1e4b6553e3
This patch backports bugfix patch series from qemu upstream v4.1.1 Signed-off-by: Ying Fang <fangying1@huawei.com>
103 lines
3.6 KiB
Diff
103 lines
3.6 KiB
Diff
From b3b76fc643912d2c86b13caff30a1151f2958702 Mon Sep 17 00:00:00 2001
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From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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Date: Tue, 4 Jun 2019 19:15:04 +0300
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Subject: [PATCH] util/iov: improve qemu_iovec_is_zero
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We'll need to check a part of qiov soon, so implement it now.
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Optimization with align down to 4 * sizeof(long) is dropped due to:
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1. It is strange: it aligns length of the buffer, but where is a
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guarantee that buffer pointer is aligned itself?
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2. buffer_is_zero() is a better place for optimizations and it has
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them.
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Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
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Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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Message-id: 20190604161514.262241-3-vsementsov@virtuozzo.com
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Message-Id: <20190604161514.262241-3-vsementsov@virtuozzo.com>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit f76889e7b947d896db51be8a4d9c941c2f70365a)
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*prereq for 292d06b9
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Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
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---
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block/io.c | 2 +-
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include/qemu/iov.h | 2 +-
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util/iov.c | 31 +++++++++++++++++++------------
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3 files changed, 21 insertions(+), 14 deletions(-)
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diff --git a/block/io.c b/block/io.c
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index 06305c6ea6..dccf687acc 100644
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--- a/block/io.c
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+++ b/block/io.c
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@@ -1715,7 +1715,7 @@ static int coroutine_fn bdrv_aligned_pwritev(BdrvChild *child,
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if (!ret && bs->detect_zeroes != BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF &&
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!(flags & BDRV_REQ_ZERO_WRITE) && drv->bdrv_co_pwrite_zeroes &&
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- qemu_iovec_is_zero(qiov)) {
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+ qemu_iovec_is_zero(qiov, 0, qiov->size)) {
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flags |= BDRV_REQ_ZERO_WRITE;
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if (bs->detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP) {
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flags |= BDRV_REQ_MAY_UNMAP;
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diff --git a/include/qemu/iov.h b/include/qemu/iov.h
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index f3787a0cf7..29957c8a72 100644
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--- a/include/qemu/iov.h
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+++ b/include/qemu/iov.h
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@@ -212,7 +212,7 @@ void qemu_iovec_concat(QEMUIOVector *dst,
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size_t qemu_iovec_concat_iov(QEMUIOVector *dst,
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struct iovec *src_iov, unsigned int src_cnt,
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size_t soffset, size_t sbytes);
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-bool qemu_iovec_is_zero(QEMUIOVector *qiov);
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+bool qemu_iovec_is_zero(QEMUIOVector *qiov, size_t qiov_offeset, size_t bytes);
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void qemu_iovec_destroy(QEMUIOVector *qiov);
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void qemu_iovec_reset(QEMUIOVector *qiov);
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size_t qemu_iovec_to_buf(QEMUIOVector *qiov, size_t offset,
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diff --git a/util/iov.c b/util/iov.c
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index 366ff9cdd1..9ac0261853 100644
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--- a/util/iov.c
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+++ b/util/iov.c
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@@ -451,23 +451,30 @@ void qemu_iovec_init_extended(
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}
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/*
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- * Check if the contents of the iovecs are all zero
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+ * Check if the contents of subrange of qiov data is all zeroes.
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*/
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-bool qemu_iovec_is_zero(QEMUIOVector *qiov)
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+bool qemu_iovec_is_zero(QEMUIOVector *qiov, size_t offset, size_t bytes)
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{
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- int i;
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- for (i = 0; i < qiov->niov; i++) {
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- size_t offs = QEMU_ALIGN_DOWN(qiov->iov[i].iov_len, 4 * sizeof(long));
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- uint8_t *ptr = qiov->iov[i].iov_base;
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- if (offs && !buffer_is_zero(qiov->iov[i].iov_base, offs)) {
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+ struct iovec *iov;
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+ size_t current_offset;
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+
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+ assert(offset + bytes <= qiov->size);
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+
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+ iov = iov_skip_offset(qiov->iov, offset, ¤t_offset);
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+
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+ while (bytes) {
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+ uint8_t *base = (uint8_t *)iov->iov_base + current_offset;
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+ size_t len = MIN(iov->iov_len - current_offset, bytes);
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+
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+ if (!buffer_is_zero(base, len)) {
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return false;
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}
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- for (; offs < qiov->iov[i].iov_len; offs++) {
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- if (ptr[offs]) {
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- return false;
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- }
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- }
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+
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+ current_offset = 0;
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+ bytes -= len;
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+ iov++;
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}
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+
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return true;
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}
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--
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2.23.0
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