btrfs: add setlease file operation

btrfs: add setlease file operation

Add the setlease file_operation to btrfs_file_operations and
btrfs_dir_file_operations, pointing to generic_setlease.  A future
patch will change the default behavior to reject lease attempts with
-EINVAL when there is no setlease file operation defined. Add
generic_setlease to retain the ability to set leases on this
filesystem.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20260108-setlease-6-20-v1-3-ea4dec9b67fa@kernel.org
Acked-by: David Sterba <dsterba@suse.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>