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2012-10-29Merge remote-tracking branch 'kwolf/for-anthony' into stagingAnthony Liguori1-2/+6
* kwolf/for-anthony: (32 commits) osdep: Less restrictive F_SEFL in qemu_dup_flags() qemu-iotests: add testcases for mirroring on-source-error/on-target-error qmp: add pull_event function mirror: add support for on-source-error/on-target-error iostatus: forward block_job_iostatus_reset to block job qemu-iotests: add mirroring test case mirror: implement completion qmp: add drive-mirror command mirror: introduce mirror job block: introduce BLOCK_JOB_READY event block: add block-job-complete block: rename block_job_complete to block_job_completed block: export dirty bitmap information in query-block block: introduce new dirty bitmap functionality block: add bdrv_open_backing_file block: add bdrv_query_stats block: add bdrv_query_info qemu-config: Add new -add-fd command line option monitor: Prevent removing fd from set during init monitor: Enable adding an inherited fd to an fd set ... Conflicts: vl.c Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2012-10-24block: introduce new dirty bitmap functionalityPaolo Bonzini1-2/+3
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: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-10-24block: add bdrv_open_backing_filePaolo Bonzini1-0/+1
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: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-10-24block: add bdrv_query_statsPaolo Bonzini1-0/+1
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: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-10-24block: add bdrv_query_infoPaolo Bonzini1-0/+1
Extract it out of the implementation of "info block". Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-10-23block: add close notifiersPaolo Bonzini1-0/+1
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: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-09-28iostatus: reorganize io error codePaolo Bonzini1-2/+3
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: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-09-28iostatus: change is_read to a boolPaolo Bonzini1-2/+2
Do this while we are touching this part of the code, before introducing more uses of "int is_read". Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-09-28iostatus: move BlockdevOnError declaration to QAPIPaolo Bonzini1-5/+0
This will let block-stream reuse the enum. Places that used the enums are renamed accordingly. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-09-28iostatus: rename BlockErrorAction, BlockQMPEventActionPaolo Bonzini1-6/+6
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: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-09-28block: move job APIs to separate filesPaolo Bonzini1-0/+2
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-09-28block: helper function, to find the base image of a chainJeff Cody1-0/+1
This is a simple helper function, that will return the base image of a given image chain. Signed-off-by: Jeff Cody <jcody@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-09-28block: add support functions for live commit, to find and delete images.Jeff Cody1-0/+4
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: Jeff Cody <jcody@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-09-24block: Framework for reopening files safelyJeff Cody1-0/+17
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: Jeff Cody <jcody@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-09-24block: correctly set the keep_read_only flagJeff Cody1-0/+1
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: Jeff Cody <jcody@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-10block: add BLOCK_O_CHECK for qemu-img checkStefan Hajnoczi1-0/+1
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: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-08-03block: create bdrv_get_backing_file_depth()Benoît Canet1-0/+1
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: Benoit Canet <benoit@irqsave.net> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2012-07-17hw/block-common: Move BlockConf & friends from block.hMarkus Armbruster1-45/+0
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: Markus Armbruster <armbru@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-07-17block: Geometry and translation hints are now useless, purge themMarkus Armbruster1-12/+0
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: Markus Armbruster <armbru@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-07-17qdev: Introduce block geometry propertiesMarkus Armbruster1-1/+7
Signed-off-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-07-17hd-geometry: Move disk geometry guessing back from block.cMarkus Armbruster1-1/+0
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: Markus Armbruster <armbru@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-07-17fdc: Move floppy geometry guessing back from block.cMarkus Armbruster1-18/+0
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: Markus Armbruster <armbru@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-07-09block: Factor bdrv_read_unthrottled() out of guess_disk_lchs()Markus Armbruster1-0/+2
To prepare move of guess_disk_lchs() into hw/, where it poking BlockDriverState member io_limits_enabled directly would be unclean. Signed-off-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-07-09block: introduce bdrv_swap, implement bdrv_append on top of itPaolo Bonzini1-0/+1
