[libvirt] [PATCH] scsi: Adjust return status from getBlockDevice

[Michal Privoznik]

On 12.06.2015 13:22, John Ferlan wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=1224233
> 
> Currently it's not possible to determine the difference between a
> fatal memory allocation or failure to open/read the directory error
> with a perhaps less fatal, I didn't find the "block" device in the
> directory (which may be a disk entry without a block device).
> 
> In the case of the latter, we shouldn't cause failure to continue
> searching in the caller (virStorageBackendSCSIFindLUs), rather we
> should allow trying reading the next directory entry.
> 
> Signed-off-by: John Ferlan <jferlan at redhat.com>
> ---
>  src/storage/storage_backend_scsi.c | 20 ++++++++++++++++++--
>  1 file changed, 18 insertions(+), 2 deletions(-)
> 
> diff --git a/src/storage/storage_backend_scsi.c b/src/storage/storage_backend_scsi.c
> index e6c8bb5..c5105ec 100644
> --- a/src/storage/storage_backend_scsi.c
> +++ b/src/storage/storage_backend_scsi.c
> @@ -329,6 +329,15 @@ getOldStyleBlockDevice(const char *lun_path ATTRIBUTE_UNUSED,
>  }
>  
>  
> +/*
> + * Search a device entry for the "block" file
> + *
> + * Returns
> + *
> + *   0 => Found it
> + *   -1 => Fatal error
> + *   -2 => Didn't find in lun_path directory
> + */
>  static int
>  getBlockDevice(uint32_t host,
>                 uint32_t bus,
> @@ -354,6 +363,10 @@ getBlockDevice(uint32_t host,
>          goto out;
>      }
>  
> +    /* As long as virDirRead doesn't fail, if we fail to find the
> +     * "block" file in this directory, allow caller to continue
> +     */
> +    retval = -2;
>      while ((direrr = virDirRead(lun_dir, &lun_dirent, lun_path)) > 0) {
>          if (STREQLEN(lun_dirent->d_name, "block", 5)) {
>              if (strlen(lun_dirent->d_name) == 5) {
> @@ -368,6 +381,9 @@ getBlockDevice(uint32_t host,
>              break;
>          }
>      }
> +    /* Keep retval = -2 unless there was a fatal error in virDirRead */
> +    if (retval == -2 && direrr < 0)
> +        retval = -1;
>  
>      closedir(lun_dir);
>  
> @@ -417,9 +433,9 @@ processLU(virStoragePoolObjPtr pool,
>      VIR_DEBUG("%u:%u:%u:%u is a Direct-Access LUN",
>                host, bus, target, lun);
>  
> -    if (getBlockDevice(host, bus, target, lun, &block_device) < 0) {
> +    if ((retval = getBlockDevice(host, bus, target, lun, &block_device)) < 0) {
>          VIR_DEBUG("Failed to find block device for this LUN");
> -        return -1;
> +        return retval;
>      }
>  
>      retval = virStorageBackendSCSINewLun(pool, host, bus, target, lun,
> 

While this would work, I think if we follow out the pattern from the
rest of our functions, we can do better. Let me propose v2 to express
what I have in mind.

Michal