Add a public interface for get. While we're at it,
rename "bdrv_get_dirty_bitmap_locked" to "bdrv_dirty_bitmap_get_locked".
(There are more functions to rename to the bdrv_dirty_bitmap_VERB form,
but they will wait until the conclusion of this series.)
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190709232550.10724-11-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
I'm surprised it didn't come up sooner, but sometimes we have a +busy
bitmap as a source. This is dangerous from the QMP API, but if we are
the owner that marked the bitmap busy, it's safe to merge it using it as
a read only source.
It is not safe in the general case to allow users to read from in-use
bitmaps, so create an internal variant that foregoes the safety
checking.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190709232550.10724-10-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
We don't need or want a new sync mode for simple differences in
semantics. Create a new mode simply named "BITMAP" that is designed to
make use of the new Bitmap Sync Mode field.
Because the only bitmap sync mode is 'on-success', this adds no new
functionality to the backup job (yet). The old incremental backup mode
is maintained as a syntactic sugar for sync=bitmap, mode=on-success.
Add all of the plumbing necessary to support this new instruction.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190709232550.10724-6-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
In my "build everything" tree, changing qemu/main-loop.h triggers a
recompile of some 5600 out of 6600 objects (not counting tests and
objects that don't depend on qemu/osdep.h). It includes block/aio.h,
which in turn includes qemu/event_notifier.h, qemu/notify.h,
qemu/processor.h, qemu/qsp.h, qemu/queue.h, qemu/thread-posix.h,
qemu/thread.h, qemu/timer.h, and a few more.
Include qemu/main-loop.h only where it's needed. Touching it now
recompiles only some 1700 objects. For block/aio.h and
qemu/event_notifier.h, these numbers drop from 5600 to 2800. For the
others, they shrink only slightly.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190812052359.30071-21-armbru@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Some of the generated qapi-types-MODULE.h are included all over the
place. Changing a QAPI type can trigger massive recompiling. Top
scorers recompile more than 1000 out of some 6600 objects (not
counting tests and objects that don't depend on qemu/osdep.h):
6300 qapi/qapi-builtin-types.h
5700 qapi/qapi-types-run-state.h
3900 qapi/qapi-types-common.h
3300 qapi/qapi-types-sockets.h
3000 qapi/qapi-types-misc.h
3000 qapi/qapi-types-crypto.h
3000 qapi/qapi-types-job.h
3000 qapi/qapi-types-block-core.h
2800 qapi/qapi-types-block.h
1300 qapi/qapi-types-net.h
Clean up headers to include generated QAPI headers only where needed.
Impact is negligible except for hw/qdev-properties.h.
This header includes qapi/qapi-types-block.h and
qapi/qapi-types-misc.h. They are used only in expansions of property
definition macros such as DEFINE_PROP_BLOCKDEV_ON_ERROR() and
DEFINE_PROP_OFF_AUTO(). Moving their inclusion from
hw/qdev-properties.h to the users of these macros avoids pointless
recompiles. This is how other property definition macros, such as
DEFINE_PROP_NETDEV(), already work.
Improves things for some of the top scorers:
3600 qapi/qapi-types-common.h
2800 qapi/qapi-types-sockets.h
900 qapi/qapi-types-misc.h
2200 qapi/qapi-types-crypto.h
2100 qapi/qapi-types-job.h
2100 qapi/qapi-types-block-core.h
270 qapi/qapi-types-block.h
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20190812052359.30071-3-armbru@redhat.com>
Back in 2016, we discussed[1] rules for headers, and these were
generally liked:
1. Have a carefully curated header that's included everywhere first. We
got that already thanks to Peter: osdep.h.
2. Headers should normally include everything they need beyond osdep.h.
If exceptions are needed for some reason, they must be documented in
the header. If all that's needed from a header is typedefs, put
those into qemu/typedefs.h instead of including the header.
3. Cyclic inclusion is forbidden.
This patch gets include/ closer to obeying 2.
It's actually extracted from my "[RFC] Baby steps towards saner
headers" series[2], which demonstrates a possible path towards
checking 2 automatically. It passes the RFC test there.
