The immediately visible effect of this patch is that it fixes committing
a temporary snapshot to its backing file. Previously, it would fail with
a "permission denied" error because bdrv_inherited_flags() forced the
backing file to be read-only, ignoring the r/w reopen of bdrv_commit().

The bigger problem this revealed is that the original open flags must
actually only be applied to the temporary snapshot, and the original
image file must be treated as a backing file of the temporary snapshot
and get the right flags for that.
Reported-by: NJan Kiszka <jan.kiszka@web.de>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Since commit 9fd3171a, BDRV_O_SNAPSHOT uses an option QDict to specify
the originally requested image as the backing file of the newly created
temporary snapshot. This means that the filename is stored in
"file.filename", which is an option that is not parsed for protocol
names. Therefore things like -drive file=nbd:localhost:10809 were
broken because it looked for a local file with the literal name
'nbd:localhost:10809'.

This patch changes the way BDRV_O_SNAPSHOT works once again. We now open
the originally requested image as normal, and then do a similar
operation as for live snapshots to put the temporary snapshot on top.
This way, both driver specific options and parsed filenames work.

As a nice side effect, this results in code movement to factor
bdrv_append_temp_snapshot() out. This is a good preparation for moving
its call to drive_init() and friends eventually.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

When using the QDict option 'filename', it is supposed to be interpreted
literally. The code did correctly avoid guessing the protocol from any
string before the first colon, but it still called bdrv_parse_filename()
which would, for example, incorrectly remove a 'file:' prefix in the
raw-posix driver.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

Using an invalid option for a block device that is opened with
BDRV_O_PROTOCOL led to drv = NULL, and when trying to include the driver
name in the error message, qemu dereferenced it:

    $ x86_64-softmmu/qemu-system-x86_64 -drive file=/tmp/test.qcow2,file.foo=bar
    Segmentation fault (core dumped)

With this patch applied, the expected error message is printed:

    $ x86_64-softmmu/qemu-system-x86_64 -drive file=/tmp/test.qcow2,file.foo=bar
    qemu-system-x86_64: -drive file=/tmp/test.qcow2,file.foo=bar: could
    not open disk image /tmp/test.qcow2: Block protocol 'file' doesn't
    support the option 'foo'
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NBenoit Canet <benoit@irqsave.net>

This fixes a regression introduced in commit 2a05cbe4 ('block: Allow
block devices without files'):

$ qemu-system-x86_64 -drive driver=file
qemu-system-x86_64: block.c:892: bdrv_open_common: Assertion
`!drv->bdrv_needs_filename || filename != ((void *)0)' failed.

Now the respective check must be performed not only in bdrv_file_open(),
but also in bdrv_open().
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>

Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

If an explicit driver option is present, but doesn't specify a valid
driver, then bdrv_open() should fail instead of probing the format.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NJeff Cody <jcody@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>

There were still a couple of instances of unquoted usage of
$TEST_IMG and $TEST_IMG.orig.  Quoted these so they will not fail
on pathnames with spaces in them.
Signed-off-by: NJeff Cody <jcody@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

A lot of image filename and paths are used unquoted.  Quote these to
make sure that directories / filenames with spaces are not problematic.
Signed-off-by: NJeff Cody <jcody@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Test that backing.file.filename option can be parsed and override the
backing file from image (backing file reflected with "info block").
Signed-off-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

This is what QMP wants to use. The options haven't been enabled in any
release yet, so we're still free to change them.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

One of the major reasons for doing something new for -blockdev and
blockdev-add was that the old block layer code parses filenames instead
of just taking them literally. So we should really leave it untouched
when it's passing using the new interfaces (like -drive
file.filename=...).

This allows opening relative file names that contain a colon.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

Specifying the wrong driver could fail an assertion:

$ qemu-system-x86_64 -drive file.driver=qcow2,file=x
qemu-system-x86_64: block.c:721: bdrv_open_common: Assertion `file !=
((void *)0)' failed.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Filter the name of the QEMU executable so the output can be diffed no
matter what QEMU_PROG is (e.g. qemu-system-x86_64).
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>