From 9114d79569a3fb858a7ecb1f21cb1dec93dc2f21 Mon Sep 17 00:00:00 2001 From: Lars Ellenberg Date: Tue, 19 Mar 2013 18:16:42 +0100 Subject: [PATCH] drbd: cleanup bogus assert message This fixes ASSERT( mdev->state.disk == D_FAILED ) in drivers/block/drbd/drbd_main.c When we detach from local disk, we let the local refcount hit zero twice. First, we transition to D_FAILED, so we won't give out new references to incoming requests; we still may give out *internal* references, though. Once the refcount hits zero [1] while in D_FAILED, we queue a transition to D_DISKLESS to our worker. We need to queue it, because we may be in atomic context when putting the reference. Once the transition to D_DISKLESS actually happened [2] from worker context, we don't give out new internal references either. Between hitting zero the first time [1] and actually transition to D_DISKLESS [2], there may be a few very short lived internal get/put, so we may hit zero more than once while being in D_FAILED, or even see a race where a an internal get_ldev() happened while D_FAILED, but the corresponding put_ldev() happens just after the transition to D_DISKLESS. That's why we have the additional test_and_set_bit(GO_DISKLESS,); and that's why the assert was placed wrong. Since there was exactly one code path left to drbd_go_diskless(), and that checks already for D_FAILED, drop that assert, and fold in the drbd_queue_work(). Signed-off-by: Philipp Reisner Signed-off-by: Lars Ellenberg Signed-off-by: Jens Axboe --- drivers/block/drbd/drbd_int.h | 7 ++++--- drivers/block/drbd/drbd_main.c | 7 ------- 2 files changed, 4 insertions(+), 10 deletions(-) diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h index 6b51afa..db504d0 100644 --- a/drivers/block/drbd/drbd_int.h +++ b/drivers/block/drbd/drbd_int.h @@ -1148,7 +1148,6 @@ extern int drbd_bitmap_io_from_worker(struct drbd_conf *mdev, char *why, enum bm_flag flags); extern int drbd_bmio_set_n_write(struct drbd_conf *mdev); extern int drbd_bmio_clear_n_write(struct drbd_conf *mdev); -extern void drbd_go_diskless(struct drbd_conf *mdev); extern void drbd_ldev_destroy(struct drbd_conf *mdev); /* Meta data layout @@ -2053,9 +2052,11 @@ static inline void put_ldev(struct drbd_conf *mdev) if (mdev->state.disk == D_DISKLESS) /* even internal references gone, safe to destroy */ drbd_ldev_destroy(mdev); - if (mdev->state.disk == D_FAILED) + if (mdev->state.disk == D_FAILED) { /* all application IO references gone. */ - drbd_go_diskless(mdev); + if (!test_and_set_bit(GO_DISKLESS, &mdev->flags)) + drbd_queue_work(&mdev->tconn->sender_work, &mdev->go_diskless); + } wake_up(&mdev->misc_wait); } } diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c index e98da67..731a28e 100644 --- a/drivers/block/drbd/drbd_main.c +++ b/drivers/block/drbd/drbd_main.c @@ -3252,13 +3252,6 @@ static int w_go_diskless(struct drbd_work *w, int unused) return 0; } -void drbd_go_diskless(struct drbd_conf *mdev) -{ - D_ASSERT(mdev->state.disk == D_FAILED); - if (!test_and_set_bit(GO_DISKLESS, &mdev->flags)) - drbd_queue_work(&mdev->tconn->sender_work, &mdev->go_diskless); -} - /** * drbd_queue_bitmap_io() - Queues an IO operation on the whole bitmap * @mdev: DRBD device. -- 2.7.4