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| author | Al Viro <viro@zeniv.linux.org.uk> | 2016-09-22 16:33:12 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2016-10-05 18:23:36 -0400 |
| commit | 241699cd72a8489c9446ae3910ddd243e9b9061b (patch) | |
| tree | efcd8d62f5788ab843cd3457cf2e85f3be7b5296 /include | |
| parent | d82718e348fee15dbce8f578ff2588982b7cc7ca (diff) | |
| download | linux-241699cd72a8489c9446ae3910ddd243e9b9061b.tar.bz2 | |
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')
| -rw-r--r-- | include/linux/splice.h | 1 | ||||
| -rw-r--r-- | include/linux/uio.h | 14 |
2 files changed, 12 insertions, 3 deletions
diff --git a/include/linux/splice.h b/include/linux/splice.h index 58b300f37534..00a21166e268 100644 --- a/include/linux/splice.h +++ b/include/linux/splice.h @@ -85,4 +85,5 @@ extern void splice_shrink_spd(struct splice_pipe_desc *); extern void spd_release_page(struct splice_pipe_desc *, unsigned int); extern const struct pipe_buf_operations page_cache_pipe_buf_ops; +extern const struct pipe_buf_operations default_pipe_buf_ops; #endif 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)); } /* |