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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 /include/scsi/scsi_device.h
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 'include/scsi/scsi_device.h')
-rw-r--r--include/scsi/scsi_device.h22
1 files changed, 22 insertions, 0 deletions
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index f6a9fe0ef09c..06b979f105b7 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -161,9 +161,29 @@ struct scsi_device {
struct execute_work ew; /* used to get process context on put */
+ struct scsi_dh_data *scsi_dh_data;
enum scsi_device_state sdev_state;
unsigned long sdev_data[0];
} __attribute__((aligned(sizeof(unsigned long))));
+
+struct scsi_device_handler {
+ /* Used by the infrastructure */
+ struct list_head list; /* list of scsi_device_handlers */
+ struct notifier_block nb;
+
+ /* Filled by the hardware handler */
+ struct module *module;
+ const char *name;
+ int (*check_sense)(struct scsi_device *, struct scsi_sense_hdr *);
+ int (*activate)(struct scsi_device *);
+ int (*prep_fn)(struct scsi_device *, struct request *);
+};
+
+struct scsi_dh_data {
+ struct scsi_device_handler *scsi_dh;
+ char buf[0];
+};
+
#define to_scsi_device(d) \
container_of(d, struct scsi_device, sdev_gendev)
#define class_to_sdev(d) \
@@ -230,7 +250,9 @@ extern struct scsi_device *__scsi_add_device(struct Scsi_Host *,
uint, uint, uint, void *hostdata);
extern int scsi_add_device(struct Scsi_Host *host, uint channel,
uint target, uint lun);
+extern int scsi_register_device_handler(struct scsi_device_handler *scsi_dh);
extern void scsi_remove_device(struct scsi_device *);
+extern int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh);
extern int scsi_device_get(struct scsi_device *);
extern void scsi_device_put(struct scsi_device *);