From 49462e2be119d38c5eb5759d0d1b712df3a41239 Mon Sep 17 00:00:00 2001
From: Bob Peterson <rpeterso@redhat.com>
Date: Thu, 28 Oct 2021 11:53:10 -0500
Subject: [PATCH] gfs2: release iopen glock early in evict
Git-commit: 49462e2be119d38c5eb5759d0d1b712df3a41239
Patch-mainline: v5.16-rc2
References: git-fixes

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@redhat.com>gl_object
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Acked-by: Anthony Iliopoulos <ailiop@suse.com>

---
 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 5b121371508a..0f93e8beca4d 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)
-- 
2.43.0