[sheepdog] [PATCH 5/9] sheepdog: Support BDRV_REQ_ZERO_WRITE for truncate

[Eric Blake]

Our .bdrv_has_zero_init_truncate always returns 1 because sheepdog
always 0-fills; we can use that same knowledge to implement
BDRV_REQ_ZERO_WRITE by ignoring it.

Signed-off-by: Eric Blake <eblake at redhat.com>
---
 block/sheepdog.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/block/sheepdog.c b/block/sheepdog.c
index ef0a6e743e27..26fd22c7f07d 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -1654,6 +1654,7 @@ static int sd_open(BlockDriverState *bs, QDict *options, int flags,
     memcpy(&s->inode, buf, sizeof(s->inode));

     bs->total_sectors = s->inode.vdi_size / BDRV_SECTOR_SIZE;
+    bs->supported_truncate_flags = BDRV_REQ_ZERO_WRITE;
     pstrcpy(s->name, sizeof(s->name), vdi);
     qemu_co_mutex_init(&s->lock);
     qemu_co_mutex_init(&s->queue_lock);
-- 
2.26.2