bcache-tools: improve is_zoned_device()HEADmaster

To check whether a block device is zoned or not, is_zoned_device()
returns true when /sys/block/<device>/queue/chunk_sectors is not zero.

Now there are devices which are not zoned devices but has non-zero
chunk-sectors values. For such situation, the more accurate method is
to read file /sys/block/<device>/queue/zoned. If the content is not
string "none", this device is not a zoned device. Otherwise (e.g.
"host-aware" or "host- managed"), it is a zoned device.

For elder kernel if the above sysfs file doesn't exist, get_zone_size()
is still called by is_zoned_device() for compatibility.

Signed-off-by: Coly Li <colyli@suse.de>

1 files changed, 19 insertions, 0 deletions

diff --git a/zoned.c b/zoned.c
index d0782865..f2147877 100644
--- a/zoned.c
+++ b/zoned.c
@@ -90,5 +90,24 @@ void check_data_offset_for_zoned_device(char *devname,
 
 int is_zoned_device(char *devname)
 {
+	char str[128];
+	FILE *file;
+	int res;
+
+	snprintf(str, sizeof(str),
+		"/sys/block/%s/queue/zoned",
+		basename(devname));
+	file = fopen(str, "r");
+	if (file) {
+		memset(str, 0, sizeof(str));
+		res = fscanf(file, "%s", str);
+		fclose(file);
+
+		/* "none" indicates non-zoned device */
+		if (res == 1)
+			return !(strcmp(str, "none") == 0);
+	}
+
+	/* Only used when "zoned" file doesn't exist */
 	return (get_zone_size(devname) != 0);
 }