vfs: add a comment to inode_permission()

Acked-by: NJ. Bruce Fields <bfields@redhat.com>
Acked-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAndreas Gruenbacher <agruen@kernel.org>
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

fs/namei.c

@@ -221,7 +221,7 @@ static int check_acl(struct inode *inode, int mask)
 }
 
 /*
- * This does basic POSIX ACL permission checking
+ * This does the basic permission checking
  */
 static int acl_permission_check(struct inode *inode, int mask)
 {
@@ -271,7 +271,7 @@ int generic_permission(struct inode *inode, int mask)
 	int ret;
 
 	/*
-	 * Do the basic POSIX ACL permission checks.
+	 * Do the basic permission checks.
 	 */
 	ret = acl_permission_check(inode, mask);
 	if (ret != -EACCES)
@@ -335,6 +335,8 @@ static inline int do_inode_permission(struct inode *inode, int mask)
  * We use "fsuid" for this, letting us set arbitrary permissions
  * for filesystem access without changing the "normal" uids which
  * are used for other things.
+ *
+ * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
  */
 int inode_permission(struct inode *inode, int mask)
 {