[1] Message-ID: <87h9g8j57d.fsf@blackfin.pond.sub.org>
https://lists.nongnu.org/archive/html/qemu-devel/2016-03/msg03345.html
[2] Message-Id: <20190711122827.18970-1-armbru@redhat.com>
https://lists.nongnu.org/archive/html/qemu-devel/2019-07/msg02715.html
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20190812052359.30071-2-armbru@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
No reason to use blocking channel for negotiation and we'll benefit in
further reconnect feature, as qio_channel reads and writes will do
qemu_coroutine_yield while waiting for io completion.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190618114328.55249-3-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Do effective copy-on-read request when we don't need data actually. It
will be used for block-stream and NBD_CMD_CACHE.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20190725100550.33801-2-vsementsov@virtuozzo.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
[eblake: comment grammar fix]
Signed-off-by: Eric Blake <eblake@redhat.com>
bdrv_set_aio_context_ignore() can only work in the main loop:
bdrv_drained_begin() only works in the main loop and the node's (old)
AioContext; and bdrv_drained_end() really only works in the main loop
and the node's (new) AioContext (contrary to its current comment, which
is just wrong).
Consequentially, bdrv_set_aio_context_ignore() must be called from the
main loop. Luckily, assuming that we can make block graph changes only
from the main loop as well, all its callers do that already.
Note that changing a node's context in a sense is an operation that
changes the block graph, so it actually makes sense to require this
function to be called from the main loop.
Also, fix bdrv_drained_end()'s description. You can only use it from
the main loop or the node's AioContext, and in the latter case, the
whole subtree must be in the same context.
Fixes: e037c09c78
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190722133054.21781-3-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
We should never poll anywhere in bdrv_do_drained_end() (including its
recursive callees like bdrv_drain_invoke()), because it does not cope
well with graph changes. In fact, it has been written based on the
postulation that no graph changes will happen in it.
Instead, the callers that want to poll must poll, i.e. all currently
globally available wrappers: bdrv_drained_end(),
bdrv_subtree_drained_end(), bdrv_unapply_subtree_drain(), and
bdrv_drain_all_end(). Graph changes there do not matter.
They can poll simply by passing a pointer to a drained_end_counter and
wait until it reaches 0.
This patch also adds a non-polling global wrapper for
bdrv_do_drained_end() that takes a drained_end_counter pointer. We need
such a variant because now no function called anywhere from
bdrv_do_drained_end() must poll. This includes
BdrvChildRole.drained_end(), which already must not poll according to
its interface documentation, but bdrv_child_cb_drained_end() just
violates that by invoking bdrv_drained_end() (which does poll).
Therefore, BdrvChildRole.drained_end() must take a *drained_end_counter
parameter, which bdrv_child_cb_drained_end() can pass on to the new
bdrv_drained_end_no_poll() function.
Note that we now have a pattern of all drained_end-related functions
either polling or receiving a *drained_end_counter to let the caller
poll based on that.
A problem with a single poll loop is that when the drained section in
bdrv_set_aio_context_ignore() ends, some nodes in the subgraph may be in
the old contexts, while others are in the new context already. To let
the collective poll in bdrv_drained_end() work correctly, we must not
hold a lock to the old context, so that the old context can make
progress in case it is different from the current context.
(In the process, remove the comment saying that the current context is
always the old context, because it is wrong.)
In all other places, all nodes in a subtree must be in the same context,
so we can just poll that. The exception of course is
bdrv_drain_all_end(), but that always runs in the main context, so we
can just poll NULL (like bdrv_drain_all_begin() does).
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
These functions are not used outside of block/io.c, there is no reason
why they should be globally available.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Commit 5cb2737e92 laid out why
bdrv_do_drained_end() must decrement the quiesce_counter after
bdrv_drain_invoke(). It did not give a very good reason why it has to
happen after bdrv_parent_drained_end(), instead only claiming symmetry
to bdrv_do_drained_begin().
It turns out that delaying it for so long is wrong.
Situation: We have an active commit job (i.e. a mirror job) from top to
base for the following graph:
filter
|
[file]
|
v
top --[backing]--> base
Now the VM is closed, which results in the job being cancelled and a
bdrv_drain_all() happening pretty much simultaneously.
Beginning the drain means the job is paused once whenever one of its
nodes is quiesced. This is reversed when the drain ends.
