[PATCH 5.16 0786/1017] ext4: correct cluster len and clusters changed accounting in ext4_mb_mark_bb

Greg Kroah-Hartman
2022-04-05T13:23:33Z

From: Ritesh Harjani <riteshh@linux.ibm.com>

[ Upstream commit a5c0e2fdf7cea535ba03259894dc184e5a4c2800 ]

ext4_mb_mark_bb() currently wrongly calculates cluster len (clen) and
flex_group->free_clusters. This patch fixes that.

Identified based on code review of ext4_mb_mark_bb() function.

Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/a0b035d536bafa88110b74456853774b64c8ac40.1644992609.git.riteshh@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/ext4/mballoc.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index e872ea582555..c0868b82a62f 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -3899,10 +3899,11 @@ void ext4_mb_mark_bb(struct super_block *sb, ext4_fsblk_t block,
struct ext4_sb_info *sbi = EXT4_SB(sb);
ext4_group_t group;
ext4_grpblk_t blkoff;
- int i, clen, err;
+ int i, err;
int already;
+ unsigned int clen, clen_changed;

- clen = EXT4_B2C(sbi, len);
+ clen = EXT4_NUM_B2C(sbi, len);

ext4_get_group_no_and_offset(sb, block, &group, &blkoff);
bitmap_bh = ext4_read_block_bitmap(sb, group);
@@ -3923,6 +3924,7 @@ void ext4_mb_mark_bb(struct super_block *sb, ext4_fsblk_t block,
if (!mb_test_bit(blkoff + i, bitmap_bh->b_data) == !state)
already++;

+ clen_changed = clen - already;
if (state)
ext4_set_bits(bitmap_bh->b_data, blkoff, clen);
else
@@ -3935,9 +3937,9 @@ void ext4_mb_mark_bb(struct super_block *sb, ext4_fsblk_t block,
group, gdp));
}
if (state)
- clen = ext4_free_group_clusters(sb, gdp) - clen + already;
+ clen = ext4_free_group_clusters(sb, gdp) - clen_changed;
else
- clen = ext4_free_group_clusters(sb, gdp) + clen - already;
+ clen = ext4_free_group_clusters(sb, gdp) + clen_changed;

ext4_free_group_clusters_set(sb, gdp, clen);
ext4_block_bitmap_csum_set(sb, group, gdp, bitmap_bh);
@@ -3947,10 +3949,13 @@ void ext4_mb_mark_bb(struct super_block *sb, ext4_fsblk_t block,

if (sbi->s_log_groups_per_flex) {
ext4_group_t flex_group = ext4_flex_group(sbi, group);
+ struct flex_groups *fg = sbi_array_rcu_deref(sbi,
+ s_flex_groups, flex_group);

- atomic64_sub(len,
- &sbi_array_rcu_deref(sbi, s_flex_groups,
- flex_group)->free_clusters);
+ if (state)
+ atomic64_sub(clen_changed, &fg->free_clusters);
+ else
+ atomic64_add(clen_changed, &fg->free_clusters);
}

err = ext4_handle_dirty_metadata(NULL, NULL, bitmap_bh);
--
2.34.1