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[Qemu-devel] [patch] qemu iovec: keep track of total size, allow partial
From: |
Gerd Hoffmann |
Subject: |
[Qemu-devel] [patch] qemu iovec: keep track of total size, allow partial copies. |
Date: |
Fri, 23 Jan 2009 13:14:02 +0100 |
User-agent: |
Thunderbird 2.0.0.19 (X11/20090105) |
Hi,
Keeping track of the total size is trivial for the helpers, and it
allows buffer allocation without looping over the iovec once.
qemu_iovec_from_buffer got a length parameter (number of bytes to copy)
so we can handle partial reads correctly.
cheers,
Gerd
>From 520c69da6d2e52b7f8b1e72d86f7b6ee8e8acad0 Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <address@hidden>
Date: Fri, 23 Jan 2009 12:32:56 +0100
Subject: [PATCH 2/3] qemu iovec: keep track of total size, allow partial copies.
Signed-off-by: Gerd Hoffmann <address@hidden>
---
block.c | 2 +-
cutils.c | 15 +++++++++++----
qemu-common.h | 3 ++-
3 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/block.c b/block.c
index 50ec589..b3d2f12 100644
--- a/block.c
+++ b/block.c
@@ -1265,7 +1265,7 @@ static void bdrv_aio_rw_vector_cb(void *opaque, int ret)
VectorTranslationState *s = opaque;
if (!s->is_write) {
- qemu_iovec_from_buffer(s->iov, s->bounce);
+ qemu_iovec_from_buffer(s->iov, s->bounce, s->iov->size);
}
qemu_free(s->bounce);
s->this_aiocb->cb(s->this_aiocb->opaque, ret);
diff --git a/cutils.c b/cutils.c
index 80a7a1d..1090aa4 100644
--- a/cutils.c
+++ b/cutils.c
@@ -109,6 +109,7 @@ void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint)
qiov->iov = qemu_malloc(alloc_hint * sizeof(struct iovec));
qiov->niov = 0;
qiov->nalloc = alloc_hint;
+ qiov->size = 0;
}
void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len)
@@ -119,6 +120,7 @@ void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t
len)
}
qiov->iov[qiov->niov].iov_base = base;
qiov->iov[qiov->niov].iov_len = len;
+ qiov->size += len;
++qiov->niov;
}
@@ -138,13 +140,18 @@ void qemu_iovec_to_buffer(QEMUIOVector *qiov, void *buf)
}
}
-void qemu_iovec_from_buffer(QEMUIOVector *qiov, const void *buf)
+void qemu_iovec_from_buffer(QEMUIOVector *qiov, const void *buf, size_t count)
{
const uint8_t *p = (const uint8_t *)buf;
+ size_t copy;
int i;
- for (i = 0; i < qiov->niov; ++i) {
- memcpy(qiov->iov[i].iov_base, p, qiov->iov[i].iov_len);
- p += qiov->iov[i].iov_len;
+ for (i = 0; i < qiov->niov && count; ++i) {
+ copy = count;
+ if (copy > qiov->iov[i].iov_len)
+ copy = qiov->iov[i].iov_len;
+ memcpy(qiov->iov[i].iov_base, p, copy);
+ p += copy;
+ count -= copy;
}
}
diff --git a/qemu-common.h b/qemu-common.h
index ae773e0..42d5e49 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -195,13 +195,14 @@ typedef struct QEMUIOVector {
struct iovec *iov;
int niov;
int nalloc;
+ size_t size;
} QEMUIOVector;
void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint);
void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len);
void qemu_iovec_destroy(QEMUIOVector *qiov);
void qemu_iovec_to_buffer(QEMUIOVector *qiov, void *buf);
-void qemu_iovec_from_buffer(QEMUIOVector *qiov, const void *buf);
+void qemu_iovec_from_buffer(QEMUIOVector *qiov, const void *buf, size_t count);
#endif /* dyngen-exec.h hack */
--
1.6.1
- [Qemu-devel] [patch] qemu iovec: keep track of total size, allow partial copies.,
Gerd Hoffmann <=