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Re: [Qemu-block] [Qemu-devel] [PATCH 2/5] nbd: Prepare for NBD_CMD_FLAG_
From: |
Eric Blake |
Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH 2/5] nbd: Prepare for NBD_CMD_FLAG_FAST_ZERO |
Date: |
Tue, 3 Sep 2019 13:49:38 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 |
On 8/30/19 1:07 PM, Vladimir Sementsov-Ogievskiy wrote:
> 23.08.2019 17:37, Eric Blake wrote:
>> Commit fe0480d6 and friends added BDRV_REQ_NO_FALLBACK as a way to
>> avoid wasting time on a preliminary write-zero request that will later
>> be rewritten by actual data, if it is known that the write-zero
>> request will use a slow fallback; but in doing so, could not optimize
>> for NBD. The NBD specification is now considering an extension that
>> will allow passing on those semantics; this patch updates the new
>> protocol bits and 'qemu-nbd --list' output to recognize the bit, as
>> well as the new errno value possible when using the new flag; while
>> upcoming patches will improve the client to use the feature when
>> present, and the server to advertise support for it.
>>
>> +++ b/nbd/server.c
>> @@ -55,6 +55,8 @@ static int system_errno_to_nbd_errno(int err)
>> return NBD_ENOSPC;
>> case EOVERFLOW:
>> return NBD_EOVERFLOW;
>> + case ENOTSUP:
>> + return NBD_ENOTSUP;
>
I'm squashing this in:
diff --git i/nbd/server.c w/nbd/server.c
index b3bd08ef2953..4992148de1c4 100644
--- i/nbd/server.c
+++ w/nbd/server.c
@@ -56,6 +56,9 @@ static int system_errno_to_nbd_errno(int err)
case EOVERFLOW:
return NBD_EOVERFLOW;
case ENOTSUP:
+#if ENOTSUP != EOPNOTSUPP
+ case EOPNOTSUPP:
+#endif
return NBD_ENOTSUP;
case ESHUTDOWN:
return NBD_ESHUTDOWN;
It makes no difference on Linux, but may matter on other platforms
(since POSIX says the two may be equivalent, but may also be distinct).
>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
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