consolidate qemu_iovec_copy() and qemu_iovec_concat() and make them consistent

qemu_iovec_concat() is currently a wrapper for
qemu_iovec_copy(), use the former (with extra
"0" arg) in a few places where it is used.

Change skip argument of qemu_iovec_copy() from
uint64_t to size_t, since size of qiov itself
is size_t, so there's no way to skip larger
sizes.  Rename it to soffset, to make it clear
that the offset is applied to src.

Also change the only usage of uint64_t in
hw/9pfs/virtio-9p.c, in v9fs_init_qiov_from_pdu() -
all callers of it actually uses size_t too,
not uint64_t.

One added restriction: as for all other iovec-related
functions, soffset must point inside src.

Order of argumens is already good:
 qemu_iovec_memset(QEMUIOVector *qiov, size_t offset,
                   int c, size_t bytes)
vs:
 qemu_iovec_concat(QEMUIOVector *dst,
                   QEMUIOVector *src,
                   size_t soffset, size_t sbytes)
(note soffset is after _src_ not dst, since it applies to src;
for memset it applies to qiov).

Note that in many places where this function is used,
the previous call is qemu_iovec_reset(), which means
many callers actually want copy (replacing dst content),
not concat.  So we may want to add a wrapper like
qemu_iovec_copy() with the same arguments but which
calls qemu_iovec_reset() before _concat().

Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

1 files changed, 2 insertions, 2 deletions

diff --git a/block.c b/block.c
index e0ef95e094..5b1a86249c 100644
--- a/block.c
+++ b/block.c
@@ -3101,13 +3101,13 @@ static int multiwrite_merge(BlockDriverState *bs, BlockRequest *reqs,
             // Add the first request to the merged one. If the requests are
             // overlapping, drop the last sectors of the first request.
             size = (reqs[i].sector - reqs[outidx].sector) << 9;
-            qemu_iovec_concat(qiov, reqs[outidx].qiov, size);
+            qemu_iovec_concat(qiov, reqs[outidx].qiov, 0, size);
 
             // We should need to add any zeros between the two requests
             assert (reqs[i].sector <= oldreq_last);
 
             // Add the second request
-            qemu_iovec_concat(qiov, reqs[i].qiov, reqs[i].qiov->size);
+            qemu_iovec_concat(qiov, reqs[i].qiov, 0, reqs[i].qiov->size);
 
             reqs[outidx].nb_sectors = qiov->size >> 9;
             reqs[outidx].qiov = qiov;