Fix some typos in pipe.c and splice.c.
Add pipes API to kernel-api.tmpl.
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

If add_to_page_cache_lru() fails, the page will not be locked. But
splice jumps to an error path that does a page release and unlock,
causing a BUG() in unlock_page().

Fix this by adding one more label that just releases the page. This bug
was actually triggered on EL5 by gurudas pai <gurudas.pai@oracle.com>
using fio.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Split ondemand readahead interface into two functions.  I think this makes it
a little clearer for non-readahead experts (like Rusty).

Internally they both call ondemand_readahead(), but the page argument is
changed to an obvious boolean flag.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NFengguang Wu <wfg@mail.ustc.edu.cn>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Pass real splice size to page_cache_readahead_ondemand().

The splice code works in chunks of 16 pages internally.  The readahead code
should be told of the overall splice size, instead of the internal chunk size.
 Otherwize bad things may happen.  Imagine some 17-page random splice reads.
The code before this patch will result in two readahead calls: readahead(16);
readahead(1); That leads to one 16-page I/O and one 32-page I/O: one extra I/O
and 31 readahead miss pages.
Signed-off-by: NFengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Move synchronous page_cache_readahead_ondemand() call out of splice loop.

This avoids one pointless page allocation/insertion in case of non-zero
ra_pages, or many pointless readahead calls in case of zero ra_pages.

Note that if a user sets ra_pages to less than PIPE_BUFFERS=16 pages, he will
not get expected readahead behavior anyway.  The splice code works in batches
of 16 pages, which can be taken as another form of synchronous readahead.
Signed-off-by: NFengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Convert splice reads to use on-demand readahead.
Signed-off-by: NFengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Jens Axboe <axboe@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> reported that he's noticed
nfsd read corruption in recent kernels, and did the hard work of
discovering that it's due to splice updating the file position twice.
This means that the next operation would start further ahead than it
should.

nfsd_vfs_read()
    splice_direct_to_actor()
        while(len) {
            do_splice_to()                     [update sd->pos]
                -> generic_file_splice_read()  [read from sd->pos]
            nfsd_direct_splice_actor()
                -> __splice_from_pipe()        [update sd->pos]

There's nothing wrong with the core splice code, but the direct
splicing is an addon that calls both input and output paths.
So it has to take care in locally caching offset so it remains correct.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

If the output actor doesn't transfer the full amount of data, we will
increment ppos too much. Two related bugs in there:

- We need to break out and return actor() retval if it is shorted than
  what we spliced into the pipe.

- Adjust ppos only according to actor() return.

Also fix loop problem in generic_file_splice_read(), it should not keep
going when data has already been transferred.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Revalidate read/write permissions for splice(2) and vmslice(2), in case
security policy has changed since the files were opened.
Acked-by: NStephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: NJames Morris <jmorris@namei.org>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

As per Andrew Mortons request, here's a set of documentation for
the generic pipe_buf_operations hooks, the pipe, and pipe_buffer
structures.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

The name 'pin' was badly chosen, it doesn't pin a pipe buffer
in the most commonly used sense in the kernel. So change the
name to 'confirm', after debating this issue with Hugh
Dickins a bit.

A good return from ->confirm() means that the buffer is really
there, and that the contents are good.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Also add fs/splice.c as a kerneldoc target with a smaller blurb that
should be expanded to better explain the overview of splice.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

relay needs this for proper consumption handling, and the network
receive support needs it as well to lookup the sk_buff on pipe
release.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

We need to move even more stuff into the header so that folks can use
the splice_to_pipe() implementation instead of open-coding a lot of
pipe knowledge (see relay implementation), so move to our own header
file finally.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

A bit of a cheat, it actually just copies the data to userspace. But
this makes the interface nice and symmetric and enables people to build
on splice, with room for future improvement in performance.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

For direct splicing (or private splicing), the output may not be a file.
So abstract out the handling into a specified actor function and put
the data in the splice_desc structure earlier, so we can build on top
of that.

This is the first step in better splice handling for drivers, and also
for implementing vmsplice _to_ user memory.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

We only ever set do_wakeup to non-zero if the pipe has an inode
backing, so it's pointless to check outside the pipe->inode
check.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

If the destination pipe is full and we already transferred
data, we break out instead of waiting for more pipe room.
The exit logic looks at spd->nr_pages to see if we moved
everything inside the spd container, but we decrement that
variable in the loop to decide when spd has emptied.

Instead we want to compare to the original page count in
the spd, so cache that in a local variable.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

As we have potentially dirtied more than 1 page, we should indicate as
such to the dirty page balancing. So call
balance_dirty_pages_ratelimited_nr() and pass in the approximate number
of pages we dirtied.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Original patch and description from Neil Brown <neilb@suse.de>,
merged and adapted to splice branch by me. Neils text follows:

__generic_file_splice_read() currently samples the i_size at the start
and doesn't do so again unless it needs to call ->readpage to load
a page.  After ->readpage it has to re-sample i_size as a truncate
may have caused that page to be filled with zeros, and the read()
call should not see these.

