qemu-kvm/kvm-util-iov-Remove-qemu_iovec_init_extended.patch

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From cc31f7eb1c362dc308a163b7364c96ed098a793a Mon Sep 17 00:00:00 2001
From: Hanna Czenczek <hreitz@redhat.com>
Date: Tue, 11 Apr 2023 19:34:17 +0200
Subject: [PATCH 3/5] util/iov: Remove qemu_iovec_init_extended()
RH-Author: Hanna Czenczek <hreitz@redhat.com>
RH-MergeRequest: 291: block: Split padded I/O vectors exceeding IOV_MAX
RH-Bugzilla: 2141964
RH-Acked-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Commit: [3/5] 19c8307ef1289f1991199d1d1f6ab6c89a4b59ce
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>
(cherry picked from commit cc63f6f6fa1aaa4b6405dd69432c693e9c8d18ca)
Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
---
include/qemu/iov.h | 5 ---
util/iov.c | 79 +++++++---------------------------------------
2 files changed, 11 insertions(+), 73 deletions(-)
diff --git a/include/qemu/iov.h b/include/qemu/iov.h
index 46fadfb27a..63a1c01965 100644
--- a/include/qemu/iov.h
+++ b/include/qemu/iov.h
@@ -222,11 +222,6 @@ static inline void *qemu_iovec_buf(QEMUIOVector *qiov)
void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint);
void qemu_iovec_init_external(QEMUIOVector *qiov, struct iovec *iov, int niov);
-int qemu_iovec_init_extended(
- QEMUIOVector *qiov,
- void *head_buf, size_t head_len,
- QEMUIOVector *mid_qiov, size_t mid_offset, size_t mid_len,
- void *tail_buf, size_t tail_len);
void qemu_iovec_init_slice(QEMUIOVector *qiov, QEMUIOVector *source,
size_t offset, size_t len);
struct iovec *qemu_iovec_slice(QEMUIOVector *qiov,
diff --git a/util/iov.c b/util/iov.c
index 3ccb530b16..af3ccc2546 100644
--- a/util/iov.c
+++ b/util/iov.c
@@ -411,70 +411,6 @@ int qemu_iovec_subvec_niov(QEMUIOVector *qiov, size_t offset, size_t len)
return niov;
}
-/*
- * Compile new iovec, combining @head_buf buffer, sub-qiov of @mid_qiov,
- * and @tail_buf buffer into new qiov.
- */
-int qemu_iovec_init_extended(
- QEMUIOVector *qiov,
- void *head_buf, size_t head_len,
- QEMUIOVector *mid_qiov, size_t mid_offset, size_t mid_len,
- void *tail_buf, size_t tail_len)
-{
- size_t mid_head, mid_tail;
- int total_niov, mid_niov = 0;
- struct iovec *p, *mid_iov = NULL;
-
- assert(mid_qiov->niov <= IOV_MAX);
-
- if (SIZE_MAX - head_len < mid_len ||
- SIZE_MAX - head_len - mid_len < tail_len)
- {
- return -EINVAL;
- }
-
- if (mid_len) {
- mid_iov = qemu_iovec_slice(mid_qiov, mid_offset, mid_len,
- &mid_head, &mid_tail, &mid_niov);
- }
-
- total_niov = !!head_len + mid_niov + !!tail_len;
- if (total_niov > IOV_MAX) {
- return -EINVAL;
- }
-
- if (total_niov == 1) {
- qemu_iovec_init_buf(qiov, NULL, 0);
- p = &qiov->local_iov;
- } else {
- qiov->niov = qiov->nalloc = total_niov;
- qiov->size = head_len + mid_len + tail_len;
- p = qiov->iov = g_new(struct iovec, qiov->niov);
- }
-
- if (head_len) {
- p->iov_base = head_buf;
- p->iov_len = head_len;
- p++;
- }
-
- assert(!mid_niov == !mid_len);
- if (mid_niov) {
- memcpy(p, mid_iov, mid_niov * sizeof(*p));
- p[0].iov_base = (uint8_t *)p[0].iov_base + mid_head;
- p[0].iov_len -= mid_head;
- p[mid_niov - 1].iov_len -= mid_tail;
- p += mid_niov;
- }
-
- if (tail_len) {
- p->iov_base = tail_buf;
- p->iov_len = tail_len;
- }
-
- return 0;
-}
-
/*
* Check if the contents of subrange of qiov data is all zeroes.
*/
@@ -506,14 +442,21 @@ bool qemu_iovec_is_zero(QEMUIOVector *qiov, size_t offset, size_t bytes)
void qemu_iovec_init_slice(QEMUIOVector *qiov, QEMUIOVector *source,
size_t offset, size_t len)
{
- int ret;
+ struct iovec *slice_iov;
+ int slice_niov;
+ size_t slice_head, slice_tail;
assert(source->size >= len);
assert(source->size - len >= offset);
- /* We shrink the request, so we can't overflow neither size_t nor MAX_IOV */
- ret = qemu_iovec_init_extended(qiov, NULL, 0, source, offset, len, NULL, 0);
- assert(ret == 0);
+ slice_iov = qemu_iovec_slice(source, offset, len,
+ &slice_head, &slice_tail, &slice_niov);
+ if (slice_niov == 1) {
+ qemu_iovec_init_buf(qiov, slice_iov[0].iov_base + slice_head, len);
+ } else {
+ qemu_iovec_init(qiov, slice_niov);
+ qemu_iovec_concat_iov(qiov, slice_iov, slice_niov, slice_head, len);
+ }
}
void qemu_iovec_destroy(QEMUIOVector *qiov)
--
2.39.3