diff options
| -rw-r--r-- | block/io.c | 2 | ||||
| -rw-r--r-- | include/qemu/iov.h | 2 | ||||
| -rw-r--r-- | util/iov.c | 31 |
3 files changed, 21 insertions, 14 deletions
@@ -1722,7 +1722,7 @@ static int coroutine_fn bdrv_aligned_pwritev(BdrvChild *child, if (!ret && bs->detect_zeroes != BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF && !(flags & BDRV_REQ_ZERO_WRITE) && drv->bdrv_co_pwrite_zeroes && - qemu_iovec_is_zero(qiov)) { + qemu_iovec_is_zero(qiov, 0, qiov->size)) { flags |= BDRV_REQ_ZERO_WRITE; if (bs->detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP) { flags |= BDRV_REQ_MAY_UNMAP; diff --git a/include/qemu/iov.h b/include/qemu/iov.h index f3787a0..29957c8 100644 --- a/include/qemu/iov.h +++ b/include/qemu/iov.h @@ -212,7 +212,7 @@ void qemu_iovec_concat(QEMUIOVector *dst, size_t qemu_iovec_concat_iov(QEMUIOVector *dst, struct iovec *src_iov, unsigned int src_cnt, size_t soffset, size_t sbytes); -bool qemu_iovec_is_zero(QEMUIOVector *qiov); +bool qemu_iovec_is_zero(QEMUIOVector *qiov, size_t qiov_offeset, size_t bytes); void qemu_iovec_destroy(QEMUIOVector *qiov); void qemu_iovec_reset(QEMUIOVector *qiov); size_t qemu_iovec_to_buf(QEMUIOVector *qiov, size_t offset, @@ -451,23 +451,30 @@ void qemu_iovec_init_extended( } /* - * Check if the contents of the iovecs are all zero + * Check if the contents of subrange of qiov data is all zeroes. */ -bool qemu_iovec_is_zero(QEMUIOVector *qiov) +bool qemu_iovec_is_zero(QEMUIOVector *qiov, size_t offset, size_t bytes) { - int i; - for (i = 0; i < qiov->niov; i++) { - size_t offs = QEMU_ALIGN_DOWN(qiov->iov[i].iov_len, 4 * sizeof(long)); - uint8_t *ptr = qiov->iov[i].iov_base; - if (offs && !buffer_is_zero(qiov->iov[i].iov_base, offs)) { + struct iovec *iov; + size_t current_offset; + + assert(offset + bytes <= qiov->size); + + iov = iov_skip_offset(qiov->iov, offset, ¤t_offset); + + while (bytes) { + uint8_t *base = (uint8_t *)iov->iov_base + current_offset; + size_t len = MIN(iov->iov_len - current_offset, bytes); + + if (!buffer_is_zero(base, len)) { return false; } - for (; offs < qiov->iov[i].iov_len; offs++) { - if (ptr[offs]) { - return false; - } - } + + current_offset = 0; + bytes -= len; + iov++; } + return true; } |