With the thread pool disabled, we add the requests in the queue to a
GList, processing by iterating over there afterwards.

For adding them, we're using "g_list_prepend()", which is more
efficient but causes the requests to be processed in reverse order,
breaking the read-ahead and request-merging optimizations in the host
for sequential operations.

According to the documentation, if you need to process the request
in-order, using "g_list_prepend()" and then reversing the list with
"g_list_reverse()" is more efficient than using "g_list_append()", so
let's do it that way.

Testing on a spinning disk (to boost the increase of read-ahead and
request-merging) shows a 4x improvement on sequential write fio test:

Test:
fio --directory=/mnt/virtio-fs --filename=fio-file1 --runtime=20
--iodepth=16 --size=4G --direct=1 --blocksize=4K --ioengine libaio
--rw write --name seqwrite-libaio

Without "g_list_reverse()":
...
Jobs: 1 (f=1): [W(1)][100.0%][w=22.4MiB/s][w=5735 IOPS][eta 00m:00s]
seqwrite-libaio: (groupid=0, jobs=1): err= 0: pid=710: Tue Aug 24 12:58:16 2021
  write: IOPS=5709, BW=22.3MiB/s (23.4MB/s)(446MiB/20002msec); 0 zone resets
...

With "g_list_reverse()":
...
Jobs: 1 (f=1): [W(1)][100.0%][w=84.0MiB/s][w=21.5k IOPS][eta 00m:00s]
seqwrite-libaio: (groupid=0, jobs=1): err= 0: pid=716: Tue Aug 24 13:00:15 2021
  write: IOPS=21.3k, BW=83.1MiB/s (87.2MB/s)(1663MiB/20001msec); 0 zone resets
...

Signed-off-by: Sergio Lopez <slp@redhat.com>
Message-Id: <20210824131158.39970-1-slp@redhat.com>
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

The virtiofsd currently crashes on s390x when doing something like
this in the guest:

 mkdir -p /mnt/myfs
 mount -t virtiofs myfs /mnt/myfs
 touch /mnt/myfs/foo.txt
 stat -f /mnt/myfs/foo.txt

The problem is that the fstatfs64 syscall is called in this case
from the virtiofsd. We have to put it on the seccomp allowlist to
avoid that the daemon gets killed in this case.

Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2001728


Suggested-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20210914123214.181885-1-thuth@redhat.com>
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Sergio Lopez <slp@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

Block patches:
- Block-status cache for data regions
- qcow2 optimization (when using subclusters)
- iotests delinting, and let 297 (lint checker) cover named iotests
- qcow2 check improvements
- Added -F (target backing file format) option to qemu-img convert
- Mirror job fix
- Fix for when a migration is initiated while a backup job runs
- Fix for uncached qemu-img convert to a volume with 4k sectors (for an
  unaligned image)
- Minor gluster driver fix

# gpg: Signature made Wed 15 Sep 2021 18:39:11 BST
# gpg:                using RSA key CB62D7A0EE3829E45F004D34A1FA40D098019CDF
# gpg:                issuer "hreitz@redhat.com"
# gpg: Good signature from "Hanna Reitz <hreitz@redhat.com>" [marginal]
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg:          It is not certain that the signature belongs to the owner.
# Primary key fingerprint: CB62 D7A0 EE38 29E4 5F00  4D34 A1FA 40D0 9801 9CDF

* remotes/hreitz/tags/pull-block-2021-09-15: (32 commits)
  qemu-img: Add -F shorthand to convert
  qcow2-refcount: check_refblocks(): add separate message for reserved
  qcow2-refcount: check_refcounts_l1(): check reserved bits
  qcow2-refcount: improve style of check_refcounts_l1()
  qcow2-refcount: check_refcounts_l2(): check reserved bits
  qcow2-refcount: check_refcounts_l2(): check l2_bitmap
  qcow2-refcount: fix_l2_entry_by_zero(): also zero L2 entry bitmap
  qcow2-refcount: introduce fix_l2_entry_by_zero()
  qcow2: introduce qcow2_parse_compressed_l2_entry() helper
  qcow2: compressed read: simplify cluster descriptor passing
  qcow2-refcount: improve style of check_refcounts_l2()
  qemu-img: Allow target be aligned to sector size
  qcow2: handle_dependencies(): relax conflict detection
  qcow2: refactor handle_dependencies() loop body
  simplebench: add img_bench_templater.py
  block: bdrv_inactivate_recurse(): check for permissions and fix crash
  tests: add migrate-during-backup
  block/mirror: fix NULL pointer dereference in mirror_wait_on_conflicts()
  iotests/297: Cover tests/
  mirror-top-perms: Fix AbnormalShutdown path
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Although we have long supported 'qemu-img convert -o
backing_file=foo,backing_fmt=bar', the fact that we have a shortcut -B
for backing_file but none for backing_fmt has made it more likely that
users accidentally run into:

