6.15-stable review patch. If anyone has any objections, please let me know.
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From: Baokun Li libaokun1@huawei.com
commit 1c320d8e92925bb7615f83a7b6e3f402a5c2ca63 upstream.
Groups with no free blocks shouldn't be in any average fragment size list. However, when all blocks in a group are allocated(i.e., bb_fragments or bb_free is 0), we currently skip updating the average fragment size, which means the group isn't removed from its previous s_mb_avg_fragment_size[old] list.
This created "zombie" groups that were always skipped during traversal as they couldn't satisfy any block allocation requests, negatively impacting traversal efficiency.
Therefore, when a group becomes completely full, bb_avg_fragment_size_order is now set to -1. If the old order was not -1, a removal operation is performed; if the new order is not -1, an insertion is performed.
Fixes: 196e402adf2e ("ext4: improve cr 0 / cr 1 group scanning") CC: stable@vger.kernel.org Signed-off-by: Baokun Li libaokun1@huawei.com Reviewed-by: Jan Kara jack@suse.cz Reviewed-by: Zhang Yi yi.zhang@huawei.com Link: https://patch.msgid.link/20250714130327.1830534-11-libaokun1@huawei.com Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ext4/mballoc.c | 34 +++++++++++++++++----------------- 1 file changed, 17 insertions(+), 17 deletions(-)
--- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -841,30 +841,30 @@ static void mb_update_avg_fragment_size(struct super_block *sb, struct ext4_group_info *grp) { struct ext4_sb_info *sbi = EXT4_SB(sb); - int new_order; + int new, old;
- if (!test_opt2(sb, MB_OPTIMIZE_SCAN) || grp->bb_fragments == 0) + if (!test_opt2(sb, MB_OPTIMIZE_SCAN)) return;
- new_order = mb_avg_fragment_size_order(sb, - grp->bb_free / grp->bb_fragments); - if (new_order == grp->bb_avg_fragment_size_order) + old = grp->bb_avg_fragment_size_order; + new = grp->bb_fragments == 0 ? -1 : + mb_avg_fragment_size_order(sb, grp->bb_free / grp->bb_fragments); + if (new == old) return;
- if (grp->bb_avg_fragment_size_order != -1) { - write_lock(&sbi->s_mb_avg_fragment_size_locks[ - grp->bb_avg_fragment_size_order]); + if (old >= 0) { + write_lock(&sbi->s_mb_avg_fragment_size_locks[old]); list_del(&grp->bb_avg_fragment_size_node); - write_unlock(&sbi->s_mb_avg_fragment_size_locks[ - grp->bb_avg_fragment_size_order]); + write_unlock(&sbi->s_mb_avg_fragment_size_locks[old]); + } + + grp->bb_avg_fragment_size_order = new; + if (new >= 0) { + write_lock(&sbi->s_mb_avg_fragment_size_locks[new]); + list_add_tail(&grp->bb_avg_fragment_size_node, + &sbi->s_mb_avg_fragment_size[new]); + write_unlock(&sbi->s_mb_avg_fragment_size_locks[new]); } - grp->bb_avg_fragment_size_order = new_order; - write_lock(&sbi->s_mb_avg_fragment_size_locks[ - grp->bb_avg_fragment_size_order]); - list_add_tail(&grp->bb_avg_fragment_size_node, - &sbi->s_mb_avg_fragment_size[grp->bb_avg_fragment_size_order]); - write_unlock(&sbi->s_mb_avg_fragment_size_locks[ - grp->bb_avg_fragment_size_order]); }
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