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authorAl Viro <viro@zeniv.linux.org.uk>2016-09-22 23:33:12 +0300
committerAl Viro <viro@zeniv.linux.org.uk>2016-10-06 01:23:36 +0300
commit241699cd72a8489c9446ae3910ddd243e9b9061b (patch)
treeefcd8d62f5788ab843cd3457cf2e85f3be7b5296 /include/linux/uio.h
parentd82718e348fee15dbce8f578ff2588982b7cc7ca (diff)
downloadlinux-241699cd72a8489c9446ae3910ddd243e9b9061b.tar.xz
new iov_iter flavour: pipe-backed
iov_iter variant for passing data into pipe. copy_to_iter() copies data into page(s) it has allocated and stuffs them into the pipe; copy_page_to_iter() stuffs there a reference to the page given to it. Both will try to coalesce if possible. iov_iter_zero() is similar to copy_to_iter(); iov_iter_get_pages() and friends will do as copy_to_iter() would have and return the pages where the data would've been copied. iov_iter_advance() will truncate everything past the spot it has advanced to. New primitive: iov_iter_pipe(), used for initializing those. pipe should be locked all along. Running out of space acts as fault would for iovec-backed ones; in other words, giving it to ->read_iter() may result in short read if the pipe overflows, or -EFAULT if it happens with nothing copied there. In other words, ->read_iter() on those acts pretty much like ->splice_read(). Moreover, all generic_file_splice_read() users, as well as many other ->splice_read() instances can be switched to that scheme - that'll happen in the next commit. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'include/linux/uio.h')
-rw-r--r--include/linux/uio.h14
1 files changed, 11 insertions, 3 deletions
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 75b4aaf31a9d..b5ebe6dca404 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -13,6 +13,7 @@
#include <uapi/linux/uio.h>
struct page;
+struct pipe_inode_info;
struct kvec {
void *iov_base; /* and that should *never* hold a userland pointer */
@@ -23,6 +24,7 @@ enum {
ITER_IOVEC = 0,
ITER_KVEC = 2,
ITER_BVEC = 4,
+ ITER_PIPE = 8,
};
struct iov_iter {
@@ -33,8 +35,12 @@ struct iov_iter {
const struct iovec *iov;
const struct kvec *kvec;
const struct bio_vec *bvec;
+ struct pipe_inode_info *pipe;
+ };
+ union {
+ unsigned long nr_segs;
+ int idx;
};
- unsigned long nr_segs;
};
/*
@@ -64,7 +70,7 @@ static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
}
#define iov_for_each(iov, iter, start) \
- if (!((start).type & ITER_BVEC)) \
+ if (!((start).type & (ITER_BVEC | ITER_PIPE))) \
for (iter = (start); \
(iter).count && \
((iov = iov_iter_iovec(&(iter))), 1); \
@@ -94,6 +100,8 @@ void iov_iter_kvec(struct iov_iter *i, int direction, const struct kvec *kvec,
unsigned long nr_segs, size_t count);
void iov_iter_bvec(struct iov_iter *i, int direction, const struct bio_vec *bvec,
unsigned long nr_segs, size_t count);
+void iov_iter_pipe(struct iov_iter *i, int direction, struct pipe_inode_info *pipe,
+ size_t count);
ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
size_t maxsize, unsigned maxpages, size_t *start);
ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
@@ -109,7 +117,7 @@ static inline size_t iov_iter_count(struct iov_iter *i)
static inline bool iter_is_iovec(struct iov_iter *i)
{
- return !(i->type & (ITER_BVEC | ITER_KVEC));
+ return !(i->type & (ITER_BVEC | ITER_KVEC | ITER_PIPE));
}
/*