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: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-07-09blkdebug: remove sync i/o eventsPaolo Bonzini1-2/+0
These are unused, except (by mistake more or less) in QED. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-06-15block: Replace bdrv_get_format() by bdrv_get_format_name()Markus Armbruster1-1/+1
So callers don't need to know anything about maximum name length. Returning a pointer is safe, because the name string lives as long as the block driver it names, and block drivers don't die. Requested by Peter Maydell. Signed-off-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-06-15block: add bdrv_set_enable_write_cachePaolo Bonzini1-0/+1
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-06-15block: New bdrv_get_flags()Markus Armbruster1-0/+1
Signed-off-by: Markus Armbruster <armbru@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-06-15qemu-img check: Print fixed clusters and recheckKevin Wolf1-0/+2
When any inconsistencies have been fixed, print the statistics and run another check to make sure everything is correct now. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-06-15qemu-img check -r for repairing imagesKevin Wolf1-1/+6
The QED block driver already provides the functionality to not only detect inconsistencies in images, but also fix them. However, this functionality cannot be manually invoked with qemu-img, but the check happens only automatically during bdrv_open(). This adds a -r switch to qemu-img check that allows manual invocation of an image repair. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-06-15stream: move is_allocated_above to block.cPaolo Bonzini1-0/+4
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-05-10qemu-img: make "info" backing file output correct and easier to usePaolo Bonzini1-0/+2
qemu-img info should use the same logic as qemu when printing the backing file path, or debugging becomes quite tricky. We can also simplify the output in case the backing file has an absolute path or a protocol. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-05block: add a function to clear incoming live migration flagsBenoît Canet1-0/+2
This function will clear all BDRV_O_INCOMING flags. Signed-off-by: Benoit Canet <benoit.canet@gmail.com> Reviewed-by: Stefan Hajnoczi <stefanha@gmail.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-05block: Add new BDRV_O_INCOMING flag to notice incoming live migrationBenoît Canet1-0/+1
From original patch with Patchwork-id: 31110 by Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> "Add a flag to indicate that incoming migration is pending and care needs to be taken for data consistency. Block drivers should not modify the image file before incoming migration is complete since the migration source host is still using the image file." The rationale for not using bdrv->read_only is the following. "Unfortunately this is not possible because too many other places in QEMU test bdrv_is_read_only() and use it for their own evil purposes. For example, ide_init_drive() will error out because read-only harddisks are not supported. We're mixing guest and host side read-only concepts so this simpler alternative does not work." Signed-off-by: Benoit Canet <benoit.canet@gmail.com> Reviewed-by: Stefan Hajnoczi <stefanha@gmail.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-05qemu-img: add dirty flag statusDong Xu Wang1-0/+1
Some block drivers can verify their image files are clean or not. So we can show it while using "qemu-img info". Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com> Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-05qemu-img: add image fragmentation statisticsDong Xu Wang1-0/+7
Discussion can be found at: http://patchwork.ozlabs.org/patch/128730/ This patch add image fragmentation statistics while using qemu-img check. Signed-off-by: Dong Xu Wang <wdongxu@linux.vnet.ibm.com> Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-05block: enforce constraints on block size propertiesStefan Hajnoczi1-4/+4
Nicolae Mogoreanu <mogo@google.com> noticed that I/O requests can lead to QEMU crashes when the logical_block_size property is smaller than 512 bytes. Using the new "blocksize" property we can properly enforce constraints on the block size such that QEMU's block layer is able to operate correctly. Reported-by: Nicolae Mogoreanu <mogo@google.com> Reported-by: Michael Halcrow <mhalcrow@google.com> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-05aio: move BlockDriverAIOCB to qemu-aio.hPaolo Bonzini1-2/+0
And remove several block_int.h inclusions that should not be there. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-03-12block: handle -EBUSY in bdrv_commit_all()Stefan Hajnoczi1-1/+1
Monitor operations that manipulate image files must not execute while a background job (like image streaming) is in progress. This prevents corruptions from happening when two pieces of code are manipulating the image file without knowledge of each other. The monitor "commit" command raises QERR_DEVICE_IN_USE when bdrv_commit() returns -EBUSY but "commit all" has no error handling. This is easy to fix, although note that we do not deliver a detailed error about which device was busy in the "commit all" case. Suggested-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-02-29qapi: Introduce blockdev-group-snapshot-sync commandJeff Cody1-0/+1
