[PATCH 1/3] tree: add support for discovering nvme paths using sysfs multipath link
Nilay Shroff
nilay at linux.ibm.com
Sat Apr 5 06:02:47 PDT 2025
With kernel v6.14, when NVMe native multipath is enabled, it is possible
to discover all paths to a shared namespace using the sysfs multipath link.
Leverage this functionality to update the path links for each shared NVMe
namespace, simplifying path discovery and management. Please note that
this change is fully backward compatible.
Signed-off-by: Nilay Shroff <nilay at linux.ibm.com>
---
src/nvme/filters.c | 6 ++
src/nvme/filters.h | 9 +++
src/nvme/private.h | 9 ++-
src/nvme/tree.c | 162 +++++++++++++++++++++++++++++++--------------
src/nvme/tree.h | 9 +++
5 files changed, 143 insertions(+), 52 deletions(-)
diff --git a/src/nvme/filters.c b/src/nvme/filters.c
index ceaba68f..4a8829db 100644
--- a/src/nvme/filters.c
+++ b/src/nvme/filters.c
@@ -105,3 +105,9 @@ int nvme_scan_ctrl_namespaces(nvme_ctrl_t c, struct dirent ***ns)
return scandir(nvme_ctrl_get_sysfs_dir(c), ns,
nvme_namespace_filter, alphasort);
}
+
+int nvme_scan_ns_head_paths(nvme_ns_head_t head, struct dirent ***paths)
+{
+ return scandir(nvme_ns_head_get_sysfs_dir(head), paths,
+ nvme_paths_filter, alphasort);
+}
diff --git a/src/nvme/filters.h b/src/nvme/filters.h
index 4ceeffd5..9e9dbb95 100644
--- a/src/nvme/filters.h
+++ b/src/nvme/filters.h
@@ -94,4 +94,13 @@ int nvme_scan_ctrl_namespace_paths(nvme_ctrl_t c, struct dirent ***paths);
*/
int nvme_scan_ctrl_namespaces(nvme_ctrl_t c, struct dirent ***ns);
+/**
+ * nvme_scan_ns_head_paths() - Scan for namespace paths
+ * @head: Namespace head node to scan
+ * @paths : Pointer to array of dirents
+ *
+ * Return: number of entries in @ents
+ */
+int nvme_scan_ns_head_paths(nvme_ns_head_t head, struct dirent ***paths);
+
#endif /* _LIBNVME_FILTERS_H */
diff --git a/src/nvme/private.h b/src/nvme/private.h
index 33cdd555..f45c5823 100644
--- a/src/nvme/private.h
+++ b/src/nvme/private.h
@@ -36,12 +36,19 @@ struct nvme_path {
int grpid;
};
+struct nvme_ns_head {
+ struct list_head paths;
+ struct nvme_ns *n;
+
+ char *sysfs_dir;
+};
+
struct nvme_ns {
struct list_node entry;
- struct list_head paths;
struct nvme_subsystem *s;
struct nvme_ctrl *c;
+ struct nvme_ns_head *head;
int fd;
__u32 nsid;
diff --git a/src/nvme/tree.c b/src/nvme/tree.c
index b0a4696f..bd7fb53e 100644
--- a/src/nvme/tree.c
+++ b/src/nvme/tree.c
@@ -564,12 +564,12 @@ nvme_ns_t nvme_subsystem_next_ns(nvme_subsystem_t s, nvme_ns_t n)
nvme_path_t nvme_namespace_first_path(nvme_ns_t ns)
{
- return list_top(&ns->paths, struct nvme_path, nentry);
+ return list_top(&ns->head->paths, struct nvme_path, nentry);
}
nvme_path_t nvme_namespace_next_path(nvme_ns_t ns, nvme_path_t p)
{
- return p ? list_next(&ns->paths, p, nentry) : NULL;
+ return p ? list_next(&ns->head->paths, p, nentry) : NULL;
}
static void __nvme_free_ns(struct nvme_ns *n)
@@ -579,6 +579,8 @@ static void __nvme_free_ns(struct nvme_ns *n)
free(n->generic_name);
free(n->name);
free(n->sysfs_dir);
+ free(n->head->sysfs_dir);
+ free(n->head);
free(n);
}
@@ -916,25 +918,6 @@ void nvme_free_path(struct nvme_path *p)
free(p);
}
-static void nvme_subsystem_set_path_ns(nvme_subsystem_t s, nvme_path_t p)
-{
- char n_name[32] = { };
