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[Qemu-devel] [PATCH v5 09/11] iov: add qemu_iovec_concat_iov()
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH v5 09/11] iov: add qemu_iovec_concat_iov() |
Date: |
Wed, 5 Dec 2012 21:47:08 +0100 |
The qemu_iovec_concat() function copies a subset of a QEMUIOVector. The
new qemu_iovec_concat_iov() function does the same for a iov/cnt pair.
It is easy to define qemu_iovec_concat() in terms of
qemu_iovec_concat_iov(). The existing code is mostly unchanged, except
for the assertion src->size >= soffset, which cannot be efficiently
checked upfront on a iov/cnt pair. Instead we assert upon hitting the
end of src with an unsatisfied soffset.
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
iov.c | 39 +++++++++++++++++++++++++++------------
qemu-common.h | 3 +++
2 files changed, 30 insertions(+), 12 deletions(-)
diff --git a/iov.c b/iov.c
index 6eed089..1d4c5fe 100644
--- a/iov.c
+++ b/iov.c
@@ -289,34 +289,49 @@ void qemu_iovec_add(QEMUIOVector *qiov, void *base,
size_t len)
}
/*
- * Concatenates (partial) iovecs from src to the end of dst.
+ * Concatenates (partial) iovecs from src_iov to the end of dst.
* It starts copying after skipping `soffset' bytes at the
* beginning of src and adds individual vectors from src to
* dst copies up to `sbytes' bytes total, or up to the end
- * of src if it comes first. This way, it is okay to specify
+ * of src_iov if it comes first. This way, it is okay to specify
* very large value for `sbytes' to indicate "up to the end
* of src".
* Only vector pointers are processed, not the actual data buffers.
*/
-void qemu_iovec_concat(QEMUIOVector *dst,
- QEMUIOVector *src, size_t soffset, size_t sbytes)
+void qemu_iovec_concat_iov(QEMUIOVector *dst,
+ struct iovec *src_iov, unsigned int src_cnt,
+ size_t soffset, size_t sbytes)
{
int i;
size_t done;
- struct iovec *siov = src->iov;
assert(dst->nalloc != -1);
- assert(src->size >= soffset);
- for (i = 0, done = 0; done < sbytes && i < src->niov; i++) {
- if (soffset < siov[i].iov_len) {
- size_t len = MIN(siov[i].iov_len - soffset, sbytes - done);
- qemu_iovec_add(dst, siov[i].iov_base + soffset, len);
+ for (i = 0, done = 0; done < sbytes && i < src_cnt; i++) {
+ if (soffset < src_iov[i].iov_len) {
+ size_t len = MIN(src_iov[i].iov_len - soffset, sbytes - done);
+ qemu_iovec_add(dst, src_iov[i].iov_base + soffset, len);
done += len;
soffset = 0;
} else {
- soffset -= siov[i].iov_len;
+ soffset -= src_iov[i].iov_len;
}
}
- /* return done; */
+ assert(soffset == 0); /* offset beyond end of src */
+}
+
+/*
+ * Concatenates (partial) iovecs from src to the end of dst.
+ * It starts copying after skipping `soffset' bytes at the
+ * beginning of src and adds individual vectors from src to
+ * dst copies up to `sbytes' bytes total, or up to the end
+ * of src if it comes first. This way, it is okay to specify
+ * very large value for `sbytes' to indicate "up to the end
+ * of src".
+ * Only vector pointers are processed, not the actual data buffers.
+ */
+void qemu_iovec_concat(QEMUIOVector *dst,
+ QEMUIOVector *src, size_t soffset, size_t sbytes)
+{
+ qemu_iovec_concat_iov(dst, src->iov, src->niov, soffset, sbytes);
}
void qemu_iovec_destroy(QEMUIOVector *qiov)
diff --git a/qemu-common.h b/qemu-common.h
index cef264c..4cc63e1 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -379,6 +379,9 @@ void qemu_iovec_init_external(QEMUIOVector *qiov, struct
iovec *iov, int niov);
void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len);
void qemu_iovec_concat(QEMUIOVector *dst,
QEMUIOVector *src, size_t soffset, size_t sbytes);
+void qemu_iovec_concat_iov(QEMUIOVector *dst,
+ struct iovec *src_iov, unsigned int src_cnt,
+ size_t soffset, size_t sbytes);
void qemu_iovec_destroy(QEMUIOVector *qiov);
void qemu_iovec_reset(QEMUIOVector *qiov);
size_t qemu_iovec_to_buf(QEMUIOVector *qiov, size_t offset,
--
1.8.0.1
- Re: [Qemu-devel] [PATCH v5 04/11] dataplane: add virtqueue vring code, (continued)
- [Qemu-devel] [PATCH v5 05/11] dataplane: add event loop, Stefan Hajnoczi, 2012/12/05
- [Qemu-devel] [PATCH v5 06/11] dataplane: add Linux AIO request queue, Stefan Hajnoczi, 2012/12/05
- [Qemu-devel] [PATCH v5 07/11] iov: add iov_discard() to remove data, Stefan Hajnoczi, 2012/12/05
- [Qemu-devel] [PATCH v5 11/11] virtio-blk: add x-data-plane=on|off performance feature, Stefan Hajnoczi, 2012/12/05
- [Qemu-devel] [PATCH v5 09/11] iov: add qemu_iovec_concat_iov(),
Stefan Hajnoczi <=
- [Qemu-devel] [PATCH v5 08/11] test-iov: add iov_discard() testcase, Stefan Hajnoczi, 2012/12/05
- [Qemu-devel] [PATCH v5 10/11] dataplane: add virtio-blk data plane code, Stefan Hajnoczi, 2012/12/05
- Re: [Qemu-devel] [PATCH v5 10/11] dataplane: add virtio-blk data plane code, Michael S. Tsirkin, 2012/12/06
- Re: [Qemu-devel] [PATCH v5 10/11] dataplane: add virtio-blk data plane code, Kevin Wolf, 2012/12/07