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

Commit 7dbb4386 authored by Philipp Reisner's avatar Philipp Reisner Committed by Jens Axboe
Browse files

drbd: make suspend_io() / resume_io() must be thread and recursion safe 



Avoid to prematurely resume application IO: don't set/clear a single
bit, but inc/dec an atomic counter.

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 f85d9f2d

drivers/block/drbd/drbd_int.h

+2 −2
Original line number Diff line number Diff line
@@ -500,7 +500,6 @@ enum { 


	MD_NO_FUA,		/* Users wants us to not use FUA/FLUSH on meta data dev */



	SUSPEND_IO,		/* suspend application io */

	BITMAP_IO,		/* suspend application io;

				   once no more io in flight, start bitmap io */

	BITMAP_IO_QUEUED,       /* Started bitmap IO */
@@ -880,6 +879,7 @@ struct drbd_device { 
	atomic_t rs_pending_cnt; /* RS request/data packets on the wire */

	atomic_t unacked_cnt;	 /* Need to send replies for */

	atomic_t local_cnt;	 /* Waiting for local completion */

	atomic_t suspend_cnt;



	/* Interval tree of pending local requests */

	struct rb_root read_requests;
@@ -2263,7 +2263,7 @@ static inline bool may_inc_ap_bio(struct drbd_device *device) 


	if (drbd_suspended(device))

		return false;

	if (test_bit(SUSPEND_IO, &device->flags))

	if (atomic_read(&device->suspend_cnt))

		return false;



	/* to avoid potential deadlock or bitmap corruption,

drivers/block/drbd/drbd_nl.c

+5 −3
Original line number Diff line number Diff line
@@ -865,9 +865,11 @@ char *ppsize(char *buf, unsigned long long size) 
 * and can be long lived.

 * This changes an device->flag, is triggered by drbd internals,

 * and should be short-lived. */

/* It needs to be a counter, since multiple threads might

   independently suspend and resume IO. */

void drbd_suspend_io(struct drbd_device *device)

{

	set_bit(SUSPEND_IO, &device->flags);

	atomic_inc(&device->suspend_cnt);

	if (drbd_suspended(device))

		return;

	wait_event(device->misc_wait, !atomic_read(&device->ap_bio_cnt));
@@ -875,7 +877,7 @@ void drbd_suspend_io(struct drbd_device *device) 


void drbd_resume_io(struct drbd_device *device)

{

	clear_bit(SUSPEND_IO, &device->flags);

	if (atomic_dec_and_test(&device->suspend_cnt))

		wake_up(&device->misc_wait);

}

drivers/block/drbd/drbd_state.c

+1 −1
Original line number Diff line number Diff line
@@ -1484,7 +1484,7 @@ int drbd_bitmap_io_from_worker(struct drbd_device *device, 
	D_ASSERT(device, current == first_peer_device(device)->connection->worker.task);



	/* open coded non-blocking drbd_suspend_io(device); */

	set_bit(SUSPEND_IO, &device->flags);

	atomic_inc(&device->suspend_cnt);



	drbd_bm_lock(device, why, flags);

	rv = io_fn(device);