Re: [Qemu-devel] [PATCH] nbd/server: introduce NBD_CMD_CACHE

[Eric Blake <eblake@redhat.com>]

On 04/13/2018 09:31 AM, Vladimir Sementsov-Ogievskiy wrote:
> Handle nbd CACHE command. Just do read, without sending read data back.
> Cache mechanism should be done by exported node driver chain.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>   include/block/nbd.h |  3 ++-
>   nbd/server.c        | 10 ++++++----
>   2 files changed, 8 insertions(+), 5 deletions(-)

Missing a change to nbd/common.c nbd_cmd_lookup().

> @@ -1911,7 +1913,7 @@ static coroutine_fn int nbd_do_cmd_read(NBDClient *client, NBDRequest *request,
>       int ret;
>       NBDExport *exp = client->exp;
>   
> -    assert(request->type == NBD_CMD_READ);
> +    assert(request->type == NBD_CMD_READ || request->type == NBD_CMD_CACHE);

Also, missing a call into this function for NBD_CMD_CACHE.

Squashing the following, then adding to my NBD queue, with:

Reviewed-by: Eric Blake <eblake@redhat.com>

diff --git i/nbd/common.c w/nbd/common.c
index 8c95c1d606e..41f5ed8d9fa 100644
--- i/nbd/common.c
+++ w/nbd/common.c
@@ -148,6 +148,8 @@ const char *nbd_cmd_lookup(uint16_t cmd)
          return "flush";
      case NBD_CMD_TRIM:
          return "trim";
+    case NBD_CMD_CACHE:
+        return "cache";
      case NBD_CMD_WRITE_ZEROES:
          return "write zeroes";
      case NBD_CMD_BLOCK_STATUS:
diff --git i/nbd/server.c w/nbd/server.c
index 323c6d84004..274604609f4 100644
--- i/nbd/server.c
+++ w/nbd/server.c
@@ -2173,6 +2173,7 @@ static coroutine_fn int 
nbd_handle_request(NBDClient *client,

      switch (request->type) {
      case NBD_CMD_READ:
+    case NBD_CMD_CACHE:
          return nbd_do_cmd_read(client, request, data, errp);

      case NBD_CMD_WRITE:


-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org