On Thu, May 26 2011 at 10:42pm -0400, Martin K. Petersen <martin.petersen@xxxxxxxxxx> wrote: > Stacking driver queue limits are typically bounded exclusively by the > capabilities of the low level devices, not by the stacking driver > itself. > > Stacking drivers are typically permissive. A feature is supported unless > an incompatible bottom device causes it to be disabled. Low-level > drivers on the other hand are restrictive and want features disabled by > default. Low-level drivers explicitly enable features as part of their > device discovery process. > > This patch introduces blk_set_stacking_limits() which has more liberal > metrics than the default queue limits function. This allows us to > inherit topology parameters from bottom devices without manually > tweaking the default limits in each driver prior to calling the stacking > function. > > Since there is now a clear distinction between stacking and low-level > devices, blk_set_default_limits() has been modified to carry the more > conservative values that we used to manually set in > blk_queue_make_request(). > > Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> Acked-by: Mike Snitzer <snitzer@xxxxxxxxxx> -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
