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bc5ee6da71
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Eric Blake bc5ee6da71 qcow2: Deprecate use of qemu-img amend to change backing file 
The use of 'qemu-img amend' to change qcow2 backing files is not
tested very well.  In particular, our implementation has a bug where
if a new backing file is provided without a format, then the prior
format is blindly reused, even if this results in data corruption, but
this is not caught by iotests.

There are also situations where amending other options needs access to
the original backing file (for example, on a downgrade to a v2 image,
knowing whether a v3 zero cluster must be allocated or may be left
unallocated depends on knowing whether the backing file already reads
as zero), but the command line does not have a nice way to tell us
both the backing file to use for opening the image as well as the
backing file to install after the operation is complete.

Even if we do allow changing the backing file, it is redundant with
the existing ability to change backing files via 'qemu-img rebase -u'.
It is time to deprecate this support (leaving the existing behavior
intact, even if it is buggy), and at a point in the future, require
the use of only 'qemu-img rebase' for adjusting backing chain
relations, saving 'qemu-img amend' for changes unrelated to the
backing chain.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200706203954.341758-8-eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2020-07-14 15:18:59 +02:00
..
monitor blockdev: Split off basic bitmap operations for qemu-img 2020-05-19 10:32:14 -05:00
accounting.c block: add empty account cookie type 2019-10-10 10:56:18 +02:00
aio_task.c block: introduce aio task pool 2019-10-10 10:56:17 +02:00
amend.c block/core: add generic infrastructure for x-blockdev-amend qmp command 2020-07-06 08:49:28 +02:00
backup-top.c block: Drop @child_class from bdrv_child_perm() 2020-05-18 19:05:25 +02:00
backup-top.h block: introduce backup-top filter driver 2019-10-10 10:56:18 +02:00
backup.c backup: Make sure that source and target size match 2020-05-08 13:26:35 +02:00
blkdebug.c error: Eliminate error_propagate() with Coccinelle, part 2 2020-07-10 15:18:08 +02:00
blklogwrites.c error: Eliminate error_propagate() with Coccinelle, part 2 2020-07-10 15:18:08 +02:00
blkreplay.c block: Use bdrv_default_perms() 2020-05-18 19:05:25 +02:00
blkverify.c error: Eliminate error_propagate() with Coccinelle, part 2 2020-07-10 15:18:08 +02:00
block-backend.c block: Pass BdrvChildRole in remaining cases 2020-05-18 19:05:25 +02:00
block-copy.c block/block-copy: block_copy_dirty_clusters: fix failure check 2020-07-06 08:33:06 +02:00
bochs.c block: Use bdrv_default_perms() 2020-05-18 19:05:25 +02:00
cloop.c block: Use bdrv_default_perms() 2020-05-18 19:05:25 +02:00
commit.c block: Drop @child_class from bdrv_child_perm() 2020-05-18 19:05:25 +02:00
copy-on-read.c block: Drop @child_class from bdrv_child_perm() 2020-05-18 19:05:25 +02:00
create.c block/create: Do not abort if a block driver is not available 2019-09-13 12:18:37 +02:00
crypto.c error: Eliminate error_propagate() with Coccinelle, part 2 2020-07-10 15:18:08 +02:00
crypto.h block/crypto: implement the encryption key management 2020-07-06 08:49:28 +02:00
curl.c error: Eliminate error_propagate() with Coccinelle, part 1 2020-07-10 15:18:08 +02:00
dirty-bitmap.c block/dirty-bitmap: add bdrv_has_named_bitmaps helper 2020-05-28 13:15:22 -05:00
dmg-bz2.c Include qemu-common.h exactly where needed 2019-06-12 13:20:20 +02:00
dmg-lzfse.c block: adding lzfse decompressing support as a module. 2018-12-14 11:52:40 +01:00
dmg.c block: Use bdrv_default_perms() 2020-05-18 19:05:25 +02:00
dmg.h Include qemu-common.h exactly where needed 2019-06-12 13:20:20 +02:00
file-posix.c file-posix: Mitigate file fragmentation with extent size hints 2020-07-14 15:18:59 +02:00
file-win32.c error: Eliminate error_propagate() with Coccinelle, part 2 2020-07-10 15:18:08 +02:00
filter-compress.c block: Use bdrv_default_perms() 2020-05-18 19:05:25 +02:00
gluster.c error: Reduce unnecessary error propagation 2020-07-10 15:18:08 +02:00
io_uring.c io_uring: use io_uring_cq_ready() to check for ready cqes 2020-06-05 09:54:48 +01:00
io.c block: drop unallocated_blocks_are_zero 2020-07-06 10:34:14 +02:00