qemu-img: warning: Deprecated use of backing file without explicit backing format

when using -B instead of -o.  For similarity with other qemu-img
commands, such as create and compare, add '-F $fmt' as the shorthand
for '-o backing_fmt=$fmt'.  Update iotest 122 for coverage of both
spellings.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210913131735.1948339-1-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

Split checking for reserved bits out of aligned offset check.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210914122454.141075-11-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210914122454.141075-10-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

 - use g_autofree for l1_table
 - better name for size in bytes variable
 - reduce code blocks nesting
 - whitespaces, braces, newlines

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210914122454.141075-9-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210914122454.141075-8-vsementsov@virtuozzo.com>
[hreitz: Separated `type` declaration from statements]
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

Check subcluster bitmap of the l2 entry for different types of
clusters:

 - for compressed it must be zero
 - for allocated check consistency of two parts of the bitmap
 - for unallocated all subclusters should be unallocated
   (or zero-plain)

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Tested-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Message-Id: <20210914122454.141075-7-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

We'll reuse the function to fix wrong L2 entry bitmap. Support it now.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210914122454.141075-6-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

Split fix_l2_entry_by_zero() out of check_refcounts_l2() to be
reused in further patch.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210914122454.141075-5-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

Add helper to parse compressed l2_entry and use it everywhere instead
of open-coding.

Note, that in most places we move to precise coffset/csize instead of
sector-aligned. Still it should work good enough for updating
refcounts.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210914122454.141075-4-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

Let's pass the whole L2 entry and not bother with
L2E_COMPRESSED_OFFSET_SIZE_MASK.

It also helps further refactoring that adds generic
qcow2_parse_compressed_l2_entry() helper.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210914122454.141075-3-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

 - don't use same name for size in bytes and in entries
 - use g_autofree for l2_table
 - add whitespace
 - fix block comment style

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210914122454.141075-2-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

If a gitlab CI job is marked as manual-only but is not marked
as allow_failure, then gitlab considers that the pipeline is
"blocked" until the job has been manually triggered. We need
to mark these manual-only jobs as also allow_failure: true
so that gitlab doesn't insist that they have run before it
will consider the pipeline to be complete.

Fixes: 4c9af1ea
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-id: 20210915123412.8232-1-peter.maydell@linaro.org
Acked-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Willian Rampazzo <willianr@redhat.com>

We cannot write to images opened with O_DIRECT unless we allow them to
be resized so they are aligned to the sector size: Since 9c60a5d1,
bdrv_node_refresh_perm() ensures that for nodes whose length is not
aligned to the request alignment and where someone has taken a WRITE
permission, the RESIZE permission is taken, too).

Let qemu-img convert pass the BDRV_O_RESIZE flag (which causes
blk_new_open() to take the RESIZE permission) when using cache=none for
the target, so that when writing to it, it can be aligned to the target
sector size.

Without this patch, an error is returned:

$ qemu-img convert -f raw -O raw -t none foo.img /mnt/tmp/foo.img
qemu-img: Could not open '/mnt/tmp/foo.img': Cannot get 'write'
permission without 'resize': Image size is not a multiple of request
alignment

Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1994266


Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210819101200.64235-1-hreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

There is no conflict and no dependency if we have parallel writes to
different subclusters of one cluster when the cluster itself is already
allocated. So, relax extra dependency.

