diff options
| -rw-r--r-- | block/io.c | 42 | ||||
| -rw-r--r-- | include/block/block.h | 12 |
2 files changed, 39 insertions, 15 deletions
diff --git a/block/io.c b/block/io.c index 4c0831149c..3a321d69d3 100644 --- a/block/io.c +++ b/block/io.c @@ -1592,6 +1592,8 @@ static int coroutine_fn bdrv_aligned_pwritev(BdrvChild *child, max_transfer = QEMU_ALIGN_DOWN(MIN_NON_ZERO(bs->bl.max_transfer, INT_MAX), align); + /* BDRV_REQ_NO_SERIALISING is only for read operation */ + assert(!(flags & BDRV_REQ_NO_SERIALISING)); waited = wait_serialising_requests(req); assert(!waited || !req->serialising); assert(req->overlap_offset <= offset); @@ -2916,7 +2918,7 @@ static int coroutine_fn bdrv_co_copy_range_internal(BdrvChild *src, BdrvRequestFlags flags, bool recurse_src) { - BdrvTrackedRequest src_req, dst_req; + BdrvTrackedRequest req; int ret; if (!dst || !dst->bs) { @@ -2943,32 +2945,42 @@ static int coroutine_fn bdrv_co_copy_range_internal(BdrvChild *src, || src->bs->encrypted || dst->bs->encrypted) { return -ENOTSUP; } - bdrv_inc_in_flight(src->bs); - bdrv_inc_in_flight(dst->bs); - tracked_request_begin(&src_req, src->bs, src_offset, - bytes, BDRV_TRACKED_READ); - tracked_request_begin(&dst_req, dst->bs, dst_offset, - bytes, BDRV_TRACKED_WRITE); - if (!(flags & BDRV_REQ_NO_SERIALISING)) { - wait_serialising_requests(&src_req); - wait_serialising_requests(&dst_req); - } if (recurse_src) { + bdrv_inc_in_flight(src->bs); + tracked_request_begin(&req, src->bs, src_offset, bytes, + BDRV_TRACKED_READ); + + if (!(flags & BDRV_REQ_NO_SERIALISING)) { + wait_serialising_requests(&req); + } + ret = src->bs->drv->bdrv_co_copy_range_from(src->bs, src, src_offset, dst, dst_offset, bytes, flags); + + tracked_request_end(&req); + bdrv_dec_in_flight(src->bs); } else { + bdrv_inc_in_flight(dst->bs); + tracked_request_begin(&req, dst->bs, dst_offset, bytes, + BDRV_TRACKED_WRITE); + + /* BDRV_REQ_NO_SERIALISING is only for read operation, + * so we ignore it in flags. + */ + wait_serialising_requests(&req); + ret = dst->bs->drv->bdrv_co_copy_range_to(dst->bs, src, src_offset, dst, dst_offset, bytes, flags); + + tracked_request_end(&req); + bdrv_dec_in_flight(dst->bs); } - tracked_request_end(&src_req); - tracked_request_end(&dst_req); - bdrv_dec_in_flight(src->bs); - bdrv_dec_in_flight(dst->bs); + return ret; } diff --git a/include/block/block.h b/include/block/block.h index 706ef009ad..f7ddff45b6 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -50,6 +50,18 @@ typedef enum { * opened with BDRV_O_UNMAP. */ BDRV_REQ_MAY_UNMAP = 0x4, + + /* + * The BDRV_REQ_NO_SERIALISING flag is only valid for reads and means that + * we don't want wait_serialising_requests() during the read operation. + * + * This flag is used for backup copy-on-write operations, when we need to + * read old data before write (write notifier triggered). It is okay since + * we already waited for other serializing requests in the initiating write + * (see bdrv_aligned_pwritev), and it is necessary if the initiating write + * is already serializing (without the flag, the read would deadlock + * waiting for the serialising write to complete). + */ BDRV_REQ_NO_SERIALISING = 0x8, BDRV_REQ_FUA = 0x10, BDRV_REQ_WRITE_COMPRESSED = 0x20, |