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authorLi Zefan <lizf@cn.fujitsu.com>2011-10-10 15:43:34 -0400
committerChris Mason <chris.mason@oracle.com>2011-10-10 15:43:34 -0400
commit2a0f7f5769992bae5b3f97157fd80b2b943be485 (patch)
treeee19a5470211f13d1e53a311cb0d9e2ccc2988fc
parentb6316429af7f365f307dfd2b6a7a42f2563aef19 (diff)
downloadlinux-linaro-2a0f7f5769992bae5b3f97157fd80b2b943be485.tar.gz
Btrfs: fix recursive auto-defrag
Follow those steps: # mount -o autodefrag /dev/sda7 /mnt # dd if=/dev/urandom of=/mnt/tmp bs=200K count=1 # sync # dd if=/dev/urandom of=/mnt/tmp bs=8K count=1 conv=notrunc and then it'll go into a loop: writeback -> defrag -> writeback ... It's because writeback writes [8K, 200K] and then writes [0, 8K]. I tried to make writeback know if the pages are dirtied by defrag, but the patch was a bit intrusive. Here I simply set writeback_index when we defrag a file. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
-rw-r--r--fs/btrfs/ioctl.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 6f89bcc4e55..df40b7c5f06 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1055,6 +1055,13 @@ int btrfs_defrag_file(struct inode *inode, struct file *file,
if (!max_to_defrag)
max_to_defrag = last_index - 1;
+ /*
+ * make writeback starts from i, so the defrag range can be
+ * written sequentially.
+ */
+ if (i < inode->i_mapping->writeback_index)
+ inode->i_mapping->writeback_index = i;
+
while (i <= last_index && defrag_count < max_to_defrag) {
/*
* make sure we stop running if someone unmounts