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Linux/fs/ext4/balloc.c

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  1 /*
  2  *  linux/fs/ext4/balloc.c
  3  *
  4  * Copyright (C) 1992, 1993, 1994, 1995
  5  * Remy Card (card@masi.ibp.fr)
  6  * Laboratoire MASI - Institut Blaise Pascal
  7  * Universite Pierre et Marie Curie (Paris VI)
  8  *
  9  *  Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
 10  *  Big-endian to little-endian byte-swapping/bitmaps by
 11  *        David S. Miller (davem@caip.rutgers.edu), 1995
 12  */
 13 
 14 #include <linux/time.h>
 15 #include <linux/capability.h>
 16 #include <linux/fs.h>
 17 #include <linux/quotaops.h>
 18 #include <linux/buffer_head.h>
 19 #include "ext4.h"
 20 #include "ext4_jbd2.h"
 21 #include "mballoc.h"
 22 
 23 #include <trace/events/ext4.h>
 24 
 25 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
 26                                             ext4_group_t block_group);
 27 /*
 28  * balloc.c contains the blocks allocation and deallocation routines
 29  */
 30 
 31 /*
 32  * Calculate block group number for a given block number
 33  */
 34 ext4_group_t ext4_get_group_number(struct super_block *sb,
 35                                    ext4_fsblk_t block)
 36 {
 37         ext4_group_t group;
 38 
 39         if (test_opt2(sb, STD_GROUP_SIZE))
 40                 group = (block -
 41                          le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block)) >>
 42                         (EXT4_BLOCK_SIZE_BITS(sb) + EXT4_CLUSTER_BITS(sb) + 3);
 43         else
 44                 ext4_get_group_no_and_offset(sb, block, &group, NULL);
 45         return group;
 46 }
 47 
 48 /*
 49  * Calculate the block group number and offset into the block/cluster
 50  * allocation bitmap, given a block number
 51  */
 52 void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
 53                 ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp)
 54 {
 55         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
 56         ext4_grpblk_t offset;
 57 
 58         blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
 59         offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb)) >>
 60                 EXT4_SB(sb)->s_cluster_bits;
 61         if (offsetp)
 62                 *offsetp = offset;
 63         if (blockgrpp)
 64                 *blockgrpp = blocknr;
 65 
 66 }
 67 
 68 /*
 69  * Check whether the 'block' lives within the 'block_group'. Returns 1 if so
 70  * and 0 otherwise.
 71  */
 72 static inline int ext4_block_in_group(struct super_block *sb,
 73                                       ext4_fsblk_t block,
 74                                       ext4_group_t block_group)
 75 {
 76         ext4_group_t actual_group;
 77 
 78         actual_group = ext4_get_group_number(sb, block);
 79         return (actual_group == block_group) ? 1 : 0;
 80 }
 81 
 82 /* Return the number of clusters used for file system metadata; this
 83  * represents the overhead needed by the file system.
 84  */
 85 static unsigned ext4_num_overhead_clusters(struct super_block *sb,
 86                                            ext4_group_t block_group,
 87                                            struct ext4_group_desc *gdp)
 88 {
 89         unsigned num_clusters;
 90         int block_cluster = -1, inode_cluster = -1, itbl_cluster = -1, i, c;
 91         ext4_fsblk_t start = ext4_group_first_block_no(sb, block_group);
 92         ext4_fsblk_t itbl_blk;
 93         struct ext4_sb_info *sbi = EXT4_SB(sb);
 94 
 95         /* This is the number of clusters used by the superblock,
 96          * block group descriptors, and reserved block group
 97          * descriptor blocks */
 98         num_clusters = ext4_num_base_meta_clusters(sb, block_group);
 99 
100         /*
101          * For the allocation bitmaps and inode table, we first need
102          * to check to see if the block is in the block group.  If it
103          * is, then check to see if the cluster is already accounted
104          * for in the clusters used for the base metadata cluster, or
105          * if we can increment the base metadata cluster to include
106          * that block.  Otherwise, we will have to track the cluster
107          * used for the allocation bitmap or inode table explicitly.
108          * Normally all of these blocks are contiguous, so the special
109          * case handling shouldn't be necessary except for *very*
110          * unusual file system layouts.
