On Tue, Mar 20, 2018 at 11:32 AM, Dongsheng Yang
<dongsheng.yang@xxxxxxxxxxxx> wrote:
> currently, the rbd_wait_state_locked() will wait forever if we
> can't get our state locked. Example:
>
> rbd map --exclusive test1 --> /dev/rbd0
> rbd map test1 --> /dev/rbd1
> dd if=/dev/zero of=/dev/rbd1 bs=1M count=1 --> IO blocked
>
> To avoid this problem, this patch introduce a timeout design
> in rbd_wait_state_locked(). Then rbd_wait_state_locked() will
> return error when we reach a timeout.
>
> Signed-off-by: Dongsheng Yang <dongsheng.yang@xxxxxxxxxxxx>
> ---
> drivers/block/rbd.c | 23 +++++++++++++++++++----
> 1 file changed, 19 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
> index 96657ad..199819d 100644
> --- a/drivers/block/rbd.c
> +++ b/drivers/block/rbd.c
> @@ -761,6 +761,7 @@ struct rbd_options {
> #define RBD_READ_ONLY_DEFAULT false
> #define RBD_LOCK_ON_READ_DEFAULT false
> #define RBD_EXCLUSIVE_DEFAULT false
> +#define RBD_WAIT_LOCK_TIMEOUT_DEFAULT MAX_SCHEDULE_TIMEOUT
#define RBD_LOCK_TIMEOUT_DEFAULT 0 /* no timeout */
Passing lock_timeout=0 on the command line for "no timeout" must be
supported. 0 -> MAX_SCHEDULE_TIMEOUT will be handled by
ceph_timeout_jiffies() in rbd_wait_state_locked().
>
> static int parse_rbd_opts_token(char *c, void *private)
> {
> @@ -3494,8 +3495,9 @@ static int rbd_obj_method_sync(struct rbd_device *rbd_dev,
> /*
> * lock_rwsem must be held for read
> */
> -static void rbd_wait_state_locked(struct rbd_device *rbd_dev)
> +static int rbd_wait_state_locked(struct rbd_device *rbd_dev)
> {
> + long timeo = RBD_WAIT_LOCK_TIMEOUT_DEFAULT;
> DEFINE_WAIT(wait);
>
> do {
> @@ -3508,12 +3510,18 @@ static void rbd_wait_state_locked(struct rbd_device *rbd_dev)
> prepare_to_wait_exclusive(&rbd_dev->lock_waitq, &wait,
> TASK_UNINTERRUPTIBLE);
> up_read(&rbd_dev->lock_rwsem);
> - schedule();
> + timeo = schedule_timeout(timeo);
> down_read(&rbd_dev->lock_rwsem);
> + if (!timeo) {
> + finish_wait(&rbd_dev->lock_waitq, &wait);
> + rbd_warn(rbd_dev, "timed out in waiting state locked");
"timed out waiting for lock"
> + return -ETIMEDOUT;
> + }
> } while (rbd_dev->lock_state != RBD_LOCK_STATE_LOCKED &&
> !test_bit(RBD_DEV_FLAG_BLACKLISTED, &rbd_dev->flags));
>
> finish_wait(&rbd_dev->lock_waitq, &wait);
> + return 0;
> }
>
> static void rbd_queue_workfn(struct work_struct *work)
> @@ -3606,7 +3614,9 @@ static void rbd_queue_workfn(struct work_struct *work)
> result = -EROFS;
> goto err_unlock;
> }
> - rbd_wait_state_locked(rbd_dev);
> + result = rbd_wait_state_locked(rbd_dev);
> + if (result)
> + goto err_unlock;
> }
> if (test_bit(RBD_DEV_FLAG_BLACKLISTED, &rbd_dev->flags)) {
> result = -EBLACKLISTED;
> @@ -5261,6 +5271,8 @@ static void rbd_dev_image_unlock(struct rbd_device *rbd_dev)
>
> static int rbd_add_acquire_lock(struct rbd_device *rbd_dev)
> {
> + int ret = 0;
> +
> if (!(rbd_dev->header.features & RBD_FEATURE_EXCLUSIVE_LOCK)) {
> rbd_warn(rbd_dev, "exclusive-lock feature is not enabled");
> return -EINVAL;
> @@ -5268,8 +5280,11 @@ static int rbd_add_acquire_lock(struct rbd_device *rbd_dev)
>
> /* FIXME: "rbd map --exclusive" should be in interruptible */
> down_read(&rbd_dev->lock_rwsem);
> - rbd_wait_state_locked(rbd_dev);
> + ret = rbd_wait_state_locked(rbd_dev);
> up_read(&rbd_dev->lock_rwsem);
> + if (ret) {
> + return ret;
> + }
Unneeded braces.
Thanks,
Ilya
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