A bitmap successor is an anonymous BdrvDirtyBitmap that is intended to
be created just prior to a sensitive operation (e.g. Incremental Backup)
that can either succeed or fail, but during the course of which we still
want a bitmap tracking writes.
On creating a successor, we "freeze" the parent bitmap which prevents
its deletion, enabling, anonymization, or creating a bitmap with the
same name.
On success, the parent bitmap can "abdicate" responsibility to the
successor, which will inherit its name. The successor will have been
tracking writes during the course of the backup operation. The parent
will be safely deleted.
On failure, we can "reclaim" the successor from the parent, unifying
them such that the resulting bitmap describes all writes occurring since
the last successful backup, for instance. Reclamation will thaw the
parent, but not explicitly re-enable it.
BdrvDirtyBitmap operations that target a single bitmap are protected
by assertions that the bitmap is not frozen and/or disabled.
BdrvDirtyBitmap operations that target a group of bitmaps, such as
bdrv_{set,reset}_dirty will ignore frozen/disabled drives with a
conditional instead.
Internal functions that enable/disable dirty bitmaps have assertions
added to them to prevent modifying frozen bitmaps.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 1429314609-29776-10-git-send-email-jsnow@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Add a status indicating the enabled/disabled state of the bitmap.
A bitmap is by default enabled, but you can lock the bitmap into
a read-only state by setting disabled = true.
A previous version of this patch added a QMP interface for changing
the state of the bitmap, but it has since been removed for now until
a use case emerges where this state must be revealed to the user.
The disabled state WILL be used internally for bitmap migration and
bitmap persistence.
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1429314609-29776-9-git-send-email-jsnow@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
We add a bitmap merge operation to assist in error cases
where we wish to combine two bitmaps together.
This is algorithmically O(bits) provided HBITMAP_LEVELS remains
constant. For a full bitmap on a 64bit machine:
sum(bits/64^k, k, 0, HBITMAP_LEVELS) ~= 1.01587 * bits
We may be able to improve running speed for particularly sparse
bitmaps by using iterators, but the running time for dense maps
will be worse.
We present the simpler solution first, and we can refine it later
if needed.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1429314609-29776-8-git-send-email-jsnow@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
As a convenience: between incremental backups, bitmap migrations
and bitmap persistence we seem to need to recalculate these a lot.
Because the lengths are a little bit-twiddly, let's just solidly
cache them and be done with it.
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1429314609-29776-7-git-send-email-jsnow@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This returns the granularity (in bytes) of dirty bitmap,
which matches the QMP interface and the existing query
interface.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1429314609-29776-6-git-send-email-jsnow@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The new command pair is added to manage a user created dirty bitmap. The
dirty bitmap's name is mandatory and must be unique for the same device,
but different devices can have bitmaps with the same names.
The granularity is an optional field. If it is not specified, we will
choose a default granularity based on the cluster size if available,
clamped to between 4K and 64K to mirror how the 'mirror' code was
already choosing granularity. If we do not have cluster size info
available, we choose 64K. This code has been factored out into a helper
shared with block/mirror.
This patch also introduces the 'block_dirty_bitmap_lookup' helper,
which takes a device name and a dirty bitmap name and validates the
lookup, returning NULL and setting errp if there is a problem with
either field. This helper will be re-used in future patches in this
series.
The types added to block-core.json will be re-used in future patches
in this series, see:
'qapi: Add transaction support to block-dirty-bitmap-{add, enable, disable}'
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 1429314609-29776-5-git-send-email-jsnow@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
We treat this field with a variety of different types everywhere
in the code. Now it's just uint32_t.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1429314609-29776-4-git-send-email-jsnow@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This field will be set for user created dirty bitmap. Also pass in an
error pointer to bdrv_create_dirty_bitmap, so when a name is already
taken on this BDS, it can report an error message. This is not global
check, two BDSes can have dirty bitmap with a common name.
Implemented bdrv_find_dirty_bitmap to find a dirty bitmap by name, will
be used later when other QMP commands want to reference dirty bitmap by
name.
Add bdrv_dirty_bitmap_make_anon. This unsets the name of dirty bitmap.
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1429314609-29776-3-git-send-email-jsnow@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 1429314609-29776-2-git-send-email-jsnow@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
the allocationmap has only a hint character. The driver always
double checks that blocks marked unallocated in the cache are
still unallocated before taking the fast path and return zeroes.
So using the allocationmap is migration safe and can
also be enabled with cache.direct=on.
Signed-off-by: Peter Lieven <pl@kamp.de>
Message-id: 1429193313-4263-10-git-send-email-pl@kamp.de
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Peter Lieven <pl@kamp.de>
Message-id: 1429193313-4263-9-git-send-email-pl@kamp.de
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
a target may issue a SCSI_STATUS_TASK_SET_FULL status
if there is more than one "BUSY" command queued already.
