[libvirt] [PATCH 03/11] storage: Add partition type checks for BLKID probing

[Michal Privoznik]

On 12/15/2016 10:42 PM, John Ferlan wrote:
> A device may be formatted using some sort of disk partition format type.
> We can check that using the blkid_ API's as well - so alter the logic to
> allow checking the device for both a filesystem and a disk partition.
> 
> Signed-off-by: John Ferlan <jferlan at redhat.com>
> ---
>  src/storage/storage_backend.c | 177 ++++++++++++++++++++++++++++++++----------
>  1 file changed, 138 insertions(+), 39 deletions(-)
> 
> diff --git a/src/storage/storage_backend.c b/src/storage/storage_backend.c
> index 108f2b9..065f2ef 100644
> --- a/src/storage/storage_backend.c
> +++ b/src/storage/storage_backend.c
> @@ -2639,37 +2639,117 @@ virStorageBackendFindGlusterPoolSources(const char *host ATTRIBUTE_UNUSED,
>  
>  
>  #if WITH_BLKID
> +
> +typedef enum {
> +    VIR_STORAGE_BLKID_PROBE_ERROR = -1,
> +    VIR_STORAGE_BLKID_PROBE_UNDEFINED, /* Nothing found */
> +    VIR_STORAGE_BLKID_PROBE_UNKNOWN,   /* Don't know libvirt fs/part type */
> +    VIR_STORAGE_BLKID_PROBE_MATCH,     /* Matches the on disk format */
> +    VIR_STORAGE_BLKID_PROBE_DIFFERENT, /* Format doesn't match on disk format */
> +} virStorageBackendBLKIDProbeResult;
> +
> +/*
> + * Utility function to probe for a file system on the device using the
> + * blkid "superblock" (e.g. default) APIs.
> + *
> + * NB: In general this helper will handle the virStoragePoolFormatFileSystem
> + *     format types; however, if called from the Disk path, the initial fstype
> + *     check will fail forcing the usage of the ProbePart helper.
> + *
> + * Returns virStorageBackendBLKIDProbeResult enum
> + */
> +static virStorageBackendBLKIDProbeResult
> +virStorageBackendBLKIDProbeFS(blkid_probe probe,
> +                              const char *device,
> +                              const char *format)
> +{
> +    const char *fstype = NULL;
> +
> +    /* Make sure we're doing a superblock probe from the start */
> +    blkid_probe_enable_superblocks(probe, true);
> +    blkid_probe_reset_superblocks_filter(probe);
> +
> +    if (blkid_do_probe(probe) != 0) {
> +        VIR_INFO("No filesystem found on device '%s'", device);
> +        return VIR_STORAGE_BLKID_PROBE_UNDEFINED;
> +    }
> +
> +    if (blkid_probe_lookup_value(probe, "TYPE", &fstype, NULL) == 0) {
> +        if (STREQ(fstype, format))
> +            return VIR_STORAGE_BLKID_PROBE_MATCH;
> +
> +        return VIR_STORAGE_BLKID_PROBE_DIFFERENT;
> +    }
> +
> +    if (blkid_known_fstype(format) == 0)
> +        return VIR_STORAGE_BLKID_PROBE_UNKNOWN;
> +
> +    return VIR_STORAGE_BLKID_PROBE_ERROR;
> +}

I'm confused. So before this patch set this function was returning
something among these lines. Then in patch #2 you make it return -1 or
0, and here we go again.

The code after this patch looks sane though. And I don't really care
that much about partial steps. The result looks good, therefore you have
my ACK.

Michal