From 169407e1f7c9afee1cdac0ee6ad0b8d5e361c4dd Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Thu, 17 Nov 2016 14:13:54 -0600 Subject: [PATCH] nbd: Allow unmap and fua during write zeroes Commit fa778fff wired up support to send the NBD_CMD_WRITE_ZEROES, but forgot to inform the block layer that FUA unmapping of zeroes is supported. Without BDRV_REQ_MAY_UNMAP listed as a supported flag, the block layer will always insist on the NBD layer passing NBD_CMD_FLAG_NO_HOLE, resulting in the server always allocating things even when it was desired to let the server punch holes. Similarly, failing to set BDRV_REQ_FUA means that the client may send unnecessary NBD_CMD_FLUSH when it could have instead used the NBD_CMD_FLAG_FUA bit. CC: qemu-stable@nongnu.org Signed-off-by: Eric Blake Message-Id: <1479413642-22463-2-git-send-email-eblake@redhat.com> Signed-off-by: Paolo Bonzini --- block/nbd-client.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/block/nbd-client.c b/block/nbd-client.c index 2a302de674..3779c6c999 100644 --- a/block/nbd-client.c +++ b/block/nbd-client.c @@ -415,6 +415,10 @@ int nbd_client_init(BlockDriverState *bs, } if (client->nbdflags & NBD_FLAG_SEND_FUA) { bs->supported_write_flags = BDRV_REQ_FUA; + bs->supported_zero_flags |= BDRV_REQ_FUA; + } + if (client->nbdflags & NBD_FLAG_SEND_WRITE_ZEROES) { + bs->supported_zero_flags |= BDRV_REQ_MAY_UNMAP; } qemu_co_mutex_init(&client->send_mutex); -- 2.39.5