From 814b330b8bd0ebc805036d2978b57e4217f78e60 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <djwong@kernel.org>
Date: Tue, 28 May 2024 21:10:54 -0700
Subject: [PATCH] xfs: iget for metadata inodes

Create a xfs_imeta_iget function for metadata inodes to ensure that when
we try to iget a metadata file, the inobt thinks a metadata inode is in
use and that the file type matches what we are expecting.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 include/libxfs.h         |  1 +
 include/xfs_inode.h      |  5 +++++
 libxfs/Makefile          |  1 +
 libxfs/inode.c           | 30 ++++++++++++++++++++++++++++++
 libxfs/libxfs_api_defs.h |  4 ++++
 libxfs/xfs_metafile.h    | 14 ++++++++++++++
 6 files changed, 55 insertions(+)
 create mode 100644 libxfs/xfs_metafile.h

diff --git a/include/libxfs.h b/include/libxfs.h
index c49f22935..1e55d42d5 100644
--- a/include/libxfs.h
+++ b/include/libxfs.h
@@ -93,6 +93,7 @@ struct iomap;
 #include "xfs_btree_mem.h"
 #include "xfs_parent.h"
 #include "xfs_ag_resv.h"
+#include "xfs_metafile.h"
 
 #ifndef ARRAY_SIZE
 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
diff --git a/include/xfs_inode.h b/include/xfs_inode.h
index 4fe2826f9..27c050357 100644
--- a/include/xfs_inode.h
+++ b/include/xfs_inode.h
@@ -210,6 +210,11 @@ static inline struct timespec64 inode_set_ctime_current(struct inode *inode)
 	return now;
 }
 
+static inline bool inode_wrong_type(const struct inode *inode, umode_t mode)
+{
+	return (inode->i_mode ^ mode) & S_IFMT;
+}
+
 typedef struct xfs_inode {
 	struct cache_node	i_node;
 	struct xfs_mount	*i_mount;	/* fs mount struct ptr */
diff --git a/libxfs/Makefile b/libxfs/Makefile
index 1f713d555..39809c498 100644
--- a/libxfs/Makefile
+++ b/libxfs/Makefile
@@ -54,6 +54,7 @@ HFILES = \
 	xfs_inode_buf.h \
 	xfs_inode_fork.h \
 	xfs_inode_util.h \
+	xfs_metafile.h \
 	xfs_parent.h \
 	xfs_quota_defs.h \
 	xfs_refcount.h \
diff --git a/libxfs/inode.c b/libxfs/inode.c
index 9230ad24a..35fc2632e 100644
--- a/libxfs/inode.c
+++ b/libxfs/inode.c
@@ -205,6 +205,36 @@ out_destroy:
 	return error;
 }
 
+/*
+ * Get a metadata inode.  The file type part of @mode must match the inode
+ * exactly.  Caller must supply a transaction (even if empty) to avoid
+ * livelocking if the inobt has a cycle.
+ */
+int
+libxfs_metafile_iget(
+	struct xfs_trans	*tp,
+	xfs_ino_t		ino,
+	umode_t			mode,
+	struct xfs_inode	**ipp)
+{
+	struct xfs_mount	*mp = tp->t_mountp;
+	struct xfs_inode	*ip;
+	int			error;
+
+	error = libxfs_iget(mp, tp, ino, XFS_IGET_UNTRUSTED, &ip);
+	if (error)
+		return error;
+
+	if (inode_wrong_type(VFS_I(ip), mode))
+		goto bad_rele;
+
+	*ipp = ip;
+	return 0;
+bad_rele:
+	libxfs_irele(ip);
+	return -EFSCORRUPTED;
+}
+
 static void
 libxfs_idestroy(
 	struct xfs_inode	*ip)
diff --git a/libxfs/libxfs_api_defs.h b/libxfs/libxfs_api_defs.h
index 48fed384a..f70fa86bd 100644
--- a/libxfs/libxfs_api_defs.h
+++ b/libxfs/libxfs_api_defs.h
@@ -185,6 +185,7 @@
 #define xfs_iext_next			libxfs_iext_next
 #define xfs_ifork_zap_attr		libxfs_ifork_zap_attr
 #define xfs_imap_to_bp			libxfs_imap_to_bp
+
 #define xfs_initialize_perag		libxfs_initialize_perag
 #define xfs_initialize_perag_data	libxfs_initialize_perag_data
 #define xfs_init_local_fork		libxfs_init_local_fork
@@ -209,8 +210,11 @@
 #define xfs_log_calc_minimum_size	libxfs_log_calc_minimum_size
 #define xfs_log_get_max_trans_res	libxfs_log_get_max_trans_res
 #define xfs_log_sb			libxfs_log_sb
+
+#define xfs_metafile_iget		libxfs_metafile_iget
 #define xfs_mode_to_ftype		libxfs_mode_to_ftype
 #define xfs_mkdir_space_res		libxfs_mkdir_space_res
+
 #define xfs_parent_addname		libxfs_parent_addname
 #define xfs_parent_finish		libxfs_parent_finish
 #define xfs_parent_hashval		libxfs_parent_hashval
diff --git a/libxfs/xfs_metafile.h b/libxfs/xfs_metafile.h
new file mode 100644
index 000000000..ea0ba76be
--- /dev/null
+++ b/libxfs/xfs_metafile.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (c) 2018-2024 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#ifndef __XFS_METAFILE_H__
+#define __XFS_METAFILE_H__
+
+/* Code specific to kernel/userspace; must be provided externally. */
+
+int xfs_metafile_iget(struct xfs_trans *tp, xfs_ino_t ino, umode_t mode,
+		struct xfs_inode **ipp);
+
+#endif /* __XFS_METAFILE_H__ */
-- 
2.50.1