block: remove AioContext locking

This is the big patch that removes
aio_context_acquire()/aio_context_release() from the block layer and
affected block layer users.

There isn't a clean way to split

block: remove AioContext locking

This is the big patch that removes
aio_context_acquire()/aio_context_release() from the block layer and
affected block layer users.

There isn't a clean way to split this patch and the reviewers are likely
the same group of people, so I decided to do it in one patch.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Message-ID: <20231205182011.1976568-7-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

graph-lock: remove AioContext locking

Stop acquiring/releasing the AioContext lock in
bdrv_graph_wrlock()/bdrv_graph_unlock() since the lock no longer has any
effect.

The distinction between bdrv_g

graph-lock: remove AioContext locking

Stop acquiring/releasing the AioContext lock in
bdrv_graph_wrlock()/bdrv_graph_unlock() since the lock no longer has any
effect.

The distinction between bdrv_graph_wrunlock() and
bdrv_graph_wrunlock_ctx() becomes meaningless and they can be collapsed
into one function.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231205182011.1976568-6-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

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block: Fix deadlocks in bdrv_graph_wrunlock()

bdrv_graph_wrunlock() calls aio_poll(), which may run callbacks that
have a nested event loop. Nested event loops can depend on other
iothreads making p

block: Fix deadlocks in bdrv_graph_wrunlock()

bdrv_graph_wrunlock() calls aio_poll(), which may run callbacks that
have a nested event loop. Nested event loops can depend on other
iothreads making progress, so in order to allow them to make progress it
must not hold the AioContext lock of another thread while calling
aio_poll().

This introduces a @bs parameter to bdrv_graph_wrunlock() whose
AioContext is temporarily dropped (which matches bdrv_graph_wrlock()),
and a bdrv_graph_wrunlock_ctx() that can be used if the BlockDriverState
doesn't necessarily exist any more when unlocking.

This also requires a change to bdrv_schedule_unref(), which was relying
on the incorrectly taken lock. It needs to take the lock itself now.
While this is a separate bug, it can't be fixed a separate patch because
otherwise the intermediate state would either deadlock or try to release
a lock that we don't even hold.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231115172012.112727-3-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
[kwolf: Fixed up bdrv_schedule_unref()]
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

block: Mark block_job_add_bdrv() GRAPH_WRLOCK

Instead of taking the writer lock internally, require callers to already
hold it when calling block_job_add_bdrv(). These callers will typically
already

block: Mark block_job_add_bdrv() GRAPH_WRLOCK

Instead of taking the writer lock internally, require callers to already
hold it when calling block_job_add_bdrv(). These callers will typically
already hold the graph lock once the locking work is completed, which
means that they can't call functions that take it internally.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231027155333.420094-6-kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

block: Mark bdrv_root_attach_child() GRAPH_WRLOCK

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_root_attach_child(). These callers will
typically

block: Mark bdrv_root_attach_child() GRAPH_WRLOCK

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_root_attach_child(). These callers will
typically already hold the graph lock once the locking work is
completed, which means that they can't call functions that take it
internally.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231027155333.420094-5-kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

block: Mark block_job_add_bdrv() GRAPH_WRLOCK

Instead of taking the writer lock internally, require callers to already
hold it when calling block_job_add_bdrv(). These callers will typically
already

block: Mark block_job_add_bdrv() GRAPH_WRLOCK

Instead of taking the writer lock internally, require callers to already
hold it when calling block_job_add_bdrv(). These callers will typically
already hold the graph lock once the locking work is completed, which
means that they can't call functions that take it internally.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231027155333.420094-6-kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

block: Mark bdrv_root_attach_child() GRAPH_WRLOCK

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_root_attach_child(). These callers will
typically

block: Mark bdrv_root_attach_child() GRAPH_WRLOCK

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_root_attach_child(). These callers will
typically already hold the graph lock once the locking work is
completed, which means that they can't call functions that take it
internally.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231027155333.420094-5-kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

blockjob: query driver-specific info via a new 'query' driver method

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Message-ID: <20231031135431.393137-9-f.ebner@proxmox.com>
Reviewed-by: Kevin Wol

blockjob: query driver-specific info via a new 'query' driver method

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Message-ID: <20231031135431.393137-9-f.ebner@proxmox.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

qapi/block-core: use JobType for BlockJobInfo's type

In preparation to turn BlockJobInfo into a union with @type as the
discriminator. That requires it to be an enum. Even without that
requirement,

qapi/block-core: use JobType for BlockJobInfo's type

In preparation to turn BlockJobInfo into a union with @type as the
discriminator. That requires it to be an enum. Even without that
requirement, it's nicer to have an enum instead of a str here.

