scsi: sd_zbc: Fix variable type and bogus comment

Fix the description of sd_zbc_check_zone_size() to correctly explain that
the returned value is a number of device blocks, not bytes.  Additionally,
the 32 bits "ret" variable used in this function may truncate the 64 bits
zone_blocks variable value upon return. To fix this, change "ret" type to
s64.

Fixes: ccce20fc ("sd_zbc: Avoid that resetting a zone fails sporadically")
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: stable@kernel.org
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/sd_zbc.c

@@ -391,7 +391,8 @@ static int sd_zbc_check_capacity(struct scsi_disk *sdkp, unsigned char *buf)
  * Check that all zones of the device are equal. The last zone can however
  * be smaller. The zone size must also be a power of two number of LBAs.
  *
- * Returns the zone size in bytes upon success or an error code upon failure.
+ * Returns the zone size in number of blocks upon success or an error code
+ * upon failure.
  */
 static s64 sd_zbc_check_zone_size(struct scsi_disk *sdkp)
 {
@@ -401,7 +402,7 @@ static s64 sd_zbc_check_zone_size(struct scsi_disk *sdkp)
 	unsigned char *rec;
 	unsigned int buf_len;
 	unsigned int list_length;
-	int ret;
+	s64 ret;
 	u8 same;
 
 	/* Get a buffer */