By adding acquire/release pairs, we ensure that .ret and .error_is_read
fields are written by block_copy_dirty_clusters before .finished is true,
and that they are read by API user after .finished is true.

The atomic here are necessary because the fields are concurrently modified
in coroutines, and read outside.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20210624072043.180494-6-eesposit@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Group various structures fields, to better understand what we need to
protect with a lock and what doesn't need it.
Then, add a CoMutex to protect concurrent access of block-copy
data structures. This mutex also protects .copy_bitmap, because its thread-safe
API does not prevent it from assigning two tasks to the same
bitmap region.

Exceptions to the lock:
- .sleep_state is handled in the series "coroutine: new sleep/wake API"
and thus here left as TODO.

- .finished, .cancelled and reads to .ret and .error_is_read will be
protected in the following patch, because are used also outside
coroutines.

- .skip_unallocated is atomic. Including it under the mutex would
increase the critical sections and make them also much more complex.
We can have it as atomic since it is only written from outside and
read by block-copy coroutines.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20210624072043.180494-5-eesposit@redhat.com>
  [vsementsov: fix typo in comment]
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Moving this function in task_end ensures to update the progress
anyways, even if there is an error.

It also helps in next patch, allowing task_end to have only
one critical section.

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20210624072043.180494-4-eesposit@redhat.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Put the logic to determine the copy size in a separate function, so
that there is a simple state machine for the possible methods of
copying data from one BlockDriverState to the other.

Use .method instead of .copy_range as in-out argument, and
include also .zeroes as an additional copy method.

While at it, store the common computation of block_copy_max_transfer
into a new field of BlockCopyState, and make sure that we always
obey max_transfer; that's more efficient even for the
COPY_RANGE_READ_WRITE case.

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210624072043.180494-3-eesposit@redhat.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Use a local variable instead of referencing BlockCopyState through a
BlockCopyCallState or BlockCopyTask every time.
This is in preparation for next patches.

No functional change intended.

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20210624072043.180494-2-eesposit@redhat.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <20210614081130.22134-3-eesposit@redhat.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Currently we update s->use_copy_range and s->copy_size in
block_copy_do_copy().

It's not very good:

1. block_copy_do_copy() is intended to be a simple function, that wraps
bdrv_co_<io> functions for need of block copy. That's why we don't pass
BlockCopyTask into it. So, block_copy_do_copy() is bad place for
manipulation with generic state of block-copy process

2. We are going to make block-copy thread-safe. So, it's good to move
manipulation with state of block-copy to the places where we'll need
critical sections anyway, to not introduce extra synchronization
primitives in block_copy_do_copy().

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210528141628.44287-3-vsementsov@virtuozzo.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Don't report successful progress on failure, when call_state->ret is
set.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210528141628.44287-2-vsementsov@virtuozzo.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Right now, users of qemu_co_sleep_ns_wakeable are simply passing
a pointer to QemuCoSleepState by reference to the function.  But
QemuCoSleepState really is just a Coroutine*; making the
content of the struct public is just as efficient and lets us
skip the user_state_pointer indirection.

Since the usage is changed, take the occasion to rename the
struct to QemuCoSleep.

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20210517100548.28806-6-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

All callers of qemu_co_sleep_wake are checking whether they are passing
a NULL argument inside the pointer-to-pointer: do the check in
qemu_co_sleep_wake itself.

As a side effect, qemu_co_sleep_wake can be called more than once and
it will only wake the coroutine once; after the first time, the argument
will be set to NULL via *sleep_state->user_state_pointer.  However, this
would not be safe unless co_sleep_cb keeps using the QemuCoSleepState*
directly, so make it go through the pointer-to-pointer instead.

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20210517100548.28806-4-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Right now, rate limiting is protected by the AioContext mutex, which is
taken for example both by the block jobs and by qmp_block_job_set_speed
(via find_block_job).

We would like to remove the dependency of block layer code on the
AioContext mutex, since most drivers and the core I/O code are already
not relying on it.  However, there is no existing lock that can easily
be taken by both ratelimit_set_speed and ratelimit_calculate_delay,
especially because the latter might run in coroutine context (and
therefore under a CoMutex) but the former will not.

