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Linux/fs/nilfs2/mdt.c

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  1 /*
  2  * mdt.c - meta data file for NILFS
  3  *
  4  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
  5  *
  6  * This program is free software; you can redistribute it and/or modify
  7  * it under the terms of the GNU General Public License as published by
  8  * the Free Software Foundation; either version 2 of the License, or
  9  * (at your option) any later version.
 10  *
 11  * This program is distributed in the hope that it will be useful,
 12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14  * GNU General Public License for more details.
 15  *
 16  * You should have received a copy of the GNU General Public License
 17  * along with this program; if not, write to the Free Software
 18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 19  *
 20  * Written by Ryusuke Konishi <ryusuke@osrg.net>
 21  */
 22 
 23 #include <linux/buffer_head.h>
 24 #include <linux/mpage.h>
 25 #include <linux/mm.h>
 26 #include <linux/writeback.h>
 27 #include <linux/backing-dev.h>
 28 #include <linux/swap.h>
 29 #include <linux/slab.h>
 30 #include "nilfs.h"
 31 #include "btnode.h"
 32 #include "segment.h"
 33 #include "page.h"
 34 #include "mdt.h"
 35 
 36 
 37 #define NILFS_MDT_MAX_RA_BLOCKS         (16 - 1)
 38 
 39 
 40 static int
 41 nilfs_mdt_insert_new_block(struct inode *inode, unsigned long block,
 42                            struct buffer_head *bh,
 43                            void (*init_block)(struct inode *,
 44                                               struct buffer_head *, void *))
 45 {
 46         struct nilfs_inode_info *ii = NILFS_I(inode);
 47         void *kaddr;
 48         int ret;
 49 
 50         /* Caller exclude read accesses using page lock */
 51 
 52         /* set_buffer_new(bh); */
 53         bh->b_blocknr = 0;
 54 
 55         ret = nilfs_bmap_insert(ii->i_bmap, block, (unsigned long)bh);
 56         if (unlikely(ret))
 57                 return ret;
 58 
 59         set_buffer_mapped(bh);
 60 
 61         kaddr = kmap_atomic(bh->b_page);
 62         memset(kaddr + bh_offset(bh), 0, 1 << inode->i_blkbits);
 63         if (init_block)
 64                 init_block(inode, bh, kaddr);
 65         flush_dcache_page(bh->b_page);
 66         kunmap_atomic(kaddr);
 67 
 68         set_buffer_uptodate(bh);
 69         mark_buffer_dirty(bh);
 70         nilfs_mdt_mark_dirty(inode);
 71         return 0;
 72 }
 73 
 74 static int nilfs_mdt_create_block(struct inode *inode, unsigned long block,
 75                                   struct buffer_head **out_bh,
 76                                   void (*init_block)(struct inode *,
 77                                                      struct buffer_head *,
 78                                                      void *))
 79 {
 80         struct super_block *sb = inode->i_sb;
 81         struct nilfs_transaction_info ti;
 82         struct buffer_head *bh;
 83         int err;
 84 
 85         nilfs_transaction_begin(sb, &ti, 0);
 86 
 87         err = -ENOMEM;
 88         bh = nilfs_grab_buffer(inode, inode->i_mapping, block, 0);
 89         if (unlikely(!bh))
 90                 goto failed_unlock;
 91 
 92         err = -EEXIST;
 93         if (buffer_uptodate(bh))
 94                 goto failed_bh;
 95 
 96         wait_on_buffer(bh);
 97         if (buffer_uptodate(bh))
 98                 goto failed_bh;
 99 
100         bh->b_bdev = sb->s_bdev;
101         err = nilfs_mdt_insert_new_block(inode, block, bh, init_block);
102         if (likely(!err)) {
103                 get_bh(bh);
104                 *out_bh = bh;
105         }
106 
107  failed_bh:
108         unlock_page(bh->b_page);
109         page_cache_release(bh->b_page);
110         brelse(bh);
111 
112  failed_unlock:
113         if (likely(!err))
114                 err = nilfs_transaction_commit(sb);
115         else
116                 nilfs_transaction_abort(sb);
117 
118         return err;
119 }
120 
121 static int
122 nilfs_mdt_submit_block(struct inode *inode, unsigned long blkoff,
123                        int mode, struct buffer_head **out_bh)
124 {
125         struct buffer_head *bh;
126         __u64 blknum = 0;
127         int ret = -ENOMEM;
128 
129         bh = nilfs_grab_buffer(inode, inode->i_mapping, blkoff, 0);
130         if (unlikely(!bh))
131                 goto failed;
132 
133         ret = -EEXIST; /* internal code */
