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util/iov: Remove qemu_iovec_init_extended()
bdrv_pad_request() was the main user of qemu_iovec_init_extended(). HEAD^ has removed that use, so we can remove qemu_iovec_init_extended() now. The only remaining user is qemu_iovec_init_slice(), which can easily inline the small part it really needs. Note that qemu_iovec_init_extended() offered a memcpy() optimization to initialize the new I/O vector. qemu_iovec_concat_iov(), which is used to replace its functionality, does not, but calls qemu_iovec_add() for every single element. If we decide this optimization was important, we will need to re-implement it in qemu_iovec_concat_iov(), which might also benefit its pre-existing users. Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru> Signed-off-by: Hanna Czenczek <hreitz@redhat.com> Message-Id: <20230411173418.19549-4-hreitz@redhat.com>
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@ -222,11 +222,6 @@ static inline void *qemu_iovec_buf(QEMUIOVector *qiov)
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void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint);
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void qemu_iovec_init_external(QEMUIOVector *qiov, struct iovec *iov, int niov);
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int qemu_iovec_init_extended(
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QEMUIOVector *qiov,
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void *head_buf, size_t head_len,
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QEMUIOVector *mid_qiov, size_t mid_offset, size_t mid_len,
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void *tail_buf, size_t tail_len);
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void qemu_iovec_init_slice(QEMUIOVector *qiov, QEMUIOVector *source,
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size_t offset, size_t len);
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struct iovec *qemu_iovec_slice(QEMUIOVector *qiov,
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79
util/iov.c
79
util/iov.c
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@ -416,70 +416,6 @@ int qemu_iovec_subvec_niov(QEMUIOVector *qiov, size_t offset, size_t len)
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return niov;
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}
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/*
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* Compile new iovec, combining @head_buf buffer, sub-qiov of @mid_qiov,
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* and @tail_buf buffer into new qiov.
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*/
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int qemu_iovec_init_extended(
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QEMUIOVector *qiov,
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void *head_buf, size_t head_len,
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QEMUIOVector *mid_qiov, size_t mid_offset, size_t mid_len,
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void *tail_buf, size_t tail_len)
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{
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size_t mid_head, mid_tail;
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int total_niov, mid_niov = 0;
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struct iovec *p, *mid_iov = NULL;
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assert(mid_qiov->niov <= IOV_MAX);
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if (SIZE_MAX - head_len < mid_len ||
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SIZE_MAX - head_len - mid_len < tail_len)
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{
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return -EINVAL;
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}
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if (mid_len) {
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mid_iov = qemu_iovec_slice(mid_qiov, mid_offset, mid_len,
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&mid_head, &mid_tail, &mid_niov);
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}
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total_niov = !!head_len + mid_niov + !!tail_len;
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if (total_niov > IOV_MAX) {
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return -EINVAL;
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}
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if (total_niov == 1) {
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qemu_iovec_init_buf(qiov, NULL, 0);
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p = &qiov->local_iov;
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} else {
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qiov->niov = qiov->nalloc = total_niov;
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qiov->size = head_len + mid_len + tail_len;
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p = qiov->iov = g_new(struct iovec, qiov->niov);
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}
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if (head_len) {
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p->iov_base = head_buf;
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p->iov_len = head_len;
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p++;
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}
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assert(!mid_niov == !mid_len);
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if (mid_niov) {
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memcpy(p, mid_iov, mid_niov * sizeof(*p));
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p[0].iov_base = (uint8_t *)p[0].iov_base + mid_head;
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p[0].iov_len -= mid_head;
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p[mid_niov - 1].iov_len -= mid_tail;
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p += mid_niov;
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}
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if (tail_len) {
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p->iov_base = tail_buf;
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p->iov_len = tail_len;
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}
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return 0;
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}
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/*
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* Check if the contents of subrange of qiov data is all zeroes.
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*/
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@ -511,14 +447,21 @@ bool qemu_iovec_is_zero(QEMUIOVector *qiov, size_t offset, size_t bytes)
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void qemu_iovec_init_slice(QEMUIOVector *qiov, QEMUIOVector *source,
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size_t offset, size_t len)
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{
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int ret;
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struct iovec *slice_iov;
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int slice_niov;
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size_t slice_head, slice_tail;
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assert(source->size >= len);
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assert(source->size - len >= offset);
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/* We shrink the request, so we can't overflow neither size_t nor MAX_IOV */
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ret = qemu_iovec_init_extended(qiov, NULL, 0, source, offset, len, NULL, 0);
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assert(ret == 0);
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slice_iov = qemu_iovec_slice(source, offset, len,
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&slice_head, &slice_tail, &slice_niov);
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if (slice_niov == 1) {
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qemu_iovec_init_buf(qiov, slice_iov[0].iov_base + slice_head, len);
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} else {
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qemu_iovec_init(qiov, slice_niov);
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qemu_iovec_concat_iov(qiov, slice_iov, slice_niov, slice_head, len);
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}
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}
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void qemu_iovec_destroy(QEMUIOVector *qiov)
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