- int i, c, nsid, ret;
- nvme_ns_t n;
-
- ret = sscanf(nvme_path_get_name(p), "nvme%dc%dn%d", &i, &c, &nsid);
- if (ret != 3)
- return;
-
- sprintf(n_name, "nvme%dn%d", i, nsid);
- nvme_subsystem_for_each_ns(s, n) {
- if (!strcmp(n_name, nvme_ns_get_name(n))) {
- list_add_tail(&n->paths, &p->nentry);
- p->n = n;
- }
- }
-}
-
static int nvme_ctrl_scan_path(nvme_root_t r, struct nvme_ctrl *c, char *name)
{
struct nvme_path *p;
@@ -973,7 +956,6 @@ static int nvme_ctrl_scan_path(nvme_root_t r, struct nvme_ctrl *c, char *name)
}
list_node_init(&p->nentry);
- nvme_subsystem_set_path_ns(c->s, p);
list_node_init(&p->entry);
list_add_tail(&c->paths, &p->entry);
return 0;
@@ -2250,8 +2232,8 @@ nvme_ctrl_t nvme_scan_ctrl(nvme_root_t r, const char *name)
return NULL;
path = NULL;
- nvme_ctrl_scan_namespaces(r, c);
nvme_ctrl_scan_paths(r, c);
+ nvme_ctrl_scan_namespaces(r, c);
return c;
}
@@ -2323,6 +2305,11 @@ const char *nvme_ns_get_sysfs_dir(nvme_ns_t n)
return n->sysfs_dir;
}
+const char *nvme_ns_head_get_sysfs_dir(nvme_ns_head_t head)
+{
+ return head->sysfs_dir;
+}
+
const char *nvme_ns_get_name(nvme_ns_t n)
{
return n->name;
@@ -2749,7 +2736,11 @@ static void nvme_ns_set_generic_name(struct nvme_ns *n, const char *name)
static nvme_ns_t nvme_ns_open(const char *sys_path, const char *name)
{
+ int ret;
struct nvme_ns *n;
+ struct nvme_ns_head *head;
+ struct stat arg;
+ _cleanup_free_ char *path = NULL;
n = calloc(1, sizeof(*n));
if (!n) {
@@ -2757,6 +2748,32 @@ static nvme_ns_t nvme_ns_open(const char *sys_path, const char *name)
return NULL;
}
+ head = calloc(1, sizeof(*head));
+ if (!head) {
+ errno = ENOMEM;
+ free(n);
+ return NULL;
+ }
+
+ head->n = n;
+ list_head_init(&head->paths);
+ ret = asprintf(&path, "%s/%s", sys_path, "multipath");
+ if (ret < 0) {
+ errno = ENOMEM;
+ goto free_ns_head;
+ }
+ /*
+ * The sysfs-dir "multipath" is available only when nvme multipath
+ * is configured and we're running kernel version >= 6.14.
+ */
+ ret = stat(path, &arg);
+ if (ret == 0) {
+ head->sysfs_dir = path;
+ path = NULL;
+ } else
+ head->sysfs_dir = NULL;
+
+ n->head = head;
n->fd = -1;
n->name = strdup(name);
@@ -2765,15 +2782,17 @@ static nvme_ns_t nvme_ns_open(const char *sys_path, const char *name)
if (nvme_ns_init(sys_path, n) != 0)
goto free_ns;
- list_head_init(&n->paths);
list_node_init(&n->entry);
nvme_ns_release_fd(n); /* Do not leak fds */
+
return n;
free_ns:
free(n->generic_name);
free(n->name);
+free_ns_head:
+ free(head);
free(n);
return NULL;
}
@@ -2836,6 +2855,71 @@ nvme_ns_t nvme_scan_namespace(const char *name)
return __nvme_scan_namespace(nvme_ns_sysfs_dir(), name);
}
+
+static void nvme_ns_head_scan_path(nvme_subsystem_t s, nvme_ns_t n, char *name)
+{
+ nvme_ctrl_t c;
+ nvme_path_t p;
+
+ nvme_subsystem_for_each_ctrl(s, c) {
+ nvme_ctrl_for_each_path(c, p) {
+ if (!strcmp(nvme_path_get_name(p), name)) {
+ list_add_tail(&n->head->paths, &p->nentry);
+ p->n = n;
+ return;
+ }
+ }
+ }
+}
+
+static void nvme_subsystem_set_ns_path(nvme_subsystem_t s, nvme_ns_t n)
+{
+ struct nvme_ns_head *head = n->head;
+
+ if (nvme_ns_head_get_sysfs_dir(head)) {
+ struct dirents paths = {};
+ int i;
+
+ /*
+ * When multipath is configured on kernel version >= 6.14,
+ * we use multipath sysfs link to get each path of a namespace.