134         if (buffer_uptodate(bh))
135                 goto out;
136 
137         if (mode == READA) {
138                 if (!trylock_buffer(bh)) {
139                         ret = -EBUSY;
140                         goto failed_bh;
141                 }
142         } else /* mode == READ */
143                 lock_buffer(bh);
144 
145         if (buffer_uptodate(bh)) {
146                 unlock_buffer(bh);
147                 goto out;
148         }
149 
150         ret = nilfs_bmap_lookup(NILFS_I(inode)->i_bmap, blkoff, &blknum);
151         if (unlikely(ret)) {
152                 unlock_buffer(bh);
153                 goto failed_bh;
154         }
155         map_bh(bh, inode->i_sb, (sector_t)blknum);
156 
157         bh->b_end_io = end_buffer_read_sync;
158         get_bh(bh);
159         submit_bh(mode, bh);
160         ret = 0;
161  out:
162         get_bh(bh);
163         *out_bh = bh;
164 
165  failed_bh:
166         unlock_page(bh->b_page);
167         page_cache_release(bh->b_page);
168         brelse(bh);
169  failed:
170         return ret;
171 }
172 
173 static int nilfs_mdt_read_block(struct inode *inode, unsigned long block,
174                                 int readahead, struct buffer_head **out_bh)
175 {
176         struct buffer_head *first_bh, *bh;
177         unsigned long blkoff;
178         int i, nr_ra_blocks = NILFS_MDT_MAX_RA_BLOCKS;
179         int err;
180 
181         err = nilfs_mdt_submit_block(inode, block, READ, &first_bh);
182         if (err == -EEXIST) /* internal code */
183                 goto out;
184 
185         if (unlikely(err))
186                 goto failed;
187 
188         if (readahead) {
189                 blkoff = block + 1;
190                 for (i = 0; i < nr_ra_blocks; i++, blkoff++) {
191                         err = nilfs_mdt_submit_block(inode, blkoff, READA, &bh);
192                         if (likely(!err || err == -EEXIST))
193                                 brelse(bh);
194                         else if (err != -EBUSY)
195                                 break;
196                                 /* abort readahead if bmap lookup failed */
197                         if (!buffer_locked(first_bh))
198                                 goto out_no_wait;
199                 }
200         }
201 
202         wait_on_buffer(first_bh);
203 
204  out_no_wait:
205         err = -EIO;
206         if (!buffer_uptodate(first_bh))
207                 goto failed_bh;
208  out:
209         *out_bh = first_bh;
210         return 0;
211 
212  failed_bh:
213         brelse(first_bh);
214  failed:
215         return err;
216 }
217 
218 /**
219  * nilfs_mdt_get_block - read or create a buffer on meta data file.
220  * @inode: inode of the meta data file
221  * @blkoff: block offset
222  * @create: create flag
223  * @init_block: initializer used for newly allocated block
224  * @out_bh: output of a pointer to the buffer_head
225  *
226  * nilfs_mdt_get_block() looks up the specified buffer and tries to create
227  * a new buffer if @create is not zero.  On success, the returned buffer is
228  * assured to be either existing or formatted using a buffer lock on success.
229  * @out_bh is substituted only when zero is returned.
230  *
231  * Return Value: On success, it returns 0. On error, the following negative
232  * error code is returned.
233  *
234  * %-ENOMEM - Insufficient memory available.
235  *
236  * %-EIO - I/O error
237  *
238  * %-ENOENT - the specified block does not exist (hole block)
239  *
240  * %-EROFS - Read only filesystem (for create mode)
241  */
242 int nilfs_mdt_get_block(struct inode *inode, unsigned long blkoff, int create,
243                         void (*init_block)(struct inode *,
244                                            struct buffer_head *, void *),
245                         struct buffer_head **out_bh)
246 {
247         int ret;
248 
249         /* Should be rewritten with merging nilfs_mdt_read_block() */
250  retry:
251         ret = nilfs_mdt_read_block(inode, blkoff, !create, out_bh);
252         if (!create || ret != -ENOENT)
253                 return ret;
254 
255         ret = nilfs_mdt_create_block(inode, blkoff, out_bh, init_block);
256         if (unlikely(ret == -EEXIST)) {
257                 /* create = 0; */  /* limit read-create loop retries */
258                 goto retry;
259         }
260         return ret;
261 }
262 
263 /**
264  * nilfs_mdt_delete_block - make a hole on the meta data file.
