It is better to present homogeneous hardware independent of the storage
technology that is chosen on the host, hence we make discard a host
parameter; the user can choose whether to pass it down to the image
format and protocol, or to ignore it.

Using DISCARD with filesystems can cause very severe fragmentation, so it
is left default-off for now.  This can change later when we implement the
"anchor" operation for efficient management of preallocated files.

There is still one choice to make: whether DISCARD has an effect on the
dirty bitmap or not.  I chose yes, though there is a disadvantage: if
the guest is buggy and issues discards for data that is in use, there
will be no way to migrate storage for that guest without downgrading
the machine type to an older one.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

There can be a need to turn output to stdout off. This patch adds a -q option
that enable "Quiet mode". In Quiet mode, only errors are printed out.
Signed-off-by: NMiroslav Rezanina <mrezanin@redhat.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

There's no synchronous wrapper for bdrv_co_is_allocated_above function
so it's not possible to check for sector allocation in an image with
a backing file.
Signed-off-by: NMiroslav Rezanina <mrezanin@redhat.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Show how many clusters are compressed.  This can be used to monitor how
many compressed clusters remain and whether to recompress the image.
Suggested-by: NCole Robinson <crobinso@redhat.com>
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

This patch adds the support for reporting the image end offset (in
bytes). This is particularly useful after a conversion (or a rebase)
where the destination is a block device in order to find the first
unused byte at the end of the image.
Signed-off-by: NFederico Simoncelli <fsimonce@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

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

This is needed in the following patch.
Reviewed-by: NLaszlo Ersek <lersek@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

This actually uses the dirty bitmap in the block layer, and converts
mirroring to use an HBitmapIter.

Reviewed-by: Laszlo Ersek <lersek@redhat.com> (except block/mirror.c parts)
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

The qiov_is_aligned() function checks whether a QEMUIOVector meets a
BlockDriverState's alignment requirements.  This is needed by
virtio-blk-data-plane so:

1. Move the function from block/raw-posix.c to block/block.c.
2. Make it public in block/block.h.
3. Rename to bdrv_qiov_is_aligned().
4. Change return type from int to bool.
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

The raw_get_aio_fd() function allows virtio-blk-data-plane to get the
file descriptor of a raw image file with Linux AIO enabled.  This
interface is really a layering violation that can be resolved once the
block layer is able to run outside the global mutex - at that point
virtio-blk-data-plane will switch from custom Linux AIO code to using
the block layer.
Signed-off-by: NStefan Hajnoczi <stefanha@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>

This makes the blkdebug suspend/resume functionality available in
qemu-io. Use it like this:

  $ ./qemu-io blkdebug::/tmp/test.qcow2
  qemu-io> break write_aio req_a
  qemu-io> aio_write 0 4k
  qemu-io> blkdebug: Suspended request 'req_a'
  qemu-io> resume req_a
  blkdebug: Resuming request 'req_a'
  qemu-io> wrote 4096/4096 bytes at offset 0
  4 KiB, 1 ops; 0:00:30.71 (133.359788 bytes/sec and 0.0326 ops/sec)
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>

Assert that write_compressed is never used with the dirty bitmap.
Setting the bits early is wrong, because a coroutine might concurrently
examine them and copy incomplete data from the source.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Mirroring runs without the backing file so that it can be copied outside
QEMU.  However, we need to add it at the time the job is completed and
QEMU switches to the target.  Factor out the common bits of opening an
image and completing a mirroring operation.

The new function does not assume that the file is closed immediately after
it returns failure, so it keeps the BDRV_O_NO_BACKING flag up-to-date.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

qmp_query_blockstat cannot have errors, remove the Error argument and
create a new public function bdrv_query_stats out of it.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

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

The first user of close notifiers will be the embedded NBD server.
It would be possible to use them to do some of the ad hoc processing
(e.g. for block jobs and I/O limits) that is currently done by
bdrv_close.
Acked-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Move the common part of IDE/SCSI/virtio error handling to the block
layer.  The new function bdrv_error_action subsumes all three of
bdrv_emit_qmp_error_event, vm_stop, bdrv_iostatus_set_err.

