tree: Add PCI physical slot number for controller

This commit introduces a physical slot field for controller, that
contains the PCI physcial slot number for controller device.

In case, there are multiple NVME drives present on the platform,
it's hard to identify which NVME drive is present in which slot.
The slot number is usually helpful in determining the location.
It is cross reference-able from lspci, but it would be nice to
have a direct option.

Signed-off-by: Umer Saleem <[email protected]>

src/libnvme.map

@@ -2,6 +2,7 @@
 
 LIBNVME_1_5 {
 	global:
+		nvme_ctrl_get_phy_slot;
 		nvme_ipaddrs_eq;
 		nvme_nbft_free;
 		nvme_nbft_read;

src/nvme/private.h

@@ -84,6 +84,7 @@ struct nvme_ctrl {
 	char *dhchap_ctrl_key;
 	char *cntrltype;
 	char *dctype;
+	char *phy_slot;
 	bool discovery_ctrl;
 	bool unique_discovery_ctrl;
 	bool discovered;

src/nvme/tree.c

@@ -34,6 +34,8 @@
 #include "log.h"
 #include "private.h"
 
+const char *nvme_slots_sysfs_dir = "/sys/bus/pci/slots";
+
 static struct nvme_host *default_host;
 
 static void __nvme_free_host(nvme_host_t h);
@@ -822,6 +824,11 @@ const char *nvme_ctrl_get_address(nvme_ctrl_t c)
 	return c->address ? c->address : "";
 }
 
+const char *nvme_ctrl_get_phy_slot(nvme_ctrl_t c)
+{
+	return c->phy_slot ? c->phy_slot : "";
+}
+
 const char *nvme_ctrl_get_firmware(nvme_ctrl_t c)
 {
 	return c->firmware;
@@ -1009,6 +1016,7 @@ void nvme_deconfigure_ctrl(nvme_ctrl_t c)
 	FREE_CTRL_ATTR(c->address);
 	FREE_CTRL_ATTR(c->dctype);
 	FREE_CTRL_ATTR(c->cntrltype);
+	FREE_CTRL_ATTR(c->phy_slot);
 }
 
 int nvme_disconnect_ctrl(nvme_ctrl_t c)
@@ -1256,6 +1264,50 @@ static char *nvme_ctrl_lookup_subsystem_name(nvme_root_t r,
 	return subsys_name;
 }
 
+static char *nvme_ctrl_lookup_phy_slot(nvme_root_t r, const char *address)
+{
+	char *target_addr;
+	char *addr;
+	char *path;
+	int found = 0;
+	int ret;
+	DIR *slots_dir;
+	struct dirent *entry;
+
+	slots_dir = opendir(nvme_slots_sysfs_dir);
+	if (!slots_dir) {
+		nvme_msg(r, LOG_WARNING, "failed to open slots dir %s\n",
+		nvme_slots_sysfs_dir);
+		return NULL;
+	}
+
+	target_addr = strndup(address, 10);
+	while (!(entry = readdir(slots_dir))) {
+		if (entry->d_type == DT_DIR &&
+		    strncmp(entry->d_name, ".", 1) != 0 &&
+		    strncmp(entry->d_name, "..", 2) != 0) {
+			ret = asprintf(&path, "/sys/bus/pci/slots/%s", entry->d_name);
+			if (ret < 0) {
+				errno = ENOMEM;
+				return NULL;
+			}
+			addr = nvme_get_attr(path, "address");
+			if (strcmp(addr, target_addr) == 0) {
+				found = 1;
+				free(path);
+				free(addr);
+				break;
+			}
+			free(path);
+			free(addr);
+		}
+	}
+	free(target_addr);
+	if (found)
+		return strdup(entry->d_name);
+	return NULL;
+}
+
 static int nvme_configure_ctrl(nvme_root_t r, nvme_ctrl_t c, const char *path,
 			       const char *name)
 {
@@ -1297,6 +1349,7 @@ static int nvme_configure_ctrl(nvme_root_t r, nvme_ctrl_t c, const char *path,
 	}
 	c->cntrltype = nvme_get_ctrl_attr(c, "cntrltype");
 	c->dctype = nvme_get_ctrl_attr(c, "dctype");
+	c->phy_slot = nvme_ctrl_lookup_phy_slot(r, c->address);
 
 	errno = 0; /* cleanup after nvme_get_ctrl_attr() */
 	return 0;

src/nvme/tree.h

@@ -801,6 +801,15 @@ const char *nvme_ctrl_get_sysfs_dir(nvme_ctrl_t c);
  */
 const char *nvme_ctrl_get_address(nvme_ctrl_t c);
 
+/**
+ * nvme_ctrl_get_phy_slot() - PCI physical slot number of a controller
+ * @c:	Controller instance
+ *
+ * Return: PCI physical slot number of @c or empty string if slot
+ * number is not present.
+ */
+const char *nvme_ctrl_get_phy_slot(nvme_ctrl_t c);
+
 /**
  * nvme_ctrl_get_firmware() - Firmware string of a controller
  * @c:	Controller instance