[PATCH v2] ndctl/bus:Handling the scrub related command more gracefully

[Tarun Sahu <tsahu@linux.ibm.com>]

The buses, that don't have nfit support, return "No such file or
directory" for start-scrub/wait-scrub command.

Presently, non-nfit support buses do not support start-scrub/
wait-scrub operation. This patch is to handle these commands
more gracefully by returning" Operation not supported".

This patch is tested on PPC64le lpar with nvdimm that does
not support scrub.

Previously:
$ ./ndctl start-scrub ndbus0
error starting scrub: No such file or directory

Now:
$ ./ndctl start-scrub ndbus0
error starting scrub: Operation not supported

- Invalid ndbus
$ sudo ./ndctl start-scrub ndbus5
error starting scrub: No such device or address

Signed-off-by: Tarun Sahu <tsahu@linux.ibm.com>
Reviewed-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com>
---
 ndctl/lib/libndctl.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/ndctl/lib/libndctl.c b/ndctl/lib/libndctl.c
index ccca8b5..8bfad6a 100644
--- a/ndctl/lib/libndctl.c
+++ b/ndctl/lib/libndctl.c
@@ -938,10 +938,14 @@ static void *add_bus(void *parent, int id, const char *ctl_base)
 	if (!bus->wait_probe_path)
 		goto err_read;
 
-	sprintf(path, "%s/device/nfit/scrub", ctl_base);
-	bus->scrub_path = strdup(path);
-	if (!bus->scrub_path)
-		goto err_read;
+	if (ndctl_bus_has_nfit(bus)) {
+		sprintf(path, "%s/device/nfit/scrub", ctl_base);
+		bus->scrub_path = strdup(path);
+		if (!bus->scrub_path)
+			goto err_read;
+	} else {
+		bus->scrub_path = NULL;
+	}
 
 	sprintf(path, "%s/device/firmware/activate", ctl_base);
 	if (sysfs_read_attr(ctx, path, buf) < 0)
@@ -1377,6 +1381,9 @@ NDCTL_EXPORT int ndctl_bus_start_scrub(struct ndctl_bus *bus)
 	struct ndctl_ctx *ctx = ndctl_bus_get_ctx(bus);
 	int rc;
 
+	if (bus->scrub_path == NULL)
+		return -EOPNOTSUPP;
+
 	rc = sysfs_write_attr(ctx, bus->scrub_path, "1\n");
 
 	/*
@@ -1447,6 +1454,9 @@ NDCTL_EXPORT int ndctl_bus_poll_scrub_completion(struct ndctl_bus *bus,
 	char in_progress;
 	int fd = 0, rc;
 
+	if (bus->scrub_path == NULL)
+		return -EOPNOTSUPP;
+
 	fd = open(bus->scrub_path, O_RDONLY|O_CLOEXEC);
 	if (fd < 0)
 		return -errno;
-- 
2.35.1