Signed-off-by: Peter Lieven <pl@kamp.de>
Message-id: 1429193313-4263-8-git-send-email-pl@kamp.de
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The idea is that a command is retried in a BUSY condition
up a time of approx. 60 seconds before it is failed. This should
be far higher than any command timeout in the guest.
Signed-off-by: Peter Lieven <pl@kamp.de>
Message-id: 1429193313-4263-7-git-send-email-pl@kamp.de
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
SCSI allowes to tell the target to not return from a write command
if the date is not written to the disk. Use this so called FUA
bit if it is supported to optimize WRITE commands if writeback is
not allowed.
In this case qemu always issues a WRITE followed by a FLUSH. This
is 2 round trip times. If we set the FUA bit we can ignore the
following FLUSH.
Signed-off-by: Peter Lieven <pl@kamp.de>
Message-id: 1429193313-4263-6-git-send-email-pl@kamp.de
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Peter Lieven <pl@kamp.de>
Message-id: 1429193313-4263-5-git-send-email-pl@kamp.de
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Peter Lieven <pl@kamp.de>
Message-id: 1429193313-4263-4-git-send-email-pl@kamp.de
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Peter Lieven <pl@kamp.de>
Message-id: 1429193313-4263-3-git-send-email-pl@kamp.de
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
We actually were always impolitely dropping the connection and
not cleanly logging out.
CC: qemu-stable@nongnu.org
Signed-off-by: Peter Lieven <pl@kamp.de>
Message-id: 1429193313-4263-2-git-send-email-pl@kamp.de
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The image field in BlockDeviceInfo is supposed to contain an ImageInfo
object. However that is being filled in by bdrv_query_info(), not by
bdrv_block_device_info(), which is where BlockDeviceInfo is actually
created.
Anyone calling bdrv_block_device_info() directly will get a null image
field. As a consequence of this, the HMP command 'info block -n -v'
crashes QEMU.
This patch moves the code that fills in that field from
bdrv_query_info() to bdrv_block_device_info().
Signed-off-by: Alberto Garcia <berto@igalia.com>
Message-id: 1429271563-3765-1-git-send-email-berto@igalia.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Since this event can occur in nodes that cannot have a device name
associated, include also a field with the node name.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 147cec5b3594f4bec0cb41c98afe5fcbfb67567c.1428485266.git.berto@igalia.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
There are several error messages that identify a BlockDriverState by
its device name. However those errors can be produced in nodes that
don't have a device name associated.
In those cases we should use bdrv_get_device_or_node_name() to fall
back to the node name and produce a more meaningful message. The
messages are also updated to use the more generic term 'node' instead
of 'device'.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 9823a1f0514fdb0692e92868661c38a9e00a12d6.1428485266.git.berto@igalia.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This function gets the device name associated with a BlockDriverState,
or its node name if the device name is empty.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 4fa30aa8d61d9052ce266fd5429a59a14e941255.1428485266.git.berto@igalia.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The 'block-stream' QMP command is documented in block-core.json but not
qmp-commands.hx. Add a summary of the command to qmp-commands.hx
(similar to the documentation for 'block-commit').
Reported-by: Kashyap Chamarthy <kchamart@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 1429094622-26218-1-git-send-email-stefanha@redhat.com
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Delay the call to blk_blockalign() until s->blk has been assigned.
This never caused a crash because blk_blockalign(NULL, size) defaults to
4096 alignment but it's technically incorrect.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1429091024-25098-1-git-send-email-stefanha@redhat.com
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Of the block devices that poked into -drive options via drive_get_next,
m25p80 was the only one who also did not attach itself to the BlockBackend.
Since sd does it, and all other devices go through a "drive" property,
with this change all block backends attached to the guest will have a
non-NULL result for blk_get_attached_dev().
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Message-id: 1429025387-11077-1-git-send-email-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
update virtio blk header from latest linux, include comment fixups.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-id: 1428854036-12806-1-git-send-email-mst@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
bdrv_aio_* APIs can use coroutines to achieve asynchronicity. However,
the coroutine may terminate without having yielded back to the caller
(for example because of something that invokes a nested event loop,
or because the coroutine is doing nothing at all). In this case,
the bdrv_aio_* API must delay the completion to the next iteration
of the main loop, because bdrv_aio_* will never invoke the callback
before returning.
