[PATCH libnvme] libnvme : record the nvme pci adapter physical slot

[Nilay Shroff]

There is a subtle bug in the nvme controller physical
slot lookup code due to which the readdir() prematurely
aborts the lookup and hence libnvme fails to record the
pci slot address of the nvme controller. This patch helps
to fix this issue.

Signed-off-by: Nilay Shroff <nilay at linux.ibm.com>
---
Hi all,

The "nvme list -v" command displays very usefule information
which includes NVMe subsystem, controllers and namespaces. 
The output also displays the phsical slot name of the controller. 
However, I found that the slot information printed in the output
is always empty. Further debugging, I found that there is a subtle 
bug in the nvme controller slot lookup code causing the observed 
symptom. This patch helps fix it.

Wihout the patch (slot is empty):

# nvme list -v -o json
{
  "Devices":[
    {
      "HostNQN":"nqn.2014-08.org.nvmexpress:uuid:12b49f6e-0276-4746-b10c-56815b7e6dc2",
      "Subsystems":[
        {
          "Subsystem":"nvme-subsys0",
          "SubsystemNQN":"nqn.1994-11.com.samsung:nvme:PM1735:2.5-inch:S6EUNA0R500358",
          "Controllers":[
            {
              "Controller":"nvme0",
              "Serial number":"S6EUNA0R500358",
              "Model number":"1.6TB NVMe Gen4 U.2 SSD",
              "Firmware":"REV.SN49",
              "Transport":"pcie",
              "Address":"0018:01:00.0",
              "Slot":"",
              "Namespaces":[
              ],
              "Paths":[
                {
                  "Path":"nvme0c0n1",
                  "ANAState":"optimized"
                }
              ]
            }
          ],
          "Namespaces":[
            {
              "Namespace":"nvme0n1",
              "Generic":"ng0n1",
              "NSID":1,
              "UsedBytes":1600321314816,
              "MaximumLBA":390703446,
              "PhysicalSize":1600321314816,
              "SectorSize":4096
            }
          ]
        }
      ]
    }
  ]
}

With the patch applied (slot contains the correct value):
#nvme list -v -o json
{
  "Devices":[
    {
      "HostNQN":"nqn.2014-08.org.nvmexpress:uuid:12b49f6e-0276-4746-b10c-56815b7e6dc2",
      "Subsystems":[
        {
          "Subsystem":"nvme-subsys0",
          "SubsystemNQN":"nqn.1994-11.com.samsung:nvme:PM1735:2.5-inch:S6EUNA0R500358",
          "Controllers":[
            {
              "Controller":"nvme0",
              "SerialNumber":"S6EUNA0R500358",
              "ModelNumber":"1.6TB NVMe Gen4 U.2 SSD",
              "Firmware":"REV.SN49",
              "Transport":"pcie",
              "Address":"0018:01:00.0",
              "Slot":"U78D4.ND0.WZS0021-P1-C8",
              "Namespaces":[
              ],
              "Paths":[
                {
                  "Path":"nvme0c0n1",
                  "ANAState":"optimized"
                }
              ]
            }
          ],
          "Namespaces":[
            {
              "NameSpace":"nvme0n1",
              "Generic":"ng0n1",
              "NSID":1,
              "UsedBytes":1600321314816,
              "MaximumLBA":3125627568,
              "PhysicalSize":12802570518528,
              "SectorSize":4096
            }
          ]
        }
      ]
    }
  ]
}

Thanks,
--Nilay
---
 src/nvme/tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/nvme/tree.c b/src/nvme/tree.c
index de6ce879..584e3f6a 100644
--- a/src/nvme/tree.c
+++ b/src/nvme/tree.c
@@ -1729,7 +1729,7 @@ static char *nvme_ctrl_lookup_phy_slot(nvme_root_t r, const char *address)
 	}
 
 	target_addr = strndup(address, 10);
-	while (!(entry = readdir(slots_dir))) {
+	while ((entry = readdir(slots_dir))) {
 		if (entry->d_type == DT_DIR &&
 		    strncmp(entry->d_name, ".", 1) != 0 &&
 		    strncmp(entry->d_name, "..", 2) != 0) {
-- 
2.43.0