Hi Al,
On Thu, Jun 12, 2014 at 8:14 PM, Linux Kernel Mailing List
<linux-kernel@vger.kernel.org> wrote:
> Gitweb:
> http://git.kernel.org/linus/;a=commit;h=8d0207652cbe27d1f962050737848e5ad4671958
> Commit: 8d0207652cbe27d1f962050737848e5ad4671958
> ->splice_write() via ->write_iter()
>
> iter_file_splice_write() - a ->splice_write() instance that gathers the
> pipe buffers, builds a bio_vec-based iov_iter covering those and feeds
> it to ->write_iter(). A bunch of simple cases coverted to that...
>
> [AV: fixed the braino spotted by Cyrill]
>
> Signed-off-by: Al Viro <v...@zeniv.linux.org.uk>
> @@ -1052,6 +1053,145 @@ generic_file_splice_write(struct pipe_inode_info
> *pipe, struct file *out,
>
> EXPORT_SYMBOL(generic_file_splice_write);
>
> +/**
> + * iter_file_splice_write - splice data from a pipe to a file
> + * @pipe: pipe info
> + * @out: file to write to
> + * @ppos: position in @out
> + * @len: number of bytes to splice
> + * @flags: splice modifier flags
> + *
> + * Description:
> + * Will either move or copy pages (determined by @flags options) from
> + * the given pipe inode to the given file.
> + * This one is ->write_iter-based.
What's the meaning of the return value? This is not documented.
> +ssize_t
> +iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
> + loff_t *ppos, size_t len, unsigned int flags)
> +{
> + struct splice_desc sd = {
> + .total_len = len,
> + .flags = flags,
> + .pos = *ppos,
> + .u.file = out,
> + };
> + int nbufs = pipe->buffers;
> + struct bio_vec *array = kcalloc(nbufs, sizeof(struct bio_vec),
> + GFP_KERNEL);
> + ssize_t ret;
fs/splice.c:954: warning: ‘ret’ may be used uninitialized in this function
> +
> + if (unlikely(!array))
> + return -ENOMEM;
> +
> + pipe_lock(pipe);
> +
> + splice_from_pipe_begin(&sd);
> + while (sd.total_len) {
If the "len" parameter is zero, this loop will be skipped, and "ret" will
be uninitialized.
What should it return? 0? -EINVAL?
> + }
> +done:
> + kfree(array);
> + splice_from_pipe_end(pipe, &sd);
> +
> + pipe_unlock(pipe);
> +
> + if (sd.num_spliced)
> + ret = sd.num_spliced;
> +
> + return ret;
> +}
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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