pipe: add support for shrinking and growing pipes
This patch adds F_GETPIPE_SZ and F_SETPIPE_SZ fcntl() actions for
growing and shrinking the size of a pipe and adjusts pipe.c and splice.c
(and relay and network splice) usage to work with these larger (or smaller)
pipes.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 93c4e06..9319817 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1417,12 +1417,13 @@
/*
* Fill page/offset/length into spd, if it can hold more pages.
*/
-static inline int spd_fill_page(struct splice_pipe_desc *spd, struct page *page,
+static inline int spd_fill_page(struct splice_pipe_desc *spd,
+ struct pipe_inode_info *pipe, struct page *page,
unsigned int *len, unsigned int offset,
struct sk_buff *skb, int linear,
struct sock *sk)
{
- if (unlikely(spd->nr_pages == PIPE_BUFFERS))
+ if (unlikely(spd->nr_pages == pipe->buffers))
return 1;
if (linear) {
@@ -1458,7 +1459,8 @@
unsigned int plen, unsigned int *off,
unsigned int *len, struct sk_buff *skb,
struct splice_pipe_desc *spd, int linear,
- struct sock *sk)
+ struct sock *sk,
+ struct pipe_inode_info *pipe)
{
if (!*len)
return 1;
@@ -1481,7 +1483,7 @@
/* the linear region may spread across several pages */
flen = min_t(unsigned int, flen, PAGE_SIZE - poff);
- if (spd_fill_page(spd, page, &flen, poff, skb, linear, sk))
+ if (spd_fill_page(spd, pipe, page, &flen, poff, skb, linear, sk))
return 1;
__segment_seek(&page, &poff, &plen, flen);
@@ -1496,9 +1498,9 @@
* Map linear and fragment data from the skb to spd. It reports failure if the
* pipe is full or if we already spliced the requested length.
*/
-static int __skb_splice_bits(struct sk_buff *skb, unsigned int *offset,
- unsigned int *len, struct splice_pipe_desc *spd,
- struct sock *sk)
+static int __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
+ unsigned int *offset, unsigned int *len,
+ struct splice_pipe_desc *spd, struct sock *sk)
{
int seg;
@@ -1508,7 +1510,7 @@
if (__splice_segment(virt_to_page(skb->data),
(unsigned long) skb->data & (PAGE_SIZE - 1),
skb_headlen(skb),
- offset, len, skb, spd, 1, sk))
+ offset, len, skb, spd, 1, sk, pipe))
return 1;
/*
@@ -1518,7 +1520,7 @@
const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];
if (__splice_segment(f->page, f->page_offset, f->size,
- offset, len, skb, spd, 0, sk))
+ offset, len, skb, spd, 0, sk, pipe))
return 1;
}
@@ -1535,8 +1537,8 @@
struct pipe_inode_info *pipe, unsigned int tlen,
unsigned int flags)
{
- struct partial_page partial[PIPE_BUFFERS];
- struct page *pages[PIPE_BUFFERS];
+ struct partial_page partial[PIPE_DEF_BUFFERS];
+ struct page *pages[PIPE_DEF_BUFFERS];
struct splice_pipe_desc spd = {
.pages = pages,
.partial = partial,
@@ -1546,12 +1548,16 @@
};
struct sk_buff *frag_iter;
struct sock *sk = skb->sk;
+ int ret = 0;
+
+ if (splice_grow_spd(pipe, &spd))
+ return -ENOMEM;
/*
* __skb_splice_bits() only fails if the output has no room left,
* so no point in going over the frag_list for the error case.
*/
- if (__skb_splice_bits(skb, &offset, &tlen, &spd, sk))
+ if (__skb_splice_bits(skb, pipe, &offset, &tlen, &spd, sk))
goto done;
else if (!tlen)
goto done;
@@ -1562,14 +1568,12 @@
skb_walk_frags(skb, frag_iter) {
if (!tlen)
break;
- if (__skb_splice_bits(frag_iter, &offset, &tlen, &spd, sk))
+ if (__skb_splice_bits(frag_iter, pipe, &offset, &tlen, &spd, sk))
break;
}
done:
if (spd.nr_pages) {
- int ret;
-
/*
* Drop the socket lock, otherwise we have reverse
* locking dependencies between sk_lock and i_mutex
@@ -1582,10 +1586,10 @@
release_sock(sk);
ret = splice_to_pipe(pipe, &spd);
lock_sock(sk);
- return ret;
}
- return 0;
+ splice_shrink_spd(pipe, &spd);
+ return ret;
}
/**