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Linux/fs/nilfs2/alloc.c

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  1 // SPDX-License-Identifier: GPL-2.0+
  2 /*
  3  * alloc.c - NILFS dat/inode allocator
  4  *
  5  * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
  6  *
  7  * Originally written by Koji Sato.
  8  * Two allocators were unified by Ryusuke Konishi and Amagai Yoshiji.
  9  */
 10 
 11 #include <linux/types.h>
 12 #include <linux/buffer_head.h>
 13 #include <linux/fs.h>
 14 #include <linux/bitops.h>
 15 #include <linux/slab.h>
 16 #include "mdt.h"
 17 #include "alloc.h"
 18 
 19 
 20 /**
 21  * nilfs_palloc_groups_per_desc_block - get the number of groups that a group
 22  *                                      descriptor block can maintain
 23  * @inode: inode of metadata file using this allocator
 24  */
 25 static inline unsigned long
 26 nilfs_palloc_groups_per_desc_block(const struct inode *inode)
 27 {
 28         return i_blocksize(inode) /
 29                 sizeof(struct nilfs_palloc_group_desc);
 30 }
 31 
 32 /**
 33  * nilfs_palloc_groups_count - get maximum number of groups
 34  * @inode: inode of metadata file using this allocator
 35  */
 36 static inline unsigned long
 37 nilfs_palloc_groups_count(const struct inode *inode)
 38 {
 39         return 1UL << (BITS_PER_LONG - (inode->i_blkbits + 3 /* log2(8) */));
 40 }
 41 
 42 /**
 43  * nilfs_palloc_init_blockgroup - initialize private variables for allocator
 44  * @inode: inode of metadata file using this allocator
 45  * @entry_size: size of the persistent object
 46  */
 47 int nilfs_palloc_init_blockgroup(struct inode *inode, unsigned int entry_size)
 48 {
 49         struct nilfs_mdt_info *mi = NILFS_MDT(inode);
 50 
 51         mi->mi_bgl = kmalloc(sizeof(*mi->mi_bgl), GFP_NOFS);
 52         if (!mi->mi_bgl)
 53                 return -ENOMEM;
 54 
 55         bgl_lock_init(mi->mi_bgl);
 56 
 57         nilfs_mdt_set_entry_size(inode, entry_size, 0);
 58 
 59         mi->mi_blocks_per_group =
 60                 DIV_ROUND_UP(nilfs_palloc_entries_per_group(inode),
 61                              mi->mi_entries_per_block) + 1;
 62                 /*
 63                  * Number of blocks in a group including entry blocks
 64                  * and a bitmap block
 65                  */
 66         mi->mi_blocks_per_desc_block =
 67                 nilfs_palloc_groups_per_desc_block(inode) *
 68                 mi->mi_blocks_per_group + 1;
 69                 /*
 70                  * Number of blocks per descriptor including the
 71                  * descriptor block
 72                  */
 73         return 0;
 74 }
 75 
 76 /**
 77  * nilfs_palloc_group - get group number and offset from an entry number
 78  * @inode: inode of metadata file using this allocator
 79  * @nr: serial number of the entry (e.g. inode number)
 80  * @offset: pointer to store offset number in the group
 81  */
 82 static unsigned long nilfs_palloc_group(const struct inode *inode, __u64 nr,
 83                                         unsigned long *offset)
 84 {
 85         __u64 group = nr;
 86 
 87         *offset = do_div(group, nilfs_palloc_entries_per_group(inode));
 88         return group;
 89 }
 90 
 91 /**
 92  * nilfs_palloc_desc_blkoff - get block offset of a group descriptor block
 93  * @inode: inode of metadata file using this allocator
 94  * @group: group number
 95  *
 96  * nilfs_palloc_desc_blkoff() returns block offset of the descriptor
 97  * block which contains a descriptor of the specified group.
 98  */
 99 static unsigned long
100 nilfs_palloc_desc_blkoff(const struct inode *inode, unsigned long group)
101 {
102         unsigned long desc_block =
103                 group / nilfs_palloc_groups_per_desc_block(inode);
104         return desc_block * NILFS_MDT(inode)->mi_blocks_per_desc_block;
105 }
106 
107 /**
108  * nilfs_palloc_bitmap_blkoff - get block offset of a bitmap block
109  * @inode: inode of metadata file using this allocator
110  * @group: group number
111  *
112  * nilfs_palloc_bitmap_blkoff() returns block offset of the bitmap
113  * block used to allocate/deallocate entries in the specified group.
