~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/fs/ext4/balloc.c

Version: ~ [ linux-5.4-rc7 ] ~ [ linux-5.3.11 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.84 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.154 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.201 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.201 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.77 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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         if ((bit_max >> 3) >= bh->b_size)
212                 return -EFSCORRUPTED;
213 
214         for (bit = 0; bit < bit_max; bit++)
215                 ext4_set_bit(bit, bh->b_data);
216 
217         start = ext4_group_first_block_no(sb, block_group);
218 
219         if (ext4_has_feature_flex_bg(sb))
220                 flex_bg = 1;
221 
222         /* Set bits for block and inode bitmaps, and inode table */
223         tmp = ext4_block_bitmap(sb, gdp);
224         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
225                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
226 
227         tmp = ext4_inode_bitmap(sb, gdp);
228         if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
229                 ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
230 
231         tmp = ext4_inode_table(sb, gdp);
232         for (; tmp < ext4_inode_table(sb, gdp) +
233                      sbi->s_itb_per_group; tmp++) {
234                 if (!flex_bg || ext4_block_in_group(sb, tmp, block_group))
235                         ext4_set_bit(EXT4_B2C(sbi, tmp - start), bh->b_data);
236         }
237 
238         /*
239          * Also if the number of blocks within the group is less than
240          * the blocksize * 8 ( which is the size of bitmap ), set rest
241          * of the block bitmap to 1
242          */
243         ext4_mark_bitmap_end(num_clusters_in_group(sb, block_group),
244                              sb->s_blocksize * 8, bh->b_data);
245         ext4_block_bitmap_csum_set(sb, block_group, gdp, bh);
246         ext4_group_desc_csum_set(sb, block_group, gdp);
247         return 0;
248 }
249 
250 /* Return the number of free blocks in a block group.  It is used when
251  * the block bitmap is uninitialized, so we can't just count the bits
252  * in the bitmap. */
253 unsigned ext4_free_clusters_after_init(struct super_block *sb,
254                                        ext4_group_t block_group,
255                                        struct ext4_group_desc *gdp)
256 {
257         return num_clusters_in_group(sb, block_group) - 
258                 ext4_num_overhead_clusters(sb, block_group, gdp);
259 }
260 
261 /*
262  * The free blocks are managed by bitmaps.  A file system contains several
263  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
264  * block for inodes, N blocks for the inode table and data blocks.
265  *
266  * The file system contains group descriptors which are located after the
267  * super block.  Each descriptor contains the number of the bitmap block and
268  * the free blocks count in the block.  The descriptors are loaded in memory
269  * when a file system is mounted (see ext4_fill_super).
270  */
271 
272 /**
273  * ext4_get_group_desc() -- load group descriptor from disk
274  * @sb:                 super block
275  * @block_group:        given block group
276  * @bh:                 pointer to the buffer head to store the block
277  *                      group descriptor
278  */
279 struct ext4_group_desc * ext4_get_group_desc(struct super_block *sb,
280                                              ext4_group_t block_group,
281                                              struct buffer_head **bh)
282 {
283         unsigned int group_desc;
284         unsigned int offset;
285         ext4_group_t ngroups = ext4_get_groups_count(sb);
286         struct ext4_group_desc *desc;
287         struct ext4_sb_info *sbi = EXT4_SB(sb);
288 
289         if (block_group >= ngroups) {
290                 ext4_error(sb, "block_group >= groups_count - block_group = %u,"
291                            " groups_count = %u", block_group, ngroups);
292 
293                 return NULL;
294         }
295 
296         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
297         offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
298         if (!sbi->s_group_desc[group_desc]) {
299                 ext4_error(sb, "Group descriptor not loaded - "
300                            "block_group = %u, group_desc = %u, desc = %u",
301                            block_group, group_desc, offset);
302                 return NULL;
303         }
304 
305         desc = (struct ext4_group_desc *)(
306                 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
307                 offset * EXT4_DESC_SIZE(sb));
308         if (bh)
309                 *bh = sbi->s_group_desc[group_desc];
310         return desc;
311 }
312 
313 /*
314  * Return the block number which was discovered to be invalid, or 0 if
315  * the block bitmap is valid.
