When mirroring runs, the backing files for the target may not yet be
ready.  However, this means that a copy-on-write operation on the target
would fill the missing sectors with zeros.  Copy-on-write only happens
if the granularity of the dirty bitmap is smaller than the cluster size
(and only for clusters that are allocated in the source after the job
has started copying).  So far, the granularity was fixed to 1MB; to avoid
the problem we detected the situation and required the backing files to
be available in that case only.

However, we want to lower the granularity for efficiency, so we need
a better solution.  The solution is to always copy a whole cluster the
first time it is touched.  The code keeps a bitmap of clusters that
have already been allocated by the mirroring job, and only does "manual"
copy-on-write if the chunk being copied is zero in the bitmap.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

We will use qemu_opts_create_nofail function, it can make code
more readable.
Signed-off-by: NDong Xu Wang <wdongxu@linux.vnet.ibm.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

This commit adds an Error ** argument to bdrv_img_create() and set it
appropriately on error.

Callers of bdrv_img_create() pass NULL for the new argument and still
rely on bdrv_img_create()'s return value. Next commits will change
callers to use the Error object instead.
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

There are QEMUMachines that have neither IF_IDE nor IF_SCSI as a
default/standard interface to their block devices / drives. Therefore,
this patch introduces a new field default_block_type per QEMUMachine
struct. The prior use_scsi field becomes thereby obsolete and is
replaced through .default_block_type = IF_SCSI.

This patch also changes the default for s390x to IF_VIRTIO and
removes an early hack that converts IF_IDE drives.
Other parties have already claimed interest (e.g. IF_SD for exynos)

To create a sane default, for machines that dont specify a
default_block_type, this patch makes IF_IDE = 0 and IF_NONE = 1.
I checked all users of IF_NONE (blockdev.c and ww/device-hotplug.c)
as well as IF_IDE and it seems that it is ok to change the defines -
in other words, I found no obvious (to me) assumption in the code
regarding IF_NONE==0. IF_NONE is only set if there is an
explicit if=none. Without if=* the interface becomes IF_DEFAULT.

I would suggest to have some additional care, e.g. by letting
this patch sit some days in the block tree.

Based on an initial patch from Einar Lueck <elelueck@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
CC: Igor Mitsyanko <i.mitsyanko@samsung.com>
CC: Markus Armbruster <armbru@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: NAlexander Graf <agraf@suse.de>
Acked-by: NIgor Mitsyanko <i.mitsyanko@samsung.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Releases of qemu-kvm will be interrupted at qemu 1.3.0.
Users should switch to plain qemu releases.
To avoid breaking scenarios which are setup with command line
options specific to qemu-kvm, port these switches from qemu-kvm
to qemu.git.

Port drive boot option. From the qemu-kvm original commit message:

We do not want to maintain this option forever. It will be removed after
a grace period of a few releases. So warn the user that this option has
no effect and will become invalid soon.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Error management is important for mirroring; otherwise, an error on the
target (even something as "innocent" as ENOSPC) requires to start again
with a full copy.  Similar to on_read_error/on_write_error, two separate
knobs are provided for on_source_error (reads) and on_target_error (writes).
The default is 'report' for both.

The 'ignore' policy will leave the sector dirty, so that it will be
retried later.  Thus, it will not cause corruption.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

This adds the monitor commands that start the mirroring job.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Even for jobs that need to be manually completed, management may want
to take care itself of the completion, not requiring the user to issue
a command to terminate the job.  In this case we want to avoid that
they poll us continuously, waiting for completion to become available.
Thus, add a new event that signals the phase switch and the availability
of the block-job-complete command.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

While streaming can be dropped as soon as it progressed through the whole
image, mirroring needs to be completed manually for two reasons: 1) so that
management knows exactly when the VM switches to the target; 2) because
for other use cases such as replication, we may leave the operation running
for the whole life of the virtual machine.

Add a new block job command that manually completes background operations.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

This simplifies some code and error checking, and also fixes a bug.

bdrv_find_backing_image() should only be passed absolute filenames,
or filenames relative to the chain.  In the QMP message handler for
block commit, when looking up the base do so from the determined top
image, so we know it is reachable from top.

Some of the error messages put out by block-commit have changed
slightly, which causes 2 tests cases for block-commit to fail.
This patch updates the test cases to look for the correct error
output.
Signed-off-by: NJeff Cody <jcody@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

This patch cleans up return sentences in the end of void functions.
Reported-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NAmos Kong <akong@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@gmail.com>

This patch adds support for error management to streaming.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Do this while we are touching this part of the code, before introducing
more uses of "int is_read".
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

This will let block-stream reuse the enum.  Places that used the enums
are renamed accordingly.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Add QMP commands matching the functionality.

Paused jobs cannot be canceled without first resuming them.  This
ensures that I/O errors are never missed by management.  However, an
optional force argument can be specified to allow that.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Job pausing reuses the existing support for cancellable sleeps.  A pause
happens at the next sleeping point and lasts until the coroutine is
re-entered explicitly.  Cancellation was already doing a forced resume,
so implement it explicitly in terms of resume.

