tree: read all attributes from sysfs when available

The kernel already exposes parts or all attributes we are looking up
with the ns id command. By reading these from the sysfs we can remove
the last command we are issuing during the topology scan.

Signed-off-by: Daniel Wagner <dwagner@suse.de>

src/nvme/tree.c

@@ -2322,60 +2322,158 @@ int nvme_ns_flush(nvme_ns_t n)
 	return nvme_flush(nvme_ns_get_fd(n), nvme_ns_get_nsid(n));
 }
 
-static void nvme_ns_parse_descriptors(struct nvme_ns *n,
-				      struct nvme_ns_id_desc *descs)
+static int nvme_strtou64(const char *str, void *res)
 {
-	void *d = descs;
-	int i, len;
+	char *endptr;
+	__u64 v;
 
-	for (i = 0; i < NVME_IDENTIFY_DATA_SIZE; i += len) {
-		struct nvme_ns_id_desc *desc = d + i;
+	errno = 0;
+	v = strtoull(str, &endptr, 0);
 
-		if (!desc->nidl)
-			break;
-		len = desc->nidl + sizeof(*desc);
+	if (errno != 0)
+		return -errno;
 
-		switch (desc->nidt) {
-		case NVME_NIDT_EUI64:
-			memcpy(n->eui64, desc->nid, sizeof(n->eui64));
-			break;
-		case NVME_NIDT_NGUID:
-			memcpy(n->nguid, desc->nid, sizeof(n->nguid));
-			break;
-		case NVME_NIDT_UUID:
-			memcpy(n->uuid, desc->nid, sizeof(n->uuid));
-			break;
-		case NVME_NIDT_CSI:
-			memcpy(&n->csi, desc->nid, sizeof(n->csi));
-			break;
+	if (endptr == str) {
+		/* no digits found */
+		return -EINVAL;
+	}
+
+	*(__u64 *)res = v;
+	return 0;
+}
+
+static int nvme_strtou32(const char *str, void *res)
+{
+	char *endptr;
+	__u32 v;
+
+	errno = 0;
+	v = strtol(str, &endptr, 0);
+
+	if (errno != 0)
+		return -errno;
+
+	if (endptr == str) {
+		/* no digits found */
+		return -EINVAL;
+	}
+
+	*(__u32 *)res = v;
+	return 0;
+}
+
+static int nvme_strtoi(const char *str, void *res)
+{
+	char *endptr;
+	int v;
+
+	errno = 0;
+	v = strtol(str, &endptr, 0);
+
+	if (errno != 0)
+		return -errno;
+
+	if (endptr == str) {
+		/* no digits found */
+		return -EINVAL;
+	}
+
+	*(int *)res = v;
+	return 0;
+}
+
+static int nvme_strtoid(const char *str, void *res)
+{
+	memcpy(&res, str, strlen(str));
+	return 0;
+}
+
+struct sysfs_attr_table {
+	void *var;
+	int (*parse)(const char *str, void *res);
+	bool mandetory;
+	const char *name;
+};
+
+#define GETSHIFT(x) (__builtin_ffsll(x) - 1)
+#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+
+static int parse_attrs(const char *path, struct sysfs_attr_table *tbl, int size)
+{
+	char *str;
+	int ret, i;
+
+	for (i = 0; i < size; i++) {
+		struct sysfs_attr_table *e = &tbl[i];
+
+		str = nvme_get_attr(path, e->name);
+		if (!str) {
+			if (!e->mandetory)
+				continue;
+			return -ENOENT;
 		}
+		ret = e->parse(str, e->var);
+		free(str);
+		if (ret)
+			return ret;
 	}
+
+	return 0;
 }
 
-static int nvme_ns_init(struct nvme_ns *n)
+static int nvme_ns_init(const char *path, struct nvme_ns *ns)
 {
-	_cleanup_free_ struct nvme_id_ns *ns;
-	_cleanup_free_ struct nvme_ns_id_desc *descs = NULL;
-	uint8_t flbas;
+	_cleanup_free_ char *attr = NULL;
+	struct stat sb;
 	int ret;
 
