[PATCH v2] core/coio_file: Use eio_sendfile_sync instead of a chunk mode
Vladimir Davydov
vdavydov.dev at gmail.com
Tue Apr 16 20:35:10 MSK 2019
On Tue, Apr 16, 2019 at 12:14:10AM +0300, Cyrill Gorcunov wrote:
> eio library provides a portable version of sendfile syscall
> which works more efficient than explicit copying fileby 4K
> chunks.
>
> Signed-off-by: Cyrill Gorcunov <gorcunov at gmail.com>
> ---
> v2:
> - Use sendfile in a cycle to address files more than 2G size
> - Proper testing of large files remains opened: current CI engine
> is hardly capable of managing it. I tested 200M files with manual
> splitting (to make sure the offsets do really work) but for longterm
> we still might need to invent something
We could use an error injection to reduce the size of data fed to
sendfile in one go.
> - Another question which remains -- what to do with partially copied
> files, neither code before the patch or after do not clean up parts
> of copied data. Should not we clean it up on error path? If yes then
> I'll prepare another patch on top.
Nobody complained => I don't think we need to do anything about it.
>
> src/lib/core/coio_file.c | 26 +++++++++++---------------
> 1 file changed, 11 insertions(+), 15 deletions(-)
>
> diff --git a/src/lib/core/coio_file.c b/src/lib/core/coio_file.c
> index c5b2db781..541e0f05a 100644
> --- a/src/lib/core/coio_file.c
> +++ b/src/lib/core/coio_file.c
> @@ -571,7 +571,7 @@ static void
> coio_do_copyfile(eio_req *req)
> {
> struct coio_file_task *eio = (struct coio_file_task *)req->data;
> -
> + ssize_t pos, ret, left;
> struct stat st;
> if (stat(eio->copyfile.source, &st) < 0) {
> goto error;
> @@ -588,22 +588,18 @@ coio_do_copyfile(eio_req *req)
> goto error_dest;
> }
>
> - enum { COPY_FILE_BUF_SIZE = 4096 };
> -
> - char buf[COPY_FILE_BUF_SIZE];
> -
> - while (true) {
> - ssize_t nread = fio_read(source_fd, buf, sizeof(buf));
> - if (nread < 0)
> - goto error_copy;
> -
> - if (nread == 0)
> - break; /* eof */
> -
> - ssize_t nwritten = fio_writen(dest_fd, buf, nread);
> - if (nwritten < 0)
> + for (left = st.st_size, pos = 0; left > 0;) {
st.st_size has time off_t while left has type ssize_t. They differ on
32-bit machines AFAIR.
> + ret = eio_sendfile_sync(dest_fd, source_fd, pos, left);
> + if (ret < 0) {
> + say_syserror("sendfile, [%s -> %s]",
> + fio_filename(source_fd),
> + fio_filename(dest_fd));
> goto error_copy;
> + }
> + pos += ret;
> + left -= ret;
> }
> +
> req->result = 0;
> close(source_fd);
> close(dest_fd);
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