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block/nfs: try to avoid the bounce buffer in pwritev

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if the passed qiov contains exactly one iov we can
pass the buffer directly.

Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Message-id: 1487349541-10201-3-git-send-email-pl@kamp.de
Signed-off-by: Jeff Cody <jcody@redhat.com>
This commit is contained in:
Peter Lieven 2017-02-17 17:39:01 +01:00 committed by Jeff Cody
parent 69785a229d
commit ef503a8417
1 changed files with 16 additions and 7 deletions
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23
block/nfs.c
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@ -302,20 +302,27 @@ static int coroutine_fn nfs_co_pwritev(BlockDriverState *bs, uint64_t offset,
NFSClient *client = bs->opaque; NFSClient *client = bs->opaque;
NFSRPC task; NFSRPC task;
char *buf = NULL; char *buf = NULL;
bool my_buffer = false;
nfs_co_init_task(bs, &task); nfs_co_init_task(bs, &task);
buf = g_try_malloc(bytes); if (iov->niov != 1) {
if (bytes && buf == NULL) { buf = g_try_malloc(bytes);
return -ENOMEM; if (bytes && buf == NULL) {
return -ENOMEM;
}
qemu_iovec_to_buf(iov, 0, buf, bytes);
my_buffer = true;
} else {
buf = iov->iov[0].iov_base;
} }
qemu_iovec_to_buf(iov, 0, buf, bytes);
if (nfs_pwrite_async(client->context, client->fh, if (nfs_pwrite_async(client->context, client->fh,
offset, bytes, buf, offset, bytes, buf,
nfs_co_generic_cb, &task) != 0) { nfs_co_generic_cb, &task) != 0) {
g_free(buf); if (my_buffer) {
g_free(buf);
}
return -ENOMEM; return -ENOMEM;
} }
@ -324,7 +331,9 @@ static int coroutine_fn nfs_co_pwritev(BlockDriverState *bs, uint64_t offset,
qemu_coroutine_yield(); qemu_coroutine_yield();
} }
g_free(buf); if (my_buffer) {
g_free(buf);
}
if (task.ret != bytes) { if (task.ret != bytes) {
return task.ret < 0 ? task.ret : -EIO; return task.ret < 0 ? task.ret : -EIO;