From 72b8ab9dde211ea518ff27e631b2046ef90c29a2 Mon Sep 17 00:00:00 2001 From: Eric Sandeen Date: Sun, 16 May 2010 11:00:00 -0400 Subject: ext4: don't use quota reservation for speculative metadata Because we can badly over-reserve metadata when we calculate worst-case, it complicates things for quota, since we must reserve and then claim later, retry on EDQUOT, etc. Quota is also a generally smaller pool than fs free blocks, so this over-reservation hurts more, and more often. I'm of the opinion that it's not the worst thing to allow metadata to push a user slightly over quota. This simplifies the code and avoids the false quota rejections that result from worst-case speculation. This patch stops the speculative quota-charging for worst-case metadata requirements, and just charges quota when the blocks are allocated at writeout. It also is able to remove the try-again loop on EDQUOT. This patch has been tested indirectly by running the xfstests suite with a hack to mount & enable quota prior to the test. I also did a more specific test of fragmenting freespace and then doing a large delalloc write under quota; quota stopped me at the right amount of file IO, and then the writeout generated enough metadata (due to the fragmentation) that it put me slightly over quota, as expected. Signed-off-by: Eric Sandeen Signed-off-by: "Theodore Ts'o" --- fs/ext4/balloc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'fs/ext4/balloc.c') diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c index d2f37a5..95b7594 100644 --- a/fs/ext4/balloc.c +++ b/fs/ext4/balloc.c @@ -591,14 +591,15 @@ ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode, ret = ext4_mb_new_blocks(handle, &ar, errp); if (count) *count = ar.len; - /* - * Account for the allocated meta blocks + * Account for the allocated meta blocks. We will never + * fail EDQUOT for metdata, but we do account for it. */ if (!(*errp) && EXT4_I(inode)->i_delalloc_reserved_flag) { spin_lock(&EXT4_I(inode)->i_block_reservation_lock); EXT4_I(inode)->i_allocated_meta_blocks += ar.len; spin_unlock(&EXT4_I(inode)->i_block_reservation_lock); + dquot_alloc_block_nofail(inode, ar.len); } return ret; } -- cgit v1.1