diff options
| -rw-r--r-- | block/io.c | 97 |
1 files changed, 95 insertions, 2 deletions
diff --git a/block/io.c b/block/io.c index ad877b0aeb..284784eea1 100644 --- a/block/io.c +++ b/block/io.c @@ -1179,6 +1179,94 @@ static int coroutine_fn bdrv_aligned_pwritev(BlockDriverState *bs, return ret; } +static int coroutine_fn bdrv_co_do_zero_pwritev(BlockDriverState *bs, + int64_t offset, + unsigned int bytes, + BdrvRequestFlags flags, + BdrvTrackedRequest *req) +{ + uint8_t *buf = NULL; + QEMUIOVector local_qiov; + struct iovec iov; + uint64_t align = MAX(BDRV_SECTOR_SIZE, bs->request_alignment); + unsigned int head_padding_bytes, tail_padding_bytes; + int ret = 0; + + head_padding_bytes = offset & (align - 1); + tail_padding_bytes = align - ((offset + bytes) & (align - 1)); + + + assert(flags & BDRV_REQ_ZERO_WRITE); + if (head_padding_bytes || tail_padding_bytes) { + buf = qemu_blockalign(bs, align); + iov = (struct iovec) { + .iov_base = buf, + .iov_len = align, + }; + qemu_iovec_init_external(&local_qiov, &iov, 1); + } + if (head_padding_bytes) { + uint64_t zero_bytes = MIN(bytes, align - head_padding_bytes); + + /* RMW the unaligned part before head. */ + mark_request_serialising(req, align); + wait_serialising_requests(req); + BLKDBG_EVENT(bs, BLKDBG_PWRITEV_RMW_HEAD); + ret = bdrv_aligned_preadv(bs, req, offset & ~(align - 1), align, + align, &local_qiov, 0); + if (ret < 0) { + goto fail; + } + BLKDBG_EVENT(bs, BLKDBG_PWRITEV_RMW_AFTER_HEAD); + + memset(buf + head_padding_bytes, 0, zero_bytes); + ret = bdrv_aligned_pwritev(bs, req, offset & ~(align - 1), align, + &local_qiov, + flags & ~BDRV_REQ_ZERO_WRITE); + if (ret < 0) { + goto fail; + } + offset += zero_bytes; + bytes -= zero_bytes; + } + + assert(!bytes || (offset & (align - 1)) == 0); + if (bytes >= align) { + /* Write the aligned part in the middle. */ + uint64_t aligned_bytes = bytes & ~(align - 1); + ret = bdrv_aligned_pwritev(bs, req, offset, aligned_bytes, + NULL, flags); + if (ret < 0) { + goto fail; + } + bytes -= aligned_bytes; + offset += aligned_bytes; + } + + assert(!bytes || (offset & (align - 1)) == 0); + if (bytes) { + assert(align == tail_padding_bytes + bytes); + /* RMW the unaligned part after tail. */ + mark_request_serialising(req, align); + wait_serialising_requests(req); + BLKDBG_EVENT(bs, BLKDBG_PWRITEV_RMW_TAIL); + ret = bdrv_aligned_preadv(bs, req, offset, align, + align, &local_qiov, 0); + if (ret < 0) { + goto fail; + } + BLKDBG_EVENT(bs, BLKDBG_PWRITEV_RMW_AFTER_TAIL); + + memset(buf, 0, bytes); + ret = bdrv_aligned_pwritev(bs, req, offset, align, + &local_qiov, flags & ~BDRV_REQ_ZERO_WRITE); + } +fail: + qemu_vfree(buf); + return ret; + +} + /* * Handle a write request in coroutine context */ @@ -1219,6 +1307,11 @@ static int coroutine_fn bdrv_co_do_pwritev(BlockDriverState *bs, */ tracked_request_begin(&req, bs, offset, bytes, true); + if (!qiov) { + ret = bdrv_co_do_zero_pwritev(bs, offset, bytes, flags, &req); + goto out; + } + if (offset & (align - 1)) { QEMUIOVector head_qiov; struct iovec head_iov; @@ -1292,14 +1385,14 @@ static int coroutine_fn bdrv_co_do_pwritev(BlockDriverState *bs, flags); fail: - tracked_request_end(&req); if (use_local_qiov) { qemu_iovec_destroy(&local_qiov); } qemu_vfree(head_buf); qemu_vfree(tail_buf); - +out: + tracked_request_end(&req); return ret; } |