[GFS2] Fix recursive locking in gfs2_permission
Since gfs2_permission may be called either from the VFS (in which case
we need to obtain a shared glock) or from GFS2 (in which case we already
have a glock) we need to test to see whether or not a lock is required.
The original test was buggy due to a potential race. This one should
be safe.
This fixes Red Hat bugzilla #217129
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/ops_inode.c b/fs/gfs2/ops_inode.c
index b247f25..fd9fee2 100644
--- a/fs/gfs2/ops_inode.c
+++ b/fs/gfs2/ops_inode.c
@@ -835,6 +835,10 @@
* @mask:
* @nd: passed from Linux VFS, ignored by us
*
+ * This may be called from the VFS directly, or from within GFS2 with the
+ * inode locked, so we look to see if the glock is already locked and only
+ * lock the glock if its not already been done.
+ *
* Returns: errno
*/
@@ -843,16 +847,19 @@
struct gfs2_inode *ip = GFS2_I(inode);
struct gfs2_holder i_gh;
int error;
+ int unlock = 0;
- if (!test_bit(GIF_INVALID, &ip->i_flags))
- return generic_permission(inode, mask, gfs2_check_acl);
-
- error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
- if (!error) {
- error = generic_permission(inode, mask, gfs2_check_acl_locked);
- gfs2_glock_dq_uninit(&i_gh);
+ if (gfs2_glock_is_locked_by_me(ip->i_gl) == 0) {
+ error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
+ if (error)
+ return error;
+ unlock = 1;
}
+ error = generic_permission(inode, mask, gfs2_check_acl_locked);
+ if (unlock)
+ gfs2_glock_dq_uninit(&i_gh);
+
return error;
}