114  */
115 static unsigned long
116 nilfs_palloc_bitmap_blkoff(const struct inode *inode, unsigned long group)
117 {
118         unsigned long desc_offset =
119                 group % nilfs_palloc_groups_per_desc_block(inode);
120         return nilfs_palloc_desc_blkoff(inode, group) + 1 +
121                 desc_offset * NILFS_MDT(inode)->mi_blocks_per_group;
122 }
123 
124 /**
125  * nilfs_palloc_group_desc_nfrees - get the number of free entries in a group
126  * @desc: pointer to descriptor structure for the group
127  * @lock: spin lock protecting @desc
128  */
129 static unsigned long
130 nilfs_palloc_group_desc_nfrees(const struct nilfs_palloc_group_desc *desc,
131                                spinlock_t *lock)
132 {
133         unsigned long nfree;
134 
135         spin_lock(lock);
136         nfree = le32_to_cpu(desc->pg_nfrees);
137         spin_unlock(lock);
138         return nfree;
139 }
140 
141 /**
142  * nilfs_palloc_group_desc_add_entries - adjust count of free entries
143  * @desc: pointer to descriptor structure for the group
144  * @lock: spin lock protecting @desc
145  * @n: delta to be added
146  */
147 static u32
148 nilfs_palloc_group_desc_add_entries(struct nilfs_palloc_group_desc *desc,
149                                     spinlock_t *lock, u32 n)
150 {
151         u32 nfree;
152 
153         spin_lock(lock);
154         le32_add_cpu(&desc->pg_nfrees, n);
155         nfree = le32_to_cpu(desc->pg_nfrees);
156         spin_unlock(lock);
157         return nfree;
158 }
159 
160 /**
161  * nilfs_palloc_entry_blkoff - get block offset of an entry block
162  * @inode: inode of metadata file using this allocator
163  * @nr: serial number of the entry (e.g. inode number)
164  */
165 static unsigned long
166 nilfs_palloc_entry_blkoff(const struct inode *inode, __u64 nr)
167 {
168         unsigned long group, group_offset;
169 
170         group = nilfs_palloc_group(inode, nr, &group_offset);
171 
172         return nilfs_palloc_bitmap_blkoff(inode, group) + 1 +
173                 group_offset / NILFS_MDT(inode)->mi_entries_per_block;
174 }
175 
176 /**
177  * nilfs_palloc_desc_block_init - initialize buffer of a group descriptor block
178  * @inode: inode of metadata file
179  * @bh: buffer head of the buffer to be initialized
180  * @kaddr: kernel address mapped for the page including the buffer
181  */
182 static void nilfs_palloc_desc_block_init(struct inode *inode,
183                                          struct buffer_head *bh, void *kaddr)
184 {
185         struct nilfs_palloc_group_desc *desc = kaddr + bh_offset(bh);
186         unsigned long n = nilfs_palloc_groups_per_desc_block(inode);
187         __le32 nfrees;
188 
189         nfrees = cpu_to_le32(nilfs_palloc_entries_per_group(inode));
190         while (n-- > 0) {
191                 desc->pg_nfrees = nfrees;
192                 desc++;
193         }
194 }
195 
196 static int nilfs_palloc_get_block(struct inode *inode, unsigned long blkoff,
197                                   int create,
198                                   void (*init_block)(struct inode *,
199                                                      struct buffer_head *,
200                                                      void *),
201                                   struct buffer_head **bhp,
202                                   struct nilfs_bh_assoc *prev,
203                                   spinlock_t *lock)
204 {
205         int ret;
206 
207         spin_lock(lock);
208         if (prev->bh && blkoff == prev->blkoff) {
209                 get_bh(prev->bh);
210                 *bhp = prev->bh;
211                 spin_unlock(lock);
212                 return 0;
213         }
214         spin_unlock(lock);
215 
216         ret = nilfs_mdt_get_block(inode, blkoff, create, init_block, bhp);
217         if (!ret) {
218                 spin_lock(lock);
219                 /*
220                  * The following code must be safe for change of the
221                  * cache contents during the get block call.
