Provide a separate function that just quiesces the users of a node to
prevent new requests from coming in, but without waiting for the already
in-flight I/O to complete.
This function can be used in contexts where polling is not allowed.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20221207131838.239125-2-kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
bdrv_common_block_status_above() is a g_c_w, and it is being called by
many "wrapper" functions like bdrv_is_allocated(),
bdrv_is_allocated_above() and bdrv_block_status_above().
Because we want to eventually split the coroutine from non-coroutine
case in g_c_w, create duplicate wrappers that take care of directly
calling the same coroutine functions called in the g_c_w.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-Id: <20221128142337.657646-2-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
All callers of bdrv_parent_drained_begin_single() pass poll=false now,
so we don't need the parameter any more.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20221118174110.55183-16-kwolf@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
In order to make sure that bdrv_replace_child_noperm() doesn't have to
poll any more, get rid of the bdrv_parent_drained_begin_single() call.
This is possible now because we can require that the parent is already
drained through the child in question when the function is called and we
don't call the parent drain callbacks more than once.
The additional drain calls needed in callers cause the test case to run
its code in the drain handler too early (bdrv_attach_child() drains
now), so modify it to only enable the code after the test setup has
completed.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20221118174110.55183-15-kwolf@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The next patch adds a parent drain to bdrv_attach_child_common(), which
shouldn't be, but is currently called from coroutines in some cases (e.g.
.bdrv_co_create implementations generally open new nodes). Therefore,
the assertion that we're not in a coroutine doesn't hold true any more.
We could just remove the assertion because there is nothing in the
function that should be in conflict with running in a coroutine, but
just to be on the safe side, we can reverse the caller relationship
between bdrv_do_drained_begin() and bdrv_do_drained_begin_quiesce() so
that the latter also just drops out of coroutine context and we can
still be certain in the future that any drain code doesn't run in
coroutines.
As a nice side effect, the structure of bdrv_do_drained_begin() is now
symmetrical with bdrv_do_drained_end().
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20221118174110.55183-14-kwolf@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
ignore_bds_parents is now ignored during drain_begin and drain_end, so
we can just remove it there. It is still a valid optimisation for
drain_all in bdrv_drained_poll(), so leave it around there.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20221118174110.55183-13-kwolf@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
We only need to call both the BlockDriver's callback and the parent
callbacks when going from undrained to drained or vice versa. A second
drain section doesn't make a difference for the driver or the parent,
they weren't supposed to send new requests before and after the second
drain.
One thing that gets in the way is the 'ignore_bds_parents' parameter in
bdrv_do_drained_begin_quiesce() and bdrv_do_drained_end(): It means that
bdrv_drain_all_begin() increases bs->quiesce_counter, but does not
quiesce the parent through BdrvChildClass callbacks. If an additional
drain section is started now, bs->quiesce_counter will be non-zero, but
we would still need to quiesce the parent through BdrvChildClass in
order to keep things consistent (and unquiesce it on the matching
bdrv_drained_end(), even though the counter would not reach 0 yet as
long as the bdrv_drain_all() section is still active).
Instead of keeping track of this, let's just get rid of the parameter.
It was introduced in commit 6cd5c9d7b2 as an optimisation so that
during bdrv_drain_all(), we wouldn't recursively drain all parents up to
the root for each node, resulting in quadratic complexity. As it happens,
calling the callbacks only once solves the same problem, so as of this
patch, we'll still have O(n) complexity and ignore_bds_parents is not
needed any more.
This patch only ignores the 'ignore_bds_parents' parameter. It will be
removed in a separate patch.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20221118174110.55183-12-kwolf@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Subtree drains are not used any more. Remove them.
After this, BdrvChildClass.attach/detach() don't poll any more.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20221118174110.55183-11-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
bdrv_drain_invoke() has now two entirely separate cases that share no
code any more and are selected depending on a bool parameter. Each case
has only one caller. Just inline the function.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20221118174110.55183-6-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
drained_end_counter is unused now, nobody changes its value any more. It
can be removed.
