[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>

1 files changed, 9 insertions, 2 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 2d053b584410..9e79a485e4f3 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1075,8 +1075,15 @@ void init_request_from_bio(struct request *req, struct bio *bio)
         /*
          * inherit FAILFAST from bio (for read-ahead, and explicit FAILFAST)
          */
-        if (bio_rw_ahead(bio) || bio_failfast(bio))
-                req->cmd_flags |= REQ_FAILFAST;
+        if (bio_rw_ahead(bio))
+                req->cmd_flags |= (REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
+                                   REQ_FAILFAST_DRIVER);
+        if (bio_failfast_dev(bio))
+                req->cmd_flags |= REQ_FAILFAST_DEV;
+        if (bio_failfast_transport(bio))
+                req->cmd_flags |= REQ_FAILFAST_TRANSPORT;
+        if (bio_failfast_driver(bio))
+                req->cmd_flags |= REQ_FAILFAST_DRIVER;
 
         /*
          * REQ_BARRIER implies no merging, but lets make it explicit