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| author | Chandra Seetharaman <sekharan@us.ibm.com> | 2008-05-01 14:49:46 -0700 |
|---|---|---|
| committer | James Bottomley <James.Bottomley@HansenPartnership.com> | 2008-06-05 09:23:40 -0500 |
| commit | a6a8d9f87eb8510a8f53672ea87703f62185d75f (patch) | |
| tree | d166e14e3c035ae0e0f26329b2b3b0495046d234 /drivers/scsi/scsi_lib.c | |
| parent | 53c8ba95402be65d412a806cda3430f0e72cd107 (diff) | |
| download | linux-a6a8d9f87eb8510a8f53672ea87703f62185d75f.tar.gz linux-a6a8d9f87eb8510a8f53672ea87703f62185d75f.tar.bz2 linux-a6a8d9f87eb8510a8f53672ea87703f62185d75f.zip | |
[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.c | 8 |
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. */ |