Since concurrent calls to ratelimit_calculate_delay are not possible,
one idea could be to use a seqlock to get a snapshot of slice_ns and
slice_quota.  But for now keep it simple, and just add a mutex to the
RateLimit struct; block jobs are generally not performance critical to
the point of optimizing the clock cycles spent in synchronization.

This also requires the introduction of init/destroy functions, so
add them to the two users of ratelimit.h.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210116214705.822267-21-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Drop unused code.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210116214705.822267-20-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

We are going to stop use of this callback in the following commit.
Still the callback handling code will be dropped in a separate commit.
So, for now let's make it optional.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210116214705.822267-16-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Add function to cancel running async block-copy call. It will be used
in backup.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210116214705.822267-8-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

We are going to directly use one async block-copy operation for backup
job, so we need rate limiter.

We want to maintain current backup behavior: only background copying is
limited and copy-before-write operations only participate in limit
calculation. Therefore we need one rate limiter for block-copy state
and boolean flag for block-copy call state for actual limitation.

Note, that we can't just calculate each chunk in limiter after
successful copying: it will not save us from starting a lot of async
sub-requests which will exceed limit too much. Instead let's use the
following scheme on sub-request creation:
1. If at the moment limit is not exceeded, create the request and
account it immediately.
2. If at the moment limit is already exceeded, drop create sub-request
and handle limit instead (by sleep).
With this approach we'll never exceed the limit more than by one
sub-request (which pretty much matches current backup behavior).

Note also, that if there is in-flight block-copy async call,
block_copy_kick() should be used after set-speed to apply new setup
faster. For that block_copy_kick() published in this patch.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210116214705.822267-7-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

It simplifies debugging.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210116214705.822267-6-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

They will be used for backup.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210116214705.822267-5-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

We'll need async block-copy invocation to use in backup directly.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210116214705.822267-4-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Refactor common path to use BlockCopyCallState pointer as parameter, to
prepare it for use in asynchronous block-copy (at least, we'll need to
run block-copy in a coroutine, passing the whole parameters as one
pointer).

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210116214705.822267-3-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Experiments show, that copy_range is not always making things faster.
So, to make experimentation simpler, let's add a parameter. Some more
perf parameters will be added soon, so here is a new struct.

For now, add new backup qmp parameter with x- prefix for the following
reasons:

 - We are going to add more performance parameters, some will be
   related to the whole block-copy process, some only to background
   copying in backup (ignored for copy-before-write operations).
 - On the other hand, we are going to use block-copy interface in other
   block jobs, which will need performance options as well.. And it
   should be the same structure or at least somehow related.

So, there are too much unclean things about how the interface and now
we need the new options mostly for testing. Let's keep them
experimental for a while.

In do_backup_common() new x-perf parameter handled in a way to
make further options addition simpler.

We add use-copy-range with default=true, and we'll change the default
in further patch, after moving backup to use block-copy.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210116214705.822267-2-vsementsov@virtuozzo.com>
[mreitz: s/5\.2/6.0/]
Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>

Since commit 42ac2144 (block/block-copy: refactor task creation)
block_copy_task_create calculates the area to be copied via
bdrv_dirty_bitmap_next_dirty_area, but that can return an unaligned byte
count if the image's last cluster end is not aligned to the bitmap's
granularity.

Always ALIGN_UP the resulting bytes value to satisfy block_copy_do_copy,
which requires the 'bytes' parameter to be aligned to cluster size.

Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
Message-Id: <20200810095523.15071-1-s.reiter@proxmox.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

ret may be > 0 on success path at this point. Fix assertion, which may
crash currently.

Fixes: 4ce5dd3e
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20200526181347.489557-1-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

block_copy_do_copy() is static, only used in block_copy_task_entry
with the error_is_read argument set. No need to check for it,
simplify.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200507121129.29760-3-philmd@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Fix when building with -Os:

    CC      block/block-copy.o
  block/block-copy.c: In function ‘block_copy_task_entry’:
  block/block-copy.c:428:38: error: ‘error_is_read’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
    428 |         t->call_state->error_is_read = error_is_read;
        |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200507121129.29760-2-philmd@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Obviously, we should g_free the task after trace point and offset
update.

