linux.git/fs/splice.c, branch v4.9

fix default_file_splice_read()

2016-11-27T01:05:42+00:00

Botched calculation of number of pages.  As the result,
we were dropping pieces when doing splice to pipe from
e.g. 9p.

Reported-by: Alexei Starovoitov 
Tested-by: Alexei Starovoitov 
Signed-off-by: Al Viro

splice: remove detritus from generic_file_splice_read()

2016-11-10T23:32:13+00:00

i_size check is a leftover from the horrors that used to play with
the page cache in that function.  With the switch to ->read_iter(),
it's neither needed nor correct - for gfs2 it ends up being buggy,
since i_size is not guaranteed to be correct until later (inside
->read_iter()).

Spotted-by: Abhi Das 
Signed-off-by: Al Viro

fix ITER_PIPE interaction with direct_IO

2016-10-10T17:36:06+00:00

by making sure we call iov_iter_advance() on original
iov_iter even if direct_IO (done on its copy) has returned 0.
It's a no-op for old iov_iter flavours and does the right thing
(== truncation of the stuff we'd allocated, but not filled) in
ITER_PIPE case.  Failures (e.g. -EIO) get caught and dealt with
by cleanup in generic_file_read_iter().

Signed-off-by: Al Viro

pipe: add pipe_buf_confirm() helper

2016-10-05T22:23:59+00:00

Signed-off-by: Miklos Szeredi 
Signed-off-by: Al Viro

pipe: add pipe_buf_release() helper

2016-10-05T22:23:58+00:00

Signed-off-by: Miklos Szeredi 
Signed-off-by: Al Viro

pipe: add pipe_buf_get() helper

2016-10-05T22:23:57+00:00

Signed-off-by: Miklos Szeredi 
Signed-off-by: Al Viro

switch default_file_splice_read() to use of pipe-backed iov_iter

2016-10-05T22:23:56+00:00

we only use iov_iter_get_pages_alloc() and iov_iter_advance() -
pages are filled by kernel_readv() via a kvec array (as we used
to do all along), so iov_iter here is used only as a way of
arranging for those pages to be in pipe.

Signed-off-by: Al Viro

switch generic_file_splice_read() to use of ->read_iter()

2016-10-05T22:23:56+00:00

... and kill the ->splice_read() instances that can be switched to it

Signed-off-by: Al Viro

new iov_iter flavour: pipe-backed

2016-10-05T22:23:36+00:00

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

new helper: add_to_pipe()

2016-10-04T00:40:55+00:00

single-buffer analogue of splice_to_pipe(); vmsplice_to_pipe() switched
to that, leaving splice_to_pipe() only for ->splice_read() instances
(and that only until they are converted as well).

Signed-off-by: Al Viro