2 * linux/fs/ext4/balloc.c
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)
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
14 #include <linux/time.h>
15 #include <linux/capability.h>
17 #include <linux/jbd2.h>
18 #include <linux/quotaops.h>
19 #include <linux/buffer_head.h>
21 #include "ext4_jbd2.h"
24 #include <trace/events/ext4.h>
26 static unsigned ext4_num_base_meta_clusters(struct super_block
*sb
,
27 ext4_group_t block_group
);
29 * balloc.c contains the blocks allocation and deallocation routines
33 * Calculate block group number for a given block number
35 ext4_group_t
ext4_get_group_number(struct super_block
*sb
,
40 if (test_opt2(sb
, STD_GROUP_SIZE
))
42 le32_to_cpu(EXT4_SB(sb
)->s_es
->s_first_data_block
)) >>
43 (EXT4_BLOCK_SIZE_BITS(sb
) + EXT4_CLUSTER_BITS(sb
) + 3);
45 ext4_get_group_no_and_offset(sb
, block
, &group
, NULL
);
50 * Calculate the block group number and offset into the block/cluster
51 * allocation bitmap, given a block number
53 void ext4_get_group_no_and_offset(struct super_block
*sb
, ext4_fsblk_t blocknr
,
54 ext4_group_t
*blockgrpp
, ext4_grpblk_t
*offsetp
)
56 struct ext4_super_block
*es
= EXT4_SB(sb
)->s_es
;
59 blocknr
= blocknr
- le32_to_cpu(es
->s_first_data_block
);
60 offset
= do_div(blocknr
, EXT4_BLOCKS_PER_GROUP(sb
)) >>
61 EXT4_SB(sb
)->s_cluster_bits
;
70 * Check whether the 'block' lives within the 'block_group'. Returns 1 if so
73 static inline int ext4_block_in_group(struct super_block
*sb
,
75 ext4_group_t block_group
)
77 ext4_group_t actual_group
;
79 actual_group
= ext4_get_group_number(sb
, block
);
80 return (actual_group
== block_group
) ? 1 : 0;
83 /* Return the number of clusters used for file system metadata; this
84 * represents the overhead needed by the file system.
86 unsigned ext4_num_overhead_clusters(struct super_block
*sb
,
87 ext4_group_t block_group
,
88 struct ext4_group_desc
*gdp
)
90 unsigned num_clusters
;
91 int block_cluster
= -1, inode_cluster
= -1, itbl_cluster
= -1, i
, c
;
92 ext4_fsblk_t start
= ext4_group_first_block_no(sb
, block_group
);
93 ext4_fsblk_t itbl_blk
;
94 struct ext4_sb_info
*sbi
= EXT4_SB(sb
);
96 /* This is the number of clusters used by the superblock,
97 * block group descriptors, and reserved block group
98 * descriptor blocks */
99 num_clusters
= ext4_num_base_meta_clusters(sb
, block_group
);
102 * For the allocation bitmaps and inode table, we first need
103 * to check to see if the block is in the block group. If it
104 * is, then check to see if the cluster is already accounted
105 * for in the clusters used for the base metadata cluster, or
106 * if we can increment the base metadata cluster to include
107 * that block. Otherwise, we will have to track the cluster
108 * used for the allocation bitmap or inode table explicitly.
109 * Normally all of these blocks are contiguous, so the special
110 * case handling shouldn't be necessary except for *very*
111 * unusual file system layouts.
