diff options
| author | Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> | 2012-01-18 14:40:42 +0000 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2012-01-26 11:45:26 +0100 |
| commit | 470c05047a09cda3de16bb3f98a130d9537357a4 (patch) | |
| tree | c101557e6ff36ca1fe1465884062433358f85714 /block.h | |
| parent | 2d3735d3bf61d5c8e154a197a11535cc65044334 (diff) | |
block: make copy-on-read a per-request flag
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>
Diffstat (limited to 'block.h')
| -rw-r--r-- | block.h | 2 |
1 files changed, 2 insertions, 0 deletions
@@ -142,6 +142,8 @@ int bdrv_pwrite_sync(BlockDriverState *bs, int64_t offset, const void *buf, int count); int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov); +int coroutine_fn bdrv_co_copy_on_readv(BlockDriverState *bs, + int64_t sector_num, int nb_sectors, QEMUIOVector *qiov); int coroutine_fn bdrv_co_writev(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov); int coroutine_fn bdrv_co_is_allocated(BlockDriverState *bs, int64_t sector_num, |