When BDSs are created by qemu itself (e.g. as filters in block jobs),
they may not have a "driver" option in their options QDict. When
generating a json:{} filename, however, it must always be present.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-31-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
While we cannot represent the latency-ns option in a filename, it is not
a strong option so not being able to should not stop us from generating
a filename nonetheless.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-30-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-29-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Both of the defaults we currently have in the curl driver are named
based on a slightly different schema, let's unify that and call both
CURL_BLOCK_OPT_${NAME}_DEFAULT.
While at it, we can add a macro for the third option for which a default
exists, namely "sslverify".
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-28-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Currently, nvme's bdrv_refresh_filename() is an exact copy of null's
implementation. However, for null, "null-co://" and "null-aio://" are
indeed valid filenames -- for nvme, they are not, as a device address is
still required.
The correct implementation should generate a filename of the form
"nvme://[PCI address]/[namespace]" (as the comment above
nvme_parse_filename() describes).
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-27-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
If a format BDS's file BDS is in turn a format BDS, we cannot simply use
the same filename, because when opening a BDS tree based on a filename
alone, qemu will create only one format node on top of one protocol node
(disregarding a potential backing file).
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-26-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Currently, BlockDriver.bdrv_refresh_filename() is supposed to both
refresh the filename (BDS.exact_filename) and set BDS.full_open_options.
Now that we have generic code in the central bdrv_refresh_filename() for
creating BDS.full_open_options, we can drop the latter part from all
BlockDriver.bdrv_refresh_filename() implementations.
This also means that we can drop all of the existing default code for
this from the global bdrv_refresh_filename() itself.
Furthermore, we now have to call BlockDriver.bdrv_refresh_filename()
after having set BDS.full_open_options, because the block driver's
implementation should now be allowed to depend on BDS.full_open_options
being set correctly.
Finally, with this patch we can drop the @options parameter from
BlockDriver.bdrv_refresh_filename(); also, add a comment on this
function's purpose in block/block_int.h while touching its interface.
This completely obsoletes blklogwrite's implementation of
.bdrv_refresh_filename().
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190201192935.18394-25-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Instead of having every block driver which implements
bdrv_refresh_filename() copy all of the strong runtime options over to
bs->full_open_options, implement this process generically in
bdrv_refresh_filename().
This patch only adds this new generic implementation, it does not remove
the old functionality. This is done in a follow-up patch.
With this patch, some superfluous information (that should never have
been there) may be removed from some JSON filenames, as can be seen in
the change to iotests 110's and 228's reference outputs.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190201192935.18394-24-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Some follow-up patches will rework the way bs->full_open_options is
refreshed in bdrv_refresh_filename(). The new implementation will remove
the need for the block drivers' bdrv_refresh_filename() implementations
to set bs->full_open_options; instead, it will be generic and use static
information from each block driver.
However, by implementing bdrv_gather_child_options(), block drivers will
still be able to override the way the full_open_options of their
children are incorporated into their own.
We need to implement this function for VMDK because we have to prevent
the generic implementation from gathering the options of all children:
It is not possible to specify options for the extents through the
runtime options.
For quorum, the child names that would be used by the generic
implementation and the ones that we actually (currently) want to use
differ. See quorum_gather_child_options() for more information.
Note that both of these are cases which are not ideal: In case of VMDK
it would probably be nice to be able to specify options for all extents.
In case of quorum, the current runtime option structure is simply broken
and needs to be fixed (but that is left for another patch).
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-23-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This new field can be set by block drivers to list the runtime options
they accept that may influence the contents of the respective BDS. As of
a follow-up patch, this list will be used by the common
bdrv_refresh_filename() implementation to decide which options to put
into BDS.full_open_options (and consequently whether a JSON filename has
to be created), thus freeing the drivers of having to implement that
logic themselves.
Additionally, this patch adds the field to all of the block drivers that
need it and sets it accordingly.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-22-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Test 110 tests relative backing filenames for complex BDS trees. Now
that the originally supposedly failing test passes, let us add a new
failing test: Quorum can never work automatically (without detecting
whether all child nodes have the same base directory, but that would be
rather inconsistent behavior).
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-21-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
bdrv_get_full_backing_filename_from_filename() breaks down when it comes
to JSON filenames. Using bdrv_dirname() as the basis is better because
since we have BDS, we can descend through the BDS tree to the protocol
layer, which gives us a greater probability of finding a non-JSON name;
also, bdrv_dirname() is more correct as it allows block drivers to
override the generation of that directory name in a protocol-specific
way.
