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drbd: fix schedule in atomic

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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: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
This commit is contained in:
Lars Ellenberg 2011-05-02 11:51:31 +02:00 committed by Philipp Reisner
parent 992d6e91d3
commit 009ba89db5
1 changed files with 9 additions and 4 deletions
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13
drivers/block/drbd/drbd_nl.c
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@ -1670,12 +1670,17 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info)
static int adm_detach(struct drbd_conf *mdev)
{
enum drbd_state_rv retcode;
int ret;
drbd_suspend_io(mdev); /* so no-one is stuck in drbd_al_begin_io */
retcode = drbd_request_state(mdev, NS(disk, D_DISKLESS));
wait_event(mdev->misc_wait,
mdev->state.disk != D_DISKLESS ||
!atomic_read(&mdev->local_cnt));
retcode = drbd_request_state(mdev, NS(disk, D_FAILED));
/* D_FAILED will transition to DISKLESS. */
ret = wait_event_interruptible(mdev->misc_wait,
mdev->state.disk != D_FAILED);
drbd_resume_io(mdev);
if ((int)retcode == (int)SS_IS_DISKLESS)
retcode = SS_NOTHING_TO_DO;
if (ret)
retcode = ERR_INTR;
return retcode;
}