xemu/block
Eric Blake 344acbd62f qcow: Tolerate backing_fmt=
qcow has no space in the metadata to store a backing format, and there
are existing qcow images backed both by raw or by other formats
(usually qcow) images, reliant on probing to tell the difference.  On
the bright side, because we probe every time, raw files are marked as
probed and we thus forbid a commit action into the backing file where
guest-controlled contents could change the result of the probe next
time around (the iotest added here proves that).

Still, allowing the user to specify the backing format during
creation, even if we can't record it, is a good thing.  This patch
blindly allows any value that resolves to a known driver, even if the
user's request is a mismatch from what probing finds; then the next
patch will further enhance things to verify that the user's request
matches what we actually probe.  With this and the next patch in
place, we will finally be ready to deprecate the creation of images
where a backing format was not explicitly specified by the user.

Note that this is only for QemuOpts usage; there is no change to the
QAPI to allow a format through -blockdev.

Add a new iotest 301 just for qcow, to demonstrate the latest
behavior, and to make it easier to show the improvements made in the
next patch.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200706203954.341758-6-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
Makefile.objs block/core: add generic infrastructure for x-blockdev-amend qmp command 2020-07-06 08:49:28 +02:00
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.c block: drop unallocated_blocks_are_zero 2020-07-06 10:34:14 +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
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
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
qcow.c qcow: Tolerate backing_fmt= 2020-07-14 15:18:59 +02:00
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 qapi: Smooth another visitor error checking pattern 2020-07-10 15:18:08 +02:00
qcow2.h qcow2: Expose bitmaps' size during measure 2020-05-28 13:16:16 -05:00
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