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Re: [Qemu-block] [PATCH v2 06/21] block: Exclude nested options only for
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-block] [PATCH v2 06/21] block: Exclude nested options only for children in append_open_options() |
Date: |
Mon, 30 Nov 2015 10:01:07 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
Am 27.11.2015 um 18:58 hat Max Reitz geschrieben:
> On 23.11.2015 16:59, Kevin Wolf wrote:
> > Some drivers have nested options (e.g. blkdebug rule arrays), which
> > don't belong to a child node and shouldn't be removed. Don't remove all
> > options with "." in their name, but check for the complete prefixes of
> > actually existing child nodes.
> >
> > Signed-off-by: Kevin Wolf <address@hidden>
> > ---
> > block.c | 19 +++++++++++++++----
> > include/block/block_int.h | 1 +
> > 2 files changed, 16 insertions(+), 4 deletions(-)
>
> Thanks, now I don't need to fix it myself. :-)
>
> (I would have had to do that for an in-work series of mine)
>
> > diff --git a/block.c b/block.c
> > index 23d9e10..02125e2 100644
> > --- a/block.c
> > +++ b/block.c
> > @@ -1101,11 +1101,13 @@ static int bdrv_fill_options(QDict **options, const
> > char **pfilename,
> >
> > static BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
> > BlockDriverState *child_bs,
> > + const char *child_name,
> > const BdrvChildRole *child_role)
> > {
> > BdrvChild *child = g_new(BdrvChild, 1);
> > *child = (BdrvChild) {
> > .bs = child_bs,
> > + .name = child_name,
> > .role = child_role,
> > };
> >
> > @@ -1165,7 +1167,7 @@ void bdrv_set_backing_hd(BlockDriverState *bs,
> > BlockDriverState *backing_hd)
> > bs->backing = NULL;
> > goto out;
> > }
> > - bs->backing = bdrv_attach_child(bs, backing_hd, &child_backing);
> > + bs->backing = bdrv_attach_child(bs, backing_hd, "backing",
> > &child_backing);
> > bs->open_flags &= ~BDRV_O_NO_BACKING;
> > pstrcpy(bs->backing_file, sizeof(bs->backing_file),
> > backing_hd->filename);
> > pstrcpy(bs->backing_format, sizeof(bs->backing_format),
> > @@ -1322,7 +1324,7 @@ BdrvChild *bdrv_open_child(const char *filename,
> > goto done;
> > }
> >
> > - c = bdrv_attach_child(parent, bs, child_role);
> > + c = bdrv_attach_child(parent, bs, bdref_key, child_role);
> >
> > done:
> > qdict_del(options, bdref_key);
> > @@ -3952,13 +3954,22 @@ static bool append_open_options(QDict *d,
> > BlockDriverState *bs)
> > {
> > const QDictEntry *entry;
> > QemuOptDesc *desc;
> > + BdrvChild *child;
> > bool found_any = false;
> > + const char *p;
> >
> > for (entry = qdict_first(bs->options); entry;
> > entry = qdict_next(bs->options, entry))
> > {
> > - /* Only take options for this level */
> > - if (strchr(qdict_entry_key(entry), '.')) {
> > + /* Exclude options for children */
> > + QLIST_FOREACH(child, &bs->children, next) {
> > + if (strstart(qdict_entry_key(entry), child->name, &p)
> > + && (!*p || *p == '.'))
> > + {
> > + break;
> > + }
> > + }
> > + if (child) {
> > continue;
> > }
> >
>
> A good general solution, but I think bdrv_refresh_filename() may be bad
> enough to break with general solutions. ;-)
>
> bdrv_refresh_filename() only considers "file" and "backing" (actually,
> it only supports "file" for now, I'm working on "backing", though). The
> only drivers with other children are quorum, blkdebug, blkverify and
> VMDK. The former three have their own implementation of
> bdrv_refresh_filename(), so they don't use append_open_options() at all.
> The latter, however, (VMDK) does not.
>
> This change to append_open_options results in the extent.%d options
> simply being omitted altogether because bdrv_refresh_filename() does not
> fetch them. Before, they were included in the VMDK BDS's options, which
> is not ideal but works more or less.
Are you sure? As far as I can tell, this patch should only keep options
that were previously removed, but not remove options that were
previously kept (with the exception of direct use of child names, which
I added here to address your review comments for v1).
Specifically for "extents.%d", this is a child name and is therefore
omitted. However, it contains a '.', so it was already removed without
this patch.
I'm accepting proof of the contrary in the form of a test case. ;-)
> In order to "fix" this, I see three ways right now:
> 1. Just care about "file" and "backing". bdrv_refresh_filename()
> doesn't support anything else, so that will be fine.
> 2. Implement bdrv_refresh_filename() specifically for VMDK so
> append_open_options() will never have to handle anything but "file"
> and "backing".
> 3. Fix bdrv_refresh_filename() so that it handles all children and not
> just "file" and "backing".
>
> Since we are shooting for 2.6 anyway (I assume ;-)), I think we should
> go for option 3. This means that this patch is fine, and I'll see to
> fixing bdrv_refresh_filename() (because I'm working on that anyway).
Yes, I agree.
Kevin
pgpIoblNbuDdN.pgp
Description: PGP signature
- [Qemu-block] [PATCH v2 00/21] block: Cache mode for children etc., Kevin Wolf, 2015/11/23
- [Qemu-block] [PATCH v2 03/21] mirror: Error out when a BDS would get two BBs, Kevin Wolf, 2015/11/23
- [Qemu-block] [PATCH v2 01/21] qcow2: Add .bdrv_join_options callback, Kevin Wolf, 2015/11/23
- [Qemu-block] [PATCH v2 07/21] block: Pass driver-specific options to .bdrv_refresh_filename(), Kevin Wolf, 2015/11/23
- [Qemu-block] [PATCH v2 09/21] block: Allow specifying child options in reopen, Kevin Wolf, 2015/11/23
- [Qemu-block] [PATCH v2 10/21] block: reopen: Document option precedence and refactor accordingly, Kevin Wolf, 2015/11/23