113 if (ext4_block_in_group(sb
, ext4_block_bitmap(sb
, gdp
), block_group
)) {
114 block_cluster
= EXT4_B2C(sbi
,
115 ext4_block_bitmap(sb
, gdp
) - start
);
116 if (block_cluster
< num_clusters
)
118 else if (block_cluster
== num_clusters
) {
124 if (ext4_block_in_group(sb
, ext4_inode_bitmap(sb
, gdp
), block_group
)) {
125 inode_cluster
= EXT4_B2C(sbi
,
126 ext4_inode_bitmap(sb
, gdp
) - start
);
127 if (inode_cluster
< num_clusters
)
129 else if (inode_cluster
== num_clusters
) {
135 itbl_blk
= ext4_inode_table(sb
, gdp
);
136 for (i
= 0; i
< sbi
->s_itb_per_group
; i
++) {
137 if (ext4_block_in_group(sb
, itbl_blk
+ i
, block_group
)) {
138 c
= EXT4_B2C(sbi
, itbl_blk
+ i
- start
);
139 if ((c
< num_clusters
) || (c
== inode_cluster
) ||
140 (c
== block_cluster
) || (c
== itbl_cluster
))
142 if (c
== num_clusters
) {
151 if (block_cluster
!= -1)
153 if (inode_cluster
!= -1)
159 static unsigned int num_clusters_in_group(struct super_block
*sb
,
160 ext4_group_t block_group
)
164 if (block_group
== ext4_get_groups_count(sb
) - 1) {
166 * Even though mke2fs always initializes the first and
167 * last group, just in case some other tool was used,
168 * we need to make sure we calculate the right free
171 blocks
= ext4_blocks_count(EXT4_SB(sb
)->s_es
) -
172 ext4_group_first_block_no(sb
, block_group
);
174 blocks
= EXT4_BLOCKS_PER_GROUP(sb
);
175 return EXT4_NUM_B2C(EXT4_SB(sb
), blocks
);
178 /* Initializes an uninitialized block bitmap */
179 void ext4_init_block_bitmap(struct super_block
*sb
, struct buffer_head
*bh
,
180 ext4_group_t block_group
,
181 struct ext4_group_desc
*gdp
)
183 unsigned int bit
, bit_max
;
184 struct ext4_sb_info
*sbi
= EXT4_SB(sb
);
185 ext4_fsblk_t start
, tmp
;
188 J_ASSERT_BH(bh
, buffer_locked(bh
));
190 /* If checksum is bad mark all blocks used to prevent allocation
191 * essentially implementing a per-group read-only flag. */
192 if (!ext4_group_desc_csum_verify(sb
, block_group
, gdp
)) {
193 ext4_error(sb
, "Checksum bad for group %u", block_group
);
194 ext4_free_group_clusters_set(sb
, gdp
, 0);
195 ext4_free_inodes_set(sb
, gdp
, 0);
196 ext4_itable_unused_set(sb
, gdp
, 0);
197 memset(bh
->b_data
, 0xff, sb
->s_blocksize
);
198 ext4_block_bitmap_csum_set(sb
, block_group
, gdp
, bh
);
201 memset(bh
->b_data
, 0, sb
->s_blocksize
);
203 bit_max
= ext4_num_base_meta_clusters(sb
, block_group
);
204 for (bit
= 0; bit
< bit_max
; bit
++)
205 ext4_set_bit(bit
, bh
->b_data
);
207 start
= ext4_group_first_block_no(sb
, block_group
);
209 if (EXT4_HAS_INCOMPAT_FEATURE(sb
, EXT4_FEATURE_INCOMPAT_FLEX_BG
))
212 /* Set bits for block and inode bitmaps, and inode table */
213 tmp
= ext4_block_bitmap(sb
, gdp
);
214 if (!flex_bg
|| ext4_block_in_group(sb
, tmp
, block_group
))
215 ext4_set_bit(EXT4_B2C(sbi
, tmp
- start
), bh
->b_data
);
217 tmp
= ext4_inode_bitmap(sb
, gdp
);
218 if (!flex_bg
|| ext4_block_in_group(sb
, tmp
, block_group
))
219 ext4_set_bit(EXT4_B2C(sbi
, tmp
- start
), bh
->b_data
);
221 tmp
= ext4_inode_table(sb
, gdp
);
222 for (; tmp
< ext4_inode_table(sb
, gdp
) +
223 sbi
->s_itb_per_group
; tmp
++) {
224 if (!flex_bg
|| ext4_block_in_group(sb
, tmp
, block_group
))
225 ext4_set_bit(EXT4_B2C(sbi
, tmp
- start
), bh
->b_data
);
229 * Also if the number of blocks within the group is less than
230 * the blocksize * 8 ( which is the size of bitmap ), set rest
231 * of the block bitmap to 1
233 ext4_mark_bitmap_end(num_clusters_in_group(sb
, block_group
),
234 sb
->s_blocksize
* 8, bh
->b_data
);
235 ext4_block_bitmap_csum_set(sb
, block_group
, gdp
, bh
);
236 ext4_group_desc_csum_set(sb
, block_group
, gdp
);
239 /* Return the number of free blocks in a block group. It is used when
240 * the block bitmap is uninitialized, so we can't just count the bits
242 unsigned ext4_free_clusters_after_init(struct super_block
*sb
,
243 ext4_group_t block_group
,
244 struct ext4_group_desc
*gdp
)
246 return num_clusters_in_group(sb
, block_group
) -
247 ext4_num_overhead_clusters(sb
, block_group
, gdp
);
251 * The free blocks are managed by bitmaps. A file system contains several
252 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
253 * block for inodes, N blocks for the inode table and data blocks.