This is a QAPI/QMP only command to take a snapshot of a group of devices. This is similar to the blockdev-snapshot-sync command, except blockdev-group-snapshot-sync accepts a list devices, filenames, and formats. It is attempted to keep the snapshot of the group atomic; if the creation or open of any of the new snapshots fails, then all of the new snapshots are abandoned, and the name of the snapshot image that failed is returned. The failure case should not interrupt any operations. Rather than use bdrv_close() along with a subsequent bdrv_open() to perform the pivot, the original image is never closed and the new image is placed 'in front' of the original image via manipulation of the BlockDriverState fields. Thus, once the new snapshot image has been successfully created, there are no more failure points before pivoting to the new snapshot. This allows the group of disks to remain consistent with each other, even across snapshot failures. Signed-off-by: Jeff Cody <jcody@redhat.com> Acked-by: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-02-29block: add a transfer rate for floppy typesHervé Poussineau1-1/+9
Floppies must be read at a specific transfer rate, depending of its own format. Update floppy description table to include required transfer rate. Signed-off-by: Hervé Poussineau <hpoussin@reactos.org> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-02-22block: bdrv_eject(): Make eject_flag a real boolLuiz Capitulino1-1/+1
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Acked-by: Kevin Wolf <kwolf@redhat.com>
2012-02-22block: Rename bdrv_mon_event() & BlockMonEventActionLuiz Capitulino1-3/+3
They are QMP events, not monitor events. Rename them accordingly. Also, move bdrv_emit_qmp_error_event() up in the file. A new event will be added soon and it's good to have them next each other. Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Acked-by: Kevin Wolf <kwolf@redhat.com>
2012-02-09block: add .bdrv_co_write_zeroes() interfaceStefan Hajnoczi1-0/+8
The ability to zero regions of an image file is a useful primitive for higher-level features such as image streaming or zero write detection. Image formats may support an optimized metadata representation instead of writing zeroes into the image file. This allows zero writes to be potentially faster than regular write operations and also preserve sparseness of the image file. The .bdrv_co_write_zeroes() interface should be implemented by block drivers that wish to provide efficient zeroing. Note that this operation is different from the discard operation, which may leave the contents of the region indeterminate. That means discarded blocks are not guaranteed to contain zeroes and may contain junk data instead. Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-01-26block: add bdrv_find_backing_imageMarcelo Tosatti1-0/+2
Add bdrv_find_backing_image: given a BlockDriverState pointer, and an id, traverse the backing image chain to locate the id. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-01-26block: make copy-on-read a per-request flagStefan Hajnoczi1-0/+2
Previously copy-on-read could only be enabled for all requests to a block device. This means requests coming from the guest as well as QEMU's internal requests would perform copy-on-read when enabled. For image streaming we want to support finer-grained behavior than just populating the image file from its backing image. Image streaming supports partial streaming where a common backing image is preserved. In this case guest requests should not perform copy-on-read because they would indiscriminately copy data which should be left in a backing image from the backing chain. Introduce a per-request flag for copy-on-read so that a block device can process both regular and copy-on-read requests. Overlapping reads and writes still need to be serialized for correctness when copy-on-read is happening, so add an in-flight reference count to track this. Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-12-15qcow2: Allow >4 GB VM stateKevin Wolf1-1/+1
This is a compatible extension to the snapshot header format that allows saving a 64 bit VM state size. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-12-14Fix spelling in comments, documentation and messagesStefan Weil1-1/+1
accidently->accidentally annother->another choosen->chosen consideres->considers decriptor->descriptor developement->development paramter->parameter preceed->precede preceeding->preceding priviledge->privilege propogation->propagation substraction->subtraction throught->through upto->up to usefull->useful Fix also grammar in posix-aio-compat.c Signed-off-by: Stefan Weil <sw@weilnetz.de> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2011-12-05block: convert qemu_aio_flush() calls to bdrv_drain_all()Stefan Hajnoczi1-0/+1
Many places in QEMU call qemu_aio_flush() to complete all pending asynchronous I/O. Most of these places actually want to drain all block requests but there is no block layer API to do so. This patch introduces the bdrv_drain_all() API to wait for requests across all BlockDriverStates to complete. As a bonus we perform checks after qemu_aio_wait() to ensure that requests really have finished. Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-12-05block: add interface to toggle copy-on-readStefan Hajnoczi1-0/+4
The bdrv_enable_copy_on_read()/bdrv_disable_copy_on_read() functions can be used to programmatically enable or disable copy-on-read for a block device. Later patches add the actual copy-on-read logic. Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>