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 445fd5d..3d607bd 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);