In cases where we had two almost identical functions that only differed
in whether the caller passes drained_end_counter, or whether they would
poll for a local drained_end_counter to reach 0, these become a single
function.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20221118174110.55183-5-kwolf@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Polling during bdrv_drained_end() can be problematic (and in the future,
we may get cases for bdrv_drained_begin() where polling is forbidden,
and we don't care about already in-flight requests, but just want to
prevent new requests from arriving).
The .bdrv_drained_begin/end callbacks running in a coroutine is the only
reason why we have to do this polling, so make them non-coroutine
callbacks again. None of the callers actually yield any more.
This means that bdrv_drained_end() effectively doesn't poll any more,
even if AIO_WAIT_WHILE() loops are still there (their condition is false
from the beginning). This is generally not a problem, but in
test-bdrv-drain, some additional explicit aio_poll() calls need to be
added because the test case wants to verify the final state after BHs
have executed.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20221118174110.55183-4-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
bdrv_parent_drained_{begin,end}_single() are supposed to operate on the
parent, not on the child, so they should not attempt to get the context
to poll from the child but the parent instead. BDRV_POLL_WHILE(c->bs)
does get the context from the child, so we should replace it with
AIO_WAIT_WHILE() on the parent's context instead.
This problem becomes apparent when bdrv_replace_child_noperm() invokes
bdrv_parent_drained_end_single() after removing a child from a subgraph
that is in an I/O thread. By the time bdrv_parent_drained_end_single()
is called, child->bs is NULL, and so BDRV_POLL_WHILE(c->bs, ...) will
poll the main loop instead of the I/O thread; but anything that
bdrv_parent_drained_end_single_no_poll() may have scheduled is going to
want to run in the I/O thread, but because we poll the main loop, the
I/O thread is never unpaused, and nothing is run, resulting in a
deadlock.
Closes: https://gitlab.com/qemu-project/qemu/-/issues/1215
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20221107151321.211175-4-hreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-16-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20221013123711.620631-3-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Registering an I/O buffer is only a performance optimization hint but it
is still necessary to return errors when it fails.
Later patches will need to detect errors when registering buffers but an
immediate advantage is that error_report() calls are no longer needed in
block driver .bdrv_register_buf() functions.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20221013185908.1297568-8-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Block drivers may optimize I/O requests accessing buffers previously
registered with bdrv_register_buf(). Checking whether all elements of a
request's QEMUIOVector are within previously registered buffers is
expensive, so we need a hint from the user to avoid costly checks.
Add a BDRV_REQ_REGISTERED_BUF request flag to indicate that all
QEMUIOVector elements in an I/O request are known to be within
previously registered buffers.
Always pass the flag through to driver read/write functions. There is
little harm in passing the flag to a driver that does not use it.
Passing the flag to drivers avoids changes across many block drivers.
Filter drivers would need to explicitly support the flag and pass
through to their children when the children support it. That's a lot of
code changes and it's hard to remember to do that everywhere, leading to
silent reduced performance when the flag is accidentally dropped.
The only problematic scenario with the approach in this patch is when a
driver passes the flag through to internal I/O requests that don't use
the same I/O buffer. In that case the hint may be set when it should
actually be clear. This is a rare case though so the risk is low.
Some drivers have assert(!flags), which no longer works when
BDRV_REQ_REGISTERED_BUF is passed in. These assertions aren't very
useful anyway since the functions are called almost exclusively by
bdrv_driver_preadv/pwritev() so if we get flags handling right there
then the assertion is not needed.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20221013185908.1297568-7-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
The only implementor of bdrv_register_buf() is block/nvme.c, where the
size is not needed when unregistering a buffer. This is because
util/vfio-helpers.c can look up mappings by address.
Future block drivers that implement bdrv_register_buf() may not be able
to do their job given only the buffer address. Add a size argument to
bdrv_unregister_buf().
