From d707d31c972b657dfc2efefd0b99cc4e14223dab Mon Sep 17 00:00:00 2001 From: Mingming Cao Date: Wed, 15 Oct 2008 22:04:01 -0700 Subject: [PATCH] ext2: fix ext2 block reservation early ENOSPC issue We could run into ENOSPC error on ext2, even when there is free blocks on the filesystem. The problem is triggered in the case the goal block group has 0 free blocks , and the rest block groups are skipped due to the check of "free_blocks < windowsz/2". Current code could fall back to non reservation allocation to prevent early ENOSPC after examing all the block groups with reservation on , but this code was bypassed if the reservation window is turned off already, which is true in this case. This patch fixed two issues: 1) We don't need to turn off block reservation if the goal block group has 0 free blocks left and continue search for the rest of block groups. Current code the intention is to turn off the block reservation if the goal allocation group has a few (some) free blocks left (not enough for make the desired reservation window),to try to allocation in the goal block group, to get better locality. But if the goal blocks have 0 free blocks, it should leave the block reservation on, and continues search for the next block groups,rather than turn off block reservation completely. 2) we don't need to check the window size if the block reservation is off. The problem was originally found and fixed in ext4. Signed-off-by: Mingming Cao Cc: Theodore Ts'o Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ext2/balloc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c index 10bb02c3f25c..6dac7ba2d22d 100644 --- a/fs/ext2/balloc.c +++ b/fs/ext2/balloc.c @@ -1295,6 +1295,7 @@ ext2_fsblk_t ext2_new_blocks(struct inode *inode, ext2_fsblk_t goal, * turn off reservation for this allocation */ if (my_rsv && (free_blocks < windowsz) + && (free_blocks > 0) && (rsv_is_empty(&my_rsv->rsv_window))) my_rsv = NULL; @@ -1332,7 +1333,7 @@ ext2_fsblk_t ext2_new_blocks(struct inode *inode, ext2_fsblk_t goal, * free blocks is less than half of the reservation * window size. */ - if (free_blocks <= (windowsz/2)) + if (my_rsv && (free_blocks <= (windowsz/2))) continue; brelse(bitmap_bh);