316  */
317 static ext4_fsblk_t ext4_valid_block_bitmap(struct super_block *sb,
318                                             struct ext4_group_desc *desc,
319                                             ext4_group_t block_group,
320                                             struct buffer_head *bh)
321 {
322         struct ext4_sb_info *sbi = EXT4_SB(sb);
323         ext4_grpblk_t offset;
324         ext4_grpblk_t next_zero_bit;
325         ext4_fsblk_t blk;
326         ext4_fsblk_t group_first_block;
327 
328         if (ext4_has_feature_flex_bg(sb)) {
329                 /* with FLEX_BG, the inode/block bitmaps and itable
330                  * blocks may not be in the group at all
331                  * so the bitmap validation will be skipped for those groups
332                  * or it has to also read the block group where the bitmaps
333                  * are located to verify they are set.
334                  */
335                 return 0;
336         }
337         group_first_block = ext4_group_first_block_no(sb, block_group);
338 
339         /* check whether block bitmap block number is set */
340         blk = ext4_block_bitmap(sb, desc);
341         offset = blk - group_first_block;
342         if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
343                 /* bad block bitmap */
344                 return blk;
345 
346         /* check whether the inode bitmap block number is set */
347         blk = ext4_inode_bitmap(sb, desc);
348         offset = blk - group_first_block;
349         if (!ext4_test_bit(EXT4_B2C(sbi, offset), bh->b_data))
350                 /* bad block bitmap */
351                 return blk;
352 
353         /* check whether the inode table block number is set */
354         blk = ext4_inode_table(sb, desc);
355         offset = blk - group_first_block;
356         next_zero_bit = ext4_find_next_zero_bit(bh->b_data,
357                         EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group),
358                         EXT4_B2C(sbi, offset));
359         if (next_zero_bit <
360             EXT4_B2C(sbi, offset + EXT4_SB(sb)->s_itb_per_group))
361                 /* bad bitmap for inode tables */
362                 return blk;
363         return 0;
364 }
365 
366 static int ext4_validate_block_bitmap(struct super_block *sb,
367                                       struct ext4_group_desc *desc,
368                                       ext4_group_t block_group,
369                                       struct buffer_head *bh)
370 {
371         ext4_fsblk_t    blk;
372         struct ext4_group_info *grp = ext4_get_group_info(sb, block_group);
373         struct ext4_sb_info *sbi = EXT4_SB(sb);
374 
375         if (buffer_verified(bh))
376                 return 0;
377         if (EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
378                 return -EFSCORRUPTED;
379 
380         ext4_lock_group(sb, block_group);
381         if (unlikely(!ext4_block_bitmap_csum_verify(sb, block_group,
382                         desc, bh))) {
383                 ext4_unlock_group(sb, block_group);
384                 ext4_error(sb, "bg %u: bad block bitmap checksum", block_group);
385                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
386                         percpu_counter_sub(&sbi->s_freeclusters_counter,
387                                            grp->bb_free);
388                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
389                 return -EFSBADCRC;
390         }
391         blk = ext4_valid_block_bitmap(sb, desc, block_group, bh);
392         if (unlikely(blk != 0)) {
393                 ext4_unlock_group(sb, block_group);
394                 ext4_error(sb, "bg %u: block %llu: invalid block bitmap",
395                            block_group, blk);
396                 if (!EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
397                         percpu_counter_sub(&sbi->s_freeclusters_counter,
398                                            grp->bb_free);
399                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
400                 return -EFSCORRUPTED;
401         }
402         set_buffer_verified(bh);
403         ext4_unlock_group(sb, block_group);
404         return 0;
405 }
406 
407 /**
408  * ext4_read_block_bitmap_nowait()
409  * @sb:                 super block
410  * @block_group:        given block group
411  *
412  * Read the bitmap for a given block_group,and validate the
413  * bits for block/inode/inode tables are set in the bitmaps
414  *
415  * Return buffer_head on success or NULL in case of failure.