Measure performance:
First, prepare build/qemu-img-old and build/qemu-img-new images.

cd scripts/simplebench
./img_bench_templater.py

Paste the following to stdin of running script:

qemu_img=../../build/qemu-img-{old|new}
$qemu_img create -f qcow2 -o extended_l2=on /ssd/x.qcow2 1G
$qemu_img bench -c 100000 -d 8 [-s 2K|-s 2K -o 512|-s $((1024*2+512))] \
        -w -t none -n /ssd/x.qcow2

The result:

All results are in seconds

------------------  ---------  ---------
                    old        new
-s 2K               6.7 ± 15%  6.2 ± 12%
                                 -7%
-s 2K -o 512        13 ± 3%    11 ± 5%
                                 -16%
-s $((1024*2+512))  9.5 ± 4%   8.4
                                 -12%
------------------  ---------  ---------

So small writes are more independent now and that helps to keep deeper
io queue which improves performance.

271 iotest output becomes racy for three allocation in one cluster.
Second and third writes may finish in different order. Second and
third requests don't depend on each other any more. Still they both
depend on first request anyway. Filter out second and third write
offsets to cover both possible outputs.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210824101517.59802-4-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
[hreitz: s/ an / and /]
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

No logic change, just prepare for the following commit. While being
here do also small grammar fix in a comment.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210824101517.59802-3-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

Add simple grammar-parsing template benchmark. New tool consume test
template written in bash with some special grammar injections and
produces multiple tests, run them and finally print a performance
comparison table of different tests produced from one template.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210824101517.59802-2-vsementsov@virtuozzo.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

We must not inactivate child when parent has write permissions on
it.

Calling .bdrv_inactivate() doesn't help: actually only qcow2 has this
handler and it is used to flush caches, not for permission
manipulations.

So, let's simply check cumulative parent permissions before
inactivating the node.

This commit fixes a crash when we do migration during backup: prior to
the commit nothing prevents all nodes inactivation at migration finish
and following backup write to the target crashes on assertion
"assert(!(bs->open_flags & BDRV_O_INACTIVE));" in
bdrv_co_write_req_prepare().

After the commit, we rely on the fact that copy-before-write filter
keeps write permission on target node to be able to write to it. So
inactivation fails and migration fails as expected.

Corresponding test now passes, so, enable it.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210911120027.8063-3-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

Add a simple test which tries to run migration during backup.
bdrv_inactivate_all() should fail. But due to bug (see next commit with
fix) it doesn't, nodes are inactivated and continued backup crashes
on assertion "assert(!(bs->open_flags & BDRV_O_INACTIVE));" in
bdrv_co_write_req_prepare().

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210911120027.8063-2-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

In mirror_iteration() we call mirror_wait_on_conflicts() with
`self` parameter set to NULL.

Starting from commit d44dae1a we dereference `self` pointer in
mirror_wait_on_conflicts() without checks if it is not NULL.

Backtrace:
  Program terminated with signal SIGSEGV, Segmentation fault.
  #0  mirror_wait_on_conflicts (self=0x0, s=<optimized out>, offset=<optimized out>, bytes=<optimized out>)
      at ../block/mirror.c:172
  172	                self->waiting_for_op = op;
  [Current thread is 1 (Thread 0x7f0908931ec0 (LWP 380249))]
  (gdb) bt
  #0  mirror_wait_on_conflicts (self=0x0, s=<optimized out>, offset=<optimized out>, bytes=<optimized out>)
      at ../block/mirror.c:172
  #1  0x00005610c5d9d631 in mirror_run (job=0x5610c76a2c00, errp=<optimized out>) at ../block/mirror.c:491
  #2  0x00005610c5d58726 in job_co_entry (opaque=0x5610c76a2c00) at ../job.c:917
  #3  0x00005610c5f046c6 in coroutine_trampoline (i0=<optimized out>, i1=<optimized out>)
      at ../util/coroutine-ucontext.c:173
  #4  0x00007f0909975820 in ?? () at ../sysdeps/unix/sysv/linux/x86_64/__start_context.S:91
      from /usr/lib64/libc.so.6

Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2001404


Fixes: d44dae1a ("block/mirror: fix active mirror dead-lock in mirror_wait_on_conflicts")
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20210910124533.288318-1-sgarzare@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

297 so far does not check the named tests, which reside in the tests/
directory (i.e. full path tests/qemu-iotests/tests).  Fix it.

