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Re: [Qemu-devel] [PATCH 1/5] block: Auto-generate node_names for each BD
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH 1/5] block: Auto-generate node_names for each BDS entry |
Date: |
Thu, 15 May 2014 08:11:28 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 |
On 05/14/2014 09:20 PM, Jeff Cody wrote:
> Currently, node_name is only filled in when done so explicitly by the
> user. If no node_name is specified, then the node name field is not
> populated.
>
> If node_names are automatically generated when not specified, that means
> that all block job operations can be done by reference to the unique
> node_name field. This eliminates ambiguity in filename pathing
"pathing" sounds weird; a non-native speaker may get confused since it
is not a real word. Maybe:
This eliminates ambiguity in resolving filenames
> (relative filenames, or file descriptors, symlinks, mounts, etc..) that
> qemu currently needs to deal with.
>
> If a node name is specified, then it will not be automatically
> generated for that BDS entry.
>
> If it is automatically generated, it will be prefaced with "__qemu##",
> followed by 8 characters of a unique number, followed by 8 random
> ASCII characters in the range of 'A-Z'. Some sample generated node-name
> strings:
> __qemu##00000000IAIYNXXR
> __qemu##00000002METXTRBQ
> __qemu##00000001FMBORDWG
>
> The prefix is to aid in identifying it as a qemu-generated name, the
> numeric portion is to guarantee uniqueness in a given qemu session, and
> the random characters are to further avoid any accidental collisions
> with user-specified node-names.
>
> Signed-off-by: Jeff Cody <address@hidden>
> ---
> block.c | 16 +++++++++++++++-
> 1 file changed, 15 insertions(+), 1 deletion(-)
>
> {
> + char gen_node_name[GEN_NODE_NAME_MAX_LEN];
> + static uint32_t counter; /* simple counter to guarantee uniqueness */
> +
> + /* if node_name is NULL, auto-generate a node name */
> if (!node_name) {
> - return;
> + int len;
> + snprintf(gen_node_name, GEN_NODE_NAME_MAX_LEN,
> + "%s%08x", GEN_NODE_NAME_PREFIX, counter++);
> + len = strlen(gen_node_name);
Why not just len = snprintf(), and avoid the strlen()?
But that micro-optimization is not on the hot path, so:
Reviewed-by: Eric Blake <address@hidden>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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- [Qemu-devel] [PATCH 0/5] block: Modify block-commit to use node-names, Jeff Cody, 2014/05/14
- Re: [Qemu-devel] [PATCH 1/5] block: Auto-generate node_names for each BDS entry,
Eric Blake <=
- Re: [Qemu-devel] [PATCH 1/5] block: Auto-generate node_names for each BDS entry, Eric Blake, 2014/05/15
- Re: [Qemu-devel] [PATCH 1/5] block: Auto-generate node_names for each BDS entry, Jeff Cody, 2014/05/15
- Re: [Qemu-devel] [PATCH 1/5] block: Auto-generate node_names for each BDS entry, Eric Blake, 2014/05/15
- Re: [Qemu-devel] [PATCH 1/5] block: Auto-generate node_names for each BDS entry, Kevin Wolf, 2014/05/16
- Re: [Qemu-devel] [PATCH 1/5] block: Auto-generate node_names for each BDS entry, Jeff Cody, 2014/05/16
- Re: [Qemu-devel] [PATCH 1/5] block: Auto-generate node_names for each BDS entry, Eric Blake, 2014/05/16
- Re: [Qemu-devel] [PATCH 1/5] block: Auto-generate node_names for each BDS entry, Kevin Wolf, 2014/05/16
[Qemu-devel] [PATCH 2/5] block: add helper function to determine if a BDS is in a chain, Jeff Cody, 2014/05/14