Also document the assumptions about
bdrv_register_buf()/bdrv_unregister_buf() calls. The same <host, size>
values that were given to bdrv_register_buf() must be given to
bdrv_unregister_buf().
gcc 11.2.1 emits a spurious warning that img_bench()'s buf_size local
variable might be uninitialized, so it's necessary to silence the
compiler.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Message-id: 20221013185908.1297568-5-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Callers of coroutine_fn must be coroutine_fn themselves, or the call
must be within "if (qemu_in_coroutine())". Apply coroutine_fn to
functions where this holds.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220922084924.201610-3-pbonzini@redhat.com>
[kwolf: Fixed up coding style]
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
There is only user of bdrv_qiov_is_aligned(), so move the alignment
function to there and make it static.
Signed-off-by: Keith Busch <kbusch@kernel.org>
Message-Id: <20220929200523.3218710-2-kbusch@meta.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Return codes of the following functions are never used in the code:
* bdrv_wait_serialising_requests_locked
* bdrv_wait_serialising_requests
* bdrv_make_request_serialising
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Kevin Wolf <kwolf@redhat.com>
CC: Hanna Reitz <hreitz@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Fam Zheng <fam@euphon.net>
CC: Ronnie Sahlberg <ronniesahlberg@gmail.com>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Peter Lieven <pl@kamp.de>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-Id: <20220817083736.40981-3-den@openvz.org>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Also convert bdrv_pwrite_sync() to being implemented using
generated_co_wrapper.
Signed-off-by: Alberto Faria <afaria@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20220609152744.3891847-9-afaria@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
bdrv_{pread,pwrite}() now return -EIO instead of -EINVAL when 'bytes' is
negative, making them consistent with bdrv_{preadv,pwritev}() and
bdrv_co_{pread,pwrite,preadv,pwritev}().
bdrv_pwrite_zeroes() now also calls trace_bdrv_co_pwrite_zeroes() and
clears the BDRV_REQ_MAY_UNMAP flag when appropriate, which it didn't
previously.
Signed-off-by: Alberto Faria <afaria@redhat.com>
Message-Id: <20220609152744.3891847-8-afaria@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
They currently return the value of their 'bytes' parameter on success.
Make them return 0 instead, for consistency with other I/O functions and
in preparation to implement them using generated_co_wrapper. This also
makes it clear that short reads/writes are not possible.
The few callers that rely on the previous behavior are adjusted
accordingly by hand.
Signed-off-by: Alberto Faria <afaria@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20220609152744.3891847-4-afaria@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
bdrv_co_drain() has not been used since commit 9a0cec664e ("mirror:
use bdrv_drained_begin/bdrv_drained_end") in 2016. Remove it so there
are fewer drain scenarios to worry about.
Use bdrv_drained_begin()/bdrv_drained_end() instead. They are "mixed"
functions that can be called from coroutine context. Unlike
bdrv_co_drain(), these functions provide control of the length of the
drained section, which is usually the right thing.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20220521122714.3837731-1-stefanha@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Alberto Faria <afaria@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
qemu_co_queue_restart_all is basically the same as qemu_co_enter_all
but without a QemuLockable argument. That's perfectly fine, but only as
long as the function is marked coroutine_fn. If used outside coroutine
context, qemu_co_queue_wait will attempt to take the lock and that
is just broken: if you are calling qemu_co_queue_restart_all outside
coroutine context, the lock is going to be a QemuMutex which cannot be
taken twice by the same thread.
The patch adds the marker to qemu_co_queue_restart_all and to its sole
non-coroutine_fn caller; it then reimplements the function in terms of
qemu_co_enter_all_impl, to remove duplicated code and to clarify that the
latter also works in coroutine context.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20220427130830.150180-4-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Replace the global variables with inlined helper functions. getpagesize() is very
likely annotated with a "const" function attribute (at least with glibc), and thus
optimization should apply even better.
