Commit 009ba89d authored by Lars Ellenberg's avatar Lars Ellenberg Committed by Philipp Reisner
Browse files

drbd: fix schedule in atomic 



An administrative detach used to request a state change directly to D_DISKLESS,
first suspending IO to avoid the last put_ldev() occuring from an endio handler,
potentially in irq context.

This is not enough on the receiving side (typically secondary), we may miss
some peer_req on the way to local disk, which then may do the last put_ldev()
from their drbd_peer_request_endio().

This patch makes the detach always go through the intermediate D_FAILED state.
We may consider to rename it D_DETACHING.

Alternative approach would be to create yet an other work item to be scheduled
on the worker, do the destructor work from there, and get the timing right.

Signed-off-by: default avatarPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: default avatarLars Ellenberg <lars.ellenberg@linbit.com>
parent 992d6e91

drivers/block/drbd/drbd_nl.c

+9 −4
Original line number Original line Diff line number Diff line
@@ -1670,12 +1670,17 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info) 
static int adm_detach(struct drbd_conf *mdev)

static int adm_detach(struct drbd_conf *mdev)

{

{

	enum drbd_state_rv retcode;

	enum drbd_state_rv retcode;

	int ret;

	drbd_suspend_io(mdev); /* so no-one is stuck in drbd_al_begin_io */

	drbd_suspend_io(mdev); /* so no-one is stuck in drbd_al_begin_io */

	retcode = drbd_request_state(mdev, NS(disk, D_DISKLESS));

	retcode = drbd_request_state(mdev, NS(disk, D_FAILED));

	wait_event(mdev->misc_wait,

	/* D_FAILED will transition to DISKLESS. */

			mdev->state.disk != D_DISKLESS ||

	ret = wait_event_interruptible(mdev->misc_wait,

			!atomic_read(&mdev->local_cnt));

			mdev->state.disk != D_FAILED);

	drbd_resume_io(mdev);

	drbd_resume_io(mdev);

	if ((int)retcode == (int)SS_IS_DISKLESS)

		retcode = SS_NOTHING_TO_DO;

	if (ret)

		retcode = ERR_INTR;

	return retcode;

	return retcode;

}

}