[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH v5 01/10] block: Auto-generate node_names for ea
From: |
Benoît Canet |
Subject: |
Re: [Qemu-devel] [PATCH v5 01/10] block: Auto-generate node_names for each BDS entry |
Date: |
Mon, 16 Jun 2014 16:10:41 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
The Friday 13 Jun 2014 à 14:52:29 (-0400), 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 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.
if the __qemu## determined a different name space no collision resolution would
be
needed.
Also Eric you must take care that these node name does not ends up in libvirt
XML since a new qemu process can generate a new different set of node name.
>
> Reviewed-by: Eric Blake <address@hidden>
> Signed-off-by: Jeff Cody <address@hidden>
> ---
> block.c | 16 +++++++++++++++-
> 1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/block.c b/block.c
> index 17f763d..fd43016 100644
> --- a/block.c
> +++ b/block.c
> @@ -844,12 +844,26 @@ static int bdrv_open_flags(BlockDriverState *bs, int
> flags)
> return open_flags;
> }
>
> +#define GEN_NODE_NAME_PREFIX "__qemu##"
> +#define GEN_NODE_NAME_MAX_LEN (sizeof(GEN_NODE_NAME_PREFIX) + 8 + 8)
> static void bdrv_assign_node_name(BlockDriverState *bs,
> const char *node_name,
> Error **errp)
> {
> + 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);
> + while (len < GEN_NODE_NAME_MAX_LEN - 1) {
> + gen_node_name[len++] = g_random_int_range('A', 'Z');
> + }
> + gen_node_name[GEN_NODE_NAME_MAX_LEN - 1] = '\0';
> + node_name = gen_node_name;
> }
>
> /* empty string node name is invalid */
> --
> 1.8.3.1
>
>
- [Qemu-devel] [PATCH v5 00/10] Modify block jobs to use node-names, Jeff Cody, 2014/06/13
- [Qemu-devel] [PATCH v5 01/10] block: Auto-generate node_names for each BDS entry, Jeff Cody, 2014/06/13
- Re: [Qemu-devel] [PATCH v5 01/10] block: Auto-generate node_names for each BDS entry,
Benoît Canet <=
- [Qemu-devel] [PATCH v5 02/10] block: add helper function to determine if a BDS is in a chain, Jeff Cody, 2014/06/13
- [Qemu-devel] [PATCH v5 03/10] block: simplify bdrv_find_base() and bdrv_find_overlay(), Jeff Cody, 2014/06/13
- [Qemu-devel] [PATCH v5 04/10] block: make 'top' argument to block-commit optional, Jeff Cody, 2014/06/13
- [Qemu-devel] [PATCH v5 06/10] block: extend block-commit to accept a string for the backing file, Jeff Cody, 2014/06/13
- [Qemu-devel] [PATCH v5 05/10] block: Accept node-name arguments for block-commit, Jeff Cody, 2014/06/13
- [Qemu-devel] [PATCH v5 07/10] block: add ability for block-stream to use node-name, Jeff Cody, 2014/06/13