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Commit 9ca1b22d authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: splice: avoid high order page splitting 



splice() can handle pages of any order, but network code tries hard to
split them in PAGE_SIZE units. Not quite successfully anyway, as
__splice_segment() assumed poff < PAGE_SIZE. This is true for
the skb->data part, not necessarily for the fragments.

This patch removes this logic to give the pages as they are in the skb.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 81135548

net/core/skbuff.c

+9 −29
Original line number Diff line number Diff line
@@ -1707,20 +1707,6 @@ static bool spd_fill_page(struct splice_pipe_desc *spd, 
	return false;

}



static inline void __segment_seek(struct page **page, unsigned int *poff,

				  unsigned int *plen, unsigned int off)

{

	unsigned long n;



	*poff += off;

	n = *poff / PAGE_SIZE;

	if (n)

		*page = nth_page(*page, n);



	*poff = *poff % PAGE_SIZE;

	*plen -= off;

}



static bool __splice_segment(struct page *page, unsigned int poff,

			     unsigned int plen, unsigned int *off,

			     unsigned int *len, struct sk_buff *skb,
@@ -1728,6 +1714,8 @@ static bool __splice_segment(struct page *page, unsigned int poff, 
			     struct sock *sk,

			     struct pipe_inode_info *pipe)

{

	unsigned int flen;



	if (!*len)

		return true;
@@ -1738,25 +1726,17 @@ static bool __splice_segment(struct page *page, unsigned int poff, 
	}



	/* ignore any bits we already processed */

	if (*off) {

		__segment_seek(&page, &poff, &plen, *off);

	poff += *off;

	plen -= *off;

	*off = 0;

	}



	do {

		unsigned int flen = min(*len, plen);



		/* the linear region may spread across several pages  */

		flen = min_t(unsigned int, flen, PAGE_SIZE - poff);

	flen = min(*len, plen);



	if (spd_fill_page(spd, pipe, page, &flen, poff, skb, linear, sk))

		return true;



		__segment_seek(&page, &poff, &plen, flen);

	*len -= flen;



	} while (*len && plen);



	return false;

}