222                  */
223                 brelse(prev->bh);
224                 get_bh(*bhp);
225                 prev->bh = *bhp;
226                 prev->blkoff = blkoff;
227                 spin_unlock(lock);
228         }
229         return ret;
230 }
231 
232 /**
233  * nilfs_palloc_delete_block - delete a block on the persistent allocator file
234  * @inode: inode of metadata file using this allocator
235  * @blkoff: block offset
236  * @prev: nilfs_bh_assoc struct of the last used buffer
237  * @lock: spin lock protecting @prev
238  */
239 static int nilfs_palloc_delete_block(struct inode *inode, unsigned long blkoff,
240                                      struct nilfs_bh_assoc *prev,
241                                      spinlock_t *lock)
242 {
243         spin_lock(lock);
244         if (prev->bh && blkoff == prev->blkoff) {
245                 brelse(prev->bh);
246                 prev->bh = NULL;
247         }
248         spin_unlock(lock);
249         return nilfs_mdt_delete_block(inode, blkoff);
250 }
251 
252 /**
253  * nilfs_palloc_get_desc_block - get buffer head of a group descriptor block
254  * @inode: inode of metadata file using this allocator
255  * @group: group number
256  * @create: create flag
257  * @bhp: pointer to store the resultant buffer head
258  */
259 static int nilfs_palloc_get_desc_block(struct inode *inode,
260                                        unsigned long group,
261                                        int create, struct buffer_head **bhp)
262 {
263         struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;
264 
265         return nilfs_palloc_get_block(inode,
266                                       nilfs_palloc_desc_blkoff(inode, group),
267                                       create, nilfs_palloc_desc_block_init,
268                                       bhp, &cache->prev_desc, &cache->lock);
269 }
270 
271 /**
272  * nilfs_palloc_get_bitmap_block - get buffer head of a bitmap block
273  * @inode: inode of metadata file using this allocator
274  * @group: group number
275  * @create: create flag
276  * @bhp: pointer to store the resultant buffer head
277  */
278 static int nilfs_palloc_get_bitmap_block(struct inode *inode,
279                                          unsigned long group,
280                                          int create, struct buffer_head **bhp)
281 {
282         struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;
283 
284         return nilfs_palloc_get_block(inode,
285                                       nilfs_palloc_bitmap_blkoff(inode, group),
286                                       create, NULL, bhp,
287                                       &cache->prev_bitmap, &cache->lock);
288 }
289 
290 /**
291  * nilfs_palloc_delete_bitmap_block - delete a bitmap block
292  * @inode: inode of metadata file using this allocator
293  * @group: group number
294  */
295 static int nilfs_palloc_delete_bitmap_block(struct inode *inode,
296                                             unsigned long group)
297 {
298         struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;
299 
300         return nilfs_palloc_delete_block(inode,
301                                          nilfs_palloc_bitmap_blkoff(inode,
302                                                                     group),
303                                          &cache->prev_bitmap, &cache->lock);
304 }
305 
306 /**
307  * nilfs_palloc_get_entry_block - get buffer head of an entry block
308  * @inode: inode of metadata file using this allocator
309  * @nr: serial number of the entry (e.g. inode number)
310  * @create: create flag
311  * @bhp: pointer to store the resultant buffer head
312  */
313 int nilfs_palloc_get_entry_block(struct inode *inode, __u64 nr,
314                                  int create, struct buffer_head **bhp)
315 {
316         struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;
317 
318         return nilfs_palloc_get_block(inode,
319                                       nilfs_palloc_entry_blkoff(inode, nr),
320                                       create, NULL, bhp,
321                                       &cache->prev_entry, &cache->lock);
322 }
323 
324 /**
325  * nilfs_palloc_delete_entry_block - delete an entry block
326  * @inode: inode of metadata file using this allocator
327  * @nr: serial number of the entry
328  */
329 static int nilfs_palloc_delete_entry_block(struct inode *inode, __u64 nr)
330 {
331         struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;
332 
