From ebbe027797f67d34708ccfabdb129886d549f9ce Mon Sep 17 00:00:00 2001 From: Robin Dong Date: Wed, 26 Oct 2011 05:14:27 -0400 Subject: [PATCH] ext4: use stream-alloc when mb_group_prealloc set to zero The kernel will crash on ext4_mb_mark_diskspace_used: BUG_ON(ac->ac_b_ex.fe_len <= 0); after we set /sys/fs/ext4/sda/mb_group_prealloc to zero and create new files in an ext4 filesystem. The reason is: ac_b_ex.fe_len also set to zero(mb_group_prealloc) in ext4_mb_normalize_group_request because the ac_flags contains EXT4_MB_HINT_GROUP_ALLOC. I think when someone set mb_group_prealloc to zero, it means DO NOT USE GROUP PREALLOCATION, so we should set alloc-strategy to STREAM in this case. Signed-off-by: Robin Dong Signed-off-by: "Theodore Ts'o" --- fs/ext4/mballoc.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index cd70b30..8976265 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4006,6 +4006,11 @@ static void ext4_mb_group_or_file(struct ext4_allocation_context *ac) return; } + if (sbi->s_mb_group_prealloc <= 0) { + ac->ac_flags |= EXT4_MB_STREAM_ALLOC; + return; + } + /* don't use group allocation for large files */ size = max(size, isize); if (size > sbi->s_mb_stream_request) { -- 2.7.4