255 * The file system contains group descriptors which are located after the
256 * super block. Each descriptor contains the number of the bitmap block and
257 * the free blocks count in the block. The descriptors are loaded in memory
258 * when a file system is mounted (see ext4_fill_super).
262 * ext4_get_group_desc() -- load group descriptor from disk
264 * @block_group: given block group
265 * @bh: pointer to the buffer head to store the block
268 struct ext4_group_desc
* ext4_get_group_desc(struct super_block
*sb
,
269 ext4_group_t block_group
,
270 struct buffer_head
**bh
)
272 unsigned int group_desc
;
274 ext4_group_t ngroups
= ext4_get_groups_count(sb
);
275 struct ext4_group_desc
*desc
;
276 struct ext4_sb_info
*sbi
= EXT4_SB(sb
);
278 if (block_group
>= ngroups
) {
279 ext4_error(sb
, "block_group >= groups_count - block_group = %u,"
280 " groups_count = %u", block_group
, ngroups
);
285 group_desc
= block_group
>> EXT4_DESC_PER_BLOCK_BITS(sb
);
286 offset
= block_group
& (EXT4_DESC_PER_BLOCK(sb
) - 1);
287 if (!sbi
->s_group_desc
[group_desc
]) {
288 ext4_error(sb
, "Group descriptor not loaded - "
289 "block_group = %u, group_desc = %u, desc = %u",
290 block_group
, group_desc
, offset
);
294 desc
= (struct ext4_group_desc
*)(
295 (__u8
*)sbi
->s_group_desc
[group_desc
]->b_data
+
296 offset
* EXT4_DESC_SIZE(sb
));
298 *bh
= sbi
->s_group_desc
[group_desc
];
303 * Return the block number which was discovered to be invalid, or 0 if
304 * the block bitmap is valid.
306 static ext4_fsblk_t
ext4_valid_block_bitmap(struct super_block
*sb
,
307 struct ext4_group_desc
*desc
,
308 unsigned int block_group
,
309 struct buffer_head
*bh
)
311 ext4_grpblk_t offset
;
312 ext4_grpblk_t next_zero_bit
;
314 ext4_fsblk_t group_first_block
;
316 if (EXT4_HAS_INCOMPAT_FEATURE(sb
, EXT4_FEATURE_INCOMPAT_FLEX_BG
)) {
317 /* with FLEX_BG, the inode/block bitmaps and itable
318 * blocks may not be in the group at all
319 * so the bitmap validation will be skipped for those groups
320 * or it has to also read the block group where the bitmaps
321 * are located to verify they are set.
