From 38490efee0abe97d4af0097d2f8f60de2330dc2e Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Thu, 29 Nov 2018 20:32:31 -0600 Subject: [PATCH] nbd/client: Make x-dirty-bitmap more reliable The implementation of x-dirty-bitmap in qemu 3.0 (commit 216ee365) silently falls back to treating the server as not supporting NBD_CMD_BLOCK_STATUS if a requested meta_context name was not negotiated, which in turn means treating the _entire_ image as data. Since our hack relied on using 'qemu-img map' to view which portions of the image were dirty by seeing what the redirected bdrv_block_status() treats as holes, this means that our fallback treats the entire image as clean. Better would have been to treat the entire image as dirty, or to fail to connect because the user's request for a specific context could not be honored. This patch goes with the latter. Signed-off-by: Eric Blake Message-Id: <20181130023232.3079982-3-eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy (cherry picked from commit 47829c40794160debdb33b4a042d182e776876d4) *avoid context dep. on 6c2e581d Signed-off-by: Michael Roth --- block/nbd-client.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/block/nbd-client.c b/block/nbd-client.c index 9686ecbd5e..f8c42a6996 100644 --- a/block/nbd-client.c +++ b/block/nbd-client.c @@ -992,6 +992,11 @@ int nbd_client_init(BlockDriverState *bs, logout("Failed to negotiate with the NBD server\n"); return ret; } + if (x_dirty_bitmap && !client->info.base_allocation) { + error_setg(errp, "requested x-dirty-bitmap %s not found", + x_dirty_bitmap); + return -EINVAL; + } if (client->info.flags & NBD_FLAG_READ_ONLY && !bdrv_is_read_only(bs)) { error_setg(errp, -- 2.39.2