333         return nilfs_palloc_delete_block(inode,
334                                          nilfs_palloc_entry_blkoff(inode, nr),
335                                          &cache->prev_entry, &cache->lock);
336 }
337 
338 /**
339  * nilfs_palloc_block_get_group_desc - get kernel address of a group descriptor
340  * @inode: inode of metadata file using this allocator
341  * @group: group number
342  * @bh: buffer head of the buffer storing the group descriptor block
343  * @kaddr: kernel address mapped for the page including the buffer
344  */
345 static struct nilfs_palloc_group_desc *
346 nilfs_palloc_block_get_group_desc(const struct inode *inode,
347                                   unsigned long group,
348                                   const struct buffer_head *bh, void *kaddr)
349 {
350         return (struct nilfs_palloc_group_desc *)(kaddr + bh_offset(bh)) +
351                 group % nilfs_palloc_groups_per_desc_block(inode);
352 }
353 
354 /**
355  * nilfs_palloc_block_get_entry - get kernel address of an entry
356  * @inode: inode of metadata file using this allocator
357  * @nr: serial number of the entry (e.g. inode number)
358  * @bh: buffer head of the buffer storing the entry block
359  * @kaddr: kernel address mapped for the page including the buffer
360  */
361 void *nilfs_palloc_block_get_entry(const struct inode *inode, __u64 nr,
362                                    const struct buffer_head *bh, void *kaddr)
363 {
364         unsigned long entry_offset, group_offset;
365 
366         nilfs_palloc_group(inode, nr, &group_offset);
367         entry_offset = group_offset % NILFS_MDT(inode)->mi_entries_per_block;
368 
369         return kaddr + bh_offset(bh) +
370                 entry_offset * NILFS_MDT(inode)->mi_entry_size;
371 }
372 
373 /**
374  * nilfs_palloc_find_available_slot - find available slot in a group
375  * @bitmap: bitmap of the group
376  * @target: offset number of an entry in the group (start point)
377  * @bsize: size in bits
378  * @lock: spin lock protecting @bitmap
379  */
380 static int nilfs_palloc_find_available_slot(unsigned char *bitmap,
381                                             unsigned long target,
382                                             unsigned int bsize,
383                                             spinlock_t *lock)
384 {
385         int pos, end = bsize;
386 
387         if (likely(target < bsize)) {
388                 pos = target;
389                 do {
390                         pos = nilfs_find_next_zero_bit(bitmap, end, pos);
391                         if (pos >= end)
392                                 break;
393                         if (!nilfs_set_bit_atomic(lock, pos, bitmap))
394                                 return pos;
395                 } while (++pos < end);
396 
397                 end = target;
398         }
399 
400         /* wrap around */
401         for (pos = 0; pos < end; pos++) {
402                 pos = nilfs_find_next_zero_bit(bitmap, end, pos);
403                 if (pos >= end)
404                         break;
405                 if (!nilfs_set_bit_atomic(lock, pos, bitmap))
406                         return pos;
407         }
408 
409         return -ENOSPC;
410 }
411 
412 /**
413  * nilfs_palloc_rest_groups_in_desc_block - get the remaining number of groups
414  *                                          in a group descriptor block
415  * @inode: inode of metadata file using this allocator
416  * @curr: current group number
417  * @max: maximum number of groups
418  */
419 static unsigned long
420 nilfs_palloc_rest_groups_in_desc_block(const struct inode *inode,
421                                        unsigned long curr, unsigned long max)
422 {
423         return min_t(unsigned long,
424                      nilfs_palloc_groups_per_desc_block(inode) -
425                      curr % nilfs_palloc_groups_per_desc_block(inode),
426                      max - curr + 1);
427 }
428 
429 /**
430  * nilfs_palloc_count_desc_blocks - count descriptor blocks number
431  * @inode: inode of metadata file using this allocator
432  * @desc_blocks: descriptor blocks number [out]
433  */
434 static int nilfs_palloc_count_desc_blocks(struct inode *inode,
435                                             unsigned long *desc_blocks)
436 {
437         __u64 blknum;
438         int ret;
439 
440         ret = nilfs_bmap_last_key(NILFS_I(inode)->i_bmap, &blknum);
441         if (likely(!ret))
442                 *desc_blocks = DIV_ROUND_UP(
443                         (unsigned long)blknum,