265  * @inode: inode of the meta data file
266  * @block: block offset
267  *
268  * Return Value: On success, zero is returned.
269  * On error, one of the following negative error code is returned.
270  *
271  * %-ENOMEM - Insufficient memory available.
272  *
273  * %-EIO - I/O error
274  */
275 int nilfs_mdt_delete_block(struct inode *inode, unsigned long block)
276 {
277         struct nilfs_inode_info *ii = NILFS_I(inode);
278         int err;
279 
280         err = nilfs_bmap_delete(ii->i_bmap, block);
281         if (!err || err == -ENOENT) {
282                 nilfs_mdt_mark_dirty(inode);
283                 nilfs_mdt_forget_block(inode, block);
284         }
285         return err;
286 }
287 
288 /**
289  * nilfs_mdt_forget_block - discard dirty state and try to remove the page
290  * @inode: inode of the meta data file
291  * @block: block offset
292  *
293  * nilfs_mdt_forget_block() clears a dirty flag of the specified buffer, and
294  * tries to release the page including the buffer from a page cache.
295  *
296  * Return Value: On success, 0 is returned. On error, one of the following
297  * negative error code is returned.
298  *
299  * %-EBUSY - page has an active buffer.
300  *
301  * %-ENOENT - page cache has no page addressed by the offset.
302  */
303 int nilfs_mdt_forget_block(struct inode *inode, unsigned long block)
304 {
305         pgoff_t index = (pgoff_t)block >>
306                 (PAGE_CACHE_SHIFT - inode->i_blkbits);
307         struct page *page;
308         unsigned long first_block;
309         int ret = 0;
310         int still_dirty;
311 
312         page = find_lock_page(inode->i_mapping, index);
313         if (!page)
314                 return -ENOENT;
315 
316         wait_on_page_writeback(page);
317 
318         first_block = (unsigned long)index <<
319                 (PAGE_CACHE_SHIFT - inode->i_blkbits);
320         if (page_has_buffers(page)) {
321                 struct buffer_head *bh;
322 
323                 bh = nilfs_page_get_nth_block(page, block - first_block);
324                 nilfs_forget_buffer(bh);
325         }
326         still_dirty = PageDirty(page);
327         unlock_page(page);
328         page_cache_release(page);
329 
330         if (still_dirty ||
331             invalidate_inode_pages2_range(inode->i_mapping, index, index) != 0)
332                 ret = -EBUSY;
333         return ret;
334 }
335 
336 /**
337  * nilfs_mdt_mark_block_dirty - mark a block on the meta data file dirty.
338  * @inode: inode of the meta data file
339  * @block: block offset
340  *
341  * Return Value: On success, it returns 0. On error, the following negative
342  * error code is returned.
343  *
344  * %-ENOMEM - Insufficient memory available.
345  *
346  * %-EIO - I/O error
347  *
348  * %-ENOENT - the specified block does not exist (hole block)
349  */
350 int nilfs_mdt_mark_block_dirty(struct inode *inode, unsigned long block)
351 {
352         struct buffer_head *bh;
353         int err;
354 
355         err = nilfs_mdt_read_block(inode, block, 0, &bh);
356         if (unlikely(err))
357                 return err;
358         mark_buffer_dirty(bh);
359         nilfs_mdt_mark_dirty(inode);
360         brelse(bh);
361         return 0;
362 }
363 
364 int nilfs_mdt_fetch_dirty(struct inode *inode)
365 {
366         struct nilfs_inode_info *ii = NILFS_I(inode);
367 
368         if (nilfs_bmap_test_and_clear_dirty(ii->i_bmap)) {
369                 set_bit(NILFS_I_DIRTY, &ii->i_state);
370                 return 1;
371         }
372         return test_bit(NILFS_I_DIRTY, &ii->i_state);
373 }
374 
375 static int
376 nilfs_mdt_write_page(struct page *page, struct writeback_control *wbc)
377 {
378         struct inode *inode = page->mapping->host;
379         struct super_block *sb;
380         int err = 0;
381 
382         if (inode && (inode->i_sb->s_flags & MS_RDONLY)) {
383                 /*
384                  * It means that filesystem was remounted in read-only
385                  * mode because of error or metadata corruption. But we
386                  * have dirty pages that try to be flushed in background.
