Jens Axboe <[email protected]> wrote:
>
> ...
>
> sys_splice() moves data to/from pipes with a file input/output. sys_vmsplice()
> moves data to a pipe, with the input being a user address range instead.
>
> ...
>
> +static void *user_page_pipe_buf_map(struct file *file,
> + struct pipe_inode_info *pipe,
> + struct pipe_buffer *buf)
> +{
> + return kmap(buf->page);
> +}
> +
> +static void user_page_pipe_buf_unmap(struct pipe_inode_info *pipe,
> + struct pipe_buffer *buf)
> +{
> + kunmap(buf->page);
> +}
All these new kmaps and kunmaps hurt. It's supposed to be
kinda-deprecated and scales poorly. Oh well.
> - while (i < nr_pages)
> - page_cache_release(pages[i++]);
> + while (i < spd->nr_pages)
> + page_cache_release(spd->pages[i++]);
grumble. I'm going to march over there and take away your `i' key. Or
make it emit "page_nr".
> +static long do_vmsplice(struct file *file, void __user *buffer, size_t len,
> + unsigned int flags)
> +{
> + unsigned long uaddr = (unsigned long) buffer;
> + struct pipe_inode_info *pipe;
> + struct page *pages[PIPE_BUFFERS];
> + unsigned int nr_pages;
> + struct splice_pipe_desc spd = {
> + .pages = pages,
> + .len = len,
> + .flags = flags,
> + .ops = &user_page_pipe_buf_ops,
> + };
> +
> + pipe = file->f_dentry->d_inode->i_pipe;
> + if (unlikely(!pipe))
> + return -EBADF;
> +
> + spd.offset = uaddr & ~PAGE_CACHE_MASK;
> + nr_pages = (len + spd.offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
Can I feed this 16TB of memory? If so, we just overflowed `nr_pages'.
> --- a/include/asm-powerpc/unistd.h
> +++ b/include/asm-powerpc/unistd.h
> @@ -303,8 +303,9 @@ #define __NR_ppoll 281
> #define __NR_unshare 282
> #define __NR_splice 283
> #define __NR_tee 284
> +#define __NR_vmsplice 285
>
> -#define __NR_syscalls 285
> +#define __NR_syscalls 286
>
Every time we do this the spufs build breaks:
long spu_sys_callback(struct spu_syscall_block *s)
{
long (*syscall)(u64 a1, u64 a2, u64 a3, u64 a4, u64 a5, u64 a6);
BUILD_BUG_ON(ARRAY_SIZE(spu_syscall_table) != __NR_syscalls);
-
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