This can be done with a bottom half, and indeed bdrv_aio_* is always
using one for simplicity. It is possible to gain some performance
(~3%) by avoiding this in the common case. A new field in the
BlockAIOCBCoroutine struct is set to true until the first time the
corotine has yielded to its creator, and completion goes through a
new function bdrv_co_complete. If the flag is false, bdrv_co_complete
invokes the callback immediately. If it is true, the caller will
notice that the coroutine has completed and schedule the bottom
half itself.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1427524638-28157-1-git-send-email-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 1428069921-2957-5-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 1428069921-2957-4-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This is necessary to suppress more IO requests from being generated from
block job coroutines.
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 1428069921-2957-3-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This patch changes block_job_pause to increase the pause counter and
block_job_resume to decrease it.
The counter will allow calling block_job_pause/block_job_resume
unconditionally on a job when we need to suspend the IO temporarily.
From now on, each block_job_resume must be paired with a block_job_pause
to keep the counter balanced.
The user pause from QMP or HMP will only trigger block_job_pause once
until it's resumed, this is achieved by adding a user_paused flag in
BlockJob.
One occurrence of block_job_resume in mirror_complete is replaced with
block_job_enter which does what is necessary.
In block_job_cancel, the cancel flag is good enough to instruct
coroutines to quit loop, so use block_job_enter to replace the unpaired
block_job_resume.
Upon block job IO error, user is notified about the entering to the
pause state, so this pause belongs to user pause, set the flag
accordingly and expect a matching QMP resume.
[Extended doc comments as suggested by Paolo Bonzini
<pbonzini@redhat.com>.
--Stefan]
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 1428069921-2957-2-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1427852740-24315-4-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reopen is used in block-commit. With this always-succeed operation, it
is now possible to test committing to a null drive, by specifying
"null-aio://" or "null-co://" as the backing image when creating the
qcow2 image.
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1427852740-24315-3-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Aio context switch should just work because the requests will be
drained, so the scheduled timer(s) on the old context will be freed.
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1427852740-24315-2-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The 'qemu coroutine <coroutine-address>' GDB command prints the
backtrace for a CoroutineUContext. This is useful for peeking inside
yielded coroutines that are waiting for file descriptor events, timers,
etc.
For example:
$ gdb tests/test-coroutine
(gdb) b test_yield
(gdb) r
(gdb) b qemu_coroutine_enter
(gdb) c
(gdb) c
Continuing.
Breakpoint 2, qemu_coroutine_enter (co=0x555555c66520, opaque=0x0) at qemu-coroutine.c:103
103 {
(gdb) source scripts/qemu-gdb.py
(gdb) qemu coroutine 0x555555c66520
#0 0x000055555557a740 in qemu_coroutine_switch (from_=<optimized out>, to_=0x7ffff7f90a70, action=COROUTINE_YIELD) at coroutine-ucontext.c:177
#1 0x0000555555566af9 in yield_5_times (opaque=0x7fffffffdbb7) at tests/test-coroutine.c:107
#2 0x000055555557a7aa in coroutine_trampoline (i0=<optimized out>, i1=<optimized out>) at coroutine-ucontext.c:80
#3 0x00007ffff08de000 in __start_context () at /lib64/libc.so.6
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1427409754-8556-1-git-send-email-stefanha@redhat.com
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This patch simplifies thread_pool_completion_bh().
The function first checks elem->state:
if (elem->state != THREAD_DONE) {
continue;
}
It then goes on to check elem->state == THREAD_DONE although we already
know this must be the case.
The QLIST_REMOVE() is duplicated down both branches of an if-else
statement so that can be lifted out as well.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1427992762-10126-1-git-send-email-stefanha@redhat.com
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Fix the length of the zero-fill for the back, which was accidentally
using the same value as for the front. This is caught by qemu-iotests
033.
For consistency, change the code for the front as well to use the length
stored in the iov (it is the same value, copied four lines above).
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Jeff Cody <jcody@redhat.com>
This is, amongst others, required for qemu-iotests 033 to run as
intended on VHDX, which uses explicit bdrv_truncate() calls to bs->file
when allocating new blocks.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
This adds a regression test for some problems that the qemu-img convert
rewrite just fixed.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
The implementation of qemu-img convert is (a) messy, (b) buggy, and
(c) less efficient than possible. The changes required to beat some
sense into it are massive enough that incremental changes would only
make my and the reviewers' life harder. So throw it away and reimplement
it from scratch.
Let me give some examples what I mean by messy, buggy and inefficient:
(a) The copying logic of qemu-img convert has two separate branches for
compressed and normal target images, which roughly do the same -
except for a little code that handles actual differences between
compressed and uncompressed images, and much more code that
implements just a different set of optimisations and bugs. This is
unnecessary code duplication, and makes the code for compressed
output (unsurprisingly) suffer from bitrot.
