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authorChandra Seetharaman <sekharan@us.ibm.com>2008-05-02 01:49:46 +0400
committerJames Bottomley <James.Bottomley@HansenPartnership.com>2008-06-05 18:23:40 +0400
commita6a8d9f87eb8510a8f53672ea87703f62185d75f (patch)
treed166e14e3c035ae0e0f26329b2b3b0495046d234 /drivers/scsi/scsi_lib.c
parent53c8ba95402be65d412a806cda3430f0e72cd107 (diff)
downloadlinux-a6a8d9f87eb8510a8f53672ea87703f62185d75f.tar.xz
[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>
Diffstat (limited to 'drivers/scsi/scsi_lib.c')
-rw-r--r--drivers/scsi/scsi_lib.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index a82d2fe80fb5..033c58a65f50 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1160,6 +1160,14 @@ int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
if (ret != BLKPREP_OK)
return ret;
+
+ if (unlikely(sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh
+ && sdev->scsi_dh_data->scsi_dh->prep_fn)) {
+ ret = sdev->scsi_dh_data->scsi_dh->prep_fn(sdev, req);
+ if (ret != BLKPREP_OK)
+ return ret;
+ }
+
/*
* Filesystem requests must transfer data.
*/