On Fri, Nov 12, 2010 at 04:22:43PM +0000, Daniel P. Berrange wrote:
> The SCSI volumes currently get a name like '17:0:0:1' based
> on $host:$bus:$target:$lun. The names are intended to be unique
> per pool and stable across pool restarts. The inclusion of the
> $host component breaks this, because the $host number for iSCSI
> pools is dynamically allocated by the kernel at time of login.
> This changes the name to be 'unit:0:0:1', ie removes the leading
> host component. THe 'unit:' prefix is just to ensure the volume
> name doesn't start with a number and make it clearer when seen
> out of context.
None of the host/bus/target/LUN values are really stable, although for
our purposes LUN is likely to be. Have you considered LUN$lun for the
volume names?
> The SCSI volumes also get a 'key' field based on the fully
> qualified volume path. All SCSI volumes have a unique serial
> available in hardware which can be obtained by sending a
> suitable SCSI command. Call out to udev's 'scsi_id' command
> to fetch this value
This is a great addition.
> * src/storage/storage_backend_scsi.c: Improve key and name
> field value stability and uniqness
> ---
> src/storage/storage_backend_scsi.c | 71
> +++++++++++++++++++++++++++++++++---
> 1 files changed, 65 insertions(+), 6 deletions(-)
>
> diff --git a/src/storage/storage_backend_scsi.c
> b/src/storage/storage_backend_scsi.c
> index 0d6b1ac..aeabd36 100644
> --- a/src/storage/storage_backend_scsi.c
> +++ b/src/storage/storage_backend_scsi.c
> @@ -163,9 +163,66 @@ cleanup:
> return ret;
> }
>
> +static char *
> +virStorageBackendSCSISerial(const char *dev)
> +{
> + const char *cmdargv[] = {
> + "/lib/udev/scsi_id",
> + "--replace-whitespace",
> + "--whitelisted",
> + "--device", dev,
> + NULL
> + };
> + int fd = -1;
> + pid_t child;
> + FILE *list = NULL;
> + char line[1024];
> + char *serial = NULL;
> + int err;
> + int exitstatus;
> +
> + /* Run the program and capture its output */
> + if (virExec(cmdargv, NULL, NULL,
> + &child, -1, &fd, NULL, VIR_EXEC_NONE) < 0)
> + goto cleanup;
> +
> + if ((list = fdopen(fd, "r")) == NULL) {
> + virStorageReportError(VIR_ERR_INTERNAL_ERROR,
> + "%s", _("cannot read fd"));
> + goto cleanup;
> + }
> +
> + if (fgets(line, sizeof(line), list)) {
> + char *nl = strchr(line, '\n');
> + if (nl)
> + *nl = '\0';
> + VIR_ERROR("GOT ID %s\n", line);
> + serial = strdup(line);
> + } else {
> + VIR_ERROR("NO ID %s\n", dev);
> + serial = strdup(dev);
> + }
> +
> + if (!serial) {
> + virReportOOMError();
> + goto cleanup;
> + }
> +
> +cleanup:
> + if (list)
> + fclose(list);
> + else
> + VIR_FORCE_CLOSE(fd);
> +
> + while ((err = waitpid(child, &exitstatus, 0) == -1) && errno == EINTR);
> +
> + return serial;
> +}
> +
> +
> static int
> virStorageBackendSCSINewLun(virStoragePoolObjPtr pool,
> - uint32_t host,
> + uint32_t host ATTRIBUTE_UNUSED,
> uint32_t bus,
> uint32_t target,
> uint32_t lun,
> @@ -183,7 +240,12 @@ virStorageBackendSCSINewLun(virStoragePoolObjPtr pool,
>
> vol->type = VIR_STORAGE_VOL_BLOCK;
>
> - if (virAsprintf(&(vol->name), "%u.%u.%u.%u", host, bus, target, lun) <
> 0) {
> + /* 'host' is dynamically allocated by the kernel, first come,
> + * first served, per HBA. As such it isn't suitable for use
> + * in the volume name. We only need uniquness per-pool, so
> + * just leave 'host' out
> + */
> + if (virAsprintf(&(vol->name), "unit:%u:%u:%u", bus, target, lun) < 0) {
> virReportOOMError();
> retval = -1;
> goto free_vol;
> @@ -231,10 +293,7 @@ virStorageBackendSCSINewLun(virStoragePoolObjPtr pool,
> goto free_vol;
> }
>
> - /* XXX should use logical unit's UUID instead */
> - vol->key = strdup(vol->target.path);
> - if (vol->key == NULL) {
> - virReportOOMError();
> + if (!(vol->key = virStorageBackendSCSISerial(vol->target.path))) {
> retval = -1;
> goto free_vol;
> }
> --
> 1.7.2.3
>
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