387                  * So, here we simply discard this dirty page.
388                  */
389                 nilfs_clear_dirty_page(page, false);
390                 unlock_page(page);
391                 return -EROFS;
392         }
393 
394         redirty_page_for_writepage(wbc, page);
395         unlock_page(page);
396 
397         if (!inode)
398                 return 0;
399 
400         sb = inode->i_sb;
401 
402         if (wbc->sync_mode == WB_SYNC_ALL)
403                 err = nilfs_construct_segment(sb);
404         else if (wbc->for_reclaim)
405                 nilfs_flush_segment(sb, inode->i_ino);
406 
407         return err;
408 }
409 
410 
411 static const struct address_space_operations def_mdt_aops = {
412         .writepage              = nilfs_mdt_write_page,
413 };
414 
415 static const struct inode_operations def_mdt_iops;
416 static const struct file_operations def_mdt_fops;
417 
418 
419 int nilfs_mdt_init(struct inode *inode, gfp_t gfp_mask, size_t objsz)
420 {
421         struct nilfs_mdt_info *mi;
422 
423         mi = kzalloc(max(sizeof(*mi), objsz), GFP_NOFS);
424         if (!mi)
425                 return -ENOMEM;
426 
427         init_rwsem(&mi->mi_sem);
428         inode->i_private = mi;
429 
430         inode->i_mode = S_IFREG;
431         mapping_set_gfp_mask(inode->i_mapping, gfp_mask);
432         inode->i_mapping->backing_dev_info = inode->i_sb->s_bdi;
433 
434         inode->i_op = &def_mdt_iops;
435         inode->i_fop = &def_mdt_fops;
436         inode->i_mapping->a_ops = &def_mdt_aops;
437 
438         return 0;
439 }
440 
441 void nilfs_mdt_set_entry_size(struct inode *inode, unsigned entry_size,
442                               unsigned header_size)
443 {
444         struct nilfs_mdt_info *mi = NILFS_MDT(inode);
445 
446         mi->mi_entry_size = entry_size;
447         mi->mi_entries_per_block = (1 << inode->i_blkbits) / entry_size;
448         mi->mi_first_entry_offset = DIV_ROUND_UP(header_size, entry_size);
449 }
450 
451 /**
452  * nilfs_mdt_setup_shadow_map - setup shadow map and bind it to metadata file
453  * @inode: inode of the metadata file
454  * @shadow: shadow mapping
455  */
456 int nilfs_mdt_setup_shadow_map(struct inode *inode,
457                                struct nilfs_shadow_map *shadow)
458 {
459         struct nilfs_mdt_info *mi = NILFS_MDT(inode);
460         struct backing_dev_info *bdi = inode->i_sb->s_bdi;
461 
462         INIT_LIST_HEAD(&shadow->frozen_buffers);
463         address_space_init_once(&shadow->frozen_data);
464         nilfs_mapping_init(&shadow->frozen_data, inode, bdi);
465         address_space_init_once(&shadow->frozen_btnodes);
466         nilfs_mapping_init(&shadow->frozen_btnodes, inode, bdi);
467         mi->mi_shadow = shadow;
468         return 0;
469 }
470 
471 /**
472  * nilfs_mdt_save_to_shadow_map - copy bmap and dirty pages to shadow map
473  * @inode: inode of the metadata file
474  */
475 int nilfs_mdt_save_to_shadow_map(struct inode *inode)
476 {
477         struct nilfs_mdt_info *mi = NILFS_MDT(inode);
478         struct nilfs_inode_info *ii = NILFS_I(inode);
479         struct nilfs_shadow_map *shadow = mi->mi_shadow;
480         int ret;
481 
482         ret = nilfs_copy_dirty_pages(&shadow->frozen_data, inode->i_mapping);
483         if (ret)
484                 goto out;
485 
486         ret = nilfs_copy_dirty_pages(&shadow->frozen_btnodes,
487                                      &ii->i_btnode_cache);
488         if (ret)
489                 goto out;
490 
491         nilfs_bmap_save(ii->i_bmap, &shadow->bmap_store);
492  out:
493         return ret;
494 }
495 
496 int nilfs_mdt_freeze_buffer(struct inode *inode, struct buffer_head *bh)
497 {
498         struct nilfs_shadow_map *shadow = NILFS_MDT(inode)->mi_shadow;
