gfs2: Silence "suspicious RCU usage in gfs2_permission" warning

[ Upstream commit 074d730 ] Commit 0abd155 added rcu_dereference() for dereferencing ip->i_gl in gfs2_permission. This now causes lockdep to complain when gfs2_permission is called in non-RCU context: WARNING: suspicious RCU usage in gfs2_permission Switch to rcu_dereference_check() and check for the MAY_NOT_BLOCK flag to shut up lockdep when we know that dereferencing ip->i_gl is safe. Fixes: 0abd155 ("gfs2: fix an oops in gfs2_permission") Reported-by: [email protected] Signed-off-by: Andreas Gruenbacher <[email protected]> Signed-off-by: Sasha Levin <[email protected]>
embeddedTS · Nov 28, 2023 · 59fadfa · 59fadfa
1 parent dedf2a0
commit 59fadfa
Showing 1 changed file with 4 additions and 3 deletions.
diff --git a/fs/gfs2/inode.c b/fs/gfs2/inode.c
@@ -1835,21 +1835,22 @@ static const char *gfs2_get_link(struct dentry *dentry,
 
 int gfs2_permission(struct inode *inode, int mask)
 {
+	int may_not_block = mask & MAY_NOT_BLOCK;
 	struct gfs2_inode *ip;
 	struct gfs2_holder i_gh;
 	struct gfs2_glock *gl;
 	int error;
 
 	gfs2_holder_mark_uninitialized(&i_gh);
 	ip = GFS2_I(inode);
-	gl = rcu_dereference(ip->i_gl);
+	gl = rcu_dereference_check(ip->i_gl, !may_not_block);
 	if (unlikely(!gl)) {
 		/* inode is getting torn down, must be RCU mode */
-		WARN_ON_ONCE(!(mask & MAY_NOT_BLOCK));
+		WARN_ON_ONCE(!may_not_block);
 		return -ECHILD;
         }
 	if (gfs2_glock_is_locked_by_me(gl) == NULL) {
-		if (mask & MAY_NOT_BLOCK)
+		if (may_not_block)
 			return -ECHILD;
 		error = gfs2_glock_nq_init(gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
 		if (error)