With how the code currently is, after base's drain ends (which means
that it will have unpaused the job once), its quiesce_counter remains at
1 while it goes to undrain its parents (bdrv_parent_drained_end()). For
some reason or another, undraining filter causes the job to be kicked
and enter mirror_exit_common(), where it proceeds to invoke
block_job_remove_all_bdrv().
Now base will be detached from the job. Because its quiesce_counter is
still 1, it will unpause the job once more. So in total, undraining
base will unpause the job twice. Eventually, this will lead to the
job's pause_count going negative -- well, it would, were there not an
assertion against this, which crashes qemu.
The general problem is that if in bdrv_parent_drained_end() we undrain
parent A, and then undrain parent B, which then leads to A detaching the
child, bdrv_replace_child_noperm() will undrain A as if we had not done
so yet; that is, one time too many.
It follows that we cannot decrement the quiesce_counter after invoking
bdrv_parent_drained_end().
Unfortunately, decrementing it before bdrv_parent_drained_end() would be
wrong, too. Imagine the above situation in reverse: Undraining A leads
to B detaching the child. If we had already decremented the
quiesce_counter by that point, bdrv_replace_child_noperm() would undrain
B one time too little; because it expects bdrv_parent_drained_end() to
issue this undrain. But bdrv_parent_drained_end() won't do that,
because B is no longer a parent.
Therefore, we have to do something else. This patch opts for
introducing a second quiesce_counter that counts how many times a
child's parent has been quiesced (though c->role->drained_*). With
that, bdrv_replace_child_noperm() just has to undrain the parent exactly
that many times when removing a child, and it will always be right.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The commit and the mirror block job must be able to drop their filter
node at any point. However, this will not be possible if any of the
BdrvChild links to them is frozen. Therefore, we need to prevent them
from ever becoming frozen.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20190703172813.6868-2-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This patch is used in the 'block/stream: introduce a bottom node'
that is following. Instead of the base node, the caller may pass
the node that has the base as its backing image to the function
bdrv_is_allocated_above() with a new parameter include_base = true
and get rid of the dependency on the base that may change during
commit/stream parallel jobs. Now, if the specified base is not
found in the backing image chain, the QEMU will abort.
Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 1559152576-281803-2-git-send-email-andrey.shinkevich@virtuozzo.com
[mreitz: Squashed in the following as a rebase on conflicting patches:]
Message-id: e3cf99ae-62e9-8b6e-5a06-d3c8b9363b85@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
If a block node uses bdrv_child_try_set_perm() to change the permission
it takes on its child, the result may be very short-lived. If anything
makes the block layer recalculate the permissions internally, it will
invoke the node driver's .bdrv_child_perm() implementation. The
permission/shared permissions masks that returns will then override the
values previously passed to bdrv_child_try_set_perm().
If drivers want a child edge to have specific values for the
permissions/shared permissions mask, it must return them in
.bdrv_child_perm(). Consequentially, there is no need for them to pass
the same values to bdrv_child_try_set_perm() then: It is better to have
a function that invokes .bdrv_child_perm() and calls
bdrv_child_try_set_perm() with the result. This patch adds such a
function under the name of bdrv_child_refresh_perms().
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Drop remaining users of bs->job:
1. assertions actually duplicated by assert(!bs->refcnt)
2. trace-point seems not enough reason to change stream_start to return
BlockJob pointer
3. Restricting creation of two jobs based on same bs is bad idea, as
3.1 Some jobs creates filters to be their main node, so, this check
don't actually prevent creating second job on same real node (which
will create another filter node) (but I hope it is restricted by
other mechanisms)
3.2 Even without bs->job we have two systems of permissions:
op-blockers and BLK_PERM
3.3 We may want to run several jobs on one node one day
And finally, drop bs->job pointer itself. Hurrah!
Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
We are going to remove bs->job pointer. Drop it's usage in
blockdev_mark_auto_del: instead of looking at bs->job let's check all
jobs for references to bs.
Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
We are going to remove bs->job pointer. Drop it's usage in replication
code. Additionally we have to return job pointer from some mirror APIs.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
No header includes qemu-common.h after this commit, as prescribed by
qemu-common.h's file comment.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190523143508.25387-5-armbru@redhat.com>
[Rebased with conflicts resolved automatically, except for
include/hw/arm/xlnx-zynqmp.h hw/arm/nrf51_soc.c hw/arm/msf2-soc.c
block/qcow2-refcount.c block/qcow2-cluster.c block/qcow2-cache.c
target/arm/cpu.h target/lm32/cpu.h target/m68k/cpu.h target/mips/cpu.h
target/moxie/cpu.h target/nios2/cpu.h target/openrisc/cpu.h
target/riscv/cpu.h target/tilegx/cpu.h target/tricore/cpu.h
target/unicore32/cpu.h target/xtensa/cpu.h; bsd-user/main.c and
net/tap-bsd.c fixed up]
This fixes at least one overflow in qcow2_process_discards, which
passes 64bit region length to bdrv_pdiscard where bytes (or sectors in
the past) parameter is int since its introduction in 0b919fae.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
All callers of bdrv_set_aio_context() are eliminated now, they have
moved to bdrv_try_set_aio_context() and related safe functions. Remove
bdrv_set_aio_context().
With this, we can now know that the .set_aio_ctx callback must be
present in bdrv_set_aio_context_ignore() because
bdrv_can_set_aio_context() would have returned false previously, so
instead of checking the condition, we can assert it.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
So far, we only made sure that updating the AioContext of a node
affected the whole subtree. However, if a node is newly attached to a
new parent, we also need to make sure that both the subtree of the node
and the parent are in the same AioContext. This tries to move the new
child node to the parent AioContext and returns an error if this isn't
possible.
BlockBackends now actually apply their AioContext to their root node.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kenneth Heitke <kenneth.heitke@intel.com>
Reviewed-by: Klaus Birkelund Jensen <klaus.jensen@cnexlabs.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Callback-based laio_submit() and laio_cancel() were left after
rewriting Linux AIO backend to coroutines in hope that they would be
used in other code that could bypass coroutines. They can be safely
removed because they have not been used since that time.
Signed-off-by: Julia Suvorova <jusual@mail.ru>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
drv_co_block_status digs bs->file for additional, more accurate search
for hole inside region, reported as DATA by bs since 5daa74a6eb.
This accuracy is not free: assume we have qcow2 disk. Actually, qcow2
knows, where are holes and where is data. But every block_status
request calls lseek additionally. Assume a big disk, full of
data, in any iterative copying block job (or img convert) we'll call
lseek(HOLE) on every iteration, and each of these lseeks will have to
iterate through all metadata up to the end of file. It's obviously
ineffective behavior. And for many scenarios we don't need this lseek
at all.
However, lseek is needed when we have metadata-preallocated image.
So, let's detect metadata-preallocation case and don't dig qcow2's
protocol file in other cases.
The idea is to compare allocation size in POV of filesystem with
allocations size in POV of Qcow2 (by refcounts). If allocation in fs is
significantly lower, consider it as metadata-preallocation case.
102 iotest changed, as our detector can't detect shrinked file as
metadata-preallocation, which don't seem to be wrong, as with metadata
preallocation we always have valid file length.
Two other iotests have a slight change in their QMP output sequence:
Active 'block-commit' returns earlier because the job coroutine yields
earlier on a blocking operation. This operation is loading the refcount
blocks in qcow2_detect_metadata_preallocation().
Suggested-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
All block nodes and users in any connected component of the block graph
must be in the same AioContext, so changing the AioContext of one node
must not only change all of its children, but all of its parents (and
in turn their children etc.) as well.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Since commit b97511c7bc, there is no reason for block drivers any more
to call these functions (see the function comment in block_int.h). They
are now just internal helper functions for bdrv_set_aio_context()
and can be made static.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Eventually, we want to make sure that all parents and all children of a
node are in the same AioContext as the node itself. This means that
changing the AioContext may fail because one of the other involved
parties (e.g. a guest device that was configured with an iothread)
cannot allow switching to a different AioContext.