111          */
112         if (ext4_block_in_group(sb, ext4_block_bitmap(sb, gdp), block_group)) {
113                 block_cluster = EXT4_B2C(sbi,
114                                          ext4_block_bitmap(sb, gdp) - start);
115                 if (block_cluster < num_clusters)
116                         block_cluster = -1;
117                 else if (block_cluster == num_clusters) {
118                         num_clusters++;
119                         block_cluster = -1;
120                 }
121         }
122 
123         if (ext4_block_in_group(sb, ext4_inode_bitmap(sb, gdp), block_group)) {
124                 inode_cluster = EXT4_B2C(sbi,
125                                          ext4_inode_bitmap(sb, gdp) - start);
126                 if (inode_cluster < num_clusters)
127                         inode_cluster = -1;
128                 else if (inode_cluster == num_clusters) {
129                         num_clusters++;
130                         inode_cluster = -1;
131                 }
132         }
133 
134         itbl_blk = ext4_inode_table(sb, gdp);
135         for (i = 0; i < sbi->s_itb_per_group; i++) {
136                 if (ext4_block_in_group(sb, itbl_blk + i, block_group)) {
137                         c = EXT4_B2C(sbi, itbl_blk + i - start);
138                         if ((c < num_clusters) || (c == inode_cluster) ||
139                             (c == block_cluster) || (c == itbl_cluster))
140                                 continue;
141                         if (c == num_clusters) {
142                                 num_clusters++;
143                                 continue;
144                         }
145                         num_clusters++;
146                         itbl_cluster = c;
147                 }
148         }
149 
150         if (block_cluster != -1)
151                 num_clusters++;
152         if (inode_cluster != -1)
153                 num_clusters++;
154 
155         return num_clusters;
156 }
157 
158 static unsigned int num_clusters_in_group(struct super_block *sb,
159                                           ext4_group_t block_group)
160 {
161         unsigned int blocks;
162 
163         if (block_group == ext4_get_groups_count(sb) - 1) {
164                 /*
165                  * Even though mke2fs always initializes the first and
166                  * last group, just in case some other tool was used,
167                  * we need to make sure we calculate the right free
168                  * blocks.
169                  */
170                 blocks = ext4_blocks_count(EXT4_SB(sb)->s_es) -
171                         ext4_group_first_block_no(sb, block_group);
172         } else
173                 blocks = EXT4_BLOCKS_PER_GROUP(sb);
174         return EXT4_NUM_B2C(EXT4_SB(sb), blocks);
175 }
176 
177 /* Initializes an uninitialized block bitmap */
178 static int ext4_init_block_bitmap(struct super_block *sb,
179                                    struct buffer_head *bh,
180                                    ext4_group_t block_group,
181                                    struct ext4_group_desc *gdp)
182 {
183         unsigned int bit, bit_max;
184         struct ext4_sb_info *sbi = EXT4_SB(sb);
185         ext4_fsblk_t start, tmp;
186         int flex_bg = 0;
187         struct ext4_group_info *grp;
188 
189         J_ASSERT_BH(bh, buffer_locked(bh));
190 
191         /* If checksum is bad mark all blocks used to prevent allocation
192          * essentially implementing a per-group read-only flag. */
193         if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
194                 grp = ext4_get_group_info(sb, block_group);
195                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
196                         percpu_counter_sub(&sbi->s_freeclusters_counter,
197                                            grp->bb_free);
198                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
199                 if (!EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) {
200                         int count;
201                         count = ext4_free_inodes_count(sb, gdp);
202                         percpu_counter_sub(&sbi->s_freeinodes_counter,
203                                            count);
204                 }
205                 set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
206                 return -EFSBADCRC;
207         }
208         memset(bh->b_data, 0, sb->s_blocksize);
209 
210         bit_max = ext4_num_base_meta_clusters(sb, block_group);
211         for (bit = 0; bit < bit_max; bit++)
212                 ext4_set_bit(bit, bh->b_data);
213 
214         start = ext4_group_first_block_no(sb, block_group);
215 
216         if (ext4_has_feature_flex_bg(sb))
217                 flex_bg = 1;
218 
219         /* Set bits for block and inode bitmaps, and inode table */
220         tmp = ext4_block_bitmap(sb, gdp);