Thanks to the previous two commits, all named tests pass its scrutiny,
so we do not have to add anything to SKIP_FILES.

Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Willian Rampazzo <willianr@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210902094017.32902-6-hreitz@redhat.com>

The AbnormalShutdown exception class is not in qemu.machine, but in
qemu.machine.machine.  (qemu.machine.AbnormalShutdown was enough for
Python to find it in order to run this test, but pylint complains about
it.)

Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210902094017.32902-5-hreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

There are a couple of things pylint takes issue with:
- The "time" import is unused
- The import order (iotests should come last)
- get_bitmap_hash() doesn't use @self and so should be a function
- Semicolons at the end of some lines
- Parentheses after "if"
- Some lines are too long (80 characters instead of 79)
- inject_test_case()'s @name parameter shadows a top-level @name
  variable
- "lambda self: mc(self)" were equivalent to just "mc", but in
  inject_test_case(), it is not equivalent, so add a comment and disable
  the warning locally
- Always put two empty lines after a function
- f'exec: cat > /dev/null' does not need to be an f-string

Fix them.

Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210902094017.32902-4-hreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

pylint complains that discards1_sha256 and all_discards_sha256 are first
set in non-__init__ methods.

These variables are not really class-variables anyway, so let them
instead be returned by start_postcopy(), thus silencing pylint.

Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210902094017.32902-3-hreitz@redhat.com>

169 and 199 have been renamed and moved to tests/ (commit a44be033:
"iotests: rename and move 169 and 199 tests"), so we can drop them from
the skip list.

Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Willian Rampazzo <willianr@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210902094017.32902-2-hreitz@redhat.com>

pylint proposes using `[]` instead of `list()` and `{}` instead of
`dict()`, because it is faster.  That seems simple enough, so heed its
advice.

Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210824153540.177128-3-hreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

As of recently, pylint complains when `open()` calls are missing an
`encoding=` specified.  Everything we have should be UTF-8 (and in fact,
everything should be UTF-8, period (exceptions apply)), so use that.

Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210824153540.177128-2-hreitz@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>

bdrv_co_block_status() does it for us, we do not need to do it here.

The advantage of not capping *pnum is that bdrv_co_block_status() can
cache larger data regions than requested by its caller.

Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210812084148.14458-7-hreitz@redhat.com>

bdrv_co_block_status() does it for us, we do not need to do it here.

The advantage of not capping *pnum is that bdrv_co_block_status() can
cache larger data regions than requested by its caller.

Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210812084148.14458-6-hreitz@redhat.com>

bdrv_co_block_status() does it for us, we do not need to do it here.

The advantage of not capping *pnum is that bdrv_co_block_status() can
cache larger data regions than requested by its caller.

Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210812084148.14458-5-hreitz@redhat.com>

.bdrv_co_block_status() implementations are free to return a *pnum that
exceeds @bytes, because bdrv_co_block_status() in block/io.c will clamp
*pnum as necessary.

On the other hand, if drivers' implementations return values for *pnum
that are as large as possible, our recently introduced block-status
cache will become more effective.

So, make a note in block_int.h that @bytes is no upper limit for *pnum.

Suggested-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210812084148.14458-4-hreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

As we have attempted before
(https://lists.gnu.org/archive/html/qemu-devel/2019-01/msg06451.html,
"file-posix: Cache lseek result for data regions";
https://lists.nongnu.org/archive/html/qemu-block/2021-02/msg00934.html,
"file-posix: Cache next hole"), this patch seeks to reduce the number of
SEEK_DATA/HOLE operations the file-posix driver has to perform.  The
main difference is that this time it is implemented as part of the
general block layer code.

The problem we face is that on some filesystems or in some
circumstances, SEEK_DATA/HOLE is unreasonably slow.  Given the
implementation is outside of qemu, there is little we can do about its
performance.

We have already introduced the want_zero parameter to
bdrv_co_block_status() to reduce the number of SEEK_DATA/HOLE calls
unless we really want zero information; but sometimes we do want that
information, because for files that consist largely of zero areas,
special-casing those areas can give large performance boosts.  So the
real problem is with files that consist largely of data, so that
inquiring the block status does not gain us much performance, but where
such an inquiry itself takes a lot of time.

