From: Bob Peterson Date: Wed, 13 Nov 2019 20:08:45 +0000 (-0600) Subject: gfs2: Don't demote a glock until its revokes are written X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=df5db5f9ee112;p=linux.git gfs2: Don't demote a glock until its revokes are written Before this patch, run_queue would demote glocks based on whether there are any more holders. But if the glock has pending revokes that haven't been written to the media, giving up the glock might end in file system corruption if the revokes never get written due to io errors, node crashes and fences, etc. In that case, another node will replay the metadata blocks associated with the glock, but because the revoke was never written, it could replay that block even though the glock had since been granted to another node who might have made changes. This patch changes the logic in run_queue so that it never demotes a glock until its count of pending revokes reaches zero. Signed-off-by: Bob Peterson Reviewed-by: Andreas Gruenbacher --- diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 6af1edabef055..73cb5bcc37a75 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -710,6 +710,9 @@ __acquires(&gl->gl_lockref.lock) goto out_unlock; if (nonblock) goto out_sched; + smp_mb(); + if (atomic_read(&gl->gl_revokes) != 0) + goto out_sched; set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags); GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE); gl->gl_target = gl->gl_demote_state;