Reported-by: Coverity (CID 1428756)
Fixes: 4ce5dd3e
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20200507183800.22626-1-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Run block_copy iterations in parallel in aio tasks.

Changes:
  - BlockCopyTask becomes aio task structure. Add zeroes field to pass
    it to block_copy_do_copy
  - add call state - it's a state of one call of block_copy(), shared
    between parallel tasks. For now used only to keep information about
    first error: is it read or not.
  - convert block_copy_dirty_clusters to aio-task loop.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20200429130847.28124-6-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Instead of just relying on the comment "Called only on full-dirty
region" in block_copy_task_create() let's move initial dirty area
search directly to block_copy_task_create(). Let's also use effective
bdrv_dirty_bitmap_next_dirty_area instead of looping through all
non-dirty clusters.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200429130847.28124-5-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

We are going to use aio-task-pool API, so we'll need state pointer in
BlockCopyTask anyway. Add it now and use where possible.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200429130847.28124-4-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

We are going to use aio-task-pool API, so tasks will be handled in
parallel. We need therefore separate allocated task on each iteration.
Introduce this logic now.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200429130847.28124-3-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

We are going to use aio-task-pool API and extend in-flight request
structure to be a successor of AioTask, so rename things appropriately.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200429130847.28124-2-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Hide structure definitions and add explicit API instead, to keep an
eye on the scope of the shared fields.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200311103004.7649-10-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Currently, block_copy operation lock the whole requested region. But
there is no reason to lock clusters, which are already copied, it will
disturb other parallel block_copy requests for no reason.

Let's instead do the following:

Lock only sub-region, which we are going to operate on. Then, after
copying all dirty sub-regions, we should wait for intersecting
requests block-copy, if they failed, we should retry these new dirty
clusters.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Message-Id: <20200311103004.7649-9-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

offset/bytes pair is more usual naming in block layer, let's use it.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200311103004.7649-8-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

We have a lot of "chunk_end - start" invocations, let's switch to
bytes/cur_bytes scheme instead.

While being here, improve check on block_copy_do_copy parameters to not
overflow when calculating nbytes and use int64_t for bytes in
block_copy for consistency.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200311103004.7649-7-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Split find_conflicting_inflight_req to be used separately.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200311103004.7649-6-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Use bdrv_block_status_above to chose effective chunk size and to handle
zeroes effectively.

This substitutes checking for just being allocated or not, and drops
old code path for it. Assistance by backup job is dropped too, as
caching block-status information is more difficult than just caching
is-allocated information in our dirty bitmap, and backup job is not
good place for this caching anyway.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200311103004.7649-5-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

In block_copy_do_copy we fallback to read+write if copy_range failed.
In this case copy_size is larger than defined for buffered IO, and
there is corresponding commit. Still, backup copies data cluster by
cluster, and most of requests are limited to one cluster anyway, so the
only source of this one bad-limited request is copy-before-write
operation.

Further patch will move backup to use block_copy directly, than for
cases where copy_range is not supported, first request will be
oversized in each backup. It's not good, let's change it now.

Fix is simple: just limit first copy_range request like buffer-based
request. If it succeed, set larger copy_range limit.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200311103004.7649-4-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Assume we have two regions, A and B, and region B is in-flight now,
region A is not yet touched, but it is unallocated and should be
skipped.

Correspondingly, as progress we have

  total = A + B
  current = 0

If we reset unallocated region A and call progress_reset_callback,
it will calculate 0 bytes dirty in the bitmap and call
job_progress_set_remaining, which will set

   total = current + 0 = 0 + 0 = 0

So, B bytes are actually removed from total accounting. When job
finishes we'll have

   total = 0
   current = B

, which doesn't sound good.

This is because we didn't considered in-flight bytes, actually when
calculating remaining, we should have set (in_flight + dirty_bytes)
as remaining, not only dirty_bytes.

To fix it, let's refactor progress calculation, moving it to block-copy
itself instead of fixing callback. And, of course, track in_flight
bytes count.

We still have to keep one callback, to maintain backup job bytes_read
calculation, but it will go on soon, when we turn the whole backup
process into one block_copy call.

Cc: qemu-stable@nongnu.org
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Message-Id: <20200311103004.7649-3-vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>