444                         NILFS_MDT(inode)->mi_blocks_per_desc_block);
445         return ret;
446 }
447 
448 /**
449  * nilfs_palloc_mdt_file_can_grow - check potential opportunity for
450  *                                      MDT file growing
451  * @inode: inode of metadata file using this allocator
452  * @desc_blocks: known current descriptor blocks count
453  */
454 static inline bool nilfs_palloc_mdt_file_can_grow(struct inode *inode,
455                                                     unsigned long desc_blocks)
456 {
457         return (nilfs_palloc_groups_per_desc_block(inode) * desc_blocks) <
458                         nilfs_palloc_groups_count(inode);
459 }
460 
461 /**
462  * nilfs_palloc_count_max_entries - count max number of entries that can be
463  *                                      described by descriptor blocks count
464  * @inode: inode of metadata file using this allocator
465  * @nused: current number of used entries
466  * @nmaxp: max number of entries [out]
467  */
468 int nilfs_palloc_count_max_entries(struct inode *inode, u64 nused, u64 *nmaxp)
469 {
470         unsigned long desc_blocks = 0;
471         u64 entries_per_desc_block, nmax;
472         int err;
473 
474         err = nilfs_palloc_count_desc_blocks(inode, &desc_blocks);
475         if (unlikely(err))
476                 return err;
477 
478         entries_per_desc_block = (u64)nilfs_palloc_entries_per_group(inode) *
479                                 nilfs_palloc_groups_per_desc_block(inode);
480         nmax = entries_per_desc_block * desc_blocks;
481 
482         if (nused == nmax &&
483                         nilfs_palloc_mdt_file_can_grow(inode, desc_blocks))
484                 nmax += entries_per_desc_block;
485 
486         if (nused > nmax)
487                 return -ERANGE;
488 
489         *nmaxp = nmax;
490         return 0;
491 }
492 
493 /**
494  * nilfs_palloc_prepare_alloc_entry - prepare to allocate a persistent object
495  * @inode: inode of metadata file using this allocator
496  * @req: nilfs_palloc_req structure exchanged for the allocation
497  */
498 int nilfs_palloc_prepare_alloc_entry(struct inode *inode,
499                                      struct nilfs_palloc_req *req)
500 {
501         struct buffer_head *desc_bh, *bitmap_bh;
502         struct nilfs_palloc_group_desc *desc;
503         unsigned char *bitmap;
504         void *desc_kaddr, *bitmap_kaddr;
505         unsigned long group, maxgroup, ngroups;
506         unsigned long group_offset, maxgroup_offset;
507         unsigned long n, entries_per_group;
508         unsigned long i, j;
509         spinlock_t *lock;
510         int pos, ret;
511 
512         ngroups = nilfs_palloc_groups_count(inode);
513         maxgroup = ngroups - 1;
514         group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);
515         entries_per_group = nilfs_palloc_entries_per_group(inode);
516 
517         for (i = 0; i < ngroups; i += n) {
518                 if (group >= ngroups) {
519                         /* wrap around */
520                         group = 0;
521                         maxgroup = nilfs_palloc_group(inode, req->pr_entry_nr,
522                                                       &maxgroup_offset) - 1;
523                 }
524                 ret = nilfs_palloc_get_desc_block(inode, group, 1, &desc_bh);
525                 if (ret < 0)
526                         return ret;
527                 desc_kaddr = kmap(desc_bh->b_page);
528                 desc = nilfs_palloc_block_get_group_desc(
529                         inode, group, desc_bh, desc_kaddr);
530                 n = nilfs_palloc_rest_groups_in_desc_block(inode, group,
531                                                            maxgroup);
532                 for (j = 0; j < n; j++, desc++, group++) {
533                         lock = nilfs_mdt_bgl_lock(inode, group);
534                         if (nilfs_palloc_group_desc_nfrees(desc, lock) > 0) {
535                                 ret = nilfs_palloc_get_bitmap_block(
536                                         inode, group, 1, &bitmap_bh);
537                                 if (ret < 0)
538                                         goto out_desc;
539                                 bitmap_kaddr = kmap(bitmap_bh->b_page);
540                                 bitmap = bitmap_kaddr + bh_offset(bitmap_bh);
541                                 pos = nilfs_palloc_find_available_slot(
542                                         bitmap, group_offset,
543                                         entries_per_group, lock);
