[dm-devel] [PATCH]multipath-tools: fix "multipath -ll" bug for Native NVME Multipath devices

[chengjike]

After "Native NVME Multipath" is configured,
the content displayed is incorrect when you run "multipath -ll" command.
Each NVME devices have the same path name. For example:

[root at localhost home]# multipath -ll
eui.710032e8fb22a86c24a52c1000000db8 [nvme]:nvme1n1 NVMe,Huawei-XSG1,1000001
size=10485760 features='n/a' hwhandler='ANA' wp=rw
|-+- policy='n/a' prio=50 status=optimized
| `- 1:4:1   nvme1c4n1 0:0 n/a   optimized live
`-+- policy='n/a' prio=50 status=optimized
  `- 1:9:1   nvme1c9n1 0:0 n/a   optimized live
eui.710032e8fb22a86b24a52c7c00000db7 [nvme]:nvme1n2 NVMe,Huawei-XSG1,1000001
size=10485760 features='n/a' hwhandler='ANA' wp=rw
|-+- policy='n/a' prio=50 status=optimized
| `- 1:4:1   nvme1c4n1 0:0 n/a   optimized live
`-+- policy='n/a' prio=50 status=optimized
  `- 1:9:1   nvme1c9n1 0:0 n/a   optimized live
[root at localhost home]#

The logical paths of "nvme1n1" and "nvme1n2" are both "nvme1c4n1" and "nvme1c9n1".
So when multipath-tools aggregates disks, use "nvme_ns_head->instance" for matching.
such as ,Use "b" in "nvmeanb" string to match "z" in "nvmexcynz"(a,b,x,y,z can be any number),
and if "b" and "z" are the same, they are related.

Signed-off-by: chengjike <chengjike.cheng at huawei.com>
---
 libmultipath/foreign/nvme.c | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/libmultipath/foreign/nvme.c b/libmultipath/foreign/nvme.c
index d40c0869..38580880 100644
--- a/libmultipath/foreign/nvme.c
+++ b/libmultipath/foreign/nvme.c
@@ -530,14 +530,18 @@ static int _dirent_controller(const struct dirent *di)
 
 /* Find the block device for a given nvme controller */
 struct udev_device *get_ctrl_blkdev(const struct context *ctx,
-				    struct udev_device *ctrl)
+				    struct udev_device *ctrl, const char *ctrl_name)
 {
+	int ctrl_num, ns_num; 
 	struct udev_list_entry *item;
 	struct udev_device *blkdev = NULL;
 	struct udev_enumerate *enm = udev_enumerate_new(ctx->udev);
 	const char *devtype;
 
-	if (enm == NULL)
+	if (enm == NULL || ctrl_name == NULL)
+		return NULL;
+
+	if (sscanf(ctrl_name, "nvme%dn%d", &ctrl_num, &ns_num) != 2)
 		return NULL;
 
 	pthread_cleanup_push(_udev_enumerate_unref, enm);
@@ -555,6 +559,8 @@ struct udev_device *get_ctrl_blkdev(const struct context *ctx,
 	     item != NULL;
 	     item = udev_list_entry_get_next(item)) {
 		struct udev_device *tmp;
+		const char *name = NULL ;
+		int m, n, l;
 
 		tmp = udev_device_new_from_syspath(ctx->udev,
 					   udev_list_entry_get_name(item));
@@ -562,11 +568,19 @@ struct udev_device *get_ctrl_blkdev(const struct context *ctx,
 			continue;
 
 		devtype = udev_device_get_devtype(tmp);
-		if (devtype && !strcmp(devtype, "disk")) {
+		if (devtype == NULL || strcmp(devtype, "disk")) {
+			udev_device_unref(tmp);
+			continue;
+		}
+
+		name = udev_device_get_sysname(tmp);
+		if (name != NULL && 
+			sscanf(name, "nvme%dc%dn%d", &m, &n, &l) == 3 &&
+			l == ns_num) {
 			blkdev = tmp;
 			break;
-		} else
-			udev_device_unref(tmp);
+		}
+		udev_device_unref(tmp);
 	}
 
 	if (blkdev == NULL)
@@ -679,7 +693,7 @@ static void _find_controllers(struct context *ctx, struct nvme_map *map)
 		}
 
 		pthread_cleanup_push(_udev_device_unref, ctrl);
-		udev = get_ctrl_blkdev(ctx, ctrl);
+		udev = get_ctrl_blkdev(ctx, ctrl, udev_device_get_sysname(map->udev));
 		/*
 		 * We give up the reference to the nvme device here and get
 		 * it back from the child below.
-- 
2.21.0.windows.1