iscsi-opts.c Include qemu/module.h where needed, drop it from qemu-common.h 2019-06-12 13:18:33 +02:00
iscsi.c iscsi: return -EIO when sense fields are meaningless 2020-07-10 18:02:23 -04:00
linux-aio.c misc: Replace zero-length arrays with flexible array member (automatic) 2020-03-16 22:07:42 +01:00
Makefile.objs block/core: add generic infrastructure for x-blockdev-amend qmp command 2020-07-06 08:49:28 +02:00
mirror.c block: Drop @child_class from bdrv_child_perm() 2020-05-18 19:05:25 +02:00
nbd.c nbd: Use ERRP_GUARD() 2020-07-10 15:18:09 +02:00
nfs.c qapi: Smooth another visitor error checking pattern 2020-07-10 15:18:08 +02:00
null.c replay: add BH oneshot event for block layer 2019-10-14 17:12:48 +02:00
nvme.c block/nvme: support nested aio_poll() 2020-06-23 15:46:08 +01:00
parallels.c error: Avoid error_propagate() after migrate_add_blocker() 2020-07-10 15:18:08 +02:00
parallels.h Clean up includes 2018-02-09 05:05:11 +01:00
qapi-sysemu.c block: Move system emulator QMP commands to block/qapi-sysemu.c 2020-03-06 17:15:38 +01:00
qapi.c block: Fix VM size field width in snapshot dump 2020-02-20 16:43:42 +01:00
qcow2-bitmap.c qcow2: Tweak comments on qcow2_get_persistent_dirty_bitmap_size 2020-06-17 14:53:39 +02:00
qcow2-cache.c core: replace getpagesize() with qemu_real_host_page_size 2019-10-26 15:38:06 +02:00
qcow2-cluster.c qcow2: Support BDRV_REQ_ZERO_WRITE for truncate 2020-04-30 17:51:07 +02:00
qcow2-refcount.c block: Comment cleanups 2020-05-05 13:17:36 +02:00
qcow2-snapshot.c qcow2: Allow resize of images with internal snapshots 2020-05-05 13:17:36 +02:00
qcow2-threads.c qcow2: add zstd cluster compression 2020-05-13 14:20:31 +02:00
qcow2.c qcow2: Deprecate use of qemu-img amend to change backing file 2020-07-14 15:18:59 +02:00
qcow2.h qcow2: Expose bitmaps' size during measure 2020-05-28 13:16:16 -05:00
qcow.c qcow: Tolerate backing_fmt= 2020-07-14 15:18:59 +02:00
qed-check.c block/qed: add missed coroutine_fn markers 2019-04-30 15:29:00 +02:00
qed-cluster.c qed: protect table cache with CoMutex 2017-07-17 11:34:11 +08:00
qed-l2-cache.c qed: protect table cache with CoMutex 2017-07-17 11:34:11 +08:00
qed-table.c block/qed: add missed coroutine_fn markers 2019-04-30 15:29:00 +02:00
qed.c qapi: Smooth another visitor error checking pattern 2020-07-10 15:18:08 +02:00
qed.h qed: Simplify backing reads 2020-07-06 10:34:14 +02:00
quorum.c error: Reduce unnecessary error propagation 2020-07-10 15:18:08 +02:00
raw-format.c error: Eliminate error_propagate() with Coccinelle, part 2 2020-07-10 15:18:08 +02:00
rbd.c qapi: Smooth another visitor error checking pattern 2020-07-10 15:18:08 +02:00
replication.c error: Reduce unnecessary error propagation 2020-07-10 15:18:08 +02:00
sheepdog.c sheepdog: Add trivial backing_fmt support 2020-07-14 15:18:59 +02:00
snapshot.c block/snapshot: rename Error ** parameter to more common errp 2019-12-18 08:43:19 +01:00
ssh.c qapi: Smooth another visitor error checking pattern 2020-07-10 15:18:08 +02:00
stream.c block/stream: Remove redundant statement in stream_run() 2020-03-09 15:59:31 +01:00
throttle-groups.c error: Eliminate error_propagate() with Coccinelle, part 1 2020-07-10 15:18:08 +02:00
throttle.c error: Eliminate error_propagate() with Coccinelle, part 2 2020-07-10 15:18:08 +02:00
trace-events block/nvme: support nested aio_poll() 2020-06-23 15:46:08 +01:00
vdi.c error: Avoid error_propagate() after migrate_add_blocker() 2020-07-10 15:18:08 +02:00
vhdx-endian.c Include qemu-common.h exactly where needed 2019-06-12 13:20:20 +02:00
vhdx-log.c block: Add flags to bdrv(_co)_truncate() 2020-04-30 17:51:07 +02:00
vhdx.c error: Avoid error_propagate() after migrate_add_blocker() 2020-07-10 15:18:08 +02:00
vhdx.h block/vhdx: Use IEC binary prefixes for size constants 2019-04-30 15:29:00 +02:00
vmdk.c vmdk: Add trivial backing_fmt support 2020-07-14 15:18:59 +02:00
vpc.c error: Avoid error_propagate() after migrate_add_blocker() 2020-07-10 15:18:08 +02:00
vvfat.c error: Avoid error_propagate() after migrate_add_blocker() 2020-07-10 15:18:08 +02:00
vxhs.c error: Reduce unnecessary error propagation 2020-07-10 15:18:08 +02:00
win32-aio.c Include qemu/module.h where needed, drop it from qemu-common.h 2019-06-12 13:18:33 +02:00
write-threshold.c qapi: Drop qapi_event_send_FOO()'s Error ** argument 2018-08-28 18:21:38 +02:00