This avoids the need for a constructor initialization too.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20220323155743.1585078-12-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
* cleanups of qemu_oom_check() and qemu_memalign()
* target/arm/translate-neon: UNDEF if VLD1/VST1 stride bits are non-zero
* target/arm/translate-neon: Simplify align field check for VLD3
* GICv3 ITS: add more trace events
* GICv3 ITS: implement 8-byte accesses properly
* GICv3: fix minor issues with some trace/log messages
* ui/cocoa: Use the standard about panel
* target/arm: Provide cpu property for controling FEAT_LPA2
* hw/arm/virt: Disable LPA2 for -machine virt-6.2
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Merge remote-tracking branch 'remotes/pmaydell/tags/pull-target-arm-20220307' into staging
target-arm queue:
* cleanups of qemu_oom_check() and qemu_memalign()
* target/arm/translate-neon: UNDEF if VLD1/VST1 stride bits are non-zero
* target/arm/translate-neon: Simplify align field check for VLD3
* GICv3 ITS: add more trace events
* GICv3 ITS: implement 8-byte accesses properly
* GICv3: fix minor issues with some trace/log messages
* ui/cocoa: Use the standard about panel
* target/arm: Provide cpu property for controling FEAT_LPA2
* hw/arm/virt: Disable LPA2 for -machine virt-6.2
# gpg: Signature made Mon 07 Mar 2022 16:46:06 GMT
# gpg: using RSA key E1A5C593CD419DE28E8315CF3C2525ED14360CDE
# gpg: issuer "peter.maydell@linaro.org"
# gpg: Good signature from "Peter Maydell <peter.maydell@linaro.org>" [ultimate]
# gpg: aka "Peter Maydell <pmaydell@gmail.com>" [ultimate]
# gpg: aka "Peter Maydell <pmaydell@chiark.greenend.org.uk>" [ultimate]
# Primary key fingerprint: E1A5 C593 CD41 9DE2 8E83 15CF 3C25 25ED 1436 0CDE
* remotes/pmaydell/tags/pull-target-arm-20220307:
hw/arm/virt: Disable LPA2 for -machine virt-6.2
target/arm: Provide cpu property for controling FEAT_LPA2
ui/cocoa: Use the standard about panel
hw/intc/arm_gicv3_cpuif: Fix register names in ICV_HPPIR read trace event
hw/intc/arm_gicv3: Fix missing spaces in error log messages
hw/intc/arm_gicv3: Specify valid and impl in MemoryRegionOps
hw/intc/arm_gicv3_its: Add trace events for table reads and writes
hw/intc/arm_gicv3_its: Add trace events for commands
target/arm/translate-neon: Simplify align field check for VLD3
target/arm/translate-neon: UNDEF if VLD1/VST1 stride bits are non-zero
osdep: Move memalign-related functions to their own header
util: Put qemu_vfree() in memalign.c
util: Use meson checks for valloc() and memalign() presence
util: Share qemu_try_memalign() implementation between POSIX and Windows
meson.build: Don't misdetect posix_memalign() on Windows
util: Return valid allocation for qemu_try_memalign() with zero size
util: Unify implementations of qemu_memalign()
util: Make qemu_oom_check() a static function
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Move the various memalign-related functions out of osdep.h and into
their own header, which we include only where they are used.
While we're doing this, add some brief documentation comments.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20220226180723.1706285-10-peter.maydell@linaro.org
Add new block driver handlers and corresponding generic wrappers.
It will be used to allow copy-before-write filter to provide
reach fleecing interface in further commit.
In future this approach may be used to allow reading qcow2 internal
snapshots, for example to export them through NBD.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220303194349.2304213-11-vsementsov@virtuozzo.com>
[hreitz: Rebased on block GS/IO split]
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
There is a bug in handling BDRV_REQ_NO_WAIT flag: we still may wait in
wait_serialising_requests() if request is unaligned. And this is
possible for the only user of this flag (preallocate filter) if
underlying file is unaligned to its request_alignment on start.
