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2009-08-22[SCSI] scsi_dh: add the interface scsi_dh_set_params()Chandra Seetharaman
When we moved the device handler functionality from dm layer to SCSI layer we dropped the parameter functionality. This path adds an interface to scsi dh layer to set device handler parameters. Basically, multipath layer need to create a string with all the parameters and call scsi_dh_set_params() after it called scsi_dh_attach() on a device. If a device handler provides such an interface it will handle the parameters as it expects them. Reported-by: Eddie Williams <Eddie.Williams@steeleye.com> Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Tested-by: Eddie Williams <Eddie.Williams@steeleye.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: James Bottomley <James.Bottomley@suse.de>
2008-07-26[SCSI] scsi_dh: attach to hardware handler from dm-mpathHannes Reinecke
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 <hare@suse.de> Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-07-26[SCSI] scsi_dh: Update EMC handlerHannes Reinecke
This patch converts the EMC device handler to use a proper state machine. We now also parse the extended INQUIRY information to determine if long trespass commands are supported. And we're now using the long trespass command correctly. And finally there's now an check at init time to refuse to attach to devices not supporting EMC-specific VPD pages. Signed-off-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-07-15[SCSI] scsi_dh: fix kconfig related build errorsChandra Seetharaman
Do not automatically "select" SCSI_DH for dm-multipath. If SCSI_DH doesn't exist,just do not allow hardware handlers to be used. Handle SCSI_DH being a module also. Make sure it doesn't allow DM_MULTIPATH to be compiled in when SCSI_DH is a module. [jejb: added comment for Kconfig syntax] Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Reported-by: Randy Dunlap <randy.dunlap@oracle.com> Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-06-05[SCSI] scsi_dh: add infrastructure for SCSI Device HandlersChandra Seetharaman
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>