499         struct buffer_head *bh_frozen;
500         struct page *page;
501         int blkbits = inode->i_blkbits;
502 
503         page = grab_cache_page(&shadow->frozen_data, bh->b_page->index);
504         if (!page)
505                 return -ENOMEM;
506 
507         if (!page_has_buffers(page))
508                 create_empty_buffers(page, 1 << blkbits, 0);
509 
510         bh_frozen = nilfs_page_get_nth_block(page, bh_offset(bh) >> blkbits);
511 
512         if (!buffer_uptodate(bh_frozen))
513                 nilfs_copy_buffer(bh_frozen, bh);
514         if (list_empty(&bh_frozen->b_assoc_buffers)) {
515                 list_add_tail(&bh_frozen->b_assoc_buffers,
516                               &shadow->frozen_buffers);
517                 set_buffer_nilfs_redirected(bh);
518         } else {
519                 brelse(bh_frozen); /* already frozen */
520         }
521 
522         unlock_page(page);
523         page_cache_release(page);
524         return 0;
525 }
526 
527 struct buffer_head *
528 nilfs_mdt_get_frozen_buffer(struct inode *inode, struct buffer_head *bh)
529 {
530         struct nilfs_shadow_map *shadow = NILFS_MDT(inode)->mi_shadow;
531         struct buffer_head *bh_frozen = NULL;
532         struct page *page;
533         int n;
534 
535         page = find_lock_page(&shadow->frozen_data, bh->b_page->index);
536         if (page) {
537                 if (page_has_buffers(page)) {
538                         n = bh_offset(bh) >> inode->i_blkbits;
539                         bh_frozen = nilfs_page_get_nth_block(page, n);
540                 }
541                 unlock_page(page);
542                 page_cache_release(page);
543         }
544         return bh_frozen;
545 }
546 
547 static void nilfs_release_frozen_buffers(struct nilfs_shadow_map *shadow)
548 {
549         struct list_head *head = &shadow->frozen_buffers;
550         struct buffer_head *bh;
551 
552         while (!list_empty(head)) {
553                 bh = list_first_entry(head, struct buffer_head,
554                                       b_assoc_buffers);
555                 list_del_init(&bh->b_assoc_buffers);
556                 brelse(bh); /* drop ref-count to make it releasable */
557         }
558 }
559 
560 /**
561  * nilfs_mdt_restore_from_shadow_map - restore dirty pages and bmap state
562  * @inode: inode of the metadata file
563  */
564 void nilfs_mdt_restore_from_shadow_map(struct inode *inode)
565 {
566         struct nilfs_mdt_info *mi = NILFS_MDT(inode);
567         struct nilfs_inode_info *ii = NILFS_I(inode);
568         struct nilfs_shadow_map *shadow = mi->mi_shadow;
569 
570         down_write(&mi->mi_sem);
571 
572         if (mi->mi_palloc_cache)
573                 nilfs_palloc_clear_cache(inode);
574 
575         nilfs_clear_dirty_pages(inode->i_mapping, true);
576         nilfs_copy_back_pages(inode->i_mapping, &shadow->frozen_data);
577 
578         nilfs_clear_dirty_pages(&ii->i_btnode_cache, true);
579         nilfs_copy_back_pages(&ii->i_btnode_cache, &shadow->frozen_btnodes);
580 
581         nilfs_bmap_restore(ii->i_bmap, &shadow->bmap_store);
582 
583         up_write(&mi->mi_sem);
584 }
585 
586 /**
587  * nilfs_mdt_clear_shadow_map - truncate pages in shadow map caches
588  * @inode: inode of the metadata file
589  */
590 void nilfs_mdt_clear_shadow_map(struct inode *inode)
591 {
592         struct nilfs_mdt_info *mi = NILFS_MDT(inode);
593         struct nilfs_shadow_map *shadow = mi->mi_shadow;
594 
595         down_write(&mi->mi_sem);
596         nilfs_release_frozen_buffers(shadow);
597         truncate_inode_pages(&shadow->frozen_data, 0);
598         truncate_inode_pages(&shadow->frozen_btnodes, 0);
599         up_write(&mi->mi_sem);
600 }
601 

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