gfs2: release iopen glock early in evict

BugLink: https://bugs.launchpad.net/bugs/1953731
[ 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@redhat.com>gl_object
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>

diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
index 6e00d15ef0a824552f3638abc70da482748d5212..cc51b5f5f52d89679c7e00b3353312120ff21ca9 100644 (file)
--- a/fs/gfs2/super.c
+++ b/fs/gfs2/super.c
@@ -1402,13 +1402,6 @@ out:
        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 @@ out:
                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)