Introduce a set of functions that allow to first check whether all
involved nodes can switch to a new context and only then do the actual
switch. The check recursively covers children and parents.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Cleaned up with scripts/clean-header-guards.pl.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190315145123.28030-9-armbru@redhat.com>
No one is using these functions anymore, all callers have switched to
the byte-based bdrv_pread() and bdrv_pwrite()
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The existing code to convert flag bits into strings looks a bit strange
now, and if we ever add more flags, it will look even stranger. Prevent
that from happening by making it look up the flag names in an array.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20190405191635.25740-1-mreitz@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
bdrv_snapshot_dump(), bdrv_image_info_specific_dump(),
bdrv_image_info_dump() and their helpers take an fprintf()-like
callback and a FILE * to pass to it.
hmp.c passes monitor_printf() cast to fprintf_function and the current
monitor cast to FILE *.
qemu-img.c and qemu-io-cmds.c pass fprintf and stdout.
The type-punning is technically undefined behaviour, but works in
practice. Clean up: drop the callback, and call qemu_printf()
instead.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20190417191805.28198-8-armbru@redhat.com>
qsp_report() takes an fprintf()-like callback and a FILE * to pass to
it.
Its only caller hmp_sync_profile() passes monitor_fprintf() and the
current monitor cast to FILE *. monitor_fprintf() casts it right
back, and is otherwise identical to monitor_printf(). The
type-punning is ugly.
Drop the callback, and call qemu_printf() instead.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20190417191805.28198-7-armbru@redhat.com>
We know that the kernel implements a slow fallback code path for
BLKZEROOUT, so if BDRV_REQ_NO_FALLBACK is given, we shouldn't call it.
The other operations we call in the context of .bdrv_co_pwrite_zeroes
should usually be quick, so no modification should be needed for them.
If we ever notice that there are additional problematic cases, we can
still make these conditional as well.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Eric Blake <eblake@redhat.com>
For qemu-img convert, we want an operation that zeroes out the whole
image if this can be done efficiently, but that returns an error
otherwise so we don't write explicit zeroes and immediately overwrite
them with the real data, potentially doubling the amount of data to be
written.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Eric Blake <eblake@redhat.com>
If we reopen a BlockDriverState and there is an option that is present
in bs->options but missing from the new set of options then we have to
return an error unless the driver is able to reset it to its default
value.
This patch adds a new 'mutable_opts' field to BlockDriver. This is
a list of runtime options that can be modified during reopen. If an
option in this list is unspecified on reopen then it must be reset (or
return an error).
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This patch allows the user to change the backing file of an image that
is being reopened. Here's what it does:
- In bdrv_reopen_prepare(): check that the value of 'backing' points
to an existing node or is null. If it points to an existing node it
also needs to make sure that replacing the backing file will not
create a cycle in the node graph (i.e. you cannot reach the parent
from the new backing file).
- In bdrv_reopen_commit(): perform the actual node replacement by
calling bdrv_set_backing_hd().
There may be temporary implicit nodes between a BDS and its backing
file (e.g. a commit filter node). In these cases bdrv_reopen_prepare()
looks for the real (non-implicit) backing file and requires that the
'backing' option points to it. Replacing or detaching a backing file
is forbidden if there are implicit nodes in the middle.
Although x-blockdev-reopen is meant to be used like blockdev-add,
there's an important thing that must be taken into account: the only
way to set a new backing file is by using a reference to an existing
node (previously added with e.g. blockdev-add). If 'backing' contains
a dictionary with a new set of options ({"driver": "qcow2", "file": {
... }}) then it is interpreted that the _existing_ backing file must
be reopened with those options.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Children in QMP are specified with BlockdevRef / BlockdevRefOrNull,
which can contain a set of child options, a child reference, or
NULL. In optional attributes like "backing" it can also be missing.
Only the first case (set of child options) is being handled properly
by bdrv_reopen_queue(). This patch deals with all the others.
Here's how these cases should be handled when bdrv_reopen_queue() is
deciding what to do with each child of a BlockDriverState:
1) Set of child options: if the child was implicitly created (i.e
inherits_from points to the parent) then the options are removed
from the parent's options QDict and are passed to the child with
a recursive bdrv_reopen_queue() call. This case was already
working fine.
2) Child reference: there's two possibilites here.
2a) Reference to the current child: if the child was implicitly
created then it is put in the reopen queue, keeping its
current set of options (since this was a child reference
there was no way to specify a different set of options).
