RCUify freeing acls, let check_acl() go ahead in RCU mode if acl is cached

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 6 insertions, 11 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 445fd5da11fa..3d607bd80e09 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -179,19 +179,14 @@ static int check_acl(struct inode *inode, int mask)
 #ifdef CONFIG_FS_POSIX_ACL
         struct posix_acl *acl;
 
-        /*
-         * Under RCU walk, we cannot even do a "get_cached_acl()",
-         * because that involves locking and getting a refcount on
-         * a cached ACL.
-         *
-         * So the only case we handle during RCU walking is the
-         * case of a cached "no ACL at all", which needs no locks
-         * or refcounts.
-         */
         if (mask & MAY_NOT_BLOCK) {
-                if (negative_cached_acl(inode, ACL_TYPE_ACCESS))
+                acl = get_cached_acl_rcu(inode, ACL_TYPE_ACCESS);
+                if (!acl)
                         return -EAGAIN;
-                return -ECHILD;
+                /* no ->get_acl() calls in RCU mode... */
+                if (acl == ACL_NOT_CACHED)
+                        return -ECHILD;
+                return posix_acl_permission(inode, acl, mask);
         }
 
         acl = get_cached_acl(inode, ACL_TYPE_ACCESS);