From 241699cd72a8489c9446ae3910ddd243e9b9061b Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 22 Sep 2016 16:33:12 -0400 Subject: 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 --- include/linux/uio.h | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) (limited to 'include/linux/uio.h') 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 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)); } /* -- cgit v1.2.3