@@ -932,7 +932,8 @@ static int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs,
return ret;
}
- if (bs->copy_on_read) {
+ /* Don't do copy-on-read if we read data before write operation */
+ if (bs->copy_on_read && !(flags & BDRV_REQ_NO_COPY_ON_READ)) {
flags |= BDRV_REQ_COPY_ON_READ;
}
@@ -1001,6 +1002,15 @@ int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num,
return bdrv_co_do_readv(bs, sector_num, nb_sectors, qiov, 0);
}
+int coroutine_fn bdrv_co_no_copy_on_readv(BlockDriverState *bs,
+ int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
+{
+ trace_bdrv_co_no_copy_on_readv(bs, sector_num, nb_sectors);
+
+ return bdrv_co_do_readv(bs, sector_num, nb_sectors, qiov,
+ BDRV_REQ_NO_COPY_ON_READ);
+}
+
int coroutine_fn bdrv_co_copy_on_readv(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
{
@@ -51,15 +51,16 @@ typedef struct BlockFragInfo {
} BlockFragInfo;
typedef enum {
- BDRV_REQ_COPY_ON_READ = 0x1,
- BDRV_REQ_ZERO_WRITE = 0x2,
+ BDRV_REQ_COPY_ON_READ = 0x1,
+ BDRV_REQ_ZERO_WRITE = 0x2,
/* The BDRV_REQ_MAY_UNMAP flag is used to indicate that the block driver
* is allowed to optimize a write zeroes request by unmapping (discarding)
* blocks if it is guaranteed that the result will read back as
* zeroes. The flag is only passed to the driver if the block device is
* opened with BDRV_O_UNMAP.
*/
- BDRV_REQ_MAY_UNMAP = 0x4,
+ BDRV_REQ_MAY_UNMAP = 0x4,
+ BDRV_REQ_NO_COPY_ON_READ = 0x8,
} BdrvRequestFlags;
typedef struct BlockSizes {
@@ -253,6 +254,8 @@ 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_no_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);
/*
@@ -69,6 +69,7 @@ bdrv_aio_write_zeroes(void *bs, int64_t sector_num, int nb_sectors, int flags, v
bdrv_lock_medium(void *bs, bool locked) "bs %p locked %d"
bdrv_co_readv(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d"
bdrv_co_copy_on_readv(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d"
+bdrv_co_no_copy_on_readv(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d"
bdrv_co_writev(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d"
bdrv_co_write_zeroes(void *bs, int64_t sector_num, int nb_sector, int flags) "bs %p sector_num %"PRId64" nb_sectors %d flags %#x"
bdrv_co_io_em(void *bs, int64_t sector_num, int nb_sectors, int is_write, void *acb) "bs %p sector_num %"PRId64" nb_sectors %d is_write %d acb %p"
In some cases, we need to disable copy-on-read, and just read the data. Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> --- block/io.c | 12 +++++++++++- include/block/block.h | 9 ++++++--- trace-events | 1 + 3 files changed, 18 insertions(+), 4 deletions(-)