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Many places in QEMU call qemu_aio_flush() to complete all pending
asynchronous I/O. Most of these places actually want to drain all block
requests but there is no block layer API to do so.
This patch introduces the bdrv_drain_all() API to wait for requests
across all BlockDriverStates to complete. As a bonus we perform checks
after qemu_aio_wait() to ensure that requests really have finished.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Debugging a reentrant request deadlock was fun but in the future we need
a quick and obvious way of detecting such bugs. Add an assert that
checks we are not about to deadlock when waiting for another request.
Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Cases beyond the end of the disk image are only implemented for block
drivers that do not provide .bdrv_co_is_allocated(). It's worth making
these cases generic so that block drivers that do implement
.bdrv_co_is_allocated() also get them for free.
Suggested-by: Mark Wu <wudxw@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
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Now that bdrv_co_is_allocated() is available we can use it instead of
the synchronous bdrv_is_allocated() interface. This is a follow-up that
Kevin Wolf <kwolf@redhat.com> pointed out after applying the series that
introduces bdrv_co_is_allocated().
It is safe to make cow_read() a coroutine_fn because its only caller is
a coroutine_fn.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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This patch adds the -drive copy-on-read=on|off command-line option:
copy-on-read=on|off
copy-on-read is "on" or "off" and enables whether to copy read backing
file sectors into the image file. Copy-on-read avoids accessing the
same backing file sectors repeatedly and is useful when the backing
file is over a slow network. By default copy-on-read is off.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Detect overlapping requests and remember to align to cluster boundaries
if the image format uses them. This assumes that allocating I/O is
performed in cluster granularity - which is true for qcow2, qed, etc.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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When copy-on-read is enabled it is necessary to wait for overlapping
requests before issuing new requests. This prevents races between the
copy-on-read and a write request.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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The bdrv_enable_copy_on_read()/bdrv_disable_copy_on_read() functions can
be used to programmatically enable or disable copy-on-read for a block
device. Later patches add the actual copy-on-read logic.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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The block layer does not know about pending requests. This information
is necessary for copy-on-read since overlapping requests must be
serialized to prevent races that corrupt the image.
The BlockDriverState gets a new tracked_request list field which
contains all pending requests. Each request is a BdrvTrackedRequest
record with sector_num, nb_sectors, and is_write fields.
Note that request tracking is always enabled but hopefully this extra
work is so small that it doesn't justify adding an enable/disable flag.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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It's common to wake up all waiting coroutines. Introduce the
qemu_co_queue_restart_all() function to do this instead of looping over
qemu_co_queue_next() in every caller.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Add macros for aligning a number to a multiple, for example:
QEMU_ALIGN_DOWN(500, 2000) = 0
QEMU_ALIGN_UP(500, 2000) = 2000
Since ALIGN_UP() is a common macro name use the QEMU_* namespace prefix.
Hopefully this will protect us from included headers that leak something
with a similar name.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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This patch introduces the public bdrv_co_is_allocated() interface which
can be used to query image allocation status while the VM is running.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Now that all block drivers have been converted to
.bdrv_co_is_allocated() we can drop .bdrv_is_allocated().
Note that the public bdrv_is_allocated() interface is still available
but is in fact a synchronous wrapper around .bdrv_co_is_allocated().
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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The cow block driver does not keep internal state for cluster lookups.
This means it is safe to perform cluster lookups in coroutine context
without risk of race conditions that corrupt internal state.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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It is trivial to switch from the synchronous .bdrv_is_allocated()
interface to .bdrv_co_is_allocated() since vdi_is_allocated() does not
block.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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It is trivial to switch from the synchronous .bdrv_is_allocated()
interface to .bdrv_co_is_allocated() since vvfat_is_allocated() does not
block.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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The qcow2, qcow, and vmdk block drivers are based on coroutines. They have a
coroutine mutex which protects internal state. We can convert the
.bdrv_is_allocated() function to .bdrv_co_is_allocated() by holding the mutex
around the cluster lookup operation.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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The bdrv_qed_is_allocated() function is a synchronous wrapper around
qed_find_cluster(), which performs the cluster lookup. In order to
convert the synchronous function to a coroutine function we yield
instead of using qemu_aio_wait(). Note that QED's cache is already safe
for parallel requests so no locking is needed.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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This patch adds the .bdrv_co_is_allocated() interface which is identical
to .bdrv_is_allocated() but runs in coroutine context. Running in
coroutine context implies that other coroutines might be performing I/O
at the same time. Therefore it must be safe to run while the following
BlockDriver functions are in-flight:
.bdrv_co_readv()
.bdrv_co_writev()
.bdrv_co_flush()
.bdrv_co_is_allocated()
The new .bdrv_co_is_allocated() interface is useful because it can be
used when a VM is running, whereas .bdrv_is_allocated() is a synchronous
interface that does not cope with parallel requests.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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There is no need for bdrv_commit() to use the BlockDriver
.bdrv_is_allocated() interface directly. Converting to the public
interface gives us the freedom to drop .bdrv_is_allocated() entirely in
favor of a new .bdrv_co_is_allocated() in the future.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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If the bdrv_read() of the snapshot's L1 table fails, return the right
error code and make sure that the old L1 table is still loaded and we
don't break the BlockDriverState completely.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
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First the snapshot must be deleted and only then the refcounts can be
decreased.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
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The refcount updates must be moved so that in the worst case we can get
cluster leaks, but refcounts may never be too low.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
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Besides fixing the return code, this adds some comments that make clear
how the code works and that it potentially breaks images if we fail in
the wrong place. Actually fixing this is left for the next patch.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
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Increase refcounts only after allocating a new L1 table has succeeded in
order to make leaks less likely. If writing the snapshot table fails,
revert in-memory state to be consistent with that on disk.