No functional change is intended.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20231031135431.393137-7-f.ebner@proxmox.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

blockjob: introduce block-job-change QMP command

which will allow changing job-type-specific options after job
creation.

In the JobVerbTable, the same allow bits as for set-speed are used,
because

blockjob: introduce block-job-change QMP command

which will allow changing job-type-specific options after job
creation.

In the JobVerbTable, the same allow bits as for set-speed are used,
because set-speed can be considered an existing change command.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20231031135431.393137-2-f.ebner@proxmox.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

blockjob: drop AioContext lock before calling bdrv_graph_wrlock()

Same rationale as in 31b2ddfea3 ("graph-lock: Unlock the AioContext
while polling"). Otherwise, a deadlock can happen.

The alternat

blockjob: drop AioContext lock before calling bdrv_graph_wrlock()

Same rationale as in 31b2ddfea3 ("graph-lock: Unlock the AioContext
while polling"). Otherwise, a deadlock can happen.

The alternative would be to pass a BlockDriverState along to
bdrv_graph_wrlock(), but there is no BlockDriverState readily
available and it's also better conceptually, because the lock is held
for the job.

The function is always called with the job's AioContext lock held, via
one of the .abort, .clean, .free or .prepare job driver functions.
Thus, it's safe to drop it.

While mirror_exit_common() does hold a second AioContext lock while
calling block_job_remove_all_bdrv(), that is for the main thread's
AioContext and does not need to be dropped (bdrv_graph_wrlock(bs) also
skips dropping the lock if bdrv_get_aio_context(bs) ==
qemu_get_aio_context()).

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Message-ID: <20231019131936.414246-2-f.ebner@proxmox.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

blockjob: query driver-specific info via a new 'query' driver method

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Message-ID: <20231031135431.393137-9-f.ebner@proxmox.com>
Reviewed-by: Kevin Wol

blockjob: query driver-specific info via a new 'query' driver method

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Message-ID: <20231031135431.393137-9-f.ebner@proxmox.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

qapi/block-core: use JobType for BlockJobInfo's type

In preparation to turn BlockJobInfo into a union with @type as the
discriminator. That requires it to be an enum. Even without that
requirement,

qapi/block-core: use JobType for BlockJobInfo's type

In preparation to turn BlockJobInfo into a union with @type as the
discriminator. That requires it to be an enum. Even without that
requirement, it's nicer to have an enum instead of a str here.

No functional change is intended.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20231031135431.393137-7-f.ebner@proxmox.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

blockjob: introduce block-job-change QMP command

which will allow changing job-type-specific options after job
creation.

In the JobVerbTable, the same allow bits as for set-speed are used,
because

blockjob: introduce block-job-change QMP command

which will allow changing job-type-specific options after job
creation.

In the JobVerbTable, the same allow bits as for set-speed are used,
because set-speed can be considered an existing change command.

Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20231031135431.393137-2-f.ebner@proxmox.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

blockjob: drop AioContext lock before calling bdrv_graph_wrlock()

Same rationale as in 31b2ddfea3 ("graph-lock: Unlock the AioContext
while polling"). Otherwise, a deadlock can happen.

The alternat

blockjob: drop AioContext lock before calling bdrv_graph_wrlock()

Same rationale as in 31b2ddfea3 ("graph-lock: Unlock the AioContext
while polling"). Otherwise, a deadlock can happen.

The alternative would be to pass a BlockDriverState along to
bdrv_graph_wrlock(), but there is no BlockDriverState readily
available and it's also better conceptually, because the lock is held
for the job.

The function is always called with the job's AioContext lock held, via
one of the .abort, .clean, .free or .prepare job driver functions.
Thus, it's safe to drop it.

While mirror_exit_common() does hold a second AioContext lock while
calling block_job_remove_all_bdrv(), that is for the main thread's
AioContext and does not need to be dropped (bdrv_graph_wrlock(bs) also
skips dropping the lock if bdrv_get_aio_context(bs) ==
qemu_get_aio_context()).

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Message-ID: <20231019131936.414246-2-f.ebner@proxmox.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

block: Mark bdrv_get_parent_name() and callers GRAPH_RDLOCK

This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_get_parent_name() need to hold a reader lock for the graph
because it a

block: Mark bdrv_get_parent_name() and callers GRAPH_RDLOCK

This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_get_parent_name() need to hold a reader lock for the graph
because it accesses the parents list of a node.

