[SCSI] block: separate failfast into multiple bits.

Multipath is best at handling transport errors. If it gets a device
error then there is not much the multipath layer can do. It will just
access the same device but from a different path.

This patch breaks up failfast into device, transport and driver errors.
The multipath layers (md and dm mutlipath) only ask the lower levels to
fast fail transport errors. The user of failfast, read ahead, will ask
to fast fail on all errors.

Note that blk_noretry_request will return true if any failfast bit
is set. This allows drivers that do not support the multipath failfast
bits to continue to fail on any failfast error like before. Drivers
like scsi that are able to fail fast specific errors can check
for the specific fail fast type. In the next patch I will convert
scsi.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

4 files changed, 10 insertions, 5 deletions

diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index 708e475896b..cb8aa3b58c2 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -109,7 +109,8 @@ static struct request *get_alua_req(struct scsi_device *sdev,
         }
 
         rq->cmd_type = REQ_TYPE_BLOCK_PC;
-        rq->cmd_flags |= REQ_FAILFAST | REQ_NOMERGE;
+        rq->cmd_flags |= REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
+                         REQ_FAILFAST_DRIVER | REQ_NOMERGE;
         rq->retries = ALUA_FAILOVER_RETRIES;
         rq->timeout = ALUA_FAILOVER_TIMEOUT;
 
diff --git a/drivers/scsi/device_handler/scsi_dh_emc.c b/drivers/scsi/device_handler/scsi_dh_emc.c
index 8f45570a8a0..0e572d2c5b0 100644
--- a/drivers/scsi/device_handler/scsi_dh_emc.c
+++ b/drivers/scsi/device_handler/scsi_dh_emc.c
@@ -303,7 +303,8 @@ static struct request *get_req(struct scsi_device *sdev, int cmd,
 
         rq->cmd[4] = len;
         rq->cmd_type = REQ_TYPE_BLOCK_PC;
-        rq->cmd_flags |= REQ_FAILFAST;
+        rq->cmd_flags |= REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
+                         REQ_FAILFAST_DRIVER;
         rq->timeout = CLARIION_TIMEOUT;
         rq->retries = CLARIION_RETRIES;
 
diff --git a/drivers/scsi/device_handler/scsi_dh_hp_sw.c b/drivers/scsi/device_handler/scsi_dh_hp_sw.c
index 5e93c88ad66..9aec4ca64e5 100644
--- a/drivers/scsi/device_handler/scsi_dh_hp_sw.c
+++ b/drivers/scsi/device_handler/scsi_dh_hp_sw.c
@@ -112,7 +112,8 @@ static int hp_sw_tur(struct scsi_device *sdev, struct hp_sw_dh_data *h)
                 return SCSI_DH_RES_TEMP_UNAVAIL;
 
         req->cmd_type = REQ_TYPE_BLOCK_PC;
-        req->cmd_flags |= REQ_FAILFAST;
+        req->cmd_flags |= REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
+                          REQ_FAILFAST_DRIVER;
         req->cmd_len = COMMAND_SIZE(TEST_UNIT_READY);
         req->cmd[0] = TEST_UNIT_READY;
         req->timeout = HP_SW_TIMEOUT;
@@ -204,7 +205,8 @@ static int hp_sw_start_stop(struct scsi_device *sdev, struct hp_sw_dh_data *h)
                 return SCSI_DH_RES_TEMP_UNAVAIL;
 
         req->cmd_type = REQ_TYPE_BLOCK_PC;
-        req->cmd_flags |= REQ_FAILFAST;
+        req->cmd_flags |= REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
+                          REQ_FAILFAST_DRIVER;
         req->cmd_len = COMMAND_SIZE(START_STOP);
         req->cmd[0] = START_STOP;
         req->cmd[4] = 1;        /* Start spin cycle */
diff --git a/drivers/scsi/device_handler/scsi_dh_rdac.c b/drivers/scsi/device_handler/scsi_dh_rdac.c
index 50bf95f3b5c..a43c3ed4df2 100644
--- a/drivers/scsi/device_handler/scsi_dh_rdac.c
+++ b/drivers/scsi/device_handler/scsi_dh_rdac.c
@@ -226,7 +226,8 @@ static struct request *get_rdac_req(struct scsi_device *sdev,
         }
 
         rq->cmd_type = REQ_TYPE_BLOCK_PC;
-        rq->cmd_flags |= REQ_FAILFAST | REQ_NOMERGE;
+        rq->cmd_flags |= REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
+                         REQ_FAILFAST_DRIVER;
         rq->retries = RDAC_RETRIES;
         rq->timeout = RDAC_TIMEOUT;