416  */
417 struct buffer_head *
418 ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
419 {
420         struct ext4_group_desc *desc;
421         struct buffer_head *bh;
422         ext4_fsblk_t bitmap_blk;
423         int err;
424 
425         desc = ext4_get_group_desc(sb, block_group, NULL);
426         if (!desc)
427                 return ERR_PTR(-EFSCORRUPTED);
428         bitmap_blk = ext4_block_bitmap(sb, desc);
429         bh = sb_getblk(sb, bitmap_blk);
430         if (unlikely(!bh)) {
431                 ext4_error(sb, "Cannot get buffer for block bitmap - "
432                            "block_group = %u, block_bitmap = %llu",
433                            block_group, bitmap_blk);
434                 return ERR_PTR(-ENOMEM);
435         }
436 
437         if (bitmap_uptodate(bh))
438                 goto verify;
439 
440         lock_buffer(bh);
441         if (bitmap_uptodate(bh)) {
442                 unlock_buffer(bh);
443                 goto verify;
444         }
445         ext4_lock_group(sb, block_group);
446         if (desc->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
447                 err = ext4_init_block_bitmap(sb, bh, block_group, desc);
448                 set_bitmap_uptodate(bh);
449                 set_buffer_uptodate(bh);
450                 ext4_unlock_group(sb, block_group);
451                 unlock_buffer(bh);
452                 if (err) {
453                         ext4_error(sb, "Failed to init block bitmap for group "
454                                    "%u: %d", block_group, err);
455                         goto out;
456                 }
457                 goto verify;
458         }
459         ext4_unlock_group(sb, block_group);
460         if (buffer_uptodate(bh)) {
461                 /*
462                  * if not uninit if bh is uptodate,
463                  * bitmap is also uptodate
464                  */
465                 set_bitmap_uptodate(bh);
466                 unlock_buffer(bh);
467                 goto verify;
468         }
469         /*
470          * submit the buffer_head for reading
471          */
472         set_buffer_new(bh);
473         trace_ext4_read_block_bitmap_load(sb, block_group);
474         bh->b_end_io = ext4_end_bitmap_read;
475         get_bh(bh);
476         submit_bh(READ | REQ_META | REQ_PRIO, bh);
477         return bh;
478 verify:
479         err = ext4_validate_block_bitmap(sb, desc, block_group, bh);
480         if (err)
481                 goto out;
482         return bh;
483 out:
484         put_bh(bh);
485         return ERR_PTR(err);
486 }
487 
488 /* Returns 0 on success, 1 on error */
489 int ext4_wait_block_bitmap(struct super_block *sb, ext4_group_t block_group,
490                            struct buffer_head *bh)
491 {
492         struct ext4_group_desc *desc;
493 
494         if (!buffer_new(bh))
495                 return 0;
496         desc = ext4_get_group_desc(sb, block_group, NULL);
497         if (!desc)
498                 return -EFSCORRUPTED;
499         wait_on_buffer(bh);
500         if (!buffer_uptodate(bh)) {
501                 ext4_error(sb, "Cannot read block bitmap - "
502                            "block_group = %u, block_bitmap = %llu",
503                            block_group, (unsigned long long) bh->b_blocknr);
504                 return -EIO;
505         }
506         clear_buffer_new(bh);
507         /* Panic or remount fs read-only if block bitmap is invalid */
508         return ext4_validate_block_bitmap(sb, desc, block_group, bh);
509 }
510 
511 struct buffer_head *
512 ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
513 {
514         struct buffer_head *bh;
515         int err;
516 
517         bh = ext4_read_block_bitmap_nowait(sb, block_group);
518         if (IS_ERR(bh))
519                 return bh;
520         err = ext4_wait_block_bitmap(sb, block_group, bh);
521         if (err) {
522                 put_bh(bh);
523                 return ERR_PTR(err);
524         }
525         return bh;
526 }
527 
528 /**
529  * ext4_has_free_clusters()
530  * @sbi:        in-core super block structure.