+ */
+ paths.num = nvme_scan_ns_head_paths(head, &paths.ents);
+
+ for (i = 0; i < paths.num; i++)
+ nvme_ns_head_scan_path(s, n, paths.ents[i]->d_name);
+ } else {
+ nvme_ctrl_t c;
+ nvme_path_t p;
+ int ns_ctrl, ns_nsid, ret;
+
+ /*
+ * If multipath is not configured or we're running on kernel
+ * version < 6.14, fallback to the old way.
+ */
+ ret = sscanf(nvme_ns_get_name(n), "nvme%dn%d",
+ &ns_ctrl, &ns_nsid);
+ if (ret != 2)
+ return;
+
+ nvme_subsystem_for_each_ctrl(s, c) {
+ nvme_ctrl_for_each_path(c, p) {
+ int p_subsys, p_ctrl, p_nsid;
+
+ ret = sscanf(nvme_path_get_name(p),
+ "nvme%dc%dn%d",
+ &p_subsys, &p_ctrl, &p_nsid);
+ if (ret != 3)
+ continue;
+ if (ns_ctrl == p_subsys && ns_nsid == p_nsid) {
+ list_add_tail(&head->paths, &p->nentry);
+ p->n = n;
+ }
+ }
+ }
+ }
+}
+
static int nvme_ctrl_scan_namespace(nvme_root_t r, struct nvme_ctrl *c,
char *name)
{
@@ -2861,33 +2945,9 @@ static int nvme_ctrl_scan_namespace(nvme_root_t r, struct nvme_ctrl *c,
n->s = c->s;
n->c = c;
list_add_tail(&c->namespaces, &n->entry);
- return 0;
-}
-
-static void nvme_subsystem_set_ns_path(nvme_subsystem_t s, nvme_ns_t n)
-{
- nvme_ctrl_t c;
- nvme_path_t p;
- int ns_ctrl, ns_nsid, ret;
-
- ret = sscanf(nvme_ns_get_name(n), "nvme%dn%d", &ns_ctrl, &ns_nsid);
- if (ret != 2)
- return;
+ nvme_subsystem_set_ns_path(c->s, n);
- nvme_subsystem_for_each_ctrl(s, c) {
- nvme_ctrl_for_each_path(c, p) {
- int p_subsys, p_ctrl, p_nsid;
-
- ret = sscanf(nvme_path_get_name(p), "nvme%dc%dn%d",
- &p_subsys, &p_ctrl, &p_nsid);
- if (ret != 3)
- continue;
- if (ns_ctrl == p_subsys && ns_nsid == p_nsid) {
- list_add_tail(&n->paths, &p->nentry);
- p->n = n;
- }
- }
- }
+ return 0;
}
static int nvme_subsystem_scan_namespace(nvme_root_t r, nvme_subsystem_t s,
@@ -2917,7 +2977,7 @@ static int nvme_subsystem_scan_namespace(nvme_root_t r, nvme_subsystem_t s,
list_del_init(&p->nentry);
p->n = NULL;
}
- list_head_init(&_n->paths);
+ list_head_init(&_n->head->paths);
__nvme_free_ns(_n);
}
n->s = s;
diff --git a/src/nvme/tree.h b/src/nvme/tree.h
index 25d4b31b..9f382e9c 100644
--- a/src/nvme/tree.h
+++ b/src/nvme/tree.h
@@ -27,6 +27,7 @@
*/
typedef struct nvme_ns *nvme_ns_t;
+typedef struct nvme_ns_head *nvme_ns_head_t;
typedef struct nvme_path *nvme_path_t;
typedef struct nvme_ctrl *nvme_ctrl_t;
typedef struct nvme_subsystem *nvme_subsystem_t;
@@ -1091,6 +1092,14 @@ void nvme_ctrl_set_dhchap_host_key(nvme_ctrl_t c, const char *key);
*/
const char *nvme_ctrl_get_dhchap_key(nvme_ctrl_t c);
+/**
+ * nvme_ns_head_get_sysfs_dir() - sysfs dir of namespave head
+ * @head: namespace head instance
+ *
+ * Returns: sysfs directory name of @head
+ */
+const char *nvme_ns_head_get_sysfs_dir(nvme_ns_head_t head);
+
/**
* nvme_ctrl_set_dhchap_key() - Set controller key
* @c: Controller for which the key should be set
--
2.49.0
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