Commit bd1a68b5 authored Apr 04, 2012 by Eric Dumazet Committed by Jens Axboe Apr 20, 2012

vmsplice: relax alignement requirements for SPLICE_F_GIFT



It seems there is no fundamental reason to limit vmsplice()
SPLICE_F_GIFT to page aligned chunks.

All helpers are prepared to cope with offsets in page.

This limitation makes vmsplice() API very impractical in the zero-copy
land.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Tom Herbert <therbert@google.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Miller <davem@davemloft.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Hugh Dickins <hughd@google.com>
Cc: Changli Gao <xiaosuo@gmail.com>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent a637120e

fs/splice.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -1385,7 +1385,7 @@ static long do_splice(struct file in, loff_t __user off_in,
		*/
		static int get_iovec_page_array(const struct iovec __user *iov,
		unsigned int nr_vecs, struct page **pages,
		struct partial_page *partial, int aligned,
		struct partial_page *partial, bool aligned,
		unsigned int pipe_buffers)
		{
		int buffers = 0, error = 0;
		@@ -1623,7 +1623,7 @@ static long vmsplice_to_pipe(struct file file, const struct iovec __user iov,
		return -ENOMEM;

		spd.nr_pages = get_iovec_page_array(iov, nr_segs, spd.pages,
		spd.partial, flags & SPLICE_F_GIFT,
		spd.partial, false,
		pipe->buffers);
		if (spd.nr_pages <= 0)
		ret = spd.nr_pages;

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