block: Add SG_IO device check in refresh_total_sectors()

This patch adds a special case check for scsi-generic devices in
refresh_total_sectors() to skip the subsequent BlockDriver->bdrv_getlength()
that will be returning -ESPIPE from block/raw-posic.c:raw_getlength() for
BlockDriverState->sg=1 devices.

Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/block.c b/block.c
index 6a95768e81..0b0966c571 100644
--- a/block.c
+++ b/block.c
@@ -361,6 +361,10 @@ static int refresh_total_sectors(BlockDriverState *bs, int64_t hint)
 {
     BlockDriver *drv = bs->drv;
 
+    /* Do not attempt drv->bdrv_getlength() on scsi-generic devices */
+    if (bs->sg)
+        return 0;
+
     /* query actual device if possible, otherwise just trust the hint */
     if (drv->bdrv_getlength) {
         int64_t length = drv->bdrv_getlength(bs);