On May 29, 2018, at 5:45 AM, Wang Shilong <wangshilong1991@xxxxxxxxx> wrote:
>
> From: Wang Shilong <wshilong@xxxxxxx>
>
> Whenever we hit block or inode bitmap corruptions we set
> bit and then reduce this block group free inode/clusters
> counter to expose right available space.
>
> However some of ext4_mark_group_bitmap_corrupted() is called
> inside group spinlock, some are not, this could make it happen
> that we double reduce one block group free counters from system.
>
> Always hold group spinlock for it could fix it, but it looks
> a little heavy, we could use test_and_set_bit() to fix race
> problems here.
>
> Signed-off-by: Wang Shilong <wshilong@xxxxxxx>
Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx>
> ---
> fs/ext4/super.c | 22 +++++++++++-----------
> 1 file changed, 11 insertions(+), 11 deletions(-)
>
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index c1c5c87..d6fa6cf 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -770,26 +770,26 @@ void ext4_mark_group_bitmap_corrupted(struct super_block *sb,
> struct ext4_sb_info *sbi = EXT4_SB(sb);
> struct ext4_group_info *grp = ext4_get_group_info(sb, group);
> struct ext4_group_desc *gdp = ext4_get_group_desc(sb, group, NULL);
> + int ret;
>
> - if ((flags & EXT4_GROUP_INFO_BBITMAP_CORRUPT) &&
> - !EXT4_MB_GRP_BBITMAP_CORRUPT(grp)) {
> - percpu_counter_sub(&sbi->s_freeclusters_counter,
> - grp->bb_free);
> - set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT,
> - &grp->bb_state);
> + if (flags & EXT4_GROUP_INFO_BBITMAP_CORRUPT) {
> + ret = ext4_test_and_set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT,
> + &grp->bb_state);
> + if (!ret)
> + percpu_counter_sub(&sbi->s_freeclusters_counter,
> + grp->bb_free);
> }
>
> - if ((flags & EXT4_GROUP_INFO_IBITMAP_CORRUPT) &&
> - !EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) {
> - if (gdp) {
> + if (flags & EXT4_GROUP_INFO_IBITMAP_CORRUPT) {
> + ret = ext4_test_and_set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT,
> + &grp->bb_state);
> + if (!ret && gdp) {
> int count;
>
> count = ext4_free_inodes_count(sb, gdp);
> percpu_counter_sub(&sbi->s_freeinodes_counter,
> count);
> }
> - set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT,
> - &grp->bb_state);
> }
> }
>
> --
> 1.8.3.1
>
Cheers, Andreas
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