-blockdev and blockdev-add silently ignore empty objects and arrays in
their argument. That's because qmp_blockdev_add() converts the
argument to a flat QDict, and qdict_flatten() eats empty QDict and
QList members. For instance, we ignore an empty BlockdevOptions
member @cache. No real harm, as absent means the same as empty there.
Thus, the flaw puts an artificial restriction on the QAPI schema: we
can't have potentially empty objects and arrays within
BlockdevOptions, except when they're optional and "empty" has the same
meaning as "absent".
Our QAPI schema satisfies this restriction (I checked), but it's a
trap for the unwary, and a temptation to employ awkward workarounds
for the wary. Let's get rid of it.
Change qdict_flatten() and qdict_crumple() to treat empty dictionaries
and lists exactly like scalars.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
When you mix scalar and non-scalar keys, whether you get an "already
set as scalar" or an "already set as dict" error depends on qdict
iteration order. Neither message makes much sense. Replace by
""Cannot mix scalar and non-scalar keys". This is similar to the
message we get for mixing list and non-list keys.
I find qdict_crumple()'s first loop hard to understand. Rearrange it
and add a comment.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
qdict_flatten_qdict() skips copying scalars from @qdict to @target
when the two are the same. Fair enough, but it uses a non-obvious
test for "same". Replace it by the obvious one. While there, improve
comments.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
There's no need to restart the loop. We don't elsewhere, e.g. in
qdict_extract_subqdict(), qdict_join() and qemu_opts_absorb_qdict().
Simplify accordingly.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Configuration flows through the block subsystem in a rather peculiar
way. Configuration made with -drive enters it as QemuOpts.
Configuration made with -blockdev / blockdev-add enters it as QAPI
type BlockdevOptions. The block subsystem uses QDict, QemuOpts and
QAPI types internally. The precise flow is next to impossible to
explain (I tried for this commit message, but gave up after wasting
several hours). What I can explain is a flaw in the BlockDriver
interface that leads to this bug:
$ qemu-system-x86_64 -blockdev node-name=n1,driver=nfs,server.type=inet,server.host=localhost,path=/foo/bar,user=1234
qemu-system-x86_64: -blockdev node-name=n1,driver=nfs,server.type=inet,server.host=localhost,path=/foo/bar,user=1234: Internal error: parameter user invalid
QMP blockdev-add is broken the same way.
Here's what happens. The block layer passes configuration represented
as flat QDict (with dotted keys) to BlockDriver methods
.bdrv_file_open(). The QDict's members are typed according to the
QAPI schema.
nfs_file_open() converts it to QAPI type BlockdevOptionsNfs, with
qdict_crumple() and a qobject input visitor.
This visitor comes in two flavors. The plain flavor requires scalars
to be typed according to the QAPI schema. That's the case here. The
keyval flavor requires string scalars. That's not the case here.
nfs_file_open() uses the latter, and promptly falls apart for members
@user, @group, @tcp-syn-count, @readahead-size, @page-cache-size,
@debug.
Switching to the plain flavor would fix -blockdev, but break -drive,
because there the scalars arrive in nfs_file_open() as strings.
The proper fix would be to replace the QDict by QAPI type
BlockdevOptions in the BlockDriver interface. Sadly, that's beyond my
reach right now.
Next best would be to fix the block layer to always pass correctly
typed QDicts to the BlockDriver methods. Also beyond my reach.
What I can do is throw another hack onto the pile: have
nfs_file_open() convert all members to string, so use of the keyval
flavor actually works, by replacing qdict_crumple() by new function
qdict_crumple_for_keyval_qiv().
The pattern "pass result of qdict_crumple() to
qobject_input_visitor_new_keyval()" occurs several times more:
* qemu_rbd_open()
Same issue as nfs_file_open(), but since BlockdevOptionsRbd has only
string members, its only a latent bug. Fix it anyway.
* parallels_co_create_opts(), qcow_co_create_opts(),
qcow2_co_create_opts(), bdrv_qed_co_create_opts(),
sd_co_create_opts(), vhdx_co_create_opts(), vpc_co_create_opts()
These work, because they create the QDict with
qemu_opts_to_qdict_filtered(), which creates only string scalars.
The function sports a TODO comment asking for better typing; that's
going to be fun. Use qdict_crumple_for_keyval_qiv() to be safe.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Pure code motion, except for two brace placements and a comment
tweaked to appease checkpatch.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