For some places, we know that they will hold the lock, but we don't have
the GRAPH_RDLOCK annotations yet. In this case, add assume_graph_lock()
with a FIXME comment. These places will be removed once everything is
properly annotated.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20230929145157.45443-13-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

block: Mark bdrv_get_parent_name() and callers GRAPH_RDLOCK

This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_get_parent_name() need to hold a reader lock for the graph
because it a

block: Mark bdrv_get_parent_name() and callers GRAPH_RDLOCK

This adds GRAPH_RDLOCK annotations to declare that callers of
bdrv_get_parent_name() need to hold a reader lock for the graph
because it accesses the parents list of a node.

For some places, we know that they will hold the lock, but we don't have
the GRAPH_RDLOCK annotations yet. In this case, add assume_graph_lock()
with a FIXME comment. These places will be removed once everything is
properly annotated.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20230929145157.45443-13-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

block: Mark bdrv_root_unref_child() GRAPH_WRLOCK

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_root_unref_child(). These callers will
typically a

block: Mark bdrv_root_unref_child() GRAPH_WRLOCK

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_root_unref_child(). These callers will
typically already hold the graph lock once the locking work is
completed, which means that they can't call functions that take it
internally.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-20-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

block: Mark bdrv_root_unref_child() GRAPH_WRLOCK

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_root_unref_child(). These callers will
typically a

block: Mark bdrv_root_unref_child() GRAPH_WRLOCK

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_root_unref_child(). These callers will
typically already hold the graph lock once the locking work is
completed, which means that they can't call functions that take it
internally.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-20-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

block: Mark bdrv_root_unref_child() GRAPH_WRLOCK

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_root_unref_child(). These callers will
typically a

block: Mark bdrv_root_unref_child() GRAPH_WRLOCK

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_root_unref_child(). These callers will
typically already hold the graph lock once the locking work is
completed, which means that they can't call functions that take it
internally.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-20-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

block: Mark bdrv_root_unref_child() GRAPH_WRLOCK

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_root_unref_child(). These callers will
typically a

block: Mark bdrv_root_unref_child() GRAPH_WRLOCK

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_root_unref_child(). These callers will
typically already hold the graph lock once the locking work is
completed, which means that they can't call functions that take it
internally.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-20-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

block: Mark bdrv_root_unref_child() GRAPH_WRLOCK

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_root_unref_child(). These callers will
typically a

block: Mark bdrv_root_unref_child() GRAPH_WRLOCK

Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_root_unref_child(). These callers will
typically already hold the graph lock once the locking work is
completed, which means that they can't call functions that take it
internally.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-20-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

blockjob: Fix AioContext locking in block_job_add_bdrv()

bdrv_root_attach_child() requires callers to hold the AioContext lock
for child_bs. Take it in block_job_add_bdrv() before calling the
functi

blockjob: Fix AioContext locking in block_job_add_bdrv()

bdrv_root_attach_child() requires callers to hold the AioContext lock
for child_bs. Take it in block_job_add_bdrv() before calling the
function.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20230605085711.21261-10-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

blockjob: Fix AioContext locking in block_job_add_bdrv()

bdrv_root_attach_child() requires callers to hold the AioContext lock
for child_bs. Take it in block_job_add_bdrv() before calling the
functi

blockjob: Fix AioContext locking in block_job_add_bdrv()

bdrv_root_attach_child() requires callers to hold the AioContext lock
for child_bs. Take it in block_job_add_bdrv() before calling the
function.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20230605085711.21261-10-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...

blockjob: Adhere to rate limit even when reentered early

When jobs are sleeping, for example to enforce a given rate limit, they
can be reentered early, in particular in order to get paused, to upda

blockjob: Adhere to rate limit even when reentered early

When jobs are sleeping, for example to enforce a given rate limit, they
can be reentered early, in particular in order to get paused, to update
the rate limit or to get cancelled.

Before this patch, they behave in this case as if they had fully
completed their rate limiting delay. This means that requests are sped
up beyond their limit, violating the constraints that the user gave us.

Change the block jobs to sleep in a loop until the necessary delay is
completed, while still allowing cancelling them immediately as well
pausing (handled by the pause point in job_sleep_ns()) and updating the
rate limit.

This change is also motivated by iotests cases being prone to fail
because drain operations pause and unpause them so often that block jobs
complete earlier than they are supposed to. In particular, the next
commit would fail iotests 030 without this change.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230510203601.418015-8-kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

show more ...