Using int for values that are only used as booleans is confusing.
While at it, rearrange a couple of members so that all the bools
are contiguous.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
It makes more sense to have ALL block size limit constraints
in the same struct. Improve the documentation while at it.
Simplify a couple of conditionals, now that we have audited and
documented that request_alignment is always non-zero.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Sector-based limits are awkward to think about; in our on-going
quest to move to byte-based interfaces, convert max_discard and
discard_alignment. Rename them, using 'pdiscard' as an aid to
track which remaining discard interfaces need conversion, and so
that the compiler will help us catch the change in semantics
across any rebased code. The BlockLimits type is now completely
byte-based; and in iscsi.c, sector_limits_lun2qemu() is no
longer needed.
pdiscard_alignment is made unsigned (we use power-of-2 alignments
as bitmasks, where unsigned is easier to think about) while
leaving max_pdiscard signed (since we still have an 'int'
interface); this is comparable to what commit cf081fc did for
write zeroes limits. We may later want to make everything an
unsigned 64-bit limit - but that requires a bigger code audit.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Improve the documentation of the write zeroes limits, to mention
additional constraints that drivers should observe. Worth squashing
into commit cf081fca, if that hadn't been pushed already :)
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Sector-based limits are awkward to think about; in our on-going
quest to move to byte-based interfaces, convert max_transfer_length
and opt_transfer_length. Rename them (dropping the _length suffix)
so that the compiler will help us catch the change in semantics
across any rebased code, and improve the documentation. Use unsigned
values, so that we don't have to worry about negative values and
so that bit-twiddling is easier; however, we are still constrained
by 2^31 of signed int in most APIs.
When a value comes from an external source (iscsi and raw-posix),
sanitize the results to ensure that opt_transfer is a power of 2.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The NBD layer was breaking up request at a limit of 2040 sectors
(just under 1M) to cater to old qemu-nbd. But the server limit
was raised to 32M in commit 2d8214885 to match the kernel, more
than three years ago; and the upstream NBD Protocol is proposing
documentation that without any explicit communication to state
otherwise, a client should be able to safely assume that a 32M
transaction will work. It is time to rely on the larger sizing,
and any downstream distro that cares about maximum
interoperability to older qemu-nbd servers can just tweak the
value of #define NBD_MAX_SECTORS.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-stable@nongnu.org
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Block jobs that use additional BDSes or event loop resources need a
callback to get their affairs in order when the AioContext is switched.
Simple block jobs don't need an attach callback, they automatically work
thanks to the generic attach/detach notifiers that this patch adds.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 1466096189-6477-7-git-send-email-stefanha@redhat.com
It's possible that an AioContext notifier user was close to finishing
when .detach_aio_context() or .attached_aio_context() is called. In
that case they may call bdrv_remove_aio_context_notifier() during the
callback.
Use safe iteration to avoid crashing when the notifier list is modified
during iteration. We must not only handle the case where the current
aio notifier is removed during a callback but also the one where any
other aio notifier is removed.
The next patch adds an AioContext notifier for block jobs and they
really could be terminating just as .detach_aio_context() is invoked.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 1466096189-6477-6-git-send-email-stefanha@redhat.com
Block jobs are coroutines that usually perform I/O but sometimes also
sleep or yield. Currently only sleeping or yielded block jobs can be
paused. This means jobs that do not sleep or yield (using
block_job_yield()) are unaffected by block_job_pause().
Add block_job_pause_point() so that block jobs can mark quiescent points
that are suitable for pausing. This solves the problem that it can take
a block job a long time to pause if it is performing a long series of
I/O operations.
Transitioning to paused state involves a .pause()/.resume() callback.
These callbacks are used to ensure that I/O and event loop activity has
ceased while the job is at a pause point.
Note that this patch introduces a stricter pause state than previously.
The job->busy flag was incorrectly documented as a quiescent state
without I/O pending. This is violated by any job that has I/O pending
across sleep or block_job_yield(), like the mirror block job.
[Add missing block_job_should_pause() check to avoid deadlock after
job->driver->pause() in block_job_pause_point().
--Stefan]
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 1466096189-6477-4-git-send-email-stefanha@redhat.com
The block_job_is_paused() function name is not great because callers
only use it to determine whether pausing has been requested. Rename it
to highlight those semantics and remove it from the public header file
as there are no external callers.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 1466096189-6477-3-git-send-email-stefanha@redhat.com
Declare a constant and use that when determining if an export
name fits within the constraints we are willing to support.
