Btrfs: do not bother to defrag an extent if it is a big real extent

$ mkfs.btrfs /dev/sdb7
$ mount /dev/sdb7 /mnt/btrfs/ -oautodefrag
$ dd if=/dev/zero of=/mnt/btrfs/foobar bs=4k count=10 oflag=direct 2>/dev/null
$ filefrag -v /mnt/btrfs/foobar
Filesystem type is: 9123683e
File size of /mnt/btrfs/foobar is 40960 (10 blocks, blocksize 4096)
 ext logical physical expected length flags
   0       0     3072              10 eof
/mnt/btrfs/foobar: 1 extent found

Now we have a big real extent [0, 40960), but autodefrag will still defrag it.

$ sync
$ filefrag -v /mnt/btrfs/foobar
Filesystem type is: 9123683e
File size of /mnt/btrfs/foobar is 40960 (10 blocks, blocksize 4096)
 ext logical physical expected length flags
   0       0     3082              10 eof
/mnt/btrfs/foobar: 1 extent found

So if we already find a big real extent, we're ok about that, just skip it.

Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 3 insertions, 6 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 6c39d1a55907..afde837644e5 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1140,12 +1140,9 @@ int btrfs_defrag_file(struct inode *inode, struct file *file,
                 if (!(inode->i_sb->s_flags & MS_ACTIVE))
                         break;
 
-                if (!newer_than &&
-                    !should_defrag_range(inode, (u64)i << PAGE_CACHE_SHIFT,
-                                        PAGE_CACHE_SIZE,
-                                        extent_thresh,
-                                        &last_len, &skip,
-                                        &defrag_end)) {
+                if (!should_defrag_range(inode, (u64)i << PAGE_CACHE_SHIFT,
+                                         PAGE_CACHE_SIZE, extent_thresh,
+                                         &last_len, &skip, &defrag_end)) {
                         unsigned long next;
                         /*
                          * the should_defrag function tells us how much to skip