325 group_first_block
= ext4_group_first_block_no(sb
, block_group
);
327 /* check whether block bitmap block number is set */
328 blk
= ext4_block_bitmap(sb
, desc
);
329 offset
= blk
- group_first_block
;
330 if (!ext4_test_bit(offset
, bh
->b_data
))
331 /* bad block bitmap */
334 /* check whether the inode bitmap block number is set */
335 blk
= ext4_inode_bitmap(sb
, desc
);
336 offset
= blk
- group_first_block
;
337 if (!ext4_test_bit(offset
, bh
->b_data
))
338 /* bad block bitmap */
341 /* check whether the inode table block number is set */
342 blk
= ext4_inode_table(sb
, desc
);
343 offset
= blk
- group_first_block
;
344 next_zero_bit
= ext4_find_next_zero_bit(bh
->b_data
,
345 offset
+ EXT4_SB(sb
)->s_itb_per_group
,
347 if (next_zero_bit
< offset
+ EXT4_SB(sb
)->s_itb_per_group
)
348 /* bad bitmap for inode tables */
353 void ext4_validate_block_bitmap(struct super_block
*sb
,
354 struct ext4_group_desc
*desc
,
355 unsigned int block_group
,
356 struct buffer_head
*bh
)
360 if (buffer_verified(bh
))
363 ext4_lock_group(sb
, block_group
);
364 blk
= ext4_valid_block_bitmap(sb
, desc
, block_group
, bh
);
365 if (unlikely(blk
!= 0)) {
366 ext4_unlock_group(sb
, block_group
);
367 ext4_error(sb
, "bg %u: block %llu: invalid block bitmap",
371 if (unlikely(!ext4_block_bitmap_csum_verify(sb
, block_group
,
373 ext4_unlock_group(sb
, block_group
);
374 ext4_error(sb
, "bg %u: bad block bitmap checksum", block_group
);
377 set_buffer_verified(bh
);
378 ext4_unlock_group(sb
, block_group
);
382 * ext4_read_block_bitmap_nowait()
384 * @block_group: given block group
386 * Read the bitmap for a given block_group,and validate the
387 * bits for block/inode/inode tables are set in the bitmaps
389 * Return buffer_head on success or NULL in case of failure.
392 ext4_read_block_bitmap_nowait(struct super_block
*sb
, ext4_group_t block_group
)
394 struct ext4_group_desc
*desc
;
395 struct buffer_head
*bh
;
396 ext4_fsblk_t bitmap_blk
;
398 desc
= ext4_get_group_desc(sb
, block_group
, NULL
);
401 bitmap_blk
= ext4_block_bitmap(sb
, desc
);
402 bh
= sb_getblk(sb
, bitmap_blk
);
404 ext4_error(sb
, "Cannot get buffer for block bitmap - "
405 "block_group = %u, block_bitmap = %llu",
406 block_group
, bitmap_blk
);
410 if (bitmap_uptodate(bh
))
414 if (bitmap_uptodate(bh
)) {
418 ext4_lock_group(sb
, block_group
);
419 if (desc
->bg_flags
& cpu_to_le16(EXT4_BG_BLOCK_UNINIT
)) {
420 ext4_init_block_bitmap(sb
, bh
, block_group
, desc
);
421 set_bitmap_uptodate(bh
);
422 set_buffer_uptodate(bh
);
423 ext4_unlock_group(sb
, block_group
);
427 ext4_unlock_group(sb
, block_group
);
428 if (buffer_uptodate(bh
)) {
430 * if not uninit if bh is uptodate,
431 * bitmap is also uptodate
433 set_bitmap_uptodate(bh
);
438 * submit the buffer_head for reading
441 trace_ext4_read_block_bitmap_load(sb
, block_group
);
442 bh
->b_end_io
= ext4_end_bitmap_read
;
444 submit_bh(READ
| REQ_META
| REQ_PRIO
, bh
);
447 ext4_validate_block_bitmap(sb
, desc
, block_group
, bh
);
451 /* Returns 0 on success, 1 on error */
452 int ext4_wait_block_bitmap(struct super_block
*sb
, ext4_group_t block_group
,
453 struct buffer_head
*bh
)
455 struct ext4_group_desc
*desc
;
459 desc
= ext4_get_group_desc(sb
, block_group
, NULL
);
463 if (!buffer_uptodate(bh
)) {
464 ext4_error(sb
, "Cannot read block bitmap - "
465 "block_group = %u, block_bitmap = %llu",
466 block_group
, (unsigned long long) bh
->b_blocknr
);
469 clear_buffer_new(bh
);
470 /* Panic or remount fs read-only if block bitmap is invalid */
471 ext4_validate_block_bitmap(sb
, desc
, block_group
, bh
);
476 ext4_read_block_bitmap(struct super_block
*sb
, ext4_group_t block_group
)
478 struct buffer_head
*bh
;
480 bh
= ext4_read_block_bitmap_nowait(sb
, block_group
);
483 if (ext4_wait_block_bitmap(sb
, block_group
, bh
)) {
491 * ext4_has_free_clusters()
492 * @sbi: in-core super block structure.