We still need to keep bdrv_get_full_backing_filename_from_filename(),
though, because it has valid callers which need it during image creation
when no BDS is available yet.
This makes a test case in qemu-iotest 110, which was supposed to fail,
work. That is actually good, but we need to change the reference output
(and the comment in 110) accordingly.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-20-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
While the basic idea is obvious and could be handled by the default
bdrv_dirname() implementation, we cannot generate a directory name if
the gid or uid are set, so we have to explicitly return NULL in those
cases.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-19-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
The generic bdrv_dirname() implementation would be able to generate some
form of directory name for many NBD nodes, but it would be always wrong.
Therefore, we have to explicitly make it an error (until NBD has some
form of specification for export paths, if it ever will).
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20190201192935.18394-18-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
While the common implementation for bdrv_dirname() should return NULL
for quorum BDSs already (because they do not have a file node and their
exact_filename field should be empty), there is no reason not to make
that explicit.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-17-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
blkverify's BDSs have a file BDS, but we do not want this to be
preferred over the raw node. There is no way to decide between the two
(and not really a reason to, either), so just return NULL in blkverify's
implementation of bdrv_dirname().
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-16-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This function may be implemented by block drivers to derive a directory
name from a BDS. Concatenating this g_free()-able string with a relative
filename must result in a valid (not necessarily existing) filename, so
this is a function that should generally be not implemented by format
drivers, because this is protocol-specific.
If a BDS's driver does not implement this function, bdrv_dirname() will
fall through to the BDS's file if it exists. If it does not, the
exact_filename field will be used to generate a directory name.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-15-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
bdrv_find_backing_image() should use bdrv_get_full_backing_filename() or
bdrv_make_absolute_filename() instead of trying to do what those
functions do by itself.
path_combine_deprecated() can now be dropped, so let's do that.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-14-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This is a general function for making a filename that is relative to a
certain BDS absolute.
It calls bdrv_get_full_backing_filename_from_filename() for now, but
that will be changed in a follow-up patch.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-13-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Make bdrv_get_full_backing_filename() return an allocated string instead
of placing the result in a caller-provided buffer.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-12-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Make bdrv_get_full_backing_filename_from_filename() return an allocated
string instead of placing the result in a caller-provided buffer.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190201192935.18394-11-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Besides being safe for arbitrary path lengths, after some follow-up
patches all callers will want a freshly allocated buffer anyway.
In the meantime, path_combine_deprecated() is added which has the same
interface as path_combine() had before this patch. All callers to that
function will be converted in follow-up patches.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-id: 20190201192935.18394-10-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This function queries a node; since we cannot do that right now, it
executes query-named-block-nodes and returns the matching node's object.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20190201192935.18394-8-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190201192935.18394-7-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Basically, bdrv_refresh_filename() should respect all children of a
BlockDriverState. However, generally those children are driver-specific,
so this function cannot handle the general case. On the other hand,
there are only few drivers which use other children than @file and
@backing (that being vmdk, quorum, and blkverify).
Most block drivers only use @file and/or @backing (if they use any
children at all). Both can be implemented directly in
bdrv_refresh_filename.
The user overriding the file's filename is already handled, however, the
user overriding the backing file is not. If this is done, opening the
BDS with the plain filename of its file will not be correct, so we may
not set bs->exact_filename in that case.
iotest 051 contains test cases for overriding the backing file, and so
its output changes with this patch applied.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-6-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
If the backing file is overridden, this most probably does change the
guest-visible data of a BDS. Therefore, we will need to consider this
in bdrv_refresh_filename().
To see whether it has been overridden, we might want to compare
bs->backing_file and bs->backing->bs->filename. However,
bs->backing_file is changed by bdrv_set_backing_hd() (which is just used
to change the backing child at runtime, without modifying the image
header), so bs->backing_file most of the time simply contains a copy of
bs->backing->bs->filename anyway, so it is useless for such a
comparison.
This patch adds an auto_backing_file BDS field which contains the
backing file path as indicated by the image header, which is not changed
by bdrv_set_backing_hd().
Because of bdrv_refresh_filename() magic, however, a BDS's filename may
differ from what has been specified during bdrv_open(). Then, the
comparison between bs->auto_backing_file and bs->backing->bs->filename
may fail even though bs->backing was opened from bs->auto_backing_file.