544                                 if (pos >= 0) {
545                                         /* found a free entry */
546                                         nilfs_palloc_group_desc_add_entries(
547                                                 desc, lock, -1);
548                                         req->pr_entry_nr =
549                                                 entries_per_group * group + pos;
550                                         kunmap(desc_bh->b_page);
551                                         kunmap(bitmap_bh->b_page);
552 
553                                         req->pr_desc_bh = desc_bh;
554                                         req->pr_bitmap_bh = bitmap_bh;
555                                         return 0;
556                                 }
557                                 kunmap(bitmap_bh->b_page);
558                                 brelse(bitmap_bh);
559                         }
560 
561                         group_offset = 0;
562                 }
563 
564                 kunmap(desc_bh->b_page);
565                 brelse(desc_bh);
566         }
567 
568         /* no entries left */
569         return -ENOSPC;
570 
571  out_desc:
572         kunmap(desc_bh->b_page);
573         brelse(desc_bh);
574         return ret;
575 }
576 
577 /**
578  * nilfs_palloc_commit_alloc_entry - finish allocation of a persistent object
579  * @inode: inode of metadata file using this allocator
580  * @req: nilfs_palloc_req structure exchanged for the allocation
581  */
582 void nilfs_palloc_commit_alloc_entry(struct inode *inode,
583                                      struct nilfs_palloc_req *req)
584 {
585         mark_buffer_dirty(req->pr_bitmap_bh);
586         mark_buffer_dirty(req->pr_desc_bh);
587         nilfs_mdt_mark_dirty(inode);
588 
589         brelse(req->pr_bitmap_bh);
590         brelse(req->pr_desc_bh);
591 }
592 
593 /**
594  * nilfs_palloc_commit_free_entry - finish deallocating a persistent object
595  * @inode: inode of metadata file using this allocator
596  * @req: nilfs_palloc_req structure exchanged for the removal
597  */
598 void nilfs_palloc_commit_free_entry(struct inode *inode,
599                                     struct nilfs_palloc_req *req)
600 {
601         struct nilfs_palloc_group_desc *desc;
602         unsigned long group, group_offset;
603         unsigned char *bitmap;
604         void *desc_kaddr, *bitmap_kaddr;
605         spinlock_t *lock;
606 
607         group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);
608         desc_kaddr = kmap(req->pr_desc_bh->b_page);
609         desc = nilfs_palloc_block_get_group_desc(inode, group,
610                                                  req->pr_desc_bh, desc_kaddr);
611         bitmap_kaddr = kmap(req->pr_bitmap_bh->b_page);
612         bitmap = bitmap_kaddr + bh_offset(req->pr_bitmap_bh);
613         lock = nilfs_mdt_bgl_lock(inode, group);
614 
615         if (!nilfs_clear_bit_atomic(lock, group_offset, bitmap))
616                 nilfs_warn(inode->i_sb,
617                            "%s (ino=%lu): entry number %llu already freed",
618                            __func__, inode->i_ino,
619                            (unsigned long long)req->pr_entry_nr);
620         else
621                 nilfs_palloc_group_desc_add_entries(desc, lock, 1);
622 
623         kunmap(req->pr_bitmap_bh->b_page);
624         kunmap(req->pr_desc_bh->b_page);
625 
626         mark_buffer_dirty(req->pr_desc_bh);
627         mark_buffer_dirty(req->pr_bitmap_bh);
628         nilfs_mdt_mark_dirty(inode);
629 
630         brelse(req->pr_bitmap_bh);
631         brelse(req->pr_desc_bh);
632 }
633 
634 /**
635  * nilfs_palloc_abort_alloc_entry - cancel allocation of a persistent object
636  * @inode: inode of metadata file using this allocator
637  * @req: nilfs_palloc_req structure exchanged for the allocation
638  */
639 void nilfs_palloc_abort_alloc_entry(struct inode *inode,
640                                     struct nilfs_palloc_req *req)
641 {
642         struct nilfs_palloc_group_desc *desc;
643         void *desc_kaddr, *bitmap_kaddr;
644         unsigned char *bitmap;
645         unsigned long group, group_offset;
646         spinlock_t *lock;
647 
648         group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);
649         desc_kaddr = kmap(req->pr_desc_bh->b_page);
650         desc = nilfs_palloc_block_get_group_desc(inode, group,
651                                                  req->pr_desc_bh, desc_kaddr);
