linux-kernel - [PATCH AUTOSEL 5.15 01/39] gfs2: release iopen glock early in evict

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Message-Id: <20211126023156.441292-1-sashal@kernel.org>
Date:   Thu, 25 Nov 2021 21:31:18 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Bob Peterson <rpeterso@...hat.com>,
        Andreas Gruenbacher <agruenba@...hat.com>,
        Sasha Levin <sashal@...nel.org>, cluster-devel@...hat.com
Subject: [PATCH AUTOSEL 5.15 01/39] gfs2: release iopen glock early in evict

From: Bob Peterson <rpeterso@...hat.com>

[ Upstream commit 49462e2be119d38c5eb5759d0d1b712df3a41239 ]

Before this patch, evict would clear the iopen glock's gl_object after
releasing the inode glock.  In the meantime, another process could reuse
the same block and thus glocks for a new inode.  It would lock the inode
glock (exclusively), and then the iopen glock (shared).  The shared
locking mode doesn't provide any ordering against the evict, so by the
time the iopen glock is reused, evict may not have gotten to setting
gl_object to NULL.

Fix that by releasing the iopen glock before the inode glock in
gfs2_evict_inode.

Signed-off-by: Bob Peterson <rpeterso@...hat.com>gl_object
Signed-off-by: Andreas Gruenbacher <agruenba@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/gfs2/super.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 6e00d15ef0a82..cc51b5f5f52d8 100644
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -1402,13 +1402,6 @@ static void gfs2_evict_inode(struct inode *inode)
 	gfs2_ordered_del_inode(ip);
 	clear_inode(inode);
 	gfs2_dir_hash_inval(ip);
-	if (ip->i_gl) {
-		glock_clear_object(ip->i_gl, ip);
-		wait_on_bit_io(&ip->i_flags, GIF_GLOP_PENDING, TASK_UNINTERRUPTIBLE);
-		gfs2_glock_add_to_lru(ip->i_gl);
-		gfs2_glock_put_eventually(ip->i_gl);
-		ip->i_gl = NULL;
-	}
 	if (gfs2_holder_initialized(&ip->i_iopen_gh)) {
 		struct gfs2_glock *gl = ip->i_iopen_gh.gh_gl;
 
@@ -1421,6 +1414,13 @@ static void gfs2_evict_inode(struct inode *inode)
 		gfs2_holder_uninit(&ip->i_iopen_gh);
 		gfs2_glock_put_eventually(gl);
 	}
+	if (ip->i_gl) {
+		glock_clear_object(ip->i_gl, ip);
+		wait_on_bit_io(&ip->i_flags, GIF_GLOP_PENDING, TASK_UNINTERRUPTIBLE);
+		gfs2_glock_add_to_lru(ip->i_gl);
+		gfs2_glock_put_eventually(ip->i_gl);
+		ip->i_gl = NULL;
+	}
 }
 
 static struct inode *gfs2_alloc_inode(struct super_block *sb)
-- 
2.33.0