nvme-discover: lookup existing persistent controllers #942
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If persistent controller connections are present they should be preferred even if no --device option is given on the commandline. To avoid selecting a temporary non-persistent controller the 'kato' attribute is checked; any controller which does not have this attribute or for which the attribute is '0' will be skipped. Signed-off-by: Hannes Reinecke <hare@suse.de>
| @@ -320,6 +320,27 @@ static bool ctrl_matches_connectargs(char *name, struct connect_args *args) | |||
| cargs.trsvcid = parse_conn_arg(addr, ' ', conarg_trsvcid); | |||
| cargs.host_traddr = parse_conn_arg(addr, ' ', conarg_host_traddr); | |||
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| if (!strcmp(cargs.subsysnqn, NVME_DISC_SUBSYS_NAME)) { | |||
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I suggest moving this test further down after the !strcmp(cargs.subsysnqn, args->subsysnqn). We don't need to test this if we aren't looking for a discovery controller.
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| * The 'kato' attribute might not be present; assume a | ||
| * non-persistent controller for these installations. | ||
| */ |
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If the device string was set by the user on the command line and there is no kato attribute, we should assume that the controller is usable (i.e. will persist at least until we try to retrieve the discovery page). Otherwise you basically disable the --device options on kernels that don't support kato.
So, this logic only makes sense to me if this function is called from find_ctrl_with_connectargs(). But OTOH, why not generally assume that the controller is persistent if there is no kato attribute? The worst thing that can happen is an error attempting to connect to it, and this error will be transient by definition.
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Forget this comment. I misread your patch. Sorry. |
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I wanted to send a PR to your branch, but github won't let me do that. So please just have a look at the two topmost commit on https://github.com/mwilck/nvme-cli/tree/persistent-discovery |
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#992 should supersede this PR. @hreinecke, please double-check. |
Yes, it does. And if not I'll rebase it on top of the (now-merged) #992. |
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Superseded by #992 |
If persistent controller connections are present they should be
preferred even if no --device option is given on the commandline.
To avoid selecting a temporary non-persistent controller the
'kato' attribute is checked; any controller which does not have
this attribute or for which the attribute is '0' will be skipped.
I have submitted a patch for adding the 'kato' sysfs controller attribute to linux-nvme.
Signed-off-by: Hannes Reinecke hare@suse.de