-	ns = __nvme_alloc(sizeof(*ns));
-	if (!ns)
-		return 0;
-	ret = nvme_ns_identify(n, ns);
+	struct sysfs_attr_table base[] = {
+		{ &ns->nsid,      nvme_strtou32, true, "nsid" },
+		{ &ns->lba_count, nvme_strtou64, true, "size" },
+		{ &ns->lba_size,  nvme_strtou64, true, "queue/physical_block_size" },
+		{ &ns->eui64,     nvme_strtoid,	false, "eui" },
+		{ &ns->nguid,     nvme_strtoid,	false, "nguid" },
+		{ &ns->uuid,      nvme_strtoid,	false, "uuid" }
+	};
+
+	ret = parse_attrs(path, base, ARRAY_SIZE(base));
 	if (ret)
 		return ret;
 
-	nvme_id_ns_flbas_to_lbaf_inuse(ns->flbas, &flbas);
-	n->lba_shift = ns->lbaf[flbas].ds;
-	n->lba_size = 1 << n->lba_shift;
-	n->lba_count = le64_to_cpu(ns->nsze);
-	n->lba_util = le64_to_cpu(ns->nuse);
-	n->meta_size = le16_to_cpu(ns->lbaf[flbas].ms);
+	ns->lba_shift = GETSHIFT(ns->lba_size);
 
-	descs = __nvme_alloc(NVME_IDENTIFY_DATA_SIZE);
-	if (descs && !nvme_ns_identify_descs(n, descs))
-		nvme_ns_parse_descriptors(n, descs);
+	if (asprintf(&attr, "%s/csi", path) < 0)
+		return -errno;
+	ret = stat(attr, &sb);
+	if (ret == 0) {
+		/* only available on kernels >= 6.x */
+		struct sysfs_attr_table ext[] = {
+			{ &ns->csi,       nvme_strtoid,	 true, "csi" },
+			{ &ns->lba_util,  nvme_strtou64, true, "nuse" },
+			{ &ns->meta_size, nvme_strtoi,	 true, "metadata_bytes"},
+
+		};
+
+		ret = parse_attrs(path, ext, ARRAY_SIZE(ext));
+		if (ret)
+			return ret;
+	} else {
+		struct nvme_id_ns *id;
+		uint8_t flbas;
+
+		id = __nvme_alloc(sizeof(*ns));
+		if (!id)
+			return -ENOMEM;
+
+		ret = nvme_ns_identify(ns, id);
+		if (ret)
+			free(ns);
+
+		nvme_id_ns_flbas_to_lbaf_inuse(id->flbas, &flbas);
+		ns->lba_count = le64_to_cpu(id->nsze);
+		ns->lba_util = le64_to_cpu(id->nuse);
+		ns->meta_size = le16_to_cpu(id->lbaf[flbas].ms);
+	}
 
 	return 0;
 }
@@ -2394,7 +2492,7 @@ static void nvme_ns_set_generic_name(struct nvme_ns *n, const char *name)
 	n->generic_name = strdup(generic_name);
 }
 
-static nvme_ns_t nvme_ns_open(const char *name)
+static nvme_ns_t nvme_ns_open(const char *sys_path, const char *name)
 {
 	struct nvme_ns *n;
 	int fd;
@@ -2414,10 +2512,7 @@ static nvme_ns_t nvme_ns_open(const char *name)
 
 	nvme_ns_set_generic_name(n, name);
 
-	if (nvme_get_nsid(fd, &n->nsid) < 0)
-		goto free_ns;
-
-	if (nvme_ns_init(n) != 0)
+	if (nvme_ns_init(sys_path, n) != 0)
 		goto free_ns;
 
 	list_head_init(&n->paths);
@@ -2477,7 +2572,7 @@ static struct nvme_ns *__nvme_scan_namespace(const char *sysfs_dir, const char *
 		return NULL;
 	}
 
-	n = nvme_ns_open(blkdev);
+	n = nvme_ns_open(path, blkdev);
 	if (!n)
 		return NULL;