221         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
222                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
223 
224         tmp = ext4_inode_bitmap(sb, gdp);
225         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
226                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
227 
228         tmp = ext4_inode_table(sb, gdp);
229         for (; tmp < ext4_inode_table(sb, gdp) +
230                      sbi->s_itb_per_group; tmp++) {
231                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
232                         ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
233         }
234 
235         /*
236          * Also if the number of blocks within the group is less than
237          * the blocksize * 8 ( which is the size of bitmap ), set rest
238          * of the block bitmap to 1
239          */
240         ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
241                              sb->s_blocksize * 8, bh->b_data);
242         ext4_block_bitmap_csum_set(sb, block_group, gdp, bh);
243         ext4_group_desc_csum_set(sb, block_group, gdp);
244         return 0;
245 }
246 
247 /* Return the number of free blocks in a block group.  It is used when
248  * the block bitmap is uninitialized, so we can't just count the bits
249  * in the bitmap. */
250 unsigned ext4_free_clusters_after_init(struct super_block *sb,
251                                        ext4_group_t block_group,
252                                        struct ext4_group_desc *gdp)
253 {
254         return num_clusters_in_group(sb, block_group) - 
255                 ext4_num_overhead_clusters(sb, block_group, gdp);
256 }
257 
258 /*
259  * The free blocks are managed by bitmaps.  A file system contains several
260  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
261  * block for inodes, N blocks for the inode table and data blocks.
262  *
263  * The file system contains group descriptors which are located after the
264  * super block.  Each descriptor contains the number of the bitmap block and
265  * the free blocks count in the block.  The descriptors are loaded in memory
266  * when a file system is mounted (see ext4_fill_super).
267  */
268 
269 /**
270  * ext4_get_group_desc() -- load group descriptor from disk
271  * @sb:                 super block
272  * @block_group:        given block group
273  * @bh:                 pointer to the buffer head to store the block
274  *                      group descriptor
275  */
276 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
277                                              ext4_group_t block_group,
278                                              struct buffer_head **bh)
279 {
280         unsigned int group_desc;
281         unsigned int offset;
282         ext4_group_t ngroups = ext4_get_groups_count(sb);
283         struct ext4_group_desc *desc;
284         struct ext4_sb_info *sbi = EXT4_SB(sb);
285 
286         if (block_group >= ngroups) {
287                 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
288                            " groups_count = %u", block_group, ngroups);
289 
290                 return NULL;
291         }
292 
293         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
294         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
295         if (!sbi->s_group_desc[group_desc]) {
296                 ext4_error(sb, "Group descriptor not loaded - "
297                            "block_group = %u, group_desc = %u, desc = %u",
298                            block_group, group_desc, offset);
299                 return NULL;
300         }
301 
302         desc = (struct ext4_group_desc *)(
303                 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
304                 offset * EXT4_DESC_SIZE(sb));
305         if (bh)
306                 *bh = sbi->s_group_desc[group_desc];
307         return desc;
308 }
309 
310 /*
311  * Return the block number which was discovered to be invalid, or 0 if
312  * the block bitmap is valid.
313  */
314 static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
315                                             struct ext4_group_desc *desc,
316                                             ext4_group_t block_group,
317                                             struct buffer_head *bh)
318 {
319         struct ext4_sb_info *sbi = EXT4_SB(sb);
320         ext4_grpblk_t offset;
321         ext4_grpblk_t next_zero_bit;
322         ext4_fsblk_t blk;
323         ext4_fsblk_t group_first_block;
324 
325         if (ext4_has_feature_flex_bg(sb)) {
326                 /* with FLEX_BG, the inode/block bitmaps and itable
327                  * blocks may not be in the group at all
328                  * so the bitmap validation will be skipped for those groups
329                  * or it has to also read the block group where the bitmaps
330                  * are located to verify they are set.