Note that upstream NBD recently documented that clients MUST
support export names of 256 bytes (not including trailing NUL),
and SHOULD support names up to 4096 bytes. 4096 is a bit big
(we would lose benefits of stack-allocation of a name array),
and we already have other limits in place (for example, qcow2
snapshot names are clamped around 1024). So for now, just
stick to the required minimum, as that's easier to audit than
a full-scale support for larger names.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1463006384-7734-12-git-send-email-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
These structs are never used to represent the bytes that go over the
network. The big-endian network data is built into a uint8_t array
in nbd_{receive,send}_{request,reply}. Remove the unused magic field,
reorder the struct to avoid holes, and remove the packed attribute.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Currently, we are trying to move the backing BDS from the source to the
target in bdrv_replace_in_backing_chain() which is called from
mirror_exit(). However, mirror_complete() already tries to open the
target's backing chain with a call to bdrv_open_backing_file().
First, we should only set the target's backing BDS once. Second, the
mirroring block job has a better idea of what to set it to than the
generic code in bdrv_replace_in_backing_chain() (in fact, the latter's
conditions on when to move the backing BDS from source to target are not
really correct).
Therefore, remove that code from bdrv_replace_in_backing_chain() and
leave it to mirror_complete().
Depending on what kind of mirroring is performed, we furthermore want to
use different strategies to open the target's backing chain:
- If blockdev-mirror is used, we can assume the user made sure that the
target already has the correct backing chain. In particular, we should
not try to open a backing file if the target does not have any yet.
- If drive-mirror with mode=absolute-paths is used, we can and should
reuse the already existing chain of nodes that the source BDS is in.
In case of sync=full, no backing BDS is required; with sync=top, we
just link the source's backing BDS to the target, and with sync=none,
we use the source BDS as the target's backing BDS.
We should not try to open these backing files anew because this would
lead to two BDSs existing per physical file in the backing chain, and
we would like to avoid such concurrent access.
- If drive-mirror with mode=existing is used, we have to use the
information provided in the physical image file which means opening
the target's backing chain completely anew, just as it has been done
already.
If the target's backing chain shares images with the source, this may
lead to multiple BDSs per physical image file. But since we cannot
reliably ascertain this case, there is nothing we can do about it.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20160610185750.30956-3-mreitz@redhat.com
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
It is always true for open images now.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
This allows drivers to share code between normal I/O and vmstate
accesses.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
This brings it in line with .bdrv_save_vmstate().
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
We already have a byte-based bdrv_pwritev(), but the read counterpart
was still missing. This commit adds it.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
In a first step to convert the common I/O path to work on bytes rather
than sectors, this converts the copy-on-read logic that is used by
bdrv_aligned_preadv().
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Add a new BDRV_REQ_MASK constant, and use it to make sure that
caller flags are always valid.
Tested with 'make check' and with qemu-iotests on both '-raw'
and '-qcow2'; the only failure turned up was fixed in the
previous commit.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Now that all drivers have been converted to a byte interface,
we no longer need a sector interface.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Rename to bdrv_pwrite_zeroes() to let the compiler ensure we
cater to the updated semantics. Do the same for bdrv_co_write_zeroes().
Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Update bdrv_co_do_write_zeroes() to be byte-based, and select
between the new byte-based bdrv_co_pwrite_zeroes() or the old
bdrv_co_write_zeroes(). The next patches will convert drivers,
then remove the old interface.
Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Another step towards removing sector-based interfaces: convert
the maximum write and minimum alignment values from sectors to
bytes. Rename the variables to let the compiler check that all
users are converted to the new semantics.
The maximum remains an int as long as BDRV_REQUEST_MAX_SECTORS
is constrained by INT_MAX (this means that we can't even
support a 2G write_zeroes, but just under it) - changing
operation lengths to unsigned or to 64-bits is a much bigger
audit, and debatable if we even want to do it (since at the
core, a 32-bit platform will still have ssize_t as its
underlying limit on write()).
Meanwhile, alignment is changed to 'uint32_t', since it makes no
sense to have an alignment larger than the maximum write, and
less painful to use an unsigned type with well-defined behavior
in bit operations than to have to worry about what happens if
a driver mistakenly supplies a negative alignment.
Add an assert that no one was trying to use sectors to get a
write zeroes larger than 2G, and therefore that a later conversion
to bytes won't be impacted by keeping the limit at 32 bits.
Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
I was thrown by the fact that the public type BlockRequest had
an anonymous union, but no obvious discriminator. Turns out
that the only client of the second branch of the union was code
internal to io.c, now that commit 91c6e4b killed public
multiwrite, so move it into io.c and improve the comments.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1463699150-19445-1-git-send-email-eblake@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
There is a single remaining user in qemu-img, and another one in a test
case, both of which can be trivially converted to using BlockJob.blk
instead.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
This changes the backup block job to use the job's BlockBackend for
performing its I/O. job->bs isn't used by the backup code any more
afterwards.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
This changes the streaming block job to use the job's BlockBackend for
performing the COR reads. job->bs isn't used by the streaming code any
more afterwards.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
This adds a new BlockBackend field to the BlockJob struct, which
coexists with the BlockDriverState while converting the individual jobs.
When creating a block job, a new BlockBackend is created on top of the
given BlockDriverState, and it is destroyed when the BlockJob ends. The
reference to the BDS is now held by the BlockBackend instead of calling
bdrv_ref/unref manually.
We have to be careful when we use bdrv_replace_in_backing_chain() in
block jobs because this changes the BDS that job->blk points to. At the
moment block jobs are too tightly coupled with their BDS, so that moving
a job to another BDS isn't easily possible; therefore, we need to just
manually undo this change afterwards.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
So far, bdrv_close_all() first removed all root BlockDriverStates of
BlockBackends and monitor owned BDSes, and then assumed that the
remaining BDSes must be related to jobs and cancelled these jobs.
This order doesn't work that well any more when block jobs use
BlockBackends internally because then they will lose their BDS before
being cancelled.
This patch changes bdrv_close_all() to first cancel all jobs and then
remove all root BDSes from the remaining BBs.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
The current way to obtain the list of existing block jobs is to
iterate over all root nodes and check which ones own a job.
Since we want to be able to support block jobs in other nodes as well,
this patch keeps a list of jobs that is updated every time one is
created or destroyed.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
When changing the BlockDriverState that a BdrvChild points to while the
node is currently drained, we must call the .drained_end() parent
callback. Conversely, when this means attaching a new node that is
already drained, we need to call .drained_begin().
bdrv_root_attach_child() takes now an opaque parameter, which is needed
because the callbacks must also be called if we're attaching a new child
to the BlockBackend when the root node is already drained, and they need
a way to identify the BlockBackend. Previously, child->opaque was set
too late and the callbacks would still see it as NULL.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
There are no callers to bdrv_open() or bdrv_open_inherit() left that
pass a pointer to a non-NULL BDS pointer as the first argument of these
functions, so we can finally drop that parameter and just make them
return the new BDS.
Generally, the following pattern is applied:
bs = NULL;
ret = bdrv_open(&bs, ..., &local_err);
if (ret < 0) {
error_propagate(errp, local_err);
...
}
by
bs = bdrv_open(..., errp);
if (!bs) {
ret = -EINVAL;
...
}
Of course, there are only a few instances where the pattern is really
pure.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
It is unused now, so we may just as well drop it.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The bdrv_next() users all leaked the BdrvNextIterator after completing
the iteration. Simply changing bdrv_next() to free the iterator before
returning NULL at the end of list doesn't work because some callers exit
the loop before looking at all BDSes.
This patch moves the BdrvNextIterator from the heap to the stack of
the caller and switches to a bdrv_first()/bdrv_next() interface for
initialising the iterator.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
This patch removes the remaining users of bs->blk, which will allow us
to have multiple BBs on top of a single BDS. In the meantime, all checks
that are currently in place to prevent the user from creating such
setups can be switched to bdrv_has_blk() instead of accessing BDS.blk.
Future patches can allow them and e.g. enable users to mirror to a block
device that already has a BlockBackend on it.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
We need to introduce a separate BdrvNextIterator struct that can keep
more state than just the current BDS in order to avoid using the bs->blk
pointer.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Since virtio-blk implements request merging itself these days, the only
remaining users are test cases for the function. That doesn't make the
function exactly useful any more.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
When block job errors were introduced, we assigned the iostatus of the
target BDS "just in case". The field has never been accessible for the
user because the target isn't listed in query-block.
Before we can allow the user to have a second BlockBackend on the
target, we need to clean this up. If anything, we would want to set the
iostatus for the internal BB of the job (which we can always do later),
but certainly not for a separate BB which the job doesn't even use.
As a nice side effect, this gets us rid of another bs->blk use.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
In order to get rid of bs->blk for bdrv_get_device_name() and
bdrv_get_device_or_node_name(), ask all parents for their name and
simply pick the first one.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
