On 2010-10-14 23:37, Mike Snitzer wrote: > On Mon, Sep 27 2010 at 2:13pm -0400, > Mike Snitzer <snitzer@xxxxxxxxxx> wrote: > >> Due to the recently identified overflow in read_capacity_16() it was >> possible for max_discard_sectors to be zero but still have discards >> enabled on the associated device's queue. >> >> Eliminate the possibility for blkdev_issue_discard to infinitely loop. >> >> Interestingly this issue wasn't identified until a device, whose >> discard_granularity was 0 due to read_capacity_16 overflow, was consumed >> by blk_stack_limits() to construct limits for a higher-level DM >> multipath device. The multipath device's resulting limits never had the >> discard limits stacked because blk_stack_limits() will only do so if >> the bottom device's discard_granularity != 0. This resulted in the >> multipath device's limits.max_discard_sectors being 0. > > Hi Jens, > > This patch would only serve as a future safety-net now that the > elimination of the overflow in read_capacity_16() has been staged for > 2.6.37. Defensive programming and all... > > What do you (and others) think about this patch? Agree, may as well play it safe(r). -- Jens Axboe -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