331                  */
332                 return 0;
333         }
334         group_first_block = ext4_group_first_block_no(sb, block_group);
335 
336         /* check whether block bitmap block number is set */
337         blk = ext4_block_bitmap(sb, desc);
338         offset = blk - group_first_block;
339         if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
340                 /* bad block bitmap */
341                 return blk;
342 
343         /* check whether the inode bitmap block number is set */
344         blk = ext4_inode_bitmap(sb, desc);
345         offset = blk - group_first_block;
346         if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
347                 /* bad block bitmap */
348                 return blk;
349 
350         /* check whether the inode table block number is set */
351         blk = ext4_inode_table(sb, desc);
352         offset = blk - group_first_block;
353         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
354                         EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group),
355                         EXT4_B2C(sbi, offset));
356         if (next_zero_bit <
357             EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group))
358                 /* bad bitmap for inode tables */
359                 return blk;
360         return 0;
361 }
362 
363 static int ext4_validate_block_bitmap(struct super_block *sb,
364                                       struct ext4_group_desc *desc,
365                                       ext4_group_t block_group,
366                                       struct buffer_head *bh)
367 {
368         ext4_fsblk_t    blk;
369         struct ext4_group_info *grp = ext4_get_group_info(sb, block_group);
370         struct ext4_sb_info *sbi = EXT4_SB(sb);
371 
372         if (buffer_verified(bh))
373                 return 0;
374         if (EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
375                 return -EFSCORRUPTED;
376 
377         ext4_lock_group(sb, block_group);
378         if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
379                         desc, bh))) {
380                 ext4_unlock_group(sb, block_group);
381                 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
382                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
383                         percpu_counter_sub(&sbi->s_freeclusters_counter,
384                                            grp->bb_free);
385                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
386                 return -EFSBADCRC;
387         }
388         blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
389         if (unlikely(blk != 0)) {
390                 ext4_unlock_group(sb, block_group);
391                 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
392                            block_group, blk);
393                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
394                         percpu_counter_sub(&sbi->s_freeclusters_counter,
395                                            grp->bb_free);
396                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
397                 return -EFSCORRUPTED;
398         }
399         set_buffer_verified(bh);
400         ext4_unlock_group(sb, block_group);
401         return 0;
402 }
403 
404 /**
405  * ext4_read_block_bitmap_nowait()
406  * @sb:                 super block
407  * @block_group:        given block group
408  *
409  * Read the bitmap for a given block_group,and validate the
410  * bits for block/inode/inode tables are set in the bitmaps
411  *
412  * Return buffer_head on success or NULL in case of failure.
413  */
414 struct buffer_head *
415 ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
416 {
417         struct ext4_group_desc *desc;
418         struct buffer_head *bh;
419         ext4_fsblk_t bitmap_blk;
420         int err;
421 
422         desc = ext4_get_group_desc(sb, block_group, NULL);
423         if (!desc)
424                 return ERR_PTR(-EFSCORRUPTED);
425         bitmap_blk = ext4_block_bitmap(sb, desc);
426         bh = sb_getblk(sb, bitmap_blk);
427         if (unlikely(!bh)) {
428                 ext4_error(sb, "Cannot get buffer for block bitmap - "
429                            "block_group = %u, block_bitmap = %llu",
430                            block_group, bitmap_blk);
431                 return ERR_PTR(-ENOMEM);
432         }
433 
434         if (bitmap_uptodate(bh))
435                 goto verify;
436 
437         lock_buffer(bh);
438         if (bitmap_uptodate(bh)) {
439                 unlock_buffer(bh);
440                 goto verify;
441         }
442         ext4_lock_group(sb, block_group);
443         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
444                 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
445                 set_bitmap_uptodate(bh);
446                 set_buffer_uptodate(bh);
447                 ext4_unlock_group(sb, block_group);
448                 unlock_buffer(bh);
449                 if (err) {
450                         ext4_error(sb, "Failed to init block bitmap for group "
451                                    "%u: %d", block_group, err);
452                         goto out;
453                 }
454                 goto verify;
455         }
456         ext4_unlock_group(sb, block_group);
457         if (buffer_uptodate(bh)) {
458                 /*
