commit 280227a7 upstream

fallocate() checks that the file is extent-based and returns
EOPNOTSUPP in case is not. Other tasks can convert from and to
indirect and extent so it's safe to check only after grabbing
the inode mutex.

[Nikolay Borisov: Bakported to 3.12.47
 - Adjusted context
 - Add the 'out' label]
Signed-off-by: Davide Italiano <dccitaliano@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>