While at it, make it return the real error codes instead of -1.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
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sn->id_str could be leaked before this. The rest of this patch changes
comments, fixes coding style or removes checks that are unnecessary with
g_malloc.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
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Failing in the middle wouldn't help with the integrity of the image, so
doing everything in a single request seems better.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
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Doesn't immediately fix anything as the callers don't use the return
value, but they will be fixed next.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
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Looks better when reviewing these source files.
Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Since common file operation functions lack of error detection,
so change them to bdrv series functions.
Signed-off-by: Li Zhi Hui <zhihuili@linux.vnet.ibm.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Xen_disk.c has support for using synchronous I/O instead of asynchronous,
but it is compiled out by default. Remove it.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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This patch is only to refactor some lines of codes to get better and more robust codes.
As you have seen, in qed_read_table_cb() it's nice to
use qiov->size because that function doesn't obviously use a single
struct iovec.
In other two functions, if qiov use more than one struct iovec, the existing way will get wrong nb_sectors.
To make the code more robust, it will be nicer to refactor the existing way as below.
Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Acked-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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A BlockDriverState should not issue requests on itself through the
public block layer interface. Nested, or reentrant, requests are
problematic because they do I/O throttling and request tracking twice.
Features like block layer copy-on-read use request tracking to avoid
race conditions between concurrent requests. The reentrant request will
have to "wait" for its parent request to complete. But the parent is
waiting for the reentrant request to make progress so we have reached
deadlock.
The solution is for block drivers to avoid the public block layer
interfaces for reentrant requests. Instead they should call their own
internal functions if they wish to perform reentrant requests.
This is also a good opportunity to make copy_sectors() a true
coroutine_fn. That means calling bdrv_co_writev() instead of
bdrv_write(). Behavior is unchanged but we're being explicit that this
executes in coroutine context.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Unlocking during COW allows for more parallelism. One change it requires is
that buffers are dynamically allocated instead of just using a per-image
buffer.
While touching the code, drop the synchronous qcow2_read() function and replace
it by a bdrv_read() call.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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Generally $(BUILD_DIR) == $(CURDIR), but that isn't necessarilly the
case, so use $(BUILD_DIR)/qapi-generated for generated files to
avoid potentionally sticking generating files in odd places outside
the build's include paths.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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Fix a bug in handling dotted paths, and exclude directory prefixes
from generated guardnames to avoid odd/pseudo-random guardnames in
generated headers.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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ATR size exceeding the limit is diagnosed, but then we merrily use it
anyway, overrunning card->atr[].
The message is read from a character device. Obvious security
implications unless the other end of the character device is trusted.
Spotted by Coverity. CVE-2011-4111.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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This reverts commit be85c90b74f56dca51782fa3080fcdf88593e045.
This patch is incorrect and breaks the build with a freshly cloned git tree.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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--*dir) option pattern precede --{en,dis}able-usb-redir) patterns in the
option analysis switch, making the latter options have no effect.
There were some --*dir that are supported by Autoconf and not by QEMU configure.
The aim was to let QEMU packagers use the rpm (or similar) macro that overrides
directories for their distribution.
Replace --*dir with exact option names.
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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strtosz() & friends require the size to be at the end of the string,
or be followed by whitespace or ','. I find this surprising, because
the name suggests it works like strtol().
The check simplifies callers that accept exactly that follow set
slightly. No such callers exist.
The check is redundant for callers that accept a smaller follow set,
and thus need to check themselves anyway. Right now, this is the case
for all but one caller. All of them neglected to check, or checked
incorrectly, but the previous few commits fixed them up.
Finally, the check is problematic for callers that accept a larger
follow set. This is the case in monitor_parse_command().
Fortunately, the problems there are relatively harmless.
monitor_parse_command() uses strtosz() for argument type 'o'. When
the last argument is of type 'o', a trailing ',' is diagnosed
differently than other trailing junk:
(qemu) migrate_set_speed 1x
invalid size
(qemu) migrate_set_speed 1,
migrate_set_speed: extraneous characters at the end of line
A related inconsistency exists with non-last arguments. No such
command exists, but let's use memsave to explore the inconsistency.
The monitor permits, but does not require whitespace between
arguments. For instance, "memsave (1-1)1024foo" is parsed as command
memsave with three arguments 0, 1024 and "foo". Yes, this is daft,
but at least it's consistently daft.
If I change memsave's second argument from 'i' to 'o', then "memsave
(1-1)1foo" is rejected, because the size is followed by an 'f'. But
"memsave (1-1)1," is still accepted, and duly saves to file ",".
We don't have any users of strtosz that profit from the check. In the
users we have, it appears to encourage sloppy error checking, or gets
in the way. Drop the bothersome check.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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strtosz_suffix() fails unless the size is followed by 0, whitespace or
','. Useless here, because we need to fail for any junk following the
size, even if it starts with whitespace or ','. Check manually.
Things like "qemu-img create xxx 1024," and "qemu-img convert -S '1024
junk'" are now caught.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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