If the child is not implicit then it keeps its current set
of options but it is not reopened (and therefore does not
inherit any new option from the parent).
2b) Reference to a different BDS: the current child is not put
in the reopen queue at all. Passing a reference to a
different BDS can be used to replace a child, although at
the moment no driver implements this, so it results in an
error. In any case, the current child is not going to be
reopened (and might in fact disappear if it's replaced)
3) NULL: This is similar to (2b). Although no driver allows this
yet it can be used to detach the current child so it should not
be put in the reopen queue.
4) Missing option: at the moment "backing" is the only case where
this can happen. With "blockdev-add", leaving "backing" out
means that the default backing file is opened. We don't want to
open a new image during reopen, so we require that "backing" is
always present. We'll relax this requirement a bit in the next
patch. If keep_old_opts is true and "backing" is missing then
this behaves like 2a (the current child is reopened).
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The bdrv_reopen_queue() function is used to create a queue with
the BDSs that are going to be reopened and their new options. Once
the queue is ready bdrv_reopen_multiple() is called to perform the
operation.
The original options from each one of the BDSs are kept, with the new
options passed to bdrv_reopen_queue() applied on top of them.
For "x-blockdev-reopen" we want a function that behaves much like
"blockdev-add". We want to ignore the previous set of options so that
only the ones actually specified by the user are applied, with the
rest having their default values.
One of the things that we need is a way to tell bdrv_reopen_queue()
whether we want to keep the old set of options or not, and that's what
this patch does. All current callers are setting this new parameter to
true and x-blockdev-reopen will set it to false.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Our permission system is useful to define what operations are allowed
on a certain block node and includes things like BLK_PERM_WRITE or
BLK_PERM_RESIZE among others.
One of the permissions is BLK_PERM_GRAPH_MOD which allows "changing
the node that this BdrvChild points to". The exact meaning of this has
never been very clear, but it can be understood as "change any of the
links connected to the node". This can be used to prevent changing a
backing link, but it's too coarse.
This patch adds a new 'frozen' attribute to BdrvChild, which forbids
detaching the link from the node it points to, and new API to freeze
and unfreeze a backing chain.
After this change a few functions can fail, so they need additional
checks.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Commit a88b179f introduced the ability to set and query bitmap
persistence, but with an atypical spelling.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-id: 20190308205845.25734-1-eblake@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
Instead of checking against busy, inconsistent, or read only directly,
use a check function with permissions bits that let us streamline the
checks without reproducing them in many places.
Included in this patch are permissions changes that simply add the
inconsistent check to existing permissions call spots, without
addressing existing bugs.
In general, this means that busy+readonly checks become BDRV_BITMAP_DEFAULT,
which checks against all three conditions. busy-only checks become
BDRV_BITMAP_ALLOW_RO.
Notably, remove allows inconsistent bitmaps, so it doesn't follow the pattern.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190301191545.8728-4-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
Add an inconsistent bit to dirty-bitmaps that allows us to report a bitmap as
persistent but potentially inconsistent, i.e. if we find bitmaps on a qcow2
that have been marked as "in use".
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190301191545.8728-2-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
These mean the same thing now. Unify them and rename the merged call
bdrv_dirty_bitmap_busy to indicate semantically what we are describing,
as well as help disambiguate from the various _locked and _unlocked
versions of bitmap helpers that refer to mutex locks.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190223000614.13894-8-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
"Frozen" was a good description a long time ago, but it isn't adequate now.
Rename the frozen predicate to has_successor to make the semantics of the
predicate more clear to outside callers.
In the process, remove some calls to frozen() that no longer semantically
make sense. For bdrv_enable_dirty_bitmap_locked and
bdrv_disable_dirty_bitmap_locked, it doesn't make sense to prohibit QEMU
internals from performing this action when we only wished to prohibit QMP
users from issuing these commands. All of the QMP API commands for bitmap
manipulation already check against user_locked() to prohibit these actions.
Several other assertions really want to check that the bitmap isn't in-use
by another operation -- use the bitmap_user_locked function for this instead,
which presently also checks for has_successor. This leaves some redundant
checks of has_successor through different helpers that are addressed in
forthcoming patches.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20190223000614.13894-3-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