459                  * if not uninit if bh is uptodate,
460                  * bitmap is also uptodate
461                  */
462                 set_bitmap_uptodate(bh);
463                 unlock_buffer(bh);
464                 goto verify;
465         }
466         /*
467          * submit the buffer_head for reading
468          */
469         set_buffer_new(bh);
470         trace_ext4_read_block_bitmap_load(sb, block_group);
471         bh->b_end_io = ext4_end_bitmap_read;
472         get_bh(bh);
473         submit_bh(READ | REQ_META | REQ_PRIO, bh);
474         return bh;
475 verify:
476         err = ext4_validate_block_bitmap(sb, desc, block_group, bh);
477         if (err)
478                 goto out;
479         return bh;
480 out:
481         put_bh(bh);
482         return ERR_PTR(err);
483 }
484 
485 /* Returns 0 on success, 1 on error */
486 int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
487                            struct buffer_head *bh)
488 {
489         struct ext4_group_desc *desc;
490 
491         if (!buffer_new(bh))
492                 return 0;
493         desc = ext4_get_group_desc(sb, block_group, NULL);
494         if (!desc)
495                 return -EFSCORRUPTED;
496         wait_on_buffer(bh);
497         if (!buffer_uptodate(bh)) {
498                 ext4_error(sb, "Cannot read block bitmap - "
499                            "block_group = %u, block_bitmap = %llu",
500                            block_group, (unsigned long long) bh->b_blocknr);
501                 return -EIO;
502         }
503         clear_buffer_new(bh);
504         /* Panic or remount fs read-only if block bitmap is invalid */
505         return ext4_validate_block_bitmap(sb, desc, block_group, bh);
506 }
507 
508 struct buffer_head *
509 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
510 {
511         struct buffer_head *bh;
512         int err;
513 
514         bh = ext4_read_block_bitmap_nowait(sb, block_group);
515         if (IS_ERR(bh))
516                 return bh;
517         err = ext4_wait_block_bitmap(sb, block_group, bh);
518         if (err) {
519                 put_bh(bh);
520                 return ERR_PTR(err);
521         }
522         return bh;
523 }
524 
525 /**
526  * ext4_has_free_clusters()
527  * @sbi:        in-core super block structure.
528  * @nclusters:  number of needed blocks
529  * @flags:      flags from ext4_mb_new_blocks()
530  *
531  * Check if filesystem has nclusters free & available for allocation.
532  * On success return 1, return 0 on failure.
533  */
534 static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
535                                   s64 nclusters, unsigned int flags)
536 {
537         s64 free_clusters, dirty_clusters, rsv, resv_clusters;
538         struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
539         struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
540 
541         free_clusters  = percpu_counter_read_positive(fcc);
542         dirty_clusters = percpu_counter_read_positive(dcc);
543         resv_clusters = atomic64_read(&sbi->s_resv_clusters);
544 
545         /*
546          * r_blocks_count should always be multiple of the cluster ratio so
547          * we are safe to do a plane bit shift only.
548          */
549         rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
550               resv_clusters;
551 
552         if (free_clusters - (nclusters + rsv + dirty_clusters) <
553                                         EXT4_FREECLUSTERS_WATERMARK) {
554                 free_clusters  = percpu_counter_sum_positive(fcc);
555                 dirty_clusters = percpu_counter_sum_positive(dcc);
556         }
557         /* Check whether we have space after accounting for current
558          * dirty clusters & root reserved clusters.
559          */
560         if (free_clusters >= (rsv + nclusters + dirty_clusters))
561                 return 1;
562 
563         /* Hm, nope.  Are (enough) root reserved clusters available? */
564         if (uid_eq(sbi->s_resuid, current_fsuid()) ||
565             (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
566             capable(CAP_SYS_RESOURCE) ||
567             (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
568 
569                 if (free_clusters >= (nclusters + dirty_clusters +
570                                       resv_clusters))
571                         return 1;
572         }
573         /* No free blocks. Let's see if we can dip into reserved pool */
574         if (flags & EXT4_MB_USE_RESERVED) {
575                 if (free_clusters >= (nclusters + dirty_clusters))
576                         return 1;
577         }
578 
579         return 0;
580 }
581 
582 int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
583                              s64 nclusters, unsigned int flags)
584 {
585         if (ext4_has_free_clusters(sbi, nclusters, flags)) {
586                 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
587                 return 0;
588         } else
589                 return -ENOSPC;
590 }
591 
592 /**
593  * ext4_should_retry_alloc()
594  * @sb:                 super block
595  * @retries             number of attemps has been made
596  *
597  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
598  * it is profitable to retry the operation, this function will wait
599  * for the current or committing transaction to complete, and then
600  * return TRUE.