The code for uncompressed ouput is run twice to count the the total
length for the progress bar. In the first run it just takes a
shortcut and runs only half the loop, and when it's done, it toggles
a boolean, jumps out of the loop with a backwards goto and starts
over. Works, but pretty is something different.
(b) Converting while keeping a backing file (-B option) is broken in
several ways. This includes not writing to the image file if the
input has zero clusters or data filled with zeros (ignoring that the
backing file will be visible instead).
It also doesn't correctly limit every iteration of the copy loop to
sectors of the same status so that too many sectors may be copied to
in the target image. For -B this gives an unexpected result, for
other images it just does more work than necessary.
Conversion with a compressed target completely ignores any target
backing file.
(c) qemu-img convert skips reading and writing an area if it knows from
metadata that copying isn't needed (except for the bug mentioned
above that ignores a status change in some cases). It does, however,
read from the source even if it knows that it will read zeros, and
then search for non-zero bytes in the read buffer, if it's possible
that a write might be needed.
This reimplementation of the copying core reorganises the code to remove
the duplication and have a much more obvious code flow, by essentially
splitting the copy iteration loop into three parts:
1. Find the number of contiguous sectors of the same status at the
current offset (This can also be called in a separate loop before the
copying loop in order to determine the total sectors for the progress
bar.)
2. Read sectors. If the status implies that there is no data there to
read (zero or unallocated cluster), don't do anything.
3. Write sectors depending on the status. If it's data, write it. If
we want the backing file to be visible (with -B), don't write it. If
it's zeroed, skip it if you can, otherwise use bdrv_write_zeroes() to
optimise the write at least where possible.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
This is the first step towards having fine-grained critical sections in
dataplane threads, which resolves lock ordering problems between
address_space_* functions (which need the BQL when doing MMIO, even
after we complete RCU-based dispatch) and the AioContext.
Because AioContext does not use contention callbacks anymore, the
unit test has to be changed.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1424449612-18215-4-git-send-email-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This is the first step in pushing down acquire/release, and will let
rfifolock drop the contention callback feature.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1424449612-18215-3-git-send-email-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
By using thread-local storage, aio_poll can stop using global data during
g_poll_ns. This will make it possible to drop callbacks from rfifolock.
[Moved npfd = 0 assignment to end of walking_handlers region as
suggested by Paolo. This resolves the assert(npfd == 0) assertion
failure in pollfds_cleanup().
--Stefan]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1424449612-18215-2-git-send-email-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Currently, throttle timers won't make any progress when VCPU is not
running, which would stall the request queue in utils, qtest, vm
suspending, and live migration, without special handling.
Block jobs are confusingly inconsistent between with and without
throttling: if user sets a bps limit, stops the vm, then start a block
job, the block job will not make any progress; in contrary, if user
unsets the bps limit, or if it's not set, the block job will run
normally.
After this patch, with the host clock, even if the VCPUs are stopped,
the throttle queues will be processed.
This patch also enables potential to add throttle to bdrv_drain_all.
Currently all requests are drained immediately. In other words whenever
it is called, IO throttling goes ineffective (examples: system reset,
migration and many block job operations.). This is a loophole that guest
could exploit. If we use the host clock, we can later just trust the
nested poll. This could be done on top.
Note that for qemu-iotests case 093, which uses qtest, we still keep vm
clock so the script can control the clock stepping in order to be
deterministic.
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Message-id: 1427268446-6426-1-git-send-email-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The ffs(3) family of functions is not portable. MinGW doesn't always
provide the function.
Use ctz32() or ctz64() instead.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1427124571-28598-10-git-send-email-stefanha@redhat.com
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The lack of ffs(3) in the MinGW headers is a hint that we shouldn't rely
on it. MinGW 4.9.2 does not make it available for linking when QEMU's
./configure --enable-debug is used (release builds are fine though).
Now that all QEMU code has been switched to ctz32() there is no need for
ffs(3).
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1427124571-28598-9-git-send-email-stefanha@redhat.com
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Rewrite the loop using level &= level - 1 to clear the least significant
bit after each iteration. This simplifies the loop and makes it easy to
replace ffs(3) with ctz32().
Cc: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1427124571-28598-8-git-send-email-stefanha@redhat.com
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
ffs() cannot be replaced with ctz32() when the argument might be zero,
because ffs(0) returns 0 while ctz32(0) returns 32.
The ffs(3) call in sd_normal_command() is a special case though. It can
be converted to ctz32() + 1 because the argument is never zero:
if (!(req.arg >> 8) || (req.arg >> (ctz32(req.arg & ~0xff) + 1))) {
~~~~~~~~~~~~~~~
^--------------- req.arg cannot be zero
Cc: Markus Armbruster <armbru@redhat.com>
Cc: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1427124571-28598-7-git-send-email-stefanha@redhat.com
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