So, we have to fix preallocate filter to do only aligned preallocate
requests.
Next, we should fix generic block/io.c somehow. Keeping in mind that
preallocate is the only user of BDRV_REQ_NO_WAIT and that we have to
fix its behavior now, it seems more safe to just assert that we never
use BDRV_REQ_NO_WAIT with unaligned requests and add corresponding
comment. Let's do so.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Denis V. Lunev <den@openvz.org>
Message-Id: <20220215121609.38570-1-vsementsov@virtuozzo.com>
[hreitz: Rebased on block GS/IO split]
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
bdrv_refresh_limits() recurses down to the node's children. That does
not seem necessary: When we refresh limits on some node, and then
recurse down and were to change one of its children's BlockLimits, then
that would mean we noticed the changed limits by pure chance. The fact
that we refresh the parent's limits has nothing to do with it, so the
reason for the change probably happened before this point in time, and
we should have refreshed the limits then.
Consequently, we should actually propagate block limits changes upwards,
not downwards. That is a separate and pre-existing issue, though, and
so will not be addressed in this patch.
The problem with recursing is that bdrv_refresh_limits() is not atomic.
It begins with zeroing BDS.bl, and only then sets proper, valid limits.
If we do not drain all nodes whose limits are refreshed, then concurrent
I/O requests can encounter invalid request_alignment values and crash
qemu. Therefore, a recursing bdrv_refresh_limits() requires the whole
subtree to be drained, which is currently not ensured by most callers.
A non-recursive bdrv_refresh_limits() only requires the node in question
to not receive I/O requests, and this is done by most callers in some
way or another:
- bdrv_open_driver() deals with a new node with no parents yet
- bdrv_set_file_or_backing_noperm() acts on a drained node
- bdrv_reopen_commit() acts only on drained nodes
- bdrv_append() should in theory require the node to be drained; in
practice most callers just lock the AioContext, which should at least
be enough to prevent concurrent I/O requests from accessing invalid
limits
So we can resolve the bug by making bdrv_refresh_limits() non-recursive.
Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1879437
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20220216105355.30729-2-hreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
block coroutines functions run in different aiocontext, and are
not protected by the BQL. Therefore are I/O.
On the other side, generated_co_wrapper functions use BDRV_POLL_WHILE,
meaning the caller can either be the main loop or a specific iothread.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-25-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Mark all I/O functions with IO_CODE, and all "I/O OR GS" with
IO_OR_GS_CODE.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-14-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-13-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Mark all I/O functions with IO_CODE, and all "I/O OR GS" with
IO_OR_GS_CODE.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-6-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
All the global state (GS) API functions will check that
qemu_in_main_thread() returns true. If not, it means
that the safety of BQL cannot be guaranteed, and
they need to be moved to I/O.
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20220303151616.325444-5-eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
We update the block-status cache whenever we get new information from a
bdrv_co_block_status() call to the block driver. However, if we have
passed want_zero=false to that call, it may flag areas containing zeroes
as data, and so we would update the block-status cache with wrong
information.
Therefore, we should not update the cache with want_zero=false.
Reported-by: Nir Soffer <nsoffer@redhat.com>
Fixes: 0bc329fbb0 ("block: block-status cache for data regions")
Reviewed-by: Nir Soffer <nsoffer@redhat.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20220118170000.49423-2-hreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Linux limits the size of iovecs to 1024 (UIO_MAXIOV in the kernel
sources, IOV_MAX in POSIX). Because of this, on some host adapters
requests with many iovecs are rejected with -EINVAL by the
io_submit() or readv()/writev() system calls.
In fact, the same limit applies to SG_IO as well. To fix both the
EINVAL and the possible performance issues from using fewer iovecs
than allowed by Linux (some HBAs have max_segments as low as 128),
introduce a separate entry in BlockLimits to hold the max_segments
value from sysfs. This new limit is used only for SG_IO and clamped
to bs->bl.max_iov anyway, just like max_hw_transfer is clamped to
bs->bl.max_transfer.
