imsm: retrieve nvme serial from sysfs

Don't rely on SCSI ioctl for reading NVMe serials - SCSI emulation for
NVMe devices can be disabled in the kernel config. Instead, try to get a
serial from /sys/block/nvme*/device/serial. If that fails for whatever
reason (i.e. no such attribute in old kernels) - fall back to the SCSI
method.

This also moves some SCSI-specific code from imsm_read_serial() to
scsi_get_serial().

Signed-off-by: Artur Paszkiewicz <artur.paszkiewicz@intel.com>
Reviewed-by: Tomasz Majchrzak <tomasz.majchrzak@intel.com>
Reviewed-by: Alexey Obitotskiy <aleksey.obitotskiy@intel.com>
Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>

1 files changed, 19 insertions, 4 deletions

diff --git a/sg_io.c b/sg_io.c
index 50ad180d..42c91e1e 100644
--- a/sg_io.c
+++ b/sg_io.c
@@ -23,20 +23,35 @@
 
 int scsi_get_serial(int fd, void *buf, size_t buf_len)
 {
-	unsigned char inq_cmd[] = {INQUIRY, 1, 0x80, 0, buf_len, 0};
+	unsigned char rsp_buf[255];
+	unsigned char inq_cmd[] = {INQUIRY, 1, 0x80, 0, sizeof(rsp_buf), 0};
 	unsigned char sense[32];
 	struct sg_io_hdr io_hdr;
+	int rv;
+	unsigned int rsp_len;
 
 	memset(&io_hdr, 0, sizeof(io_hdr));
 	io_hdr.interface_id = 'S';
 	io_hdr.cmdp = inq_cmd;
 	io_hdr.cmd_len = sizeof(inq_cmd);
-	io_hdr.dxferp = buf;
-	io_hdr.dxfer_len = buf_len;
+	io_hdr.dxferp = rsp_buf;
+	io_hdr.dxfer_len = sizeof(rsp_buf);
 	io_hdr.dxfer_direction = SG_DXFER_FROM_DEV;
 	io_hdr.sbp = sense;
 	io_hdr.mx_sb_len = sizeof(sense);
 	io_hdr.timeout = 5000;
 
-	return ioctl(fd, SG_IO, &io_hdr);
+	rv = ioctl(fd, SG_IO, &io_hdr);
+
+	if (rv)
+		return rv;
+
+	rsp_len = rsp_buf[3];
+
+	if (!rsp_len || buf_len < rsp_len)
+		return -1;
+
+	memcpy(buf, &rsp_buf[4], rsp_len);
+
+	return 0;
 }