quota: Fix dquot_transfer for filesystems different from ext4

commit 05b5d898235401c489c68e1f3bc5706a29ad5713 upstream.

Commit fd8fbfc1 modified the way we find amount of reserved space
belonging to an inode. The amount of reserved space is checked
from dquot_transfer and thus inode_reserved_space gets called
even for filesystems that don't provide get_reserved_space callback
which results in a BUG.

Fix the problem by checking get_reserved_space callback and return 0 if
the filesystem does not provide it.

CC: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index c4d07a803bd0eb6c93b83c3f9b9d6a2595127183..253498739978f16937d0bce16306f378c8f33a3e 100644 (file)
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -1425,6 +1425,9 @@ static void inode_sub_rsv_space(struct inode *inode, qsize_t number)
 static qsize_t inode_get_rsv_space(struct inode *inode)
 {
        qsize_t ret;
+
+       if (!inode->i_sb->dq_op->get_reserved_space)
+               return 0;
        spin_lock(&inode->i_lock);
        ret = *inode_reserved_space(inode);
        spin_unlock(&inode->i_lock);