493 * @nclusters: number of needed blocks
494 * @flags: flags from ext4_mb_new_blocks()
496 * Check if filesystem has nclusters free & available for allocation.
497 * On success return 1, return 0 on failure.
499 static int ext4_has_free_clusters(struct ext4_sb_info
*sbi
,
500 s64 nclusters
, unsigned int flags
)
502 s64 free_clusters
, dirty_clusters
, rsv
, resv_clusters
;
503 struct percpu_counter
*fcc
= &sbi
->s_freeclusters_counter
;
504 struct percpu_counter
*dcc
= &sbi
->s_dirtyclusters_counter
;
506 free_clusters
= percpu_counter_read_positive(fcc
);
507 dirty_clusters
= percpu_counter_read_positive(dcc
);
508 resv_clusters
= atomic64_read(&sbi
->s_resv_clusters
);
511 * r_blocks_count should always be multiple of the cluster ratio so
512 * we are safe to do a plane bit shift only.
514 rsv
= (ext4_r_blocks_count(sbi
->s_es
) >> sbi
->s_cluster_bits
) +
517 if (free_clusters
- (nclusters
+ rsv
+ dirty_clusters
) <
518 EXT4_FREECLUSTERS_WATERMARK
) {
519 free_clusters
= percpu_counter_sum_positive(fcc
);
520 dirty_clusters
= percpu_counter_sum_positive(dcc
);
522 /* Check whether we have space after accounting for current
523 * dirty clusters & root reserved clusters.
525 if (free_clusters
>= (rsv
+ nclusters
+ dirty_clusters
))
528 /* Hm, nope. Are (enough) root reserved clusters available? */
529 if (uid_eq(sbi
->s_resuid
, current_fsuid()) ||
530 (!gid_eq(sbi
->s_resgid
, GLOBAL_ROOT_GID
) && in_group_p(sbi
->s_resgid
)) ||
531 capable(CAP_SYS_RESOURCE
) ||
532 (flags
& EXT4_MB_USE_ROOT_BLOCKS
)) {
534 if (free_clusters
>= (nclusters
+ dirty_clusters
+
538 /* No free blocks. Let's see if we can dip into reserved pool */
539 if (flags
& EXT4_MB_USE_RESERVED
) {
540 if (free_clusters
>= (nclusters
+ dirty_clusters
))
547 int ext4_claim_free_clusters(struct ext4_sb_info
*sbi
,
548 s64 nclusters
, unsigned int flags
)
550 if (ext4_has_free_clusters(sbi
, nclusters
, flags
)) {
551 percpu_counter_add(&sbi
->s_dirtyclusters_counter
, nclusters
);
558 * ext4_should_retry_alloc()
560 * @retries number of attemps has been made
562 * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
563 * it is profitable to retry the operation, this function will wait
564 * for the current or committing transaction to complete, and then
567 * if the total number of retries exceed three times, return FALSE.
569 int ext4_should_retry_alloc(struct super_block
*sb
, int *retries
)
571 if (!ext4_has_free_clusters(EXT4_SB(sb
), 1, 0) ||
573 !EXT4_SB(sb
)->s_journal
)
576 jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb
->s_id
);
578 return jbd2_journal_force_commit_nested(EXT4_SB(sb
)->s_journal
);
582 * ext4_new_meta_blocks() -- allocate block for meta data (indexing) blocks
584 * @handle: handle to this transaction
586 * @goal: given target block(filesystem wide)
587 * @count: pointer to total number of clusters needed
590 * Return 1st allocated block number on success, *count stores total account
591 * error stores in errp pointer
593 ext4_fsblk_t
ext4_new_meta_blocks(handle_t
*handle
, struct inode
*inode
,
594 ext4_fsblk_t goal
, unsigned int flags
,
595 unsigned long *count
, int *errp
)
597 struct ext4_allocation_request ar
;
600 memset(&ar
, 0, sizeof(ar
));
601 /* Fill with neighbour allocated blocks */
604 ar
.len
= count
? *count
: 1;
607 ret
= ext4_mb_new_blocks(handle
, &ar
, errp
);
611 * Account for the allocated meta blocks. We will never
612 * fail EDQUOT for metdata, but we do account for it.
