Many changes were necessary this time around:
* QAPI was changed to avoid redundant has_* variables, see commit
44ea9d9be3 ("qapi: Start to elide redundant has_FOO in generated C")
for details. This affected many QMP commands added by Proxmox too.
* Pending querying for migration got split into two functions, one to
estimate, one for exact value, see commit c8df4a7aef ("migration:
Split save_live_pending() into state_pending_*") for details. Relevant
for savevm-async and PBS dirty bitmap.
* Some block (driver) functions got converted to coroutines, so the
Proxmox block drivers needed to be adapted.
* Alloc track auto-detaching during PBS live restore got broken by
AioContext-related changes resulting in a deadlock. The current, hacky
method was replaced by a simpler one. Stefan apparently ran into a
problem with that when he wrote the driver, but there were
improvements in the stream job code since then and I didn't manage to
reproduce the issue. It's a separate patch "alloc-track: fix deadlock
during drop" for now, you can find the details there.
* Async snapshot-related changes:
- The pending querying got adapted to the above-mentioned split and
a patch is added to optimize it/make it more similar to what
upstream code does.
- Added initialization of the compression counters (for
future-proofing).
- It's necessary the hold the BQL (big QEMU lock = iothread mutex)
during the setup phase, because block layer functions are used there
and not doing so leads to racy, hard-to-debug crashes or hangs. It's
necessary to change some upstream code too for this, a version of
the patch "migration: for snapshots, hold the BQL during setup
callbacks" is intended to be upstreamed.
- Need to take the bdrv graph read lock before flushing.
* hmp_info_balloon was moved to a different file.
* Needed to include a new headers from time to time to still get the
correct functions.
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
User-facing breaking change:
The slirp submodule for user networking got removed. It would be
necessary to add the --enable-slirp option to the build and/or install
the appropriate library to continue building it. Since PVE is not
explicitly supporting it, it would require additionally installing the
libslirp0 package on all installations and there is *very* little
mention on the community forum when searching for "slirp" or
"netdev user", the plan is to only enable it again if there is some
real demand for it.
Notable changes:
* The big change for this release is the rework of job locking, using
a job mutex and introducing _locked() variants of job API functions
moving away from call-side AioContext locking. See (in the qemu
submodule) commit 6f592e5aca ("job.c: enable job lock/unlock and
remove Aiocontext locks") and previous commits for context.
Changes required for the backup patches:
* Use WITH_JOB_LOCK_GUARD() and call the _locked() variant of job
API functions where appropriate (many are only availalbe as
a _locked() variant).
* Remove acquiring/releasing AioContext around functions taking the
job mutex lock internally.
The patch introducing sequential transaction support for jobs needs
to temporarily unlock the job mutex to call job_start() when
starting the next job in the transaction.
* The zeroinit block driver now marks its child as primary.
The documentation in include/block/block-common.h states:
> Filter node has exactly one FILTERED|PRIMARY child, and may have
> other children which must not have these bits
Without this, an assert will trigger when copying to a zeroinit target
with qemu-img convert, because bdrv_child_cb_attach() expects any
non-PRIMARY child to be not FILTERED:
> qemu-img convert -n -p -f raw -O raw input.raw zeroinit:output.raw
> qemu-img: ../block.c:1476: bdrv_child_cb_attach: Assertion
> `!(child->role & BDRV_CHILD_FILTERED)' failed.
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Notable changes:
* The only big change is the switch to using a custom QIOChannel for
savevm-async, because the previously used QEMUFileOps was dropped.
Changes to the current implementation:
* Switch to vector based methods as required for an IO channel. For
short reads the passed-in IO vector is stuffed with zeroes at the
end, just to be sure.
* For reading: The documentation in include/io/channel.h states that
at least one byte should be read, so also error out when whe are
at the very end instead of returning 0.
* For reading: Fix off-by-one error when request goes beyond end.
The wrong code piece was:
if ((pos + size) > maxlen) {
size = maxlen - pos - 1;
}
Previously, the last byte would not be read. It's actually
possible to get a snapshot .raw file that has content all the way
up the final 512 byte (= BDRV_SECTOR_SIZE) boundary without any
trailing zero bytes (I wrote a script to do it).
Luckily, it didn't cause a real issue, because qemu_loadvm_state()
is not interested in the final (i.e. QEMU_VM_VMDESCRIPTION)
section. The buffer for reading it is simply freed up afterwards
and the function will assume that it read the whole section, even
if that's not the case.
* For writing: Make use of the generated blk_pwritev() wrapper
instead of manually wrapping the coroutine to simplify and save a
few lines.
* Adapt to changed interfaces for blk_{pread,pwrite}:
* a9262f551e ("block: Change blk_{pread,pwrite}() param order")
* 3b35d4542c ("block: Add a 'flags' param to blk_pread()")
* bf5b16fa40 ("block: Make blk_{pread,pwrite}() return 0 on success")
Those changes especially affected the qemu-img dd patches, because
the context also changed, but also some of our block drivers used
the functions.
* Drop qemu-common.h include: it got renamed after essentially
everything was moved to other headers. The only remaining user I
could find for things dropped from the header between 7.0 and 7.1
was qemu_get_vm_name() in the iscsi-initiatorname patch, but it
already includes the header to which the function was moved.
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Fiona Ebner