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nbd/client: Send NBD_CMD_DISC if open fails after connect 

If nbd_client_init() fails after we are already connected,
then the server will spam logs with:

Disconnect client, due to: Unexpected end-of-file before all bytes were read

unless we gracefully disconnect before closing the connection.

Ways to trigger this:

$ opts=driver=nbd,export=foo,server.type=inet,server.host=localhost,server.port=10809
$  qemu-img map --output=json --image-opts $opts,read-only=off
$  qemu-img map --output=json --image-opts $opts,x-dirty-bitmap=nosuch:

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20181130023232.3079982-4-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
This commit is contained in:
Eric Blake 2018-11-29 20:32:32 -06:00
parent 47829c4079
commit c688e6ca7b
1 changed files with 16 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
block/nbd-client.c
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@ -995,12 +995,13 @@ int nbd_client_init(BlockDriverState *bs,
if (x_dirty_bitmap && !client->info.base_allocation) {
error_setg(errp, "requested x-dirty-bitmap %s not found",
x_dirty_bitmap);
return -EINVAL;
ret = -EINVAL;
goto fail;
}
if (client->info.flags & NBD_FLAG_READ_ONLY) {
ret = bdrv_apply_auto_read_only(bs, "NBD export is read-only", errp);
if (ret < 0) {
return ret;
goto fail;
}
}
if (client->info.flags & NBD_FLAG_SEND_FUA) {
@ -1029,4 +1030,17 @@ int nbd_client_init(BlockDriverState *bs,
logout("Established connection with NBD server\n");
return 0;
fail:
/*
* We have connected, but must fail for other reasons. The
* connection is still blocking; send NBD_CMD_DISC as a courtesy
* to the server.
*/
{
NBDRequest request = { .type = NBD_CMD_DISC };
nbd_send_request(client->ioc ?: QIO_CHANNEL(sioc), &request);
return ret;
}
}