To mitigate this, we can copy the real BDS's filename (after the whole
bdrv_open() and bdrv_refresh_filename() process) into
bs->auto_backing_file, if we know the former has been opened based on
the latter. This is only possible if no options modifying the backing
file's behavior have been specified, though. To simplify things, this
patch only copies the filename from the backing file if no options have
been specified for it at all.
Furthermore, there are cases where an overlay is created by qemu which
already contains a BDS's filename (e.g. in blockdev-snapshot-sync). We
do not need to worry about updating the overlay's bs->auto_backing_file
there, because we actually wrote a post-bdrv_refresh_filename() filename
into the image header.
So all in all, there will be false negatives where (as of a future
patch) bdrv_refresh_filename() will assume that the backing file differs
from what was specified in the image header, even though it really does
not. However, these cases should be limited to where (1) the user
actually did override something in the backing chain (e.g. by specifying
options for the backing file), or (2) the user executed a QMP command to
change some node's backing file (e.g. change-backing-file or
block-commit with @backing-file given) where the given filename does not
happen to coincide with qemu's idea of the backing BDS's filename.
Then again, (1) really is limited to -drive. With -blockdev or
blockdev-add, you have to adhere to the schema, so a user cannot give
partial "unimportant" options (e.g. by just setting backing.node-name
and leaving the rest to the image header). Therefore, trying to fix
this would mean trying to fix something for -drive only.
To improve on (2), we would need a full infrastructure to "canonicalize"
an arbitrary filename (+ options), so it can be compared against
another. That seems a bit over the top, considering that filenames
nowadays are there mostly for the user's entertainment.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-5-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
bdrv_refresh_filename() should simply skip all implicit nodes. They are
supposed to be invisible to the user, so they should not appear in
filename information.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-4-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
bdrv_refresh_filename() should invoke itself recursively on all
children, not just on file.
With that change, we can remove the manual invocations in blkverify,
quorum, commit, mirror, and blklogwrites.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190201192935.18394-3-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Before this patch, bdrv_refresh_filename() is used in a pushing manner:
Whenever the BDS graph is modified, the parents of the modified edges
are supposed to be updated (recursively upwards). However, that is
nonviable, considering that we want child changes not to concern
parents.
Also, in the long run we want a pull model anyway: Here, we would have a
bdrv_filename() function which returns a BDS's filename, freshly
constructed.
This patch is an intermediate step. It adds bdrv_refresh_filename()
calls before every place a BDS.filename value is used. The only
exceptions are protocol drivers that use their own filename, which
clearly would not profit from refreshing that filename before.
Also, bdrv_get_encrypted_filename() is removed along the way (as a user
of BDS.filename), since it is completely unused.
In turn, all of the calls to bdrv_refresh_filename() before this patch
are removed, because we no longer have to call this function on graph
changes.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190201192935.18394-2-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
The QEMU_PACKED is causing a compiler warning/error with GCC 9:
CC block/nvme.o
block/nvme.c: In function ‘nvme_create_queue_pair’:
block/nvme.c:209:22: error: taking address of packed member of
‘struct <anonymous>’ may result in an unaligned pointer value
[-Werror=address-of-packed-member]
209 | q->sq.doorbell = &s->regs->doorbells[idx * 2 * s->doorbell_scale];
All members of the struct are naturally aligned, so there should
not be the need for QEMU_PACKED here, and the following QEMU_BUILD_BUG_ON
also ensures that there is no padding. Thus simply remove the QEMU_PACKED
here.
Buglink: https://bugs.launchpad.net/qemu/+bug/1817525
Reported-by: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
L1 table entries have a field to store the offset of an L2 table.
The rest of the bits of the entry are currently reserved except from
bit 63, which stores the COPIED flag.
The offset is always taken from the entry using L1E_OFFSET_MASK to
ensure that we only use the bits that belong to that field.
While that mask is used every time we read from the L1 table, it is
never used when we write to it. Due to the limits set elsewhere in the
code QEMU can never produce L2 table offsets that don't fit in that
field so any such offset when allocating an L2 table would indicate a
bug in QEMU.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Add two tests of node graph modification.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
bdrv_check_perm in it's recursion checks each node in context of new
permissions for one parent, because of nature of DFS. It works well,
while children subgraph of top-most updated node is a tree, i.e. it
doesn't have any kind of loops. But if we have a loop (not oriented,
of course), i.e. we have two different ways from top-node to some
child-node, then bdrv_check_perm will do wrong thing:
top
| \
| |
v v
A B
| |
v v
node
It will once check new permissions of node in context of new A
permissions and old B permissions and once visa-versa. It's a wrong way
and may lead to corruption of permission system. We may start with
no-permissions and all-shared for both A->node and B->node relations
and finish up with non shared write permission for both ways.