601  *
602  * if the total number of retries exceed three times, return FALSE.
603  */
604 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
605 {
606         if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
607             (*retries)++ > 3 ||
608             !EXT4_SB(sb)->s_journal)
609                 return 0;
610 
611         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
612 
613         return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
614 }
615 
616 /*
617  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
618  *
619  * @handle:             handle to this transaction
620  * @inode:              file inode
621  * @goal:               given target block(filesystem wide)
622  * @count:              pointer to total number of clusters needed
623  * @errp:               error code
624  *
625  * Return 1st allocated block number on success, *count stores total account
626  * error stores in errp pointer
627  */
628 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
629                                   ext4_fsblk_t goal, unsigned int flags,
630                                   unsigned long *count, int *errp)
631 {
632         struct ext4_allocation_request ar;
633         ext4_fsblk_t ret;
634 
635         memset(&ar, 0, sizeof(ar));
636         /* Fill with neighbour allocated blocks */
637         ar.inode = inode;
638         ar.goal = goal;
639         ar.len = count ? *count : 1;
640         ar.flags = flags;
641 
642         ret = ext4_mb_new_blocks(handle, &ar, errp);
643         if (count)
644                 *count = ar.len;
645         /*
646          * Account for the allocated meta blocks.  We will never
647          * fail EDQUOT for metdata, but we do account for it.
648          */
649         if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) {
650                 dquot_alloc_block_nofail(inode,
651                                 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
652         }
653         return ret;
654 }
655 
656 /**
657  * ext4_count_free_clusters() -- count filesystem free clusters
658  * @sb:         superblock
659  *
660  * Adds up the number of free clusters from each block group.
661  */
662 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
663 {
664         ext4_fsblk_t desc_count;
665         struct ext4_group_desc *gdp;
666         ext4_group_t i;
667         ext4_group_t ngroups = ext4_get_groups_count(sb);
668         struct ext4_group_info *grp;
669 #ifdef EXT4FS_DEBUG
670         struct ext4_super_block *es;
671         ext4_fsblk_t bitmap_count;
672         unsigned int x;
673         struct buffer_head *bitmap_bh = NULL;
674 
675         es = EXT4_SB(sb)->s_es;
676         desc_count = 0;
677         bitmap_count = 0;
678         gdp = NULL;
679 
680         for (i = 0; i < ngroups; i++) {
681                 gdp = ext4_get_group_desc(sb, i, NULL);
682                 if (!gdp)
683                         continue;
684                 grp = NULL;
685                 if (EXT4_SB(sb)->s_group_info)
686                         grp = ext4_get_group_info(sb, i);
687                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
688                         desc_count += ext4_free_group_clusters(sb, gdp);
689                 brelse(bitmap_bh);
690                 bitmap_bh = ext4_read_block_bitmap(sb, i);
691                 if (IS_ERR(bitmap_bh)) {
692                         bitmap_bh = NULL;
693                         continue;
694                 }
695 
696                 x = ext4_count_free(bitmap_bh->b_data,
697                                     EXT4_CLUSTERS_PER_GROUP(sb) / 8);
698                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
699                         i, ext4_free_group_clusters(sb, gdp), x);
700                 bitmap_count += x;
701         }
702         brelse(bitmap_bh);
703         printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
704                ", computed = %llu, %llu\n",
705                EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
706                desc_count, bitmap_count);
707         return bitmap_count;
708 #else
709         desc_count = 0;
710         for (i = 0; i < ngroups; i++) {
711                 gdp = ext4_get_group_desc(sb, i, NULL);
712                 if (!gdp)
713                         continue;
714                 grp = NULL;
715                 if (EXT4_SB(sb)->s_group_info)
716                         grp = ext4_get_group_info(sb, i);
717                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
718                         desc_count += ext4_free_group_clusters(sb, gdp);
719         }
720 
721         return desc_count;
722 #endif
723 }
724 
725 static inline int test_root(ext4_group_t a, int b)
726 {
727         while (1) {
728                 if (a < b)
729                         return 0;
730                 if (a == b)
731                         return 1;
732                 if ((a % b) != 0)
733                         return 0;
734                 a = a / b;
735         }
736 }
737 
738 /**
739  *      ext4_bg_has_super - number of blocks used by the superblock in group
740  *      @sb: superblock for filesystem
741  *      @group: group number to check
742  *
743  *      Return the number of blocks used by the superblock (primary or backup)
744  *      in this group.  Currently this will be only 0 or 1.
