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Re: [libvirt] [PATCH 10/11] Improve SCSI volume key and name generation



On 11/12/2010 09:22 AM, 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

s/THe/The/

> name doesn't start with a number and make it clearer when seen
> out of context.
> 
> 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

I don't know if you adequately answered the usage questions raised by
others, but from the code review aspect, I hadn't seen an ack yet.

> 
> * src/storage/storage_backend_scsi.c: Improve key and name
>   field value stability and uniqness

s/uniqness/uniqueness/

> +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;

All the more reason for me to get my virCommand patch cleaned up per
comments and pushed.  This patch seems better off to rebase on top of
virCommand.

> +
> +    if ((list = fdopen(fd, "r")) == NULL) {

VIR_FDOPEN (hmm, I really need to get that promised syntax-check going
for fdopen/[f]close).

>  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

s/uniquness/uniqueness/ (cute - two unique mis-spellings for the same
word :)

-- 
Eric Blake   eblake redhat com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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