615 ext4_test_inode_state(inode
, EXT4_STATE_DELALLOC_RESERVED
)) {
616 spin_lock(&EXT4_I(inode
)->i_block_reservation_lock
);
617 EXT4_I(inode
)->i_allocated_meta_blocks
+= ar
.len
;
618 spin_unlock(&EXT4_I(inode
)->i_block_reservation_lock
);
619 dquot_alloc_block_nofail(inode
,
620 EXT4_C2B(EXT4_SB(inode
->i_sb
), ar
.len
));
626 * ext4_count_free_clusters() -- count filesystem free clusters
629 * Adds up the number of free clusters from each block group.
631 ext4_fsblk_t
ext4_count_free_clusters(struct super_block
*sb
)
633 ext4_fsblk_t desc_count
;
634 struct ext4_group_desc
*gdp
;
636 ext4_group_t ngroups
= ext4_get_groups_count(sb
);
638 struct ext4_super_block
*es
;
639 ext4_fsblk_t bitmap_count
;
641 struct buffer_head
*bitmap_bh
= NULL
;
643 es
= EXT4_SB(sb
)->s_es
;
648 for (i
= 0; i
< ngroups
; i
++) {
649 gdp
= ext4_get_group_desc(sb
, i
, NULL
);
652 desc_count
+= ext4_free_group_clusters(sb
, gdp
);
654 bitmap_bh
= ext4_read_block_bitmap(sb
, i
);
655 if (bitmap_bh
== NULL
)
658 x
= ext4_count_free(bitmap_bh
->b_data
,
659 EXT4_BLOCKS_PER_GROUP(sb
) / 8);
660 printk(KERN_DEBUG
"group %u: stored = %d, counted = %u\n",
661 i
, ext4_free_group_clusters(sb
, gdp
), x
);
665 printk(KERN_DEBUG
"ext4_count_free_clusters: stored = %llu"
666 ", computed = %llu, %llu\n",
667 EXT4_NUM_B2C(EXT4_SB(sb
), ext4_free_blocks_count(es
)),
668 desc_count
, bitmap_count
);
672 for (i
= 0; i
< ngroups
; i
++) {
673 gdp
= ext4_get_group_desc(sb
, i
, NULL
);
676 desc_count
+= ext4_free_group_clusters(sb
, gdp
);
683 static inline int test_root(ext4_group_t a
, int b
)
696 static int ext4_group_sparse(ext4_group_t group
)
702 return (test_root(group
, 7) || test_root(group
, 5) ||
703 test_root(group
, 3));
707 * ext4_bg_has_super - number of blocks used by the superblock in group
708 * @sb: superblock for filesystem
709 * @group: group number to check
711 * Return the number of blocks used by the superblock (primary or backup)
712 * in this group. Currently this will be only 0 or 1.
714 int ext4_bg_has_super(struct super_block
*sb
, ext4_group_t group
)
716 if (EXT4_HAS_RO_COMPAT_FEATURE(sb
,
717 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER
) &&
718 !ext4_group_sparse(group
))
723 static unsigned long ext4_bg_num_gdb_meta(struct super_block
*sb
,
726 unsigned long metagroup
= group
/ EXT4_DESC_PER_BLOCK(sb
);
727 ext4_group_t first
= metagroup
* EXT4_DESC_PER_BLOCK(sb
);
728 ext4_group_t last
= first
+ EXT4_DESC_PER_BLOCK(sb
) - 1;
730 if (group
== first
|| group
== first
+ 1 || group
== last
)
735 static unsigned long ext4_bg_num_gdb_nometa(struct super_block
*sb
,
738 if (!ext4_bg_has_super(sb
, group
))
741 if (EXT4_HAS_INCOMPAT_FEATURE(sb
,EXT4_FEATURE_INCOMPAT_META_BG
))
742 return le32_to_cpu(EXT4_SB(sb
)->s_es
->s_first_meta_bg
);
744 return EXT4_SB(sb
)->s_gdb_count
;
748 * ext4_bg_num_gdb - number of blocks used by the group table in group
749 * @sb: superblock for filesystem
750 * @group: group number to check
752 * Return the number of blocks used by the group descriptor table
753 * (primary or backup) in this group. In the future there may be a
754 * different number of descriptor blocks in each group.
