fs: fold __inode_permission() into inode_permission()

Since commit 9c630ebefe ("ovl: simplify permission checking"),
overlayfs doesn't call __inode_permission() anymore, which leaves no
users other than inode_permission().  So just fold it back into
inode_permission().

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namei.c

@@ -390,50 +390,6 @@ static inline int do_inode_permission(struct inode *inode, int mask)
 	return generic_permission(inode, mask);
 }
 
-/**
- * __inode_permission - Check for access rights to a given inode
- * @inode: Inode to check permission on
- * @mask: Right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
- *
- * Check for read/write/execute permissions on an inode.
- *
- * When checking for MAY_APPEND, MAY_WRITE must also be set in @mask.
- *
- * This does not check for a read-only file system.  You probably want
- * inode_permission().
- */
-int __inode_permission(struct inode *inode, int mask)
-{
-	int retval;
-
-	if (unlikely(mask & MAY_WRITE)) {
-		/*
-		 * Nobody gets write access to an immutable file.
-		 */
-		if (IS_IMMUTABLE(inode))
-			return -EPERM;
-
-		/*
-		 * Updating mtime will likely cause i_uid and i_gid to be
-		 * written back improperly if their true value is unknown
-		 * to the vfs.
-		 */
-		if (HAS_UNMAPPED_ID(inode))
-			return -EACCES;
-	}
-
-	retval = do_inode_permission(inode, mask);
-	if (retval)
-		return retval;
-
-	retval = devcgroup_inode_permission(inode, mask);
-	if (retval)
-		return retval;
-
-	return security_inode_permission(inode, mask);
-}
-EXPORT_SYMBOL(__inode_permission);
-
 /**
  * sb_permission - Check superblock-level permissions
  * @sb: Superblock of inode to check permission on
@@ -472,7 +428,32 @@ int inode_permission(struct inode *inode, int mask)
 	retval = sb_permission(inode->i_sb, inode, mask);
 	if (retval)
 		return retval;
-	return __inode_permission(inode, mask);
+
+	if (unlikely(mask & MAY_WRITE)) {
+		/*
+		 * Nobody gets write access to an immutable file.
+		 */
+		if (IS_IMMUTABLE(inode))
+			return -EPERM;
+
+		/*
+		 * Updating mtime will likely cause i_uid and i_gid to be
+		 * written back improperly if their true value is unknown
+		 * to the vfs.
+		 */
+		if (HAS_UNMAPPED_ID(inode))
+			return -EACCES;
+	}
+
+	retval = do_inode_permission(inode, mask);
+	if (retval)
+		return retval;
+
+	retval = devcgroup_inode_permission(inode, mask);
+	if (retval)
+		return retval;
+
+	return security_inode_permission(inode, mask);
 }
 EXPORT_SYMBOL(inode_permission);
 

include/linux/fs.h

@@ -2699,7 +2699,6 @@ extern sector_t bmap(struct inode *, sector_t);
 #endif
 extern int notify_change(struct dentry *, struct iattr *, struct inode **);
 extern int inode_permission(struct inode *, int);
-extern int __inode_permission(struct inode *, int);
 extern int generic_permission(struct inode *, int);
 extern int __check_sticky(struct inode *dir, struct inode *inode);