The same scheme will be used for errors in 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>

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>

We want to remove knowledge of BLOCK_ERR_STOP_ENOSPC from drivers;
drivers should only be told whether to stop/report/ignore the error.
On the other hand, we want to keep using the nicer BlockErrorAction
name in the drivers.  So rename the enums, while leaving aside the
names of the enum values for now.
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>

This is a simple helper function, that will return the base image
of a given image chain.
Signed-off-by: NJeff Cody <jcody@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Add bdrv_find_overlay(), and bdrv_drop_intermediate().

bdrv_find_overlay():  given 'bs' and the active (topmost) BDS of an image chain,
                    find the image that is the immediate top of 'bs'

bdrv_drop_intermediate():
                    Given 3 BDS (active, top, base), drop images above
                    base up to and including top, and set base to be the
                    backing file of top's overlay node.

                    E.g., this converts:

                    bottom <- base <- intermediate <- top <- active

                    to

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

This is based on Supriya Kannery's bdrv_reopen() patch series.

This provides a transactional method to reopen multiple
images files safely.

Image files are queue for reopen via bdrv_reopen_queue(), and the
reopen occurs when bdrv_reopen_multiple() is called.  Changes are
staged in bdrv_reopen_prepare() and in the equivalent driver level
functions.  If any of the staged images fails a prepare, then all
of the images left untouched, and the staged changes for each image
abandoned.

Block drivers are passed a reopen state structure, that contains:
    * BDS to reopen
    * flags for the reopen
    * opaque pointer for any driver-specific data that needs to be
      persistent from _prepare to _commit/_abort
    * reopen queue pointer, if the driver needs to queue additional
      BDS for a reopen
Signed-off-by: NJeff Cody <jcody@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

I believe the bs->keep_read_only flag is supposed to reflect
the initial open state of the device. If the device is initially
opened R/O, then commit operations, or reopen operations changing
to R/W, are prohibited.

Currently, the keep_read_only flag is only accurate for the active
layer, and its backing file. Subsequent images end up always having
the keep_read_only flag set.

For instance, what happens now:

[  base  ]  kro = 1, ro = 1
    |
    v
[ snap-1 ]  kro = 1, ro = 1
    |
    v
[ snap-2 ]  kro = 0, ro = 1
    |
    v
[ active ]  kro = 0, ro = 0

What we want:

[  base  ]  kro = 0, ro = 1
    |
    v
[ snap-1 ]  kro = 0, ro = 1
    |
    v
[ snap-2 ]  kro = 0, ro = 1
    |
    v
[ active ]  kro = 0, ro = 0
Signed-off-by: NJeff Cody <jcody@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Image formats with a dirty bit, like qed and qcow2, repair dirty image
files upon open with BDRV_O_RDWR.  Performing automatic repair when
qemu-img check runs is not ideal because the bdrv_open() call repairs
the image before the actual bdrv_check() call from qemu-img.c.

Fix this "double repair" since it leads to confusing output from
qemu-img check.  Tell the block driver that this image is being opened
just for bdrv_check().  This skips automatic repair and qemu-img.c can
invoke it manually with bdrv_check().

Update the golden output for qemu-iotests 039 to reflect the new
qemu-img check output.
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Create bdrv_get_backing_file_depth() in order to be able to show
in QMP and HMP how many ancestors backing an image a block device
have.
Signed-off-by: NBenoit Canet <benoit@irqsave.net>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>

This stuff doesn't belong to block layer, and was put there only
because a better home didn't exist then.  Now it does.
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>

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

Commit f3d54fc4 factored it out of hw/ide.c for reuse.  Sensible,
except it was put into block.c.  Device-specific functionality should
be kept in device code, not the block layer.  Move it to
hw/hd-geometry.c, and make stylistic changes required to keep
checkpatch.pl happy.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Commit 5bbdbb46 moved it to block.c because "other geometry guessing
functions already reside in block.c".  Device-specific functionality
should be kept in device code, not the block layer.  Move it back.

Disk geometry guessing is still in block.c.  To be moved out in a
later patch series.

Bonus: the floppy type used in pc_cmos_init() now obviously matches
the one in the FDrive.  Before, we relied on
bdrv_get_floppy_geometry_hint() picking the same type both in
fd_revalidate() and in pc_cmos_init().
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

To prepare move of guess_disk_lchs() into hw/, where it poking
BlockDriverState member io_limits_enabled directly would be unclean.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

The new function can be made a bit nicer than bdrv_append.  It swaps the
whole contents, and then swaps back (using the usual t=a;a=b;b=t idiom)
the fields that need to stay on top.  Thus, it does not need explicit
bdrv_detach_dev, bdrv_iostatus_disable, etc.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

These are unused, except (by mistake more or less) in QED.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>