[PATCH v2] Btrfs: add missing compression property remove in btrfs_ioctl_setflags

[Filipe Manana <fdmanana@suse.com>]

The behaviour of a 'chattr -c' consists of getting the current flags,
clearing the FS_COMPR_FL bit and then sending the result to the set
flags ioctl - this means the bit FS_NOCOMP_FL isn't set in the flags
passed to the ioctl. This results in the compression property not being
cleared from the inode - it was cleared only if the bit FS_NOCOMP_FL
was set in the received flags.

Reproducer:

    $ mkfs.btrfs -f /dev/sdd
    $ mount /dev/sdd /mnt && cd /mnt
    $ mkdir a
    $ chattr +c a
    $ touch a/file
    $ lsattr a/file
    --------c------- a/file
    $ chattr -c a
    $ touch a/file2
    $ lsattr a/file2
    --------c------- a/file2
    $ lsattr -d a
    ---------------- a

Reported-by: Andreas Schneider <asn@cryptomilk.org>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
---

V2: Ensure BTRFS_INODE_NOCOMPRESS isn't set (unless the bit FS_NOCOMP_FL is set).

 fs/btrfs/ioctl.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index a010c44..a46c169 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -332,6 +332,9 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
 			goto out_drop;
 
 	} else {
+		ret = btrfs_set_prop(inode, "btrfs.compression", NULL, 0, 0);
+		if (ret && ret != -ENODATA)
+			goto out_drop;
 		ip->flags &= ~(BTRFS_INODE_COMPRESS | BTRFS_INODE_NOCOMPRESS);
 	}
 
-- 
1.9.1