tree dab9946544c452937d165239df74d667d16bddf9
parent 3ae31f6a7b6e442fc6a92f29330fbad230dc3992
author Chandra Seetharaman <sekharan@us.ibm.com> 1256142171 -0700
committer James Bottomley <James.Bottomley@suse.de> 1259949647 -0600

[SCSI] scsi_dh: Make rdac hardware handler's activate() async

Batch up MODE_SELECT in rdac device handler.

LSI RDAC storage has the capability of handling mode selects for
multiple luns in a same command. Make use of that ability to send
as few MODE SELECTs as possible to the storage controller as possible.

This patch creates a work queue and queues up activate requests
when a MODE SELECT is sent down the wire. When that MODE SELECT
completes, it compiles queued up activate requests for multiple
luns into a single MODE SELECT.

This reduces the time to do failover/failback of large number of LUNS.

Signed-off-by: Babu Moger <babu.moger@lsi.com>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>