Paused jobs cannot be canceled without first resuming them.  This ensures
that I/O errors are never missed by management.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Extract it out of the implementation of info block-jobs.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

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

The DeviceNotActive text is not a particularly good match, add
a separate text while keeping the same class.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

The command for live block commit is added, which has the following
arguments:

device: the block device to perform the commit on (mandatory)
base:   the base image to commit into; optional (if not specified,
        it is the underlying original image)
top:    the top image of the commit - all data from inside top down
        to base will be committed into base (mandatory for now; see
        note, below)

speed:  maximum speed, in bytes/sec

Note: Eventually this command will support merging down the active layer,
      but that code is not yet complete.  If the active layer is passed
      in as top, then an error will be returned.  Once merging down the
      active layer is supported, the 'top' argument may become optional,
      and default to the active layer.

The is done as a block job, so upon completion a BLOCK_JOB_COMPLETED will
be emitted.
Signed-off-by: NJeff Cody <jcody@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

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

Currently, after a live snapshot of a drive, the image that has
been 'demoted' to be below the new active layer remains r/w.
This patch reopens it read-only.

Note that we do not check for error on the reopen(), because we
will not abort the snapshots if the reopen fails.

This patch depends on the bdrv_reopen() series.
Signed-off-by: NJeff Cody <jcody@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

If readonly=on is given at device creation time, the ->readonly flag
needs to be set in the block driver state for this device so that
readonly-ness is preserved across media changes (qmp change command).
Similarly, to preserve the snapshot property requires ->open_flags to
be correct.
Signed-off-by: NKevin Shanahan <kmshanah@disenchant.net>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Now all major device models (IDE, SCSI, virtio) can choose between
writethrough and writeback at run-time, and virtio will even revert
to writethrough if the guest is not capable of sending flushes.  So
we can change the default to writeback at last.

Tested, for lack of a better idea, with a breakpoint on bdrv_open
and all cache choices one by one.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

For command line options which permit '?' meaning 'please list the
permitted values', add support for 'help' as a synonym, by abstracting
the check out into a helper function.

This change means that in some cases where we were being lazy in
our string parsing, "?junk" will now be rejected as an invalid option
rather than being (undocumentedly) treated the same way as "?".

Update the documentation to use 'help' rather than '?', since '?'
is a shell metacharacter and thus prone to fail confusingly if there
is a single character filename in the current working directory and
the '?' has not been escaped. It's therefore better to steer users
towards 'help', though '?' is retained for backwards compatibility.

We do not, however, update the output of the system emulator's -help
(or any documentation autogenerated from the qemu-options.hx which
is the source of the -help text) because libvirt parses our -help
output and will break. At a later date when QEMU provides a better
interface so libvirt can avoid having to do this, we can update the
-help text too.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

All current users (IDE, SCSI and virtio-blk) happen to share this 20
characters limit.  Still, it should be left to device models.  They
already enforce their limits.  They have to, as the DriveInfo limit
only affects legacy -drive serial=..., not the qdev properties.

usb-storage, which doesn't limit serial number length, also uses
DriveInfo for -usbdevice.  But that doesn't provide access to
DriveInfo serial.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Leave it to ide_init_drive().
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

There are two producers of these hints: drive_init() on behalf of
-drive, and hd_geometry_guess().

The only consumer of the hint is hd_geometry_guess().

The callers of hd_geometry_guess() call it only when drive_init()
didn't set the hints.  Therefore, drive_init()'s hints are never used.

Thus, hd_geometry_guess() only ever sees hints it produced itself in a
prior call.  Only the first call computes something, subsequent calls
just repeat the first call's results.  However, hd_geometry_guess() is
never called more than once: the device models don't, and the block
device is destroyed on unplug.  Thus, dropping the repeat feature
doesn't break anything now.

If a block device wasn't destroyed on unplug and could be reused with
a new device, then repeating old results would be wrong.  Thus,
dropping the repeat feature prevents future breakage.

This renders the hints unused.  Purge them from the block layer.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

In preparation of purging it from the block layer, which will happen
later in this series.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

If the image is read-only then it's not possible to copy read data into
it.  Therefore copy-on-read is automatically disabled for read-only
images.

Up until now this behavior was silent, add a warning so the user knows
why copy-on-read is not working.
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

This commit converts qemu_opts_create() from qerror_report() to
error_set().

Currently, most calls to qemu_opts_create() can't fail, so most
callers don't need any changes.

The two cases where code checks for qemu_opts_create() erros are:

 1. Initialization code in vl.c. All of them print their own
    error messages directly to stderr, no need to pass the Error
    object

 2. The functions opts_parse(), qemu_opts_from_qdict() and
    qemu_chr_parse_compat() make use of the error information and
    they can be called from HMP or QMP. In this case, to allow for
    incremental conversion, we propagate the error up using
    qerror_report_err(), which keeps the QError semantics
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>
Reviewed-By: NLaszlo Ersek <lersek@redhat.com>