raw-posix: Fix /dev/cdrom magic on OS X

The raw-posix driver has code to provide a /dev/cdrom on OS X even
though it doesn't really exist. However, since commit c66a6157 the real
filename is dismissed after finding it, so opening /dev/cdrom fails.
Put the filename back into the options QDict to make this work again.

Cc: qemu-stable@nongnu.org
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
notify: add NotiferWithReturn so notifier list can abort

notifier_list_notify() has no return value.  This is fine when we just
want to invoke side-effects.

Sometimes it's useful for notifiers to produce a return value.  This
allows notifiers to "veto" an operation and will be used by the block
layer before-write notifier.

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
block: add bdrv_add_before_write_notifier()

The bdrv_add_before_write_notifier() function installs a callback that
is invoked before a write request is processed.  This will be used to
implement copy-on-write point-in-time snapshots where we need to copy
out old data before overwriting it.

Note that BdrvTrackedRequest is moved to block_int.h since it is passed
to .notify() functions.

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
block: add basic backup support to block driver

backup_start() creates a block job that copies a point-in-time snapshot
of a block device to a target block device.

We call backup_do_cow() for each write during backup. That function
reads the original data from the block device before it gets
overwritten.  The data is then written to the target device.

Currently backup cluster size is hardcoded to 65536 bytes.

[I made a number of changes to Dietmar's original patch and folded them
in to make code review easy.  Here is the full list:

 * Drop BackupDumpFunc interface in favor of a target block device
 * Detect zero clusters with buffer_is_zero() and use bdrv_co_write_zeroes()
 * Use 0 delay instead of 1us, like other block jobs
 * Unify creation/start functions into backup_start()
 * Simplify cleanup, free bitmap in backup_run() instead of cb
 * function
 * Use HBitmap to avoid duplicating bitmap code
 * Use bdrv_getlength() instead of accessing ->total_sectors
 * directly
 * Delete the backup.h header file, it is no longer necessary
 * Move ./backup.c to block/backup.c
 * Remove #ifdefed out code
 * Coding style and whitespace cleanups
 * Use bdrv_add_before_write_notifier() instead of blockjob-specific hooks
 * Keep our own in-flight CowRequest list instead of using block.c
   tracked requests.  This means a little code duplication but is much
   simpler than trying to share the tracked requests list and use the
   backup block size.
 * Add on_source_error and on_target_error error handling.
 * Use trace events instead of DPRINTF()

-- stefanha]

Signed-off-by: Dietmar Maurer <dietmar@proxmox.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
blockdev: drop redundant proto_drv check

It is not necessary to check that we can find a protocol block driver
since we create or open the image file.  This produces the error that we
need anyway.

Besides, the QERR_INVALID_BLOCK_FORMAT is inappropriate since the
protocol is incorrect rather than the format.

Also drop an empty line between bdrv_open() and checking its return
value.  This may be due to copy-pasting from earlier code that performed
other operations before handling errors.

Reported-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
blockdev: use bdrv_getlength() in qmp_drive_mirror()

Use bdrv_getlength() for its byte units and error return instead of
bdrv_get_geometry().

Reported-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
block: add drive-backup QMP command

@drive-backup

Start a point-in-time copy of a block device to a new destination.  The
status of ongoing drive-backup operations can be checked with
query-block-jobs where the BlockJobInfo.type field has the value 'backup'.
The operation can be stopped before it has completed using the
block-job-cancel command.

@device: the name of the device which should be copied.

@target: the target of the new image. If the file exists, or if it
         is a device, the existing file/device will be used as the new
         destination.  If it does not exist, a new file will be created.

@format: #optional the format of the new destination, default is to
         probe if @mode is 'existing', else the format of the source

@mode: #optional whether and how QEMU should create a new image, default is
       'absolute-paths'.

@speed: #optional the maximum speed, in bytes per second

@on-source-error: #optional the action to take on an error on the source,
                  default 'report'.  'stop' and 'enospc' can only be used
                  if the block device supports io-status (see BlockInfo).

@on-target-error: #optional the action to take on an error on the target,
                  default 'report' (no limitations, since this applies to
                  a different block device than @device).

Note that @on-source-error and @on-target-error only affect background I/O.
If an error occurs during a guest write request, the device's rerror/werror
actions will be used.

Returns: nothing on success
         If @device is not a valid block device, DeviceNotFound

Since 1.6

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
blockdev: rename BlkTransactionStates to singular

The QMP 'transaction' command keeps a list of in-flight transactions.
The transaction state structure is called BlkTransactionStates even
though it only deals with a single transaction.  The only plural thing
is the linked list of transaction states.

I find it confusing to call the single structure "States".  This patch
renames it to "State", just like BlockDriverState is singular.

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
blockdev: allow BdrvActionOps->commit() to be NULL

Some QMP 'transaction' types don't need to do anything on .commit().
Make .commit() optional just like .abort().

The "drive-backup" action will take advantage of this, it only needs to
cancel the block job on .abort().  Other block job actions will probably
follow the same pattern, so allow .commit() to be NULL.

Suggested-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
blockdev: add DriveBackup transaction

This patch adds a transactional version of the drive-backup QMP command.
It allows atomic snapshots of multiple drives along with automatic
cleanup if there is a failure to start one of the backup jobs.

