Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 6434f404 authored by Lars Ellenberg's avatar Lars Ellenberg Committed by Jens Axboe
Browse files

drbd: fix refcount error during detach of an already failed disk 



A D_FAILED disk transitions as quickly as possible to
D_DISKLESS. But in the "unresponsive local disk" case,
there remains a time window where a administrative detach command could
find the disk already failed, but some internal meta data IO against the
unresponsive local disk still pending.

In that case, drbd_md_get_buffer() will return NULL.
Don't unconditionally call drbd_md_put_buffer(), or it will cause
refcount imbalance, and prevent any further re-attach on this volume
(until it is deleted and re-created).

Signed-off-by: default avatarPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: default avatarLars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 2b479766

drivers/block/drbd/drbd_nl.c

+7 −3
Original line number Original line Diff line number Diff line
@@ -1915,6 +1915,7 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info) 
static int adm_detach(struct drbd_device *device, int force)

static int adm_detach(struct drbd_device *device, int force)

{

{

	enum drbd_state_rv retcode;

	enum drbd_state_rv retcode;

	void *buffer;

	int ret;

	int ret;





	if (force) {

	if (force) {
@@ -1925,9 +1926,12 @@ static int adm_detach(struct drbd_device *device, int force) 
	}

	}





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

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

	drbd_md_get_buffer(device, __func__); /* make sure there is no in-flight meta-data IO */

	buffer = drbd_md_get_buffer(device, __func__); /* make sure there is no in-flight meta-data IO */

	if (buffer) {

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

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

		drbd_md_put_buffer(device);

		drbd_md_put_buffer(device);

	} else /* already <= D_FAILED */

		retcode = SS_NOTHING_TO_DO;

	/* D_FAILED will transition to DISKLESS. */

	/* D_FAILED will transition to DISKLESS. */

	drbd_resume_io(device);

	drbd_resume_io(device);

	ret = wait_event_interruptible(device->misc_wait,

	ret = wait_event_interruptible(device->misc_wait,