[SCSI] scsi_dh: add infrastructure for SCSI Device Handlers
authorChandra Seetharaman <sekharan@us.ibm.com>
Thu, 1 May 2008 21:49:46 +0000 (14:49 -0700)
committerJames Bottomley <James.Bottomley@HansenPartnership.com>
Thu, 5 Jun 2008 14:23:40 +0000 (09:23 -0500)
commita6a8d9f87eb8510a8f53672ea87703f62185d75f
treed166e14e3c035ae0e0f26329b2b3b0495046d234
parent53c8ba95402be65d412a806cda3430f0e72cd107
[SCSI] scsi_dh: add infrastructure for SCSI Device Handlers

Some of the storage devices (that can be accessed through multiple paths),
do need some special handling for
1. Activating the passive path of the storage access.
2. Decode and handle the special sense codes returned by the devices.
3. Handle the I/Os being sent to the passive path, especially
           during the device probe time.
when accessed through multiple paths.

As of today this special device handling is done at the dm-multipath
layer using dm-handlers. That works well for (1); for (2) to be handled
at dm layer, scsi sense information need to be exported from SCSI to dm-layer,
which is not very attractive; (3) cannot be done at all at the dm layer.

Device handler has been moved to SCSI mainly to handle (2) and (3) properly.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Mike Anderson <andmike@linux.vnet.ibm.com>
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
drivers/scsi/Kconfig
drivers/scsi/Makefile
drivers/scsi/device_handler/Kconfig [new file with mode: 0644]
drivers/scsi/device_handler/Makefile [new file with mode: 0644]
drivers/scsi/device_handler/scsi_dh.c [new file with mode: 0644]
drivers/scsi/scsi_error.c
drivers/scsi/scsi_lib.c
drivers/scsi/scsi_sysfs.c
include/scsi/scsi.h
include/scsi/scsi_device.h
include/scsi/scsi_dh.h [new file with mode: 0644]