Note that QMP events are emitted for block job completion/cancellation
and the block job will be listed by query-block-jobs.

@device: the name of the device whose writes should be mirrored.

@target: the target of the new image. If the file exists, or if it
         is a device, the existing file/device will be used as the new
         destination.  If it does not exist, a new file will be created.

@format: #optional the format of the new destination, default is to
         probe if @mode is 'existing', else the format of the source

@mode: #optional whether and how QEMU should create a new image, default is
       'absolute-paths'.

@speed: #optional the maximum speed, in bytes per second

@on-source-error: #optional the action to take on an error on the source,
                  default 'report'.  'stop' and 'enospc' can only be used
                  if the block device supports io-status (see BlockInfo).

@on-target-error: #optional the action to take on an error on the target,
                  default 'report' (no limitations, since this applies to
                  a different block device than @device).

Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
blockdev: add Abort transaction

The Abort action can be used to test QMP 'transaction' failure.  Add it
as the last action to exercise the .abort() and .cleanup() code paths
for all previous actions.

Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
qemu-iotests: extract wait_until_completed() into iotests.py

The 'drive-mirror' tests often issue 'block-job-complete' and wait for
the QMP completion event.  Other types of block jobs also want to wait
for completion but they may not need to issue 'block-job-complete'.

Extract wait_until_completed() from 041 and put it into iotests.py.
Return the QMP event object so the caller can make additional
assertions, if necessary.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
qemu-iotests: add 055 drive-backup test case

Testing drive-backup is similar to image streaming and drive mirroring.
This test case is based on 041.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
block: Make BlockJobTypes const

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
block/ssh: Set bdrv_has_zero_init according to the file type.

If the remote is a regular file, set it to true (ie. reads of
uninitialized areas in a newly created file will return zeroes).
If we can't prove that, return false (a safe default).

Tested by adding a debugging print statement [not part of this commit]
and creating a remote file and a remote block device:

  $ ./qemu-img create ssh://localhost/tmp/new 100M
  Formatting 'ssh://localhost/tmp/new', fmt=raw size=104857600
  filename ssh://localhost/tmp/new: has_zero_init = 1
  $ sudo lvcreate -L 1G -n tmp /dev/fedora
    Logical volume "tmp" created
  $ ./qemu-img create ssh://localhost/dev/fedora/tmp 1G
  Formatting 'ssh://localhost/dev/fedora/tmp', fmt=raw size=1073741824
  filename ssh://localhost/dev/fedora/tmp: has_zero_init = 0

Cc: Kevin Wolf <kwolf@redhat.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
gluster: Return bdrv_has_zero_init = 0

GlusterFS volumes can be backed by block devices, in which case
bdrv_create() doesn't make sure that the image is zeroed out. It is
currently not possibly to detect whether a given image is backed by a
file or a block device, and incorrectly assuming that it is zeroed
corrupts images during qemu-img convert, so let's err on the side of
caution and always return 0.

Cc: qemu-stable@nongnu.org
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
vmdk: remove wrong calculation of relative path

When creating image with backing file, the driver tries to calculate the
relative path from created image file to backing file, but the path
computation is incorrect. e.g.:

    $ qemu-img create -f vmdk -b vmdk-data-disk.vmdk vmdk-data-snapshot1
    Formatting 'vmdk-data-snapshot1', fmt=vmdk size=10737418240
    backing_file='vmdk-data-disk.vmdk' compat6=off zeroed_grain=off

    $ qemu-img info vmdk-data-snapshot1
    image: vmdk-data-snapshot1
    file format: vmdk
    virtual size: 10G (10737418240 bytes)
    disk size: 12K
->  backing file: disk.vmdk

The common part in file names, "vmdk-data-", is incorrectly forgotten by
relative_path(). As the VMDK specification has no restriction on
parentNameHint to be relative path, we simply remove this by using the
backing_file option.

Cc: qemu-stable@nongnu.org
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
vpc: Implement .bdrv_has_zero_init

Depending on the subformat, has_zero_init on VHD must behave like raw
and query the underlying storage (fixed) or like other sparse formats
that can always return 1 (dynamic, differencing).

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
block: change default of .has_zero_init to 0

.has_zero_init defaults to 1 for all formats and protocols.

this is a dangerous default since this means that all
new added drivers need to manually overwrite it to 0 if
they do not ensure that a device is zero initialized
after bdrv_create().

if a driver needs to explicitly set this value to
1 its easier to verify the correctness in the review process.

during review of the existing drivers it turned out
that ssh and gluster had a wrong default of 1.
both protocols support host_devices as backend
which are not by default zero initialized. this
wrong assumption will lead to possible corruption
if qemu-img convert is used to write to such a backend.

vpc and vmdk also defaulted to 1 altough they support
fixed respectively flat extends. this has to be addresses
in separate patches. both formats as well as the mentioned
ssh and gluster are turned to the default of 0 with this
patch for safety.

a similar problem with the wrong default existed for
iscsi most likely because the driver developer did
oversee the default value of 1.

Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
cmd646: fix build when DEBUG_IDE is enabled.

Make sure we use the correct TARGET/PRI macros in the debug statements.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
CC: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>