On Fri, Jan 19 2018 at 11:41am -0500, Jens Axboe <axboe@xxxxxxxxx> wrote: > On 1/19/18 9:37 AM, Ming Lei wrote: > > On Fri, Jan 19, 2018 at 09:27:46AM -0700, Jens Axboe wrote: > >> On 1/19/18 9:26 AM, Ming Lei wrote: > >>> On Fri, Jan 19, 2018 at 09:19:24AM -0700, Jens Axboe wrote: > >> > >> There are no pending requests for this case, nothing to restart the > >> queue. When you fail that blk_get_request(), you are idle, nothing > >> is pending. > > > > I think we needn't worry about that, once a device is attached to > > dm-rq, it can't be mounted any more, and usually user don't use the device > > directly and by dm-mpath at the same time. > > Even if it doesn't happen for a normal dm setup, it is a case that > needs to be handled. The request allocation is just one example of > a wider scope resource that can be unavailable. If the driver returns > NO_DEV_RESOURCE (or whatever name), it will be a possibility that > the device itself is currently idle. How would a driver's resources be exhausted yet the device is idle (so as not to be able to benefit from RESTART)? -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
