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qemu-img: Add --skip-broken-bitmaps for 'convert --bitmaps'

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The point of 'qemu-img convert --bitmaps' is to be a convenience for
actions that are already possible through a string of smaller
'qemu-img bitmap' sub-commands.  One situation not accounted for
already is that if a source image contains an inconsistent bitmap (for
example, because a qemu process died abruptly before flushing bitmap
state), the user MUST delete those inconsistent bitmaps before
anything else useful can be done with the image.

We don't want to delete inconsistent bitmaps by default: although a
corrupt bitmap is only a loss of optimization rather than a corruption
of user-visible data, it is still nice to require the user to opt in
to the fact that they are aware of the loss of the bitmap.  Still,
requiring the user to check 'qemu-img info' to see whether bitmaps are
consistent, then use 'qemu-img bitmap --remove' to remove offenders,
all before using 'qemu-img convert', is a lot more work than just
adding a knob 'qemu-img convert --bitmaps --skip-broken-bitmaps' which
opts in to skipping the broken bitmaps.

After testing the new option, also demonstrate the way to manually fix
things (either deleting bad bitmaps, or re-creating them as empty) so
that it is possible to convert without the option.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1946084
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210709153951.2801666-4-eblake@redhat.com>
[eblake: warning message tweak, test enhancements]
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
This commit is contained in:
Eric Blake 2021-07-21 10:53:48 -05:00
parent 74a4320f30
commit 955171e441
4 changed files with 79 additions and 9 deletions
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8
docs/tools/qemu-img.rst
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@ -414,7 +414,7 @@ Command description:
4
Error on reading data
.. option:: convert [--object OBJECTDEF] [--image-opts] [--target-image-opts] [--target-is-zero] [--bitmaps] [-U] [-C] [-c] [-p] [-q] [-n] [-f FMT] [-t CACHE] [-T SRC_CACHE] [-O OUTPUT_FMT] [-B BACKING_FILE] [-o OPTIONS] [-l SNAPSHOT_PARAM] [-S SPARSE_SIZE] [-r RATE_LIMIT] [-m NUM_COROUTINES] [-W] FILENAME [FILENAME2 [...]] OUTPUT_FILENAME
.. option:: convert [--object OBJECTDEF] [--image-opts] [--target-image-opts] [--target-is-zero] [--bitmaps [--skip-broken-bitmaps]] [-U] [-C] [-c] [-p] [-q] [-n] [-f FMT] [-t CACHE] [-T SRC_CACHE] [-O OUTPUT_FMT] [-B BACKING_FILE] [-o OPTIONS] [-l SNAPSHOT_PARAM] [-S SPARSE_SIZE] [-r RATE_LIMIT] [-m NUM_COROUTINES] [-W] FILENAME [FILENAME2 [...]] OUTPUT_FILENAME
Convert the disk image *FILENAME* or a snapshot *SNAPSHOT_PARAM*
to disk image *OUTPUT_FILENAME* using format *OUTPUT_FMT*. It can
@ -456,6 +456,12 @@ Command description:
*NUM_COROUTINES* specifies how many coroutines work in parallel during
the convert process (defaults to 8).
Use of ``--bitmaps`` requests that any persistent bitmaps present in
the original are also copied to the destination. If any bitmap is
inconsistent in the source, the conversion will fail unless
``--skip-broken-bitmaps`` is also specified to copy only the
consistent bitmaps.
.. option:: create [--object OBJECTDEF] [-q] [-f FMT] [-b BACKING_FILE] [-F BACKING_FMT] [-u] [-o OPTIONS] FILENAME [SIZE]
Create the new disk image *FILENAME* of size *SIZE* and format