nvme: allow retry for requests with REQ_FAILFAST_TRANSPORT set
REQ_FAILFAST_TRANSPORT may be designed for SCSI, because SCSI protocol
does not define the local retry mechanism. SCSI implements a fuzzy
local retry mechanism, so REQ_FAILFAST_TRANSPORT is needed to allow
higher-level multipathing software to perform failover/retry.
NVMe is different with SCSI about this. It defines a local retry
mechanism and path error codes, so NVMe should retry local for non
path error. If path related error, whether to retry and how to retry
is still determined by higher-level multipathing's failover.
Unlike SCSI, NVMe shouldn't prevent retry if REQ_FAILFAST_TRANSPORT
because NVMe's local retry is needed -- as is NVMe specific logic to
categorize whether an error is path related.
In this way, the mechanism of NVMe multipath or other multipath are
now equivalent. The mechanism is: non path related error will be
retry local, path related error is handled by multipath.
Signed-off-by: Chao Leng <lengchao@huawei.com>
[snitzer: edited header for grammar and clarity, also added code comment]
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
1 file changed
