There is no reason why the format drivers need to truncate the protocol
node when formatting it.  When using the old .bdrv_co_create_ops()
interface, the file will be created with no size option anyway, which
generally gives it a size of 0.  (Exceptions are block devices, which
cannot be truncated anyway.)

When using blockdev-create, the user must have given the file node some
size anyway, so there is no reason why we should override that.

qed is an exception, it needs the file to start completely empty (as
explained by c743849b).

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190918095144.955-4-mreitz@redhat.com
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

No other filter driver has a .bdrv_co_truncate() implementation, and
there is no need to because the general block layer code can handle it
just as well.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190918095144.955-3-mreitz@redhat.com
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Make the filter truncation (passing it through to bs->file) a
first-class citizen and handle it exactly as if it was the filter
driver's native implementation of .bdrv_co_truncate().

I do not see a reason not to, it makes the code a bit shorter, and may
be even more correct because this gets us to finish the write_req that
we prepared before (may be important to e.g. bring dirty bitmaps to the
correct size).

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190918095144.955-2-mreitz@redhat.com
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Add a test how our qcow2 driver handles extra data in snapshot table
entries, and how it repairs overly long snapshot tables.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191011152814.14791-17-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191011152814.14791-16-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

qcow2 v3 images require every snapshot table entry to have at least 16
bytes of extra data.  If they do not, let qemu-img check -r all fix it.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191011152814.14791-15-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

The user cannot choose which snapshots are removed.  This is fine
because we have chosen the maximum snapshot table size to be so large
(65536 entries) that it cannot be reasonably reached.  If the snapshot
table exceeds this size, the image has probably been corrupted in some
way; in this case, it is most important to just make the image usable
such that the user can copy off at least the active layer.
(Also note that the snapshots will be removed only with "-r all", so a
plain "check" or "check -r leaks" will not delete any data.)

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191011152814.14791-14-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

We currently refuse to open qcow2 images with overly long snapshot
tables.  This patch makes qemu-img check -r all drop all offending
entries past what we deem acceptable.

The user cannot choose which snapshots are removed.  This is fine
because we have chosen the maximum snapshot table size to be so large
(64 MB) that it cannot be reasonably reached.  If the snapshot table
exceeds this size, the image has probably been corrupted in some way; in
this case, it is most important to just make the image usable such that
the user can copy off at least the active layer.
(Also note that the snapshots will be removed only with "-r all", so a
plain "check" or "check -r leaks" will not delete any data.)

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191011152814.14791-13-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

When repairing the snapshot table, we truncate entries that have too
much extra data.  This frees up space that we do not have to count
towards the snapshot table size.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191011152814.14791-12-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

The only case where we currently reject snapshot table entries is when
they have too much extra data.  Fix them with qemu-img check -r all by
counting it as a corruption, reducing their extra_data_size, and then
letting qcow2_check_fix_snapshot_table() do the rest.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191011152814.14791-11-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

qcow2_check_read_snapshot_table() can perform consistency checks, but it
cannot fix everything.  Specifically, it cannot allocate new clusters,
because that should wait until the refcount structures are known to be
consistent (i.e., after qcow2_check_refcounts()).  Thus, it cannot call
qcow2_write_snapshots().

Do that in qcow2_check_fix_snapshot_table(), which is called after
qcow2_check_refcounts().

Currently, there is nothing that would set result->corruptions, so this
is a no-op.  A follow-up patch will change that.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191011152814.14791-10-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

Reading the snapshot table can fail.  That is a problem when we want to
repair the image.

Therefore, stop reading the snapshot table in qcow2_do_open() in check
mode.  Instead, add a new function qcow2_check_read_snapshot_table()
that reads the snapshot table at a later point.  In the future, we want
to handle errors here and fix them.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191011152814.14791-9-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

qcow2 v3 requires every snapshot table entry to have two extra data
fields: The 64-bit VM state size, and the virtual disk size.  Both are
optional for v2 images, so they may not be present.

qcow2_upgrade() therefore should update the snapshot table to ensure all
entries have these extra data fields.

Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1727347


Reported-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191011152814.14791-8-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

This does not make sense right now, but it will make sense once we need
to do more than to just update s->qcow_version.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191011152814.14791-7-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

Updating the snapshot list will be useful when upgrading a v2 image to
v3, so we will need to call this function in qcow2.c.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191011152814.14791-6-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

The qcow2 specification says to ignore unknown extra data fields in
snapshot table entries.  Currently, we discard it whenever we update the
image, which is a bit different from "ignore".

This patch makes the qcow2 driver keep all unknown extra data fields
when updating an image's snapshot table.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191011152814.14791-5-mreitz@redhat.com
[mreitz: Adjusted comments as proposed by Eric]
Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191011152814.14791-4-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191011152814.14791-3-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

endof() is a useful macro, we can make use of it outside of virtio.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191011152814.14791-2-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

mirror_exit_common() may be called twice (if it is called from
mirror_prepare() and fails, it will be called from mirror_abort()
again).

In such a case, many of the pointers in the MirrorBlockJob object will
already be freed.  This can be seen most reliably for s->target, which
is set to NULL (and then dereferenced by blk_bs()).

Cc: qemu-stable@nongnu.org
Fixes: 737efc1e
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20191014153931.20699-2-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-id: 20190913133627.28450-3-mlevitsk@redhat.com
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-id: 20190913133627.28450-2-mlevitsk@redhat.com
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

No reason to limit buffered copy to one cluster. Let's allow up to 1
MiB.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20191022111805.3432-7-vsementsov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

Currently total allocation for parallel requests to block-copy instance
is unlimited. Let's limit it to 128 MiB.

For now block-copy is used only in backup, so actually we limit total
allocation for backup job.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20191022111805.3432-6-vsementsov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

Introduce an API for some shared splittable resource, like memory.
It's going to be used by backup. Backup uses both read/write io and
copy_range. copy_range may consume memory implictly, so the new API is
abstract: it doesn't allocate any real memory but only hands out
tickets.

The idea is that we have some total amount of something and callers
should wait in coroutine queue if there is not enough of the resource
at the moment.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20191022111805.3432-5-vsementsov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

Merge copying code into one function block_copy_do_copy, which only
calls bdrv_ io functions and don't do any synchronization (like dirty
bitmap set/reset).

Refactor block_copy() function so that it takes full decision about
size of chunk to be copied and does all the synchronization (checking
intersecting requests, set/reset dirty bitmaps).

It will help:
 - introduce parallel processing of block_copy iterations: we need to
   calculate chunk size, start async chunk copying and go to the next
   iteration
 - simplify synchronization improvement (like memory limiting in
   further commit and reducing critical section (now we lock the whole
   requested range, when actually we need to lock only dirty region
   which we handle at the moment))

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20191022111805.3432-4-vsementsov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

Large copy range may imply memory allocation and large io effort, so
using 2G copy range request may be bad idea. Let's limit it to 16 MiB.
It also helps the following patch to refactor copy-with-offload
fallback to copy-with-bounce-buffer.

Note, that total memory usage of backup is still not limited, it will
be fixed in further commit.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20191022111805.3432-3-vsementsov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

Move bounce_buffer allocation block_copy_with_bounce_buffer. This
commit simplifies further work on implementing copying by larger chunks
(of different size) and further asynchronous handling of block_copy
iterations (with help of block/aio_task API).

Allocation works fast, a lot faster than disk io, so it's not a problem
that we now allocate/free bounce_buffer more times. And we anyway will
have to allocate several bounce_buffers for parallel execution of loop
iterations in future.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20191022111805.3432-2-vsementsov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

Sockets should be placed into $SOCK_DIR instead of $TEST_DIR, so remove
the $TEST_DIR filter from _filter_nbd.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191017133155.5327-24-mreitz@redhat.com
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191017133155.5327-23-mreitz@redhat.com
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191017133155.5327-22-mreitz@redhat.com
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191017133155.5327-21-mreitz@redhat.com
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191017133155.5327-20-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191017133155.5327-19-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191017133155.5327-18-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191017133155.5327-17-mreitz@redhat.com
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191017133155.5327-16-mreitz@redhat.com
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191017133155.5327-15-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20191017133155.5327-14-mreitz@redhat.com
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-id: 20191017133155.5327-13-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>