The following commit will add a test, which shows this bug.
To fix this situation, let's really set BdrvChild permissions during
bdrv_check_perm procedure. And we are happy here, as check-perm is
already written in transaction manner, so we just need to restore
backed-up permissions in _abort.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
As it already said in the comment, we don't want to create loops in
parent->child relations. So, when we try to append @to to @c, we should
check that @c is not in @to children subtree, and we should check it
recursively, not only the first level. The patch provides BFS-based
search, to check the relations.
This is needed for further fleecing-hook filter usage: we need to
append it to source, when the hook is already a parent of target, and
source may be in a backing chain of target (fleecing-scheme). So, on
appending, the hook should not became a child (direct or through
children subtree) of the target.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
aio_poll() has an existing assertion that the function is only called
from the AioContext's home thread if blocking is allowed.
This is not enough, some handlers make assumptions about the thread they
run in. Extend the assertion to non-blocking calls, too.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Now that bdrv_set_aio_context() works inside drained sections, it can
also use the real drain function instead of open coding something
similar.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
When a drained node changes its AioContext, we need to move its
aio_disable_external() to the new context, too.
Without this fix, drain_end will try to reenable the new context, which
has never been disabled, so an assertion failure is triggered.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
The explicit aio_poll() call in bdrv_set_aio_context() was added in
commit c2b6428d38 as a workaround for bdrv_drain() failing to achieve
to actually quiesce everything (specifically the NBD client code to
switch AioContext).
Now that the NBD client has been fixed to complete this operation during
bdrv_drain(), we don't need the workaround any more.
It was wrong anyway: aio_poll() must always be run in the home thread of
the AioContext.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
bdrv_drain() must not leave connection_co scheduled, so bs->in_flight
needs to be increased while the coroutine is waiting to be scheduled
in the new AioContext after nbd_client_attach_aio_context().
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Instead of using the convenience wrapper qio_channel_read_all_eof(), use
the lower level QIOChannel API. This means duplicating some code, but
we'll need this because this coroutine yield is special: We want it to
be interruptible so that nbd_client_attach_aio_context() can correctly
reenter the coroutine.
This moves the bdrv_dec/inc_in_flight() pair into nbd_read_eof(), so
that connection_co will always sit in this exact qio_channel_yield()
call when bdrv_drain() returns.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
The only caller of nbd_read_eof() is nbd_receive_reply(), so it doesn't
have to live in the header file, but can move next to its caller.
Also add the missing coroutine_fn to the function and its caller.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
qio_channel_yield() now updates ioc->read_write/coroutine and calls
qio_channel_set_aio_fd_handlers(), so the code in the handlers has
become redundant and can be removed.
This does not make a difference in intermediate states because
aio_co_wake() really enters the coroutine immediately here: These
handlers are never run in coroutine context, and we're in the right
AioContext because qio_channel_attach_aio_context() asserts that the
handlers are inactive.
To make these conditions more obvious, assert the right AioContext.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Similar to how qemu_co_sleep_ns() allows preemption from an external
coroutine entry, allow reentering qio_channel_yield() early.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
nbd_client_attach_aio_context() schedules connection_co in the new
AioContext and this way reenters it in any arbitrary place that has
yielded. We can restrict this a bit to the function call where the
coroutine actually sits waiting when it's idle.
This doesn't solve any bug yet, but it shows where in the code we need
to support this random reentrance and where we don't have to care.
Add FIXME comments for the existing bugs that the rest of this series
will fix.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
virtio_blk_dma_restart_bh() submits new requests, so in order to make
sure that these requests are not started inside a drained section of the
attached BlockBackend, we need to make sure that draining the
BlockBackend waits for the BH to be executed.
This BH is still questionable because its scheduled in the main thread
instead of the configured iothread. Leave a FIXME comment for this.
But with this fix, enabling the data plane at least waits for these
requests (in bdrv_set_aio_context()) instead of changing the AioContext
under their feet and making them run in the wrong thread, causing
crashes and failures (e.g. due to missing locking).
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
For some users of BlockBackends, just increasing the in_flight counter
is easier than implementing separate handlers in BlockDevOps. Make the
helper functions for this public.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
