gfs2: Recursive gfs2_quota_hold in gfs2_iomap_end

When starting an iomap write, gfs2_quota_lock_check -> gfs2_quota_lock
-> gfs2_quota_hold is called from gfs2_iomap_begin.  At the end of the
write, before unlocking the quotas, punch_hole -> gfs2_quota_hold can be
called again in gfs2_iomap_end, which is incorrect and leads to a failed
assertion.  Instead, move the call to gfs2_quota_unlock before the call
to punch_hole to fix that.

Fixes: 64bc06b ("gfs2: iomap buffered write support")
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Author: Andreas Gruenbacher

fs/gfs2/bmap.c

@@ -1230,6 +1230,9 @@ static int gfs2_iomap_end(struct inode *inode, loff_t pos, loff_t length,
 
 	gfs2_inplace_release(ip);
 
+	if (ip->i_qadata && ip->i_qadata->qa_qd_num)
+		gfs2_quota_unlock(ip);
+
 	if (length != written && (iomap->flags & IOMAP_F_NEW)) {
 		/* Deallocate blocks that were just allocated. */
 		loff_t blockmask = i_blocksize(inode) - 1;
@@ -1242,9 +1245,6 @@ static int gfs2_iomap_end(struct inode *inode, loff_t pos, loff_t length,
 		}
 	}
 
-	if (ip->i_qadata && ip->i_qadata->qa_qd_num)
-		gfs2_quota_unlock(ip);
-
 	if (unlikely(!written))
 		goto out_unlock;