[PATCH v5] nvme-fabrics: reject I/O to offline device

[Ewan D. Milne]

I'm seeing an I/O hang followed by errors returned to userspace on
NVMe/FC and NVMe multipath with the v4 patch.  It fails right away.
This is with a test that does alternating link bouncing on the target.

-Ewan


On Tue, 2020-06-30 at 17:18 -0700, Sagi Grimberg wrote:
> > @@ -612,6 +613,8 @@ bool __nvmf_check_ready(struct nvme_ctrl *ctrl,
> > struct request *rq,
> >   	{ NVMF_OPT_NR_WRITE_QUEUES,	"nr_write_queues=%d"	},
> >   	{ NVMF_OPT_NR_POLL_QUEUES,	"nr_poll_queues=%d"	},
> >   	{ NVMF_OPT_TOS,			"tos=%d"		},
> > +	{ NVMF_OPT_FAIL_FAST_TMO,	"fast_io_fail_tmo=%d"	},
> > +	{ NVMF_OPT_FAIL_FAST_TMO,	"fast_io_fail_tmo=%s"	},
> >   	{ NVMF_OPT_ERR,			NULL			}
> >   };
> > 
> > @@ -631,6 +634,7 @@ static int nvmf_parse_options(struct
> > nvmf_ctrl_options *opts,
> >   	opts->reconnect_delay = NVMF_DEF_RECONNECT_DELAY;
> >   	opts->kato = NVME_DEFAULT_KATO;
> >   	opts->duplicate_connect = false;
> > +	opts->fast_io_fail_tmo = NVMF_DEF_FAIL_FAST_TMO;
> >   	opts->hdr_digest = false;
> >   	opts->data_digest = false;
> >   	opts->tos = -1; /* < 0 == use transport default */
> > @@ -751,6 +755,28 @@ static int nvmf_parse_options(struct
> > nvmf_ctrl_options *opts,
> >   				pr_warn("ctrl_loss_tmo < 0 will
> > reconnect forever\n");
> >   			ctrl_loss_tmo = token;
> >   			break;
> > +		case NVMF_OPT_FAIL_FAST_TMO:
> > +			if (match_int(args, &token)) {
> > +				p = match_strdup(args);
> > +				if (!p) {
> > +					ret = -EINVAL;
> > +					goto out;
> > +				}
> > +
> > +				token = strcasecmp(p, "off") ? 0 : -1;
> > +				kfree(p);
> > +
> > +				if (!token) {
> > +					ret = -EINVAL;
> > +					goto out;
> > +				}
> 
> Rethinking about this when reading the code, let's drop the "off"
> string
> option, nvme-cli is probably the better place for free text
> processing...
> 
> I think that overall this looks reasonable. But I'd like to hear
> others
> on this. Keith, Christoph, Chaitanya, James, Hannes, please review
> this approach.
> 
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