652         bitmap_kaddr = kmap(req->pr_bitmap_bh->b_page);
653         bitmap = bitmap_kaddr + bh_offset(req->pr_bitmap_bh);
654         lock = nilfs_mdt_bgl_lock(inode, group);
655 
656         if (!nilfs_clear_bit_atomic(lock, group_offset, bitmap))
657                 nilfs_warn(inode->i_sb,
658                            "%s (ino=%lu): entry number %llu already freed",
659                            __func__, inode->i_ino,
660                            (unsigned long long)req->pr_entry_nr);
661         else
662                 nilfs_palloc_group_desc_add_entries(desc, lock, 1);
663 
664         kunmap(req->pr_bitmap_bh->b_page);
665         kunmap(req->pr_desc_bh->b_page);
666 
667         brelse(req->pr_bitmap_bh);
668         brelse(req->pr_desc_bh);
669 
670         req->pr_entry_nr = 0;
671         req->pr_bitmap_bh = NULL;
672         req->pr_desc_bh = NULL;
673 }
674 
675 /**
676  * nilfs_palloc_prepare_free_entry - prepare to deallocate a persistent object
677  * @inode: inode of metadata file using this allocator
678  * @req: nilfs_palloc_req structure exchanged for the removal
679  */
680 int nilfs_palloc_prepare_free_entry(struct inode *inode,
681                                     struct nilfs_palloc_req *req)
682 {
683         struct buffer_head *desc_bh, *bitmap_bh;
684         unsigned long group, group_offset;
685         int ret;
686 
687         group = nilfs_palloc_group(inode, req->pr_entry_nr, &group_offset);
688         ret = nilfs_palloc_get_desc_block(inode, group, 1, &desc_bh);
689         if (ret < 0)
690                 return ret;
691         ret = nilfs_palloc_get_bitmap_block(inode, group, 1, &bitmap_bh);
692         if (ret < 0) {
693                 brelse(desc_bh);
694                 return ret;
695         }
696 
697         req->pr_desc_bh = desc_bh;
698         req->pr_bitmap_bh = bitmap_bh;
699         return 0;
700 }
701 
702 /**
703  * nilfs_palloc_abort_free_entry - cancel deallocating a persistent object
704  * @inode: inode of metadata file using this allocator
705  * @req: nilfs_palloc_req structure exchanged for the removal
706  */
707 void nilfs_palloc_abort_free_entry(struct inode *inode,
708                                    struct nilfs_palloc_req *req)
709 {
710         brelse(req->pr_bitmap_bh);
711         brelse(req->pr_desc_bh);
712 
713         req->pr_entry_nr = 0;
714         req->pr_bitmap_bh = NULL;
715         req->pr_desc_bh = NULL;
716 }
717 
718 /**
719  * nilfs_palloc_freev - deallocate a set of persistent objects
720  * @inode: inode of metadata file using this allocator
721  * @entry_nrs: array of entry numbers to be deallocated
722  * @nitems: number of entries stored in @entry_nrs
723  */
724 int nilfs_palloc_freev(struct inode *inode, __u64 *entry_nrs, size_t nitems)
725 {
726         struct buffer_head *desc_bh, *bitmap_bh;
727         struct nilfs_palloc_group_desc *desc;
728         unsigned char *bitmap;
729         void *desc_kaddr, *bitmap_kaddr;
730         unsigned long group, group_offset;
731         __u64 group_min_nr, last_nrs[8];
732         const unsigned long epg = nilfs_palloc_entries_per_group(inode);
733         const unsigned int epb = NILFS_MDT(inode)->mi_entries_per_block;
734         unsigned int entry_start, end, pos;
735         spinlock_t *lock;
736         int i, j, k, ret;
737         u32 nfree;
738 
739         for (i = 0; i < nitems; i = j) {
740                 int change_group = false;
741                 int nempties = 0, n = 0;
742 
743                 group = nilfs_palloc_group(inode, entry_nrs[i], &group_offset);
744                 ret = nilfs_palloc_get_desc_block(inode, group, 0, &desc_bh);
745                 if (ret < 0)
746                         return ret;
747                 ret = nilfs_palloc_get_bitmap_block(inode, group, 0,
748                                                     &bitmap_bh);
749                 if (ret < 0) {
750                         brelse(desc_bh);
751                         return ret;
752                 }
753 
754                 /* Get the first entry number of the group */
755                 group_min_nr = (__u64)group * epg;
756 
757                 bitmap_kaddr = kmap(bitmap_bh->b_page);
758                 bitmap = bitmap_kaddr + bh_offset(bitmap_bh);
759                 lock = nilfs_mdt_bgl_lock(inode, group);
760 
761                 j = i;
762                 entry_start = rounddown(group_offset, epb);
763                 do {
764                         if (!nilfs_clear_bit_atomic(lock, group_offset,
765                                                     bitmap)) {
