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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Alexander Ahring Oder Aring <aahringo@redhat.com>,
        Andreas Gruenbacher <agruenba@redhat.com>
Subject: [PATCH 5.9 059/133] gfs2: Dont call cancel_delayed_work_sync from within delete work function
Date:   Mon,  9 Nov 2020 13:55:21 +0100
Message-Id: <20201109125033.568736123@linuxfoundation.org>
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From: Andreas Gruenbacher <agruenba@redhat.com>

commit 6bd1c7bd4ee7b17980cdc347522dcb76feac9b98 upstream.

Right now, we can end up calling cancel_delayed_work_sync from within
delete_work_func via gfs2_lookup_by_inum -> gfs2_inode_lookup ->
gfs2_cancel_delete_work.  When that happens, it will result in a
deadlock.  Instead, gfs2_inode_lookup should skip the call to
gfs2_cancel_delete_work when called from delete_work_func (blktype ==
GFS2_BLKST_UNLINKED).

Reported-by: Alexander Ahring Oder Aring <aahringo@redhat.com>
Fixes: a0e3cc65fa29 ("gfs2: Turn gl_delete into a delayed work")
Cc: stable@vger.kernel.org # v5.8+
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/gfs2/inode.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/gfs2/inode.c
+++ b/fs/gfs2/inode.c
@@ -180,7 +180,8 @@ struct inode *gfs2_inode_lookup(struct s
 		error = gfs2_glock_nq_init(io_gl, LM_ST_SHARED, GL_EXACT, &ip->i_iopen_gh);
 		if (unlikely(error))
 			goto fail;
-		gfs2_cancel_delete_work(ip->i_iopen_gh.gh_gl);
+		if (blktype != GFS2_BLKST_UNLINKED)
+			gfs2_cancel_delete_work(ip->i_iopen_gh.gh_gl);
 		glock_set_object(ip->i_iopen_gh.gh_gl, ip);
 		gfs2_glock_put(io_gl);
 		io_gl = NULL;