756 unsigned long ext4_bg_num_gdb(struct super_block
*sb
, ext4_group_t group
)
758 unsigned long first_meta_bg
=
759 le32_to_cpu(EXT4_SB(sb
)->s_es
->s_first_meta_bg
);
760 unsigned long metagroup
= group
/ EXT4_DESC_PER_BLOCK(sb
);
762 if (!EXT4_HAS_INCOMPAT_FEATURE(sb
,EXT4_FEATURE_INCOMPAT_META_BG
) ||
763 metagroup
< first_meta_bg
)
764 return ext4_bg_num_gdb_nometa(sb
, group
);
766 return ext4_bg_num_gdb_meta(sb
,group
);
771 * This function returns the number of file system metadata clusters at
772 * the beginning of a block group, including the reserved gdt blocks.
774 static unsigned ext4_num_base_meta_clusters(struct super_block
*sb
,
775 ext4_group_t block_group
)
777 struct ext4_sb_info
*sbi
= EXT4_SB(sb
);
780 /* Check for superblock and gdt backups in this group */
781 num
= ext4_bg_has_super(sb
, block_group
);
783 if (!EXT4_HAS_INCOMPAT_FEATURE(sb
, EXT4_FEATURE_INCOMPAT_META_BG
) ||
784 block_group
< le32_to_cpu(sbi
->s_es
->s_first_meta_bg
) *
785 sbi
->s_desc_per_block
) {
787 num
+= ext4_bg_num_gdb(sb
, block_group
);
788 num
+= le16_to_cpu(sbi
->s_es
->s_reserved_gdt_blocks
);
790 } else { /* For META_BG_BLOCK_GROUPS */
791 num
+= ext4_bg_num_gdb(sb
, block_group
);
793 return EXT4_NUM_B2C(sbi
, num
);
796 * ext4_inode_to_goal_block - return a hint for block allocation
797 * @inode: inode for block allocation
799 * Return the ideal location to start allocating blocks for a
800 * newly created inode.
802 ext4_fsblk_t
ext4_inode_to_goal_block(struct inode
*inode
)
804 struct ext4_inode_info
*ei
= EXT4_I(inode
);
805 ext4_group_t block_group
;
806 ext4_grpblk_t colour
;
807 int flex_size
= ext4_flex_bg_size(EXT4_SB(inode
->i_sb
));
808 ext4_fsblk_t bg_start
;
809 ext4_fsblk_t last_block
;
811 block_group
= ei
->i_block_group
;
812 if (flex_size
>= EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
) {
814 * If there are at least EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME
815 * block groups per flexgroup, reserve the first block
816 * group for directories and special files. Regular
817 * files will start at the second block group. This
818 * tends to speed up directory access and improves
821 block_group
&= ~(flex_size
-1);
822 if (S_ISREG(inode
->i_mode
))
825 bg_start
= ext4_group_first_block_no(inode
->i_sb
, block_group
);
826 last_block
= ext4_blocks_count(EXT4_SB(inode
->i_sb
)->s_es
) - 1;
829 * If we are doing delayed allocation, we don't need take
830 * colour into account.
832 if (test_opt(inode
->i_sb
, DELALLOC
))
835 if (bg_start
+ EXT4_BLOCKS_PER_GROUP(inode
->i_sb
) <= last_block
)
836 colour
= (current
->pid
% 16) *
837 (EXT4_BLOCKS_PER_GROUP(inode
->i_sb
) / 16);
839 colour
= (current
->pid
% 16) * ((last_block
- bg_start
) / 16);
840 return bg_start
+ colour
;