From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
To: qemu-devel@nongnu.org, qemu-block@nongnu.org
Cc: fam@euphon.net, kwolf@redhat.com, vsementsov@virtuozzo.com,
mreitz@redhat.com, stefanha@redhat.com, den@openvz.org,
jsnow@redhat.com
Subject: [Qemu-devel] [PATCH v2 01/12] util/iov: introduce qemu_iovec_init_extended
Date: Tue, 4 Jun 2019 19:15:03 +0300 [thread overview]
Message-ID: <20190604161514.262241-2-vsementsov@virtuozzo.com> (raw)
In-Reply-To: <20190604161514.262241-1-vsementsov@virtuozzo.com>
Introduce new initialization API, to create requests with padding. Will
be used in the following patch. New API uses qemu_iovec_init_buf if
resulting io vector has only one element, to avoid extra allocations.
So, we need to update qemu_iovec_destroy to support destroying such
QIOVs.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
include/qemu/iov.h | 7 +++
util/iov.c | 112 +++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 114 insertions(+), 5 deletions(-)
diff --git a/include/qemu/iov.h b/include/qemu/iov.h
index 48b45987b7..f3787a0cf7 100644
--- a/include/qemu/iov.h
+++ b/include/qemu/iov.h
@@ -199,6 +199,13 @@ 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);
+void 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);
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);
diff --git a/util/iov.c b/util/iov.c
index 74e6ca8ed7..39b6e31494 100644
--- a/util/iov.c
+++ b/util/iov.c
@@ -353,6 +353,103 @@ void qemu_iovec_concat(QEMUIOVector *dst,
qemu_iovec_concat_iov(dst, src->iov, src->niov, soffset, sbytes);
}
+/*
+ * qiov_find_iov
+ *
+ * Return pointer to iovec structure, where byte at @offset in original vector
+ * @iov exactly is.
+ * Set @remaining_offset to be offset inside that iovec to the same byte.
+ */
+static struct iovec *iov_skip_offset(struct iovec *iov, size_t offset,
+ size_t *remaining_offset)
+{
+ while (offset > 0 && offset >= iov->iov_len) {
+ offset -= iov->iov_len;
+ iov++;
+ }
+ *remaining_offset = offset;
+
+ return iov;
+}
+
+/*
+ * qiov_slice
+ *
+ * Find subarray of iovec's, containing requested range. @head would
+ * be offset in first iov (returned by the function), @tail would be
+ * count of extra bytes in last iovec (returned iov + @niov - 1).
+ */
+static struct iovec *qiov_slice(QEMUIOVector *qiov,
+ size_t offset, size_t len,
+ size_t *head, size_t *tail, int *niov)
+{
+ struct iovec *iov, *end_iov;
+
+ assert(offset + len <= qiov->size);
+
+ iov = iov_skip_offset(qiov->iov, offset, head);
+ end_iov = iov_skip_offset(iov, *head + len, tail);
+
+ if (*tail > 0) {
+ assert(*tail < end_iov->iov_len);
+ *tail = end_iov->iov_len - *tail;
+ end_iov++;
+ }
+
+ *niov = end_iov - iov;
+
+ return iov;
+}
+
+/*
+ * Compile new iovec, combining @head_buf buffer, sub-qiov of @mid_qiov,
+ * and @tail_buf buffer into new qiov.
