On Tue, Nov 25, 2014 at 12:34:34AM -0500, Theodore Ts'o wrote:

The only reason btrfs cloned code from the VFS layer was so it could
add a check to see if a subvolume is read-ony.  Instead of doing that,
let's add a new inode operation which allows a file system to return
an error if the inode is read-only, and use that in update_time().
There may be other places where the VFS layer may want to know that
btrfs would want to treat an inode is read-only.

With this commit, there are no remaining users of update_time() in the
inode operations structure, so we can remove it and simply things
further.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: linux-btrfs@vger.kernel.org

Reviewed-by: David Sterba <redacted>