766                                 nilfs_warn(inode->i_sb,
767                                            "%s (ino=%lu): entry number %llu already freed",
768                                            __func__, inode->i_ino,
769                                            (unsigned long long)entry_nrs[j]);
770                         } else {
771                                 n++;
772                         }
773 
774                         j++;
775                         if (j >= nitems || entry_nrs[j] < group_min_nr ||
776                             entry_nrs[j] >= group_min_nr + epg) {
777                                 change_group = true;
778                         } else {
779                                 group_offset = entry_nrs[j] - group_min_nr;
780                                 if (group_offset >= entry_start &&
781                                     group_offset < entry_start + epb) {
782                                         /* This entry is in the same block */
783                                         continue;
784                                 }
785                         }
786 
787                         /* Test if the entry block is empty or not */
788                         end = entry_start + epb;
789                         pos = nilfs_find_next_bit(bitmap, end, entry_start);
790                         if (pos >= end) {
791                                 last_nrs[nempties++] = entry_nrs[j - 1];
792                                 if (nempties >= ARRAY_SIZE(last_nrs))
793                                         break;
794                         }
795 
796                         if (change_group)
797                                 break;
798 
799                         /* Go on to the next entry block */
800                         entry_start = rounddown(group_offset, epb);
801                 } while (true);
802 
803                 kunmap(bitmap_bh->b_page);
804                 mark_buffer_dirty(bitmap_bh);
805                 brelse(bitmap_bh);
806 
807                 for (k = 0; k < nempties; k++) {
808                         ret = nilfs_palloc_delete_entry_block(inode,
809                                                               last_nrs[k]);
810                         if (ret && ret != -ENOENT)
811                                 nilfs_warn(inode->i_sb,
812                                            "error %d deleting block that object (entry=%llu, ino=%lu) belongs to",
813                                            ret, (unsigned long long)last_nrs[k],
814                                            inode->i_ino);
815                 }
816 
817                 desc_kaddr = kmap_atomic(desc_bh->b_page);
818                 desc = nilfs_palloc_block_get_group_desc(
819                         inode, group, desc_bh, desc_kaddr);
820                 nfree = nilfs_palloc_group_desc_add_entries(desc, lock, n);
821                 kunmap_atomic(desc_kaddr);
822                 mark_buffer_dirty(desc_bh);
823                 nilfs_mdt_mark_dirty(inode);
824                 brelse(desc_bh);
825 
826                 if (nfree == nilfs_palloc_entries_per_group(inode)) {
827                         ret = nilfs_palloc_delete_bitmap_block(inode, group);
828                         if (ret && ret != -ENOENT)
829                                 nilfs_warn(inode->i_sb,
830                                            "error %d deleting bitmap block of group=%lu, ino=%lu",
831                                            ret, group, inode->i_ino);
832                 }
833         }
834         return 0;
835 }
836 
837 void nilfs_palloc_setup_cache(struct inode *inode,
838                               struct nilfs_palloc_cache *cache)
839 {
840         NILFS_MDT(inode)->mi_palloc_cache = cache;
841         spin_lock_init(&cache->lock);
842 }
843 
844 void nilfs_palloc_clear_cache(struct inode *inode)
845 {
846         struct nilfs_palloc_cache *cache = NILFS_MDT(inode)->mi_palloc_cache;
847 
848         spin_lock(&cache->lock);
849         brelse(cache->prev_desc.bh);
850         brelse(cache->prev_bitmap.bh);
851         brelse(cache->prev_entry.bh);
852         cache->prev_desc.bh = NULL;
853         cache->prev_bitmap.bh = NULL;
854         cache->prev_entry.bh = NULL;
855         spin_unlock(&cache->lock);
856 }
857 
858 void nilfs_palloc_destroy_cache(struct inode *inode)
859 {
860         nilfs_palloc_clear_cache(inode);
861         NILFS_MDT(inode)->mi_palloc_cache = NULL;
862 }
863 

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