[PATCH 2/5] libmultipath: nvme: shorter topology output

[Martin Wilck <mwilck@suse.com>]

The nvme foreign code maps the NVMe subsys NQN to the "%n"
wildcard ("alias"). Some real-world devices use very lengthy
expressions for the subsys NQN (counted 95 characters on one
system here), making the "multipath -ll" output hardly readable
for humans. Use a shorter and more concise printout instead,
based on the WWID only.

The subsys NQN is still available via the "%n" wildcard:
"multipathd show maps format %n".

Signed-off-by: Martin Wilck <mwilck@suse.com>
---
 libmultipath/foreign/nvme.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/libmultipath/foreign/nvme.c b/libmultipath/foreign/nvme.c
index fca3235f..8887a755 100644
--- a/libmultipath/foreign/nvme.c
+++ b/libmultipath/foreign/nvme.c
@@ -286,10 +286,18 @@ static int snprint_nvme_path(const struct gen_path *gp,
 	return 0;
 }
 
+static int nvme_style(const struct gen_multipath* gm,
+		      char *buf, int len, int verbosity)
+{
+	int n = snprintf(buf, len, "%%w [%%G]:%%d %%s");
+
+	return (n < len ? n : len - 1);
+}
+
 static const struct gen_multipath_ops nvme_map_ops = {
 	.get_pathgroups = nvme_mp_get_pgs,
 	.rel_pathgroups = nvme_mp_rel_pgs,
-	.style = generic_style,
+	.style = nvme_style,
 	.snprint = snprint_nvme_map,
 };
 
-- 
2.18.0