To address this, we want to cache data regions.  Most of the time, when
bad performance is reported, it is in places where the image is iterated
over from start to end (qemu-img convert or the mirror job), so a simple
yet effective solution is to cache only the current data region.

(Note that only caching data regions but not zero regions means that
returning false information from the cache is not catastrophic: Treating
zeroes as data is fine.  While we try to invalidate the cache on zero
writes and discards, such incongruences may still occur when there are
other processes writing to the image.)

We only use the cache for nodes without children (i.e. protocol nodes),
because that is where the problem is: Drivers that rely on block-status
implementations outside of qemu (e.g. SEEK_DATA/HOLE).

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/307


Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Message-Id: <20210812084148.14458-3-hreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
[hreitz: Added `local_file == bs` assertion, as suggested by Vladimir]
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

There is a comment above the BDS definition stating care must be taken
to consider handling newly added fields in bdrv_append().

Actually, this comment should have said "bdrv_swap()" as of 4ddc07ca
(nine years ago), and in any case, bdrv_swap() was dropped in
8e419aef (six years ago).  So no such care is necessary anymore.

Signed-off-by: Hanna Reitz <hreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20210812084148.14458-2-hreitz@redhat.com>

gluster's block-status implementation is basically a copy of that in
block/file-posix.c, there is only one thing missing, and that is
aligning trailing data extents to the request alignment (as added by
commit 9c3db310).

Note that 9c3db310 mentions that "there seems to be no other block
driver that sets request_alignment and [...]", but while block/gluster.c
does indeed not set request_alignment, block/io.c's
bdrv_refresh_limits() will still default to an alignment of 512 because
block/gluster.c does not provide a byte-aligned read function.
Therefore, unaligned tails can conceivably occur, and so we should apply
the change from 9c3db310 to gluster's block-status implementation.

Reported-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210805143603.59503-1-mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>

Fix translation race condition for user-only.
Fix tcg/i386 encoding for VPSLLVQ, VPSRLVQ.
Fix tcg/arm tcg_out_vec_op signature.
Fix tcg/ppc (32bit) build with clang.
Remove dupluate TCG_KICK_PERIOD definition.
Remove unused tcg_global_reg_new.
Restrict cpu_exec_interrupt and its callees to sysemu.
Cleanups for tcg/arm.

# gpg: Signature made Tue 14 Sep 2021 20:28:35 BST
# gpg:                using RSA key 7A481E78868B4DB6A85A05C064DF38E8AF7E215F
# gpg:                issuer "richard.henderson@linaro.org"
# gpg: Good signature from "Richard Henderson <richard.henderson@linaro.org>" [full]
# Primary key fingerprint: 7A48 1E78 868B 4DB6 A85A  05C0 64DF 38E8 AF7E 215F

* remotes/rth-gitlab/tags/pull-tcg-20210914-4: (43 commits)
  tcg/arm: More use of the TCGReg enum
  tcg/arm: More use of the ARMInsn enum
  tcg/arm: Give enum arm_cond_code_e a typedef and use it
  tcg/arm: Drop inline markers
  tcg/arm: Simplify usage of encode_imm
  tcg/arm: Split out tcg_out_ldstm
  tcg/arm: Support armv4t in tcg_out_goto and tcg_out_call
  tcg/arm: Simplify use_armv5t_instructions
  tcg/arm: Standardize on tcg_out_<branch>_{reg,imm}
  tcg/arm: Remove fallback definition of __ARM_ARCH
  accel/tcg/user-exec: Fix read-modify-write of code on s390 hosts
  user: Remove cpu_get_pic_interrupt() stubs
  accel/tcg: Restrict TCGCPUOps::cpu_exec_interrupt() to sysemu
  target/xtensa: Restrict cpu_exec_interrupt() handler to sysemu
  target/rx: Restrict cpu_exec_interrupt() handler to sysemu
  target/sparc: Restrict cpu_exec_interrupt() handler to sysemu
  target/sh4: Restrict cpu_exec_interrupt() handler to sysemu
  target/riscv: Restrict cpu_exec_interrupt() handler to sysemu
  target/ppc: Restrict cpu_exec_interrupt() handler to sysemu
  target/openrisc: Restrict cpu_exec_interrupt() handler to sysemu
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>