gfs2: Grab glock reference sooner in gfs2_add_revoke

[ Upstream commit f4e2f5e1a527ce58fc9f85145b03704779a3123e ]

This patch rearranges gfs2_add_revoke so that the extra glock
reference is added earlier on in the function to avoid races in which
the glock is freed before the new reference is taken.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 47bc27d..110e5c4 100644 (file)
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -598,13 +598,13 @@ void gfs2_add_revoke(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd)
        struct buffer_head *bh = bd->bd_bh;
        struct gfs2_glock *gl = bd->bd_gl;
 
+       sdp->sd_log_num_revoke++;
+       if (atomic_inc_return(&gl->gl_revokes) == 1)
+               gfs2_glock_hold(gl);
        bh->b_private = NULL;
        bd->bd_blkno = bh->b_blocknr;
        gfs2_remove_from_ail(bd); /* drops ref on bh */
        bd->bd_bh = NULL;
-       sdp->sd_log_num_revoke++;
-       if (atomic_inc_return(&gl->gl_revokes) == 1)
-               gfs2_glock_hold(gl);
        set_bit(GLF_LFLUSH, &gl->gl_flags);
        list_add(&bd->bd_list, &sdp->sd_log_revokes);
 }