531  * @nclusters:  number of needed blocks
532  * @flags:      flags from ext4_mb_new_blocks()
533  *
534  * Check if filesystem has nclusters free & available for allocation.
535  * On success return 1, return 0 on failure.
536  */
537 static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
538                                   s64 nclusters, unsigned int flags)
539 {
540         s64 free_clusters, dirty_clusters, rsv, resv_clusters;
541         struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
542         struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
543 
544         free_clusters  = percpu_counter_read_positive(fcc);
545         dirty_clusters = percpu_counter_read_positive(dcc);
546         resv_clusters = atomic64_read(&sbi->s_resv_clusters);
547 
548         /*
549          * r_blocks_count should always be multiple of the cluster ratio so
550          * we are safe to do a plane bit shift only.
551          */
552         rsv = (ext4_r_blocks_count(sbi->s_es) >> sbi->s_cluster_bits) +
553               resv_clusters;
554 
555         if (free_clusters - (nclusters + rsv + dirty_clusters) <
556                                         EXT4_FREECLUSTERS_WATERMARK) {
557                 free_clusters  = percpu_counter_sum_positive(fcc);
558                 dirty_clusters = percpu_counter_sum_positive(dcc);
559         }
560         /* Check whether we have space after accounting for current
561          * dirty clusters & root reserved clusters.
562          */
563         if (free_clusters >= (rsv + nclusters + dirty_clusters))
564                 return 1;
565 
566         /* Hm, nope.  Are (enough) root reserved clusters available? */
567         if (uid_eq(sbi->s_resuid, current_fsuid()) ||
568             (!gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) && in_group_p(sbi->s_resgid)) ||
569             capable(CAP_SYS_RESOURCE) ||
570             (flags & EXT4_MB_USE_ROOT_BLOCKS)) {
571 
572                 if (free_clusters >= (nclusters + dirty_clusters +
573                                       resv_clusters))
574                         return 1;
575         }
576         /* No free blocks. Let's see if we can dip into reserved pool */
577         if (flags & EXT4_MB_USE_RESERVED) {
578                 if (free_clusters >= (nclusters + dirty_clusters))
579                         return 1;
580         }
581 
582         return 0;
583 }
584 
585 int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
586                              s64 nclusters, unsigned int flags)
587 {
588         if (ext4_has_free_clusters(sbi, nclusters, flags)) {
589                 percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
590                 return 0;
591         } else
592                 return -ENOSPC;
593 }
594 
595 /**
596  * ext4_should_retry_alloc()
597  * @sb:                 super block
598  * @retries             number of attemps has been made
599  *
600  * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
601  * it is profitable to retry the operation, this function will wait
602  * for the current or committing transaction to complete, and then
603  * return TRUE.
604  *
605  * if the total number of retries exceed three times, return FALSE.
606  */
607 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
608 {
609         if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
610             (*retries)++ > 3 ||
611             !EXT4_SB(sb)->s_journal)
612                 return 0;
613 
614         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
615 
616         return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
617 }
618 
619 /*
620  * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
621  *
622  * @handle:             handle to this transaction
623  * @inode:              file inode
624  * @goal:               given target block(filesystem wide)
625  * @count:              pointer to total number of clusters needed
626  * @errp:               error code
627  *
628  * Return 1st allocated block number on success, *count stores total account
629  * error stores in errp pointer
630  */
631 ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
632                                   ext4_fsblk_t goal, unsigned int flags,
633                                   unsigned long *count, int *errp)
634 {
635         struct ext4_allocation_request ar;
636         ext4_fsblk_t ret;
637 
638         memset(&ar, 0, sizeof(ar));
639         /* Fill with neighbour allocated blocks */
640         ar.inode = inode;
641         ar.goal = goal;
642         ar.len = count ? *count : 1;
643         ar.flags = flags;
644 
645         ret = ext4_mb_new_blocks(handle, &ar, errp);
646         if (count)
647                 *count = ar.len;
648         /*
649          * Account for the allocated meta blocks.  We will never
650          * fail EDQUOT for metdata, but we do account for it.
