From: Jeff Cody <jcody@redhat.com>
To: Eric Blake <eblake@redhat.com>
Cc: kwolf@redhat.com, benoit.canet@irqsave.net, pkrempa@redhat.com,
famz@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com
Subject: Re: [Qemu-devel] [PATCH 1/5] block: Auto-generate node_names for each BDS entry
Date: Thu, 15 May 2014 14:41:03 -0400 [thread overview]
Message-ID: <20140515184103.GM8452@localhost.localdomain> (raw)
In-Reply-To: <5374E445.9070609@redhat.com>
On Thu, May 15, 2014 at 09:59:01AM -0600, Eric Blake wrote:
> 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
> > (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 <jcody@redhat.com>
> > ---
> > block.c | 16 +++++++++++++++-
> > 1 file changed, 15 insertions(+), 1 deletion(-)
>
> This patch feels incomplete. We probably also ought to modify
> qapi-schema.json to make BlockDeviceInfo's output of 'node-name' by
> unconditional (as an output-only struct, changing from optional to
> mandatory is a safe change for back-compat API considerations); which
> implies further modifying code to get rid of has_node_name arguments in
> all places that generate BlockDeviceInfo details.
I think it should be a separate patch (but still in this series).
Strictly speaking, this patch doesn't force the argument to be
mandatory, the value just happens to always be populated now.
> See also my thoughts on patch 5/5 - can this patch be rebased to be LAST
> in the series, rather than first, so that it serves as a reliable
> witness that everything else related to block operations on node-names
> is complete?
>
How about this becomes the penultimate patch, and the patch to make
BlockDeviceInfo's node-name field to be unconditional becomes the last
patch?
The only thing I don't like about moving this further back in the
patch series is it makes the earlier patches untestable; I can't
easily test the usage of the node-names for various intermediate BDS
because they don't have node-names set. So that means I'll just need
to rebase the patches prior to sending. So let me revise my above
statement - how about this patch stays at the beginning, which makes
development / testing easier, with the patch that modifies
BlockDeviceInfo as the final (not including tests) patch?
next prev parent reply other threads:[~2014-05-15 18:41 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-15 3:20 [Qemu-devel] [PATCH 0/5] block: Modify block-commit to use node-names Jeff Cody
2014-05-15 3:20 ` [Qemu-devel] [PATCH 1/5] block: Auto-generate node_names for each BDS entry Jeff Cody
2014-05-15 11:58 ` Benoît Canet
2014-05-15 12:06 ` Jeff Cody
2014-05-15 12:32 ` Benoît Canet
2014-05-15 12:37 ` Jeff Cody
2014-05-15 14:11 ` Eric Blake
2014-05-15 15:59 ` Eric Blake
2014-05-15 18:41 ` Jeff Cody [this message]
2014-05-15 19:12 ` Eric Blake
2014-05-16 9:39 ` Kevin Wolf
2014-05-16 11:35 ` Jeff Cody
2014-05-16 12:47 ` Eric Blake
2014-05-16 17:16 ` Kevin Wolf
2014-05-15 3:20 ` [Qemu-devel] [PATCH 2/5] block: add helper function to determine if a BDS is in a chain Jeff Cody
2014-05-15 11:48 ` Benoît Canet
2014-05-15 14:16 ` Eric Blake
2014-05-15 14:24 ` Kevin Wolf
2014-05-15 14:31 ` Jeff Cody
2014-05-15 3:20 ` [Qemu-devel] [PATCH 3/5] block: make 'top' argument to block-commit optional Jeff Cody
2014-05-15 11:47 ` Benoît Canet
2014-05-15 11:49 ` Jeff Cody
2014-05-15 15:07 ` Eric Blake
2014-05-15 3:20 ` [Qemu-devel] [PATCH 4/5] block: Accept node-name arguments for block-commit Jeff Cody
2014-05-15 12:09 ` Benoît Canet
2014-05-15 15:42 ` Eric Blake
2014-05-15 18:04 ` Jeff Cody
2014-05-15 3:20 ` [Qemu-devel] [PATCH 5/5] block: extend block-commit to accept a string for the backing file Jeff Cody
2014-05-15 12:26 ` Benoît Canet
2014-05-15 12:57 ` Eric Blake
2014-05-15 13:10 ` Jeff Cody
2014-05-15 13:14 ` Eric Blake
2014-05-15 16:06 ` Eric Blake
2014-05-15 18:22 ` Jeff Cody
2014-05-15 18:52 ` Eric Blake
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