From: Bob Peterson rpeterso@redhat.com
[ Upstream commit df5db5f9ee112e76b5202fbc331f990a0fc316d6 ]
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 rpeterso@redhat.com Reviewed-by: Andreas Gruenbacher agruenba@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/gfs2/glock.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index efd44d5645d83..adc1a97cfe96d 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -548,6 +548,9 @@ __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;