Reported-by: Halil Pasic <pasic@linux.ibm.com>
Cc: Hanna Reitz <hreitz@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: qemu-block@nongnu.org
Cc: qemu-stable@nongnu.org
Fixes: 18473467d5 ("file-posix: try BLKSECTGET on block devices too, do not round to power of 2", 2021-06-25)
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210923130436.1187591-1-pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Now that all drivers are updated by the previous commit, we can drop
the last limiter on pdiscard path: INT_MAX in bdrv_co_pdiscard().
Now everything is prepared for implementing incredibly cool and fast
big-discard requests in NBD and qcow2. And any other driver which wants
it of course.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210903102807.27127-12-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
We are going to support 64 bit discard requests. Now update the
limit variable. It's absolutely safe. The variable is set in some
drivers, and used in bdrv_co_pdiscard().
Update also max_pdiscard variable in bdrv_co_pdiscard(), so that
bdrv_co_pdiscard() is now prepared for 64bit requests. The remaining
logic including num, offset and bytes variables is already
supporting 64bit requests.
So the only thing that prevents 64 bit requests is limiting
max_pdiscard variable to INT_MAX in bdrv_co_pdiscard().
We'll drop this limitation after updating all block drivers.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210903102807.27127-10-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Now that all drivers are updated by previous commit, we can drop two
last limiters on write-zeroes path: INT_MAX in
bdrv_co_do_pwrite_zeroes() and bdrv_check_request32() in
bdrv_co_pwritev_part().
Now everything is prepared for implementing incredibly cool and fast
big-write-zeroes in NBD and qcow2. And any other driver which wants it
of course.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210903102807.27127-9-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
We are going to support 64 bit write-zeroes requests. Now update the
limit variable. It's absolutely safe. The variable is set in some
drivers, and used in bdrv_co_do_pwrite_zeroes().
Update also max_write_zeroes variable in bdrv_co_do_pwrite_zeroes(), so
that bdrv_co_do_pwrite_zeroes() is now prepared to 64bit requests. The
remaining logic including num, offset and bytes variables is already
supporting 64bit requests.
So the only thing that prevents 64 bit requests is limiting
max_write_zeroes variable to INT_MAX in bdrv_co_do_pwrite_zeroes().
We'll drop this limitation after updating all block drivers.
Ah, we also have bdrv_check_request32() in bdrv_co_pwritev_part(). It
will be modified to do bdrv_check_request() for write-zeroes path.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210903102807.27127-7-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
We are generally moving to int64_t for both offset and bytes parameters
on all io paths.
Main motivation is realization of 64-bit write_zeroes operation for
fast zeroing large disk chunks, up to the whole disk.
We chose signed type, to be consistent with off_t (which is signed) and
with possibility for signed return type (where negative value means
error).
So, convert driver write handlers parameters which are already 64bit to
signed type.
While being here, convert also flags parameter to be BdrvRequestFlags.
Now let's consider all callers. Simple
git grep '\->bdrv_\(aio\|co\)_pwritev\(_part\)\?'
shows that's there three callers of driver function:
bdrv_driver_pwritev() and bdrv_driver_pwritev_compressed() in
block/io.c, both pass int64_t, checked by bdrv_check_qiov_request() to
be non-negative.
qcow2_save_vmstate() does bdrv_check_qiov_request().
Still, the functions may be called directly, not only by drv->...
