queue-5.15/gfs2-add-metapath_dibh-helper.patch

From b0af0d8c79922ac633d11ff9671f5f7f5e72477a Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Fri, 20 Oct 2023 01:32:15 +0200
Subject: gfs2: Add metapath_dibh helper

From: Andreas Gruenbacher <agruenba@redhat.com>

[ Upstream commit 92099f0c92270c8c7a79e6bc6e0312ad248ea331 ]

Add a metapath_dibh() helper for extracting the inode's buffer head from
a metapath.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Stable-dep-of: faddeb848305 ("gfs2: Fix use-after-free in iomap inline data write path")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/gfs2/bmap.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index d2011c3c33fc2..7425c90e47eb5 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -318,6 +318,12 @@ static void gfs2_metapath_ra(struct gfs2_glock *gl, __be64 *start, __be64 *end)
 	}
 }
 
+static inline struct buffer_head *
+metapath_dibh(struct metapath *mp)
+{
+	return mp->mp_bh[0];
+}
+
 static int __fillup_metapath(struct gfs2_inode *ip, struct metapath *mp,
 			     unsigned int x, unsigned int h)
 {
@@ -662,7 +668,7 @@ static int __gfs2_iomap_alloc(struct inode *inode, struct iomap *iomap,
 {
 	struct gfs2_inode *ip = GFS2_I(inode);
 	struct gfs2_sbd *sdp = GFS2_SB(inode);
-	struct buffer_head *dibh = mp->mp_bh[0];
+	struct buffer_head *dibh = metapath_dibh(mp);
 	u64 bn;
 	unsigned n, i, blks, alloced = 0, iblks = 0, branch_start = 0;
 	size_t dblks = iomap->length >> inode->i_blkbits;
-- 
2.51.0