745  */
746 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
747 {
748         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
749 
750         if (group == 0)
751                 return 1;
752         if (ext4_has_feature_sparse_super2(sb)) {
753                 if (group == le32_to_cpu(es->s_backup_bgs[0]) ||
754                     group == le32_to_cpu(es->s_backup_bgs[1]))
755                         return 1;
756                 return 0;
757         }
758         if ((group <= 1) || !ext4_has_feature_sparse_super(sb))
759                 return 1;
760         if (!(group & 1))
761                 return 0;
762         if (test_root(group, 3) || (test_root(group, 5)) ||
763             test_root(group, 7))
764                 return 1;
765 
766         return 0;
767 }
768 
769 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
770                                         ext4_group_t group)
771 {
772         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
773         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
774         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
775 
776         if (group == first || group == first + 1 || group == last)
777                 return 1;
778         return 0;
779 }
780 
781 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
782                                         ext4_group_t group)
783 {
784         if (!ext4_bg_has_super(sb, group))
785                 return 0;
786 
787         if (ext4_has_feature_meta_bg(sb))
788                 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
789         else
790                 return EXT4_SB(sb)->s_gdb_count;
791 }
792 
793 /**
794  *      ext4_bg_num_gdb - number of blocks used by the group table in group
795  *      @sb: superblock for filesystem
796  *      @group: group number to check
797  *
798  *      Return the number of blocks used by the group descriptor table
799  *      (primary or backup) in this group.  In the future there may be a
800  *      different number of descriptor blocks in each group.
801  */
802 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
803 {
804         unsigned long first_meta_bg =
805                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
806         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
807 
808         if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg)
809                 return ext4_bg_num_gdb_nometa(sb, group);
810 
811         return ext4_bg_num_gdb_meta(sb,group);
812 
813 }
814 
815 /*
816  * This function returns the number of file system metadata clusters at
817  * the beginning of a block group, including the reserved gdt blocks.
818  */
819 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
820                                      ext4_group_t block_group)
821 {
822         struct ext4_sb_info *sbi = EXT4_SB(sb);
823         unsigned num;
824 
825         /* Check for superblock and gdt backups in this group */
826         num = ext4_bg_has_super(sb, block_group);
827 
828         if (!ext4_has_feature_meta_bg(sb) ||
829             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
830                           sbi->s_desc_per_block) {
831                 if (num) {
832                         num += ext4_bg_num_gdb(sb, block_group);
833                         num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
834                 }
835         } else { /* For META_BG_BLOCK_GROUPS */
836                 num += ext4_bg_num_gdb(sb, block_group);
837         }
838         return EXT4_NUM_B2C(sbi, num);
839 }
840 /**
841  *      ext4_inode_to_goal_block - return a hint for block allocation
842  *      @inode: inode for block allocation
843  *
844  *      Return the ideal location to start allocating blocks for a
845  *      newly created inode.
846  */
847 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
848 {
849         struct ext4_inode_info *ei = EXT4_I(inode);
850         ext4_group_t block_group;
851         ext4_grpblk_t colour;
852         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
853         ext4_fsblk_t bg_start;
854         ext4_fsblk_t last_block;
855 
856         block_group = ei->i_block_group;
857         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
858                 /*
859                  * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
860                  * block groups per flexgroup, reserve the first block
861                  * group for directories and special files.  Regular
862                  * files will start at the second block group.  This
863                  * tends to speed up directory access and improves
864                  * fsck times.
865                  */
866                 block_group &= ~(flex_size-1);
867                 if (S_ISREG(inode->i_mode))
868                         block_group++;
869         }
870         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
871         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
872 
873         /*
874          * If we are doing delayed allocation, we don't need take
875          * colour into account.
876          */
877         if (test_opt(inode->i_sb, DELALLOC))
878                 return bg_start;
879 
880         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
881                 colour = (current->pid % 16) *
882                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
883         else
884                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
885         return bg_start + colour;
886 }
887 
888 

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