651          */
652         if (!(*errp) && (flags & EXT4_MB_DELALLOC_RESERVED)) {
653                 dquot_alloc_block_nofail(inode,
654                                 EXT4_C2B(EXT4_SB(inode->i_sb), ar.len));
655         }
656         return ret;
657 }
658 
659 /**
660  * ext4_count_free_clusters() -- count filesystem free clusters
661  * @sb:         superblock
662  *
663  * Adds up the number of free clusters from each block group.
664  */
665 ext4_fsblk_t ext4_count_free_clusters(struct super_block *sb)
666 {
667         ext4_fsblk_t desc_count;
668         struct ext4_group_desc *gdp;
669         ext4_group_t i;
670         ext4_group_t ngroups = ext4_get_groups_count(sb);
671         struct ext4_group_info *grp;
672 #ifdef EXT4FS_DEBUG
673         struct ext4_super_block *es;
674         ext4_fsblk_t bitmap_count;
675         unsigned int x;
676         struct buffer_head *bitmap_bh = NULL;
677 
678         es = EXT4_SB(sb)->s_es;
679         desc_count = 0;
680         bitmap_count = 0;
681         gdp = NULL;
682 
683         for (i = 0; i < ngroups; i++) {
684                 gdp = ext4_get_group_desc(sb, i, NULL);
685                 if (!gdp)
686                         continue;
687                 grp = NULL;
688                 if (EXT4_SB(sb)->s_group_info)
689                         grp = ext4_get_group_info(sb, i);
690                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
691                         desc_count += ext4_free_group_clusters(sb, gdp);
692                 brelse(bitmap_bh);
693                 bitmap_bh = ext4_read_block_bitmap(sb, i);
694                 if (IS_ERR(bitmap_bh)) {
695                         bitmap_bh = NULL;
696                         continue;
697                 }
698 
699                 x = ext4_count_free(bitmap_bh->b_data,
700                                     EXT4_CLUSTERS_PER_GROUP(sb) / 8);
701                 printk(KERN_DEBUG "group %u: stored = %d, counted = %u\n",
702                         i, ext4_free_group_clusters(sb, gdp), x);
703                 bitmap_count += x;
704         }
705         brelse(bitmap_bh);
706         printk(KERN_DEBUG "ext4_count_free_clusters: stored = %llu"
707                ", computed = %llu, %llu\n",
708                EXT4_NUM_B2C(EXT4_SB(sb), ext4_free_blocks_count(es)),
709                desc_count, bitmap_count);
710         return bitmap_count;
711 #else
712         desc_count = 0;
713         for (i = 0; i < ngroups; i++) {
714                 gdp = ext4_get_group_desc(sb, i, NULL);
715                 if (!gdp)
716                         continue;
717                 grp = NULL;
718                 if (EXT4_SB(sb)->s_group_info)
719                         grp = ext4_get_group_info(sb, i);
720                 if (!grp || !EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
721                         desc_count += ext4_free_group_clusters(sb, gdp);
722         }
723 
724         return desc_count;
725 #endif
726 }
727 
728 static inline int test_root(ext4_group_t a, int b)
729 {
730         while (1) {
731                 if (a < b)
732                         return 0;
733                 if (a == b)
734                         return 1;
735                 if ((a % b) != 0)
736                         return 0;
737                 a = a / b;
738         }
739 }
740 
741 /**
742  *      ext4_bg_has_super - number of blocks used by the superblock in group
743  *      @sb: superblock for filesystem
744  *      @group: group number to check
745  *
746  *      Return the number of blocks used by the superblock (primary or backup)
747  *      in this group.  Currently this will be only 0 or 1.