+ */
+void 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;
+ struct iovec *p, *mid_iov;
+
+ if (mid_len) {
+ mid_iov = qiov_slice(mid_qiov, mid_offset, mid_len,
+ &mid_head, &mid_tail, &mid_niov);
+ }
+
+ total_niov = !!head_len + mid_niov + !!tail_len;
+ 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++;
+ }
+
+ if (mid_len) {
+ 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;
+ }
+}
+
/*
* Check if the contents of the iovecs are all zero
*/
@@ -374,14 +471,19 @@ bool qemu_iovec_is_zero(QEMUIOVector *qiov)
return true;
}
+void qemu_iovec_init_slice(QEMUIOVector *qiov, QEMUIOVector *source,
+ size_t offset, size_t len)
+{
+ qemu_iovec_init_extended(qiov, NULL, 0, source, offset, len, NULL, 0);
+}
+
void qemu_iovec_destroy(QEMUIOVector *qiov)
{
- assert(qiov->nalloc != -1);
+ if (qiov->nalloc != -1) {
+ g_free(qiov->iov);
+ }
- qemu_iovec_reset(qiov);
- g_free(qiov->iov);
- qiov->nalloc = 0;
- qiov->iov = NULL;
+ memset(qiov, 0, sizeof(*qiov));
}
void qemu_iovec_reset(QEMUIOVector *qiov)
--
2.18.0
next prev parent reply other threads:[~2019-06-04 16:18 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-04 16:15 [Qemu-devel] [PATCH v2 00/12] block: qiov_offset parameter for io Vladimir Sementsov-Ogievskiy
2019-06-04 16:15 ` Vladimir Sementsov-Ogievskiy [this message]
2019-06-05 11:54 ` [Qemu-devel] [PATCH v2 01/12] util/iov: introduce qemu_iovec_init_extended Vladimir Sementsov-Ogievskiy
2019-06-04 16:15 ` [Qemu-devel] [PATCH v2 02/12] util/iov: improve qemu_iovec_is_zero Vladimir Sementsov-Ogievskiy
2019-06-04 16:15 ` [Qemu-devel] [PATCH v2 03/12] block/io: refactor padding Vladimir Sementsov-Ogievskiy
2019-06-04 16:15 ` [Qemu-devel] [PATCH v2 04/12] block: define .*_part io handlers in BlockDriver Vladimir Sementsov-Ogievskiy
2019-06-04 16:15 ` [Qemu-devel] [PATCH v2 05/12] block/io: bdrv_co_do_copy_on_readv: use and support qiov_offset Vladimir Sementsov-Ogievskiy
2019-06-04 16:15 ` [Qemu-devel] [PATCH v2 06/12] block/io: bdrv_co_do_copy_on_readv: lazy allocation Vladimir Sementsov-Ogievskiy
2019-06-04 16:15 ` [Qemu-devel] [PATCH v2 07/12] block/io: bdrv_aligned_preadv: use and support qiov_offset Vladimir Sementsov-Ogievskiy
2019-06-04 16:15 ` [Qemu-devel] [PATCH v2 08/12] block/io: bdrv_aligned_pwritev: " Vladimir Sementsov-Ogievskiy
2019-06-04 16:15 ` [Qemu-devel] [PATCH v2 09/12] block/io: introduce bdrv_co_p{read, write}v_part Vladimir Sementsov-Ogievskiy
2019-06-04 16:15 ` [Qemu-devel] [PATCH v2 10/12] block/qcow2: refactor qcow2_co_preadv to use buffer-based io Vladimir Sementsov-Ogievskiy
2019-06-04 16:15 ` [Qemu-devel] [PATCH v2 11/12] block/qcow2: implement .bdrv_co_preadv_part Vladimir Sementsov-Ogievskiy
2019-06-04 16:15 ` [Qemu-devel] [PATCH v2 12/12] block/qcow2: implement .bdrv_co_pwritev(_compressed)_part Vladimir Sementsov-Ogievskiy
2019-06-04 17:48 ` [Qemu-devel] [PATCH v2 00/12] block: qiov_offset parameter for io no-reply
2019-06-28 8:43 ` Stefan Hajnoczi
2019-07-25 8:28 ` Vladimir Sementsov-Ogievskiy
2019-07-29 15:24 ` Stefan Hajnoczi
2019-07-29 15:34 ` Vladimir Sementsov-Ogievskiy
2019-08-15 11:12 ` Vladimir Sementsov-Ogievskiy
2019-08-22 14:48 ` [Qemu-devel] [Qemu-block] " Stefan Hajnoczi
2019-08-22 15:50 ` [Qemu-devel] " Stefan Hajnoczi
2019-08-22 17:24 ` Vladimir Sementsov-Ogievskiy
2019-08-22 17:39 ` Vladimir Sementsov-Ogievskiy
2019-08-22 17:59 ` Vladimir Sementsov-Ogievskiy
2019-08-23 16:21 ` Stefan Hajnoczi
2019-08-24 10:15 ` Vladimir Sementsov-Ogievskiy
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