linux-toradex.git/drivers/scsi/device_handler/scsi_dh.c, branch v2.6.27-rc4

[SCSI] scsi_dh: create lookup cache

2008-07-26T19:14:54+00:00

Create a cache of devices that are seen in a system. This will avoid
the unnecessary traversal of the device list in the scsi_dh when there
are multiple luns of a same type.

Signed-off-by: Chandra Seetharaman 
Signed-off-by: Hannes Reinecke 
Signed-off-by: James Bottomley

[SCSI] scsi_dh: attach to hardware handler from dm-mpath

2008-07-26T19:14:53+00:00

multipath keeps a separate device table which may be
more current than the built-in one.
So we should make sure to always call ->attach whenever
a multipath map with hardware handler is instantiated.
And we should call ->detach on removal, too.

[sekharan: update as per comments from agk]
Signed-off-by: Hannes Reinecke 
Signed-off-by: Chandra Seetharaman 
Signed-off-by: James Bottomley

[SCSI] scsi_dh: Add 'dh_state' sysfs attribute

2008-07-26T19:14:51+00:00

Implement a 'dh_state' sdev attribute for dynamic device handler
manipulation. A read on the attribute will return the name of
the currently attached device handler or 'detached' if no handler
is attached.
The attribute allows the following strings to be written:
- The name of the device handler to be attached if the state is
  'detached'.
- 'activate' to trigger path activation if a device handler
  is attached.
- 'detach' to detach the currently attached device handler.

Signed-off-by: Hannes Reinecke 
Signed-off-by: Chandra Seetharaman 
Signed-off-by: James Bottomley

[SCSI] scsi_dh: Implement common device table handling

2008-07-26T19:14:51+00:00

Instead of having each and every driver implement its own
device table scanning code we should rather implement a common
routine and scan the device tables there.
This allows us also to implement a general notifier chain
callback for all device handler instead for one per handler.

[sekharan: Fix rejections caused by conflicting bug fix]
Signed-off-by: Hannes Reinecke 
Signed-off-by: Chandra Seetharaman 
Signed-off-by: James Bottomley

[SCSI] scsi_dh: add infrastructure for SCSI Device Handlers

2008-06-05T14:23:40+00:00

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 
Signed-off-by: Mike Anderson 
Signed-off-by: Mike Christie 
Signed-off-by: James Bottomley