Let's check:
git grep '\.bdrv_\(aio\|co\)_pwritev\(_part\)\?\s*=' | \
awk '{print $4}' | sed 's/,//' | sed 's/&//' | sort | uniq | \
while read func; do git grep "$func(" | \
grep -v "$func(BlockDriverState"; done
shows several callers:
qcow2:
qcow2_co_truncate() write at most up to @offset, which is checked in
generic qcow2_co_truncate() by bdrv_check_request().
qcow2_co_pwritev_compressed_task() pass the request (or part of the
request) that already went through normal write path, so it should
be OK
qcow:
qcow_co_pwritev_compressed() pass int64_t, it's updated by this patch
quorum:
quorum_co_pwrite_zeroes() pass int64_t and int - OK
throttle:
throttle_co_pwritev_compressed() pass int64_t, it's updated by this
patch
vmdk:
vmdk_co_pwritev_compressed() pass int64_t, it's updated by this
patch
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210903102807.27127-5-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
We modify the request by adding an offset to vmstate. Let's check the
modified request. It will help us to safely move .bdrv_co_preadv_part
and .bdrv_co_pwritev_part to int64_t type of offset and bytes.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210903102807.27127-3-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Only qcow2 driver supports vmstate.
In qcow2 these requests go through .bdrv_co_p{read,write}v_part
handlers.
So, let's do our basic check for the request on vmstate generic
handlers.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210903102807.27127-2-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
As we have attempted before
(https://lists.gnu.org/archive/html/qemu-devel/2019-01/msg06451.html,
"file-posix: Cache lseek result for data regions";
https://lists.nongnu.org/archive/html/qemu-block/2021-02/msg00934.html,
"file-posix: Cache next hole"), this patch seeks to reduce the number of
SEEK_DATA/HOLE operations the file-posix driver has to perform. The
main difference is that this time it is implemented as part of the
general block layer code.
The problem we face is that on some filesystems or in some
circumstances, SEEK_DATA/HOLE is unreasonably slow. Given the
implementation is outside of qemu, there is little we can do about its
performance.
We have already introduced the want_zero parameter to
bdrv_co_block_status() to reduce the number of SEEK_DATA/HOLE calls
unless we really want zero information; but sometimes we do want that
information, because for files that consist largely of zero areas,
special-casing those areas can give large performance boosts. So the
real problem is with files that consist largely of data, so that
inquiring the block status does not gain us much performance, but where
such an inquiry itself takes a lot of time.
To address this, we want to cache data regions. Most of the time, when
bad performance is reported, it is in places where the image is iterated
over from start to end (qemu-img convert or the mirror job), so a simple
yet effective solution is to cache only the current data region.
(Note that only caching data regions but not zero regions means that
returning false information from the cache is not catastrophic: Treating
zeroes as data is fine. While we try to invalidate the cache on zero
writes and discards, such incongruences may still occur when there are
other processes writing to the image.)
We only use the cache for nodes without children (i.e. protocol nodes),
because that is where the problem is: Drivers that rely on block-status
implementations outside of qemu (e.g. SEEK_DATA/HOLE).
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/307
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210812084148.14458-3-hreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
[hreitz: Added `local_file == bs` assertion, as suggested by Vladimir]
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
When bdrv_pad_request() fails in bdrv_co_preadv_part(), bs->in_flight
has been increased, but is never decreased again. This leads to a hang
when trying to drain the block node.
This bug was observed with Windows guests which issue a request that
fully uses IOV_MAX during installation, so that when padding is
necessary (O_DIRECT with a 4k sector size block device on the host),
adding another entry causes failure.
Call bdrv_dec_in_flight() to fix this. There is a larger problem to
solve here because this request shouldn't even fail, but Windows doesn't
seem to care and with this minimal fix the installation succeeds. So
given that we're already in freeze, let's take this minimal fix for 6.1.
Fixes: 98ca45494f
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1972079
Reported-by: Qing Wang <qinwang@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210727154923.91067-1-kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Kevin Wolf
Emanuele Giuseppe Esposito
Hanna Reitz
Stefan Hajnoczi
Alberto Faria
Paolo Bonzini
Keith Busch
Denis V. Lunev
Marc-André Lureau
Peter Maydell
Vladimir Sementsov-Ogievskiy