mirrors
/
linux-stable
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
1
0
Fork 0
Code Issues Releases Wiki Activity

ext4: avoid bb_free and bb_fragments inconsistency in mb_free_blocks() 

After updating bb_free in mb_free_blocks, it is possible to return without
updating bb_fragments because the block being freed is found to have
already been freed, which leads to inconsistency between bb_free and
bb_fragments.

Since the group may be unlocked in ext4_grp_locked_error(), this can lead
to problems such as dividing by zero when calculating the average fragment
length. Hence move the update of bb_free to after the block double-free
check guarantees that the corresponding statistics are updated only after
the core block bitmap is modified.

Fixes: eabe0444df ("ext4: speed-up releasing blocks on commit")
CC:  <stable@vger.kernel.org> # 3.10
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240104142040.2835097-5-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Baokun Li 2024-01-04 22:20:36 +08:00 committed by Theodore Ts'o
parent c9b528c357
commit 2331fd4a49
1 changed files with 21 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
fs/ext4/mballoc.c
View File

@ -1909,11 +1909,6 @@ static void mb_free_blocks(struct inode *inode, struct ext4_buddy *e4b,
mb_check_buddy(e4b);
mb_free_blocks_double(inode, e4b, first, count);
this_cpu_inc(discard_pa_seq);
e4b->bd_info->bb_free += count;
if (first < e4b->bd_info->bb_first_free)
e4b->bd_info->bb_first_free = first;
/* access memory sequentially: check left neighbour,
* clear range and then check right neighbour
*/
@ -1927,23 +1922,31 @@ static void mb_free_blocks(struct inode *inode, struct ext4_buddy *e4b,
struct ext4_sb_info *sbi = EXT4_SB(sb);
ext4_fsblk_t blocknr;
/*
* Fastcommit replay can free already freed blocks which
* corrupts allocation info. Regenerate it.
*/
if (sbi->s_mount_state & EXT4_FC_REPLAY) {
mb_regenerate_buddy(e4b);
goto check;
}
blocknr = ext4_group_first_block_no(sb, e4b->bd_group);
blocknr += EXT4_C2B(sbi, block);
if (!(sbi->s_mount_state & EXT4_FC_REPLAY)) {
ext4_grp_locked_error(sb, e4b->bd_group,
inode ? inode->i_ino : 0,
blocknr,
"freeing already freed block (bit %u); block bitmap corrupt.",
block);
ext4_mark_group_bitmap_corrupted(
sb, e4b->bd_group,
ext4_grp_locked_error(sb, e4b->bd_group,
inode ? inode->i_ino : 0, blocknr,
"freeing already freed block (bit %u); block bitmap corrupt.",
block);
ext4_mark_group_bitmap_corrupted(sb, e4b->bd_group,
EXT4_GROUP_INFO_BBITMAP_CORRUPT);
} else {
mb_regenerate_buddy(e4b);
}
goto done;
return;
}
this_cpu_inc(discard_pa_seq);
e4b->bd_info->bb_free += count;
if (first < e4b->bd_info->bb_first_free)
e4b->bd_info->bb_first_free = first;
/* let's maintain fragments counter */
if (left_is_free && right_is_free)
e4b->bd_info->bb_fragments--;
@ -1968,9 +1971,9 @@ static void mb_free_blocks(struct inode *inode, struct ext4_buddy *e4b,
if (first <= last)
mb_buddy_mark_free(e4b, first >> 1, last >> 1);
done:
mb_set_largest_free_order(sb, e4b->bd_info);
mb_update_avg_fragment_size(sb, e4b->bd_info);
check:
mb_check_buddy(e4b);
}