From 4cb13e5d6ecc47b91b24a35f8fbc2c9f33d075fe Mon Sep 17 00:00:00 2001 From: Liu Bo Date: Thu, 29 Mar 2012 09:57:45 -0400 Subject: [PATCH] Btrfs: fix recursive defragment with autodefrag option $ mkfs.btrfs disk $ mount disk /mnt -o autodefrag $ dd if=/dev/zero of=/mnt/foobar bs=4k count=10 2>/dev/null && sync $ for i in `seq 9 -2 0`; do dd if=/dev/zero of=/mnt/foobar bs=4k count=1 \ seek=$i conv=notrunc 2> /dev/null; done && sync then we'll get to defrag "foobar" again and again. So does option "-o autodefrag,compress". Reasons: When the cleaner kthread gets to fetch inodes from the defrag tree and defrag them, it will dirty pages and submit them, this will comes to another DATA COW where the processing inode will be inserted to the defrag tree again. This patch sets a rule for COW code, i.e. insert an inode when we're really going to make some defragments. Signed-off-by: Liu Bo Signed-off-by: Chris Mason --- fs/btrfs/inode.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index eb6aec7bbacb..1be31368e881 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -347,8 +347,9 @@ static noinline int compress_file_range(struct inode *inode, int will_compress; int compress_type = root->fs_info->compress_type; - /* if this is a small write inside eof, kick off a defragbot */ - if (end <= BTRFS_I(inode)->disk_i_size && (end - start + 1) < 16 * 1024) + /* if this is a small write inside eof, kick off a defrag */ + if ((end - start + 1) < 16 * 1024 && + (start > 0 || end + 1 < BTRFS_I(inode)->disk_i_size)) btrfs_add_inode_defrag(NULL, inode); actual_end = min_t(u64, isize, end + 1); @@ -843,7 +844,8 @@ static noinline int cow_file_range(struct inode *inode, ret = 0; /* if this is a small write inside eof, kick off defrag */ - if (end <= BTRFS_I(inode)->disk_i_size && num_bytes < 64 * 1024) + if (num_bytes < 64 * 1024 && + (start > 0 || end + 1 < BTRFS_I(inode)->disk_i_size)) btrfs_add_inode_defrag(trans, inode); if (start == 0) {