sysfs: dprintf when we fail to write a sysfs file

When arrays do not startup correctly it would be nice to know why.  Need
to move the dprintf definition to mdadm.h

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/sysfs.c b/sysfs.c
index 727e250..291a1dc 100644
--- a/sysfs.c
+++ b/sysfs.c
@@ -389,8 +389,11 @@ int sysfs_set_str(struct mdinfo *sra, struct mdinfo *dev,
 		return -1;
 	n = write(fd, val, strlen(val));
 	close(fd);
-	if (n != strlen(val))
+	if (n != strlen(val)) {
+		dprintf(Name ": failed to write '%s' to '%s' (%s)\n",
+			val, fname, strerror(errno));
 		return -1;
+	}
 	return 0;
 }