diff options
authorChris Mason <>2011-10-11 11:41:40 -0400
committerChris Mason <>2011-10-11 11:45:55 -0400
commitf7f43cc84152e53b5687cd0eb8823310ba065524 (patch)
parent2a0f7f5769992bae5b3f97157fd80b2b943be485 (diff)
Btrfs: make sure not to defrag extents past i_size
The btrfs file defrag code will loop through the extents and force COW on them. But there is a concurrent truncate in the middle of the defrag, it might end up defragging the same range over and over again. The problem is that writepage won't go through and do anything on pages past i_size, so the cow won't happen, so the file will appear to still be fragmented. defrag will end up hitting the same extents again and again. In the worst case, the truncate can actually live lock with the defrag because the defrag keeps creating new ordered extents which the truncate code keeps waiting on. The fix here is to make defrag check for i_size inside the main loop, instead of just once before the looping starts. Signed-off-by: Chris Mason <>
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index df40b7c5f06b..efc4e4a85a69 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1062,7 +1062,9 @@ int btrfs_defrag_file(struct inode *inode, struct file *file,
if (i < inode->i_mapping->writeback_index)
inode->i_mapping->writeback_index = i;
- while (i <= last_index && defrag_count < max_to_defrag) {
+ while (i <= last_index && defrag_count < max_to_defrag &&
+ (i < (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
* make sure we stop running if someone unmounts
* the FS