748  */
749 int ext4_bg_has_super(struct super_block *sb, ext4_group_t group)
750 {
751         struct ext4_super_block *es = EXT4_SB(sb)->s_es;
752 
753         if (group == 0)
754                 return 1;
755         if (ext4_has_feature_sparse_super2(sb)) {
756                 if (group == le32_to_cpu(es->s_backup_bgs[0]) ||
757                     group == le32_to_cpu(es->s_backup_bgs[1]))
758                         return 1;
759                 return 0;
760         }
761         if ((group <= 1) || !ext4_has_feature_sparse_super(sb))
762                 return 1;
763         if (!(group & 1))
764                 return 0;
765         if (test_root(group, 3) || (test_root(group, 5)) ||
766             test_root(group, 7))
767                 return 1;
768 
769         return 0;
770 }
771 
772 static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb,
773                                         ext4_group_t group)
774 {
775         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
776         ext4_group_t first = metagroup * EXT4_DESC_PER_BLOCK(sb);
777         ext4_group_t last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
778 
779         if (group == first || group == first + 1 || group == last)
780                 return 1;
781         return 0;
782 }
783 
784 static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb,
785                                         ext4_group_t group)
786 {
787         if (!ext4_bg_has_super(sb, group))
788                 return 0;
789 
790         if (ext4_has_feature_meta_bg(sb))
791                 return le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
792         else
793                 return EXT4_SB(sb)->s_gdb_count;
794 }
795 
796 /**
797  *      ext4_bg_num_gdb - number of blocks used by the group table in group
798  *      @sb: superblock for filesystem
799  *      @group: group number to check
800  *
801  *      Return the number of blocks used by the group descriptor table
802  *      (primary or backup) in this group.  In the future there may be a
803  *      different number of descriptor blocks in each group.
804  */
805 unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
806 {
807         unsigned long first_meta_bg =
808                         le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
809         unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
810 
811         if (!ext4_has_feature_meta_bg(sb) || metagroup < first_meta_bg)
812                 return ext4_bg_num_gdb_nometa(sb, group);
813 
814         return ext4_bg_num_gdb_meta(sb,group);
815 
816 }
817 
818 /*
819  * This function returns the number of file system metadata clusters at
820  * the beginning of a block group, including the reserved gdt blocks.
821  */
822 static unsigned ext4_num_base_meta_clusters(struct super_block *sb,
823                                      ext4_group_t block_group)
824 {
825         struct ext4_sb_info *sbi = EXT4_SB(sb);
826         unsigned num;
827 
828         /* Check for superblock and gdt backups in this group */
829         num = ext4_bg_has_super(sb, block_group);
830 
831         if (!ext4_has_feature_meta_bg(sb) ||
832             block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
833                           sbi->s_desc_per_block) {
834                 if (num) {
835                         num += ext4_bg_num_gdb(sb, block_group);
836                         num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
837                 }
838         } else { /* For META_BG_BLOCK_GROUPS */
839                 num += ext4_bg_num_gdb(sb, block_group);
840         }
841         return EXT4_NUM_B2C(sbi, num);
842 }
843 /**
844  *      ext4_inode_to_goal_block - return a hint for block allocation
845  *      @inode: inode for block allocation
846  *
847  *      Return the ideal location to start allocating blocks for a
848  *      newly created inode.
849  */
850 ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
851 {
852         struct ext4_inode_info *ei = EXT4_I(inode);
853         ext4_group_t block_group;
854         ext4_grpblk_t colour;
855         int flex_size = ext4_flex_bg_size(EXT4_SB(inode->i_sb));
856         ext4_fsblk_t bg_start;
857         ext4_fsblk_t last_block;
858 
859         block_group = ei->i_block_group;
860         if (flex_size >= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME) {
861                 /*
862                  * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
863                  * block groups per flexgroup, reserve the first block
864                  * group for directories and special files.  Regular
865                  * files will start at the second block group.  This
866                  * tends to speed up directory access and improves
867                  * fsck times.
868                  */
869                 block_group &= ~(flex_size-1);
870                 if (S_ISREG(inode->i_mode))
871                         block_group++;
872         }
873         bg_start = ext4_group_first_block_no(inode->i_sb, block_group);
874         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
875 
876         /*
877          * If we are doing delayed allocation, we don't need take
878          * colour into account.
879          */
880         if (test_opt(inode->i_sb, DELALLOC))
881                 return bg_start;
882 
883         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
884                 colour = (current->pid % 16) *
885                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
886         else
887                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
888         return bg_start + colour;
889 }
890 
891 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp