[PATCH nvme-cli] fabrics: Use corresponding hostid when hostnqn is generated

[Shin'ichiro Kawasaki]

After the kernel commit ae8bd606e09b ("nvme-fabrics: prevent overriding
of existing host"), kernel ensures hostid and hostnqn maintain 1:1
mapping and "non 1:1 mapping will be rejected". This makes 'nvme
discover' and 'nvme connect' commands fail when they generate hostnqn,
since it does not use corresponding hostid.

To avoid the failures, prepare and use corresponding hostid to the
generated hostnqn, taking the hostid from the hostnqn string. Also warn
when the hostid is different from that in hostid file.

Link: https://lore.kernel.org/linux-nvme/l7vk7fnzltpmvkwujsbf2btrzip6wh7ug62iwa3totqcda25l6@siqx7tj6lt3l/
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki at wdc.com>
---
 fabrics.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/fabrics.c b/fabrics.c
index ac240cad..2eeea48c 100644
--- a/fabrics.c
+++ b/fabrics.c
@@ -677,6 +677,26 @@ static int nvme_read_volatile_config(nvme_root_t r)
 	return ret;
 }
 
+char *nvmf_hostid_from_hostnqn(const char *hostnqn)
+{
+	const char *uuid;
+	const char *hostid_from_file;
+
+	if (!hostnqn)
+		return NULL;
+
+	uuid = strstr(hostnqn, "uuid:");
+	if (!uuid)
+		return NULL;
+	uuid += strlen("uuid:");
+
+	hostid_from_file = nvmf_hostid_from_file();
+	if (hostid_from_file && strcmp(uuid, hostid_from_file))
+		fprintf(stderr, "warning: use generated hostid instead of hostid file\n");
+
+	return strdup(uuid);
+}
+
 int nvmf_discover(const char *desc, int argc, char **argv, bool connect)
 {
 	char *subsysnqn = NVME_DISC_SUBSYS_NAME;
@@ -753,8 +773,10 @@ int nvmf_discover(const char *desc, int argc, char **argv, bool connect)
 	hostid_arg = hostid;
 	if (!hostnqn)
 		hostnqn = hnqn = nvmf_hostnqn_from_file();
-	if (!hostnqn)
+	if (!hostnqn) {
 		hostnqn = hnqn = nvmf_hostnqn_generate();
+		hostid = hid = nvmf_hostid_from_hostnqn(hostnqn);
+	}
 	if (!hostid)
 		hostid = hid = nvmf_hostid_from_file();
 	h = nvme_lookup_host(r, hostnqn, hostid);
@@ -966,8 +988,10 @@ int nvmf_connect(const char *desc, int argc, char **argv)
 
 	if (!hostnqn)
 		hostnqn = hnqn = nvmf_hostnqn_from_file();
-	if (!hostnqn)
+	if (!hostnqn) {
 		hostnqn = hnqn = nvmf_hostnqn_generate();
+		hostid = hid = nvmf_hostid_from_hostnqn(hostnqn);
+	}
 	if (!hostid)
 		hostid = hid = nvmf_hostid_from_file();
 	h = nvme_lookup_host(r, hostnqn, hostid);
-- 
2.40.1