However there are other activities that might cause ->readpage to be
called on a page between the time that __generic_file_splice_read()
samples i_size and when it finds that it has an uptodate page. These
include at least read-ahead and possibly another thread performing a
read

So we must sample i_size *after* it has an uptodate page.  Thus the
current sampling at the start and after a read can be replaced with a
sampling before page addition into spd.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

__generic_file_splice_read's partial page check, at eof after readpage,
not only got its calculations wrong, but also reused the loff variable:
causing data corruption when splicing from a non-0 offset in the file's
last page (revealed by ext2 -b 1024 testing on a loop of a tmpfs file).
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

I've seen inode related deadlocks, so move this call outside of the
actor itself, which may hold the inode lock.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

It's only supposed to be used by do_sendfile(), which is never
modular. So kill the export.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Don't try to guess what the read-ahead logic will do, allow it
to make its own decisions.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Eric Dumazet, thank you for disclosing this bug.

Readahead logic somehow fails to populate the page range with data.
It can be because

1) the readahead routine is not always called in the following lines of

fs/splice.c:
        if (!loff || nr_pages > 1)
                page_cache_readahead(mapping, &in->f_ra, in, index, nr_pages);

2) even called, page_cache_readahead() wont guarantee the pages are there.
It wont submit readahead I/O for pages already in the radix tree, or when
(ra_pages == 0), or after 256 cache hits.

In your case, it should be because of the retried reads, which lead to
excessive cache hits, and disables readahead at some time.

And that _one_ failure of readahead blocks the whole read process.
The application receives EAGAIN and retries the read, but
__generic_file_splice_read() refuse to make progress:

- in the previous invocation, it has allocated a blank page and inserted it
  into the radix tree, but never has the chance to start I/O for it: the test
  of SPLICE_F_NONBLOCK goes before that.

- in the retried invocation, the readahead code will neither get out of the
  cache hit mode, nor will it submit I/O for an already existing page.

Cc: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Currently if partial write has happened while ->commit_write() then page
wasn't marked as accessed and rebalanced.
Signed-off-by: NMonakhov Dmitriy <dmonakhov@openvz.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Ocfs2 wants to implement it's own splice write actor so that it can better
manage cluster / page locks. This lets us re-use the rest of splice write
while only providing our own code where it's actually important.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Splice does not need to readpage to bring the page uptodate before writing
to it, because prepare_write will take care of that for us.

Splice is also wrong to SetPageUptodate before the page is actually uptodate.
This results in the old uninitialised memory leak. This gets fixed as a
matter of course when removing the readpage logic.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Stealing pages with splice is problematic because we cannot just insert
an uptodate page into the pagecache and hope the filesystem can take care
of it later.

We also cannot just ClearPageUptodate, then hope prepare_write does not
write anything into the page, because I don't think prepare_write gives
that guarantee.

Remove support for SPLICE_F_MOVE for now. If we really want to bring it
back, we might be able to do so with a the new filesystem buffered write
aops APIs I'm working on. If we really don't want to bring it back, then
we should decide that sooner rather than later, and remove the flag and
all the stealing infrastructure before anybody starts using it.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

- pipe/splice should use const pipe_buf_operations and file_operations

- struct pipe_inode_info has an unused field "start" : get rid of it.
Signed-off-by: NEric Dumazet <dada1@cosmosbay.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch changes struct file to use struct path instead of having
independent pointers to struct dentry and struct vfsmount, and converts all
users of f_{dentry,vfsmnt} in fs/ to use f_path.{dentry,mnt}.

Additionally, it adds two #define's to make the transition easier for users of
the f_dentry and f_vfsmnt.
Signed-off-by: NJosef "Jeff" Sipek <jsipek@cs.sunysb.edu>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

After the inode slimming patch that unionised i_pipe/i_bdev/i_cdev, it's
no longer enough to check for existance of ->i_pipe to verify that this
is a pipe.

Original patch from Eric Dumazet <dada1@cosmosbay.com>
Final solution suggested by Linus.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

- Consolidate page_cache_alloc

- Fix splice: only the pagecache pages and filesystem data need to use
  mapping_gfp_mask.

- Fix grab_cache_page_nowait: same as splice, also honour NUMA placement.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Originally from Mark Fasheh <mark.fasheh@oracle.com>

generic_file_splice_write() does not remove S_ISUID or S_ISGID. This is
inconsistent with the way we generally write to files.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

This allows file systems to manage their own i_mutex locking while
still re-using the generic_file_splice_write() logic.

OCFS2 in particular wants this so that it can order cluster locks within
i_mutex.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

The splice_actor may be calling ->prepare_write() and ->commit_write(). We
want i_mutex on the inode being written to before calling those so that we
don't race i_size changes.

The double locking behavior is done elsewhere in splice.c, and if we
eventually want _nolock variants of generic_file_splice_write(), fs modules
might have to replicate the nasty locking code. We introduce
inode_double_lock() and inode_double_unlock() to consolidate the locking
rules into one set of functions.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Don't jump to the unlock+release path, we already did that.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

As people often look for the copyright in files to see who to mail,
update the link to a neutral one.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Several issues noticed/fixed:

- We cannot reliably block in link_pipe() while holding both input and output
  mutexes. So do preparatory checks before locking down both mutexes and doing
  the link.

- The ipipe->nrbufs vs i check was bad, because we could have dropped the
  ipipe lock in-between. This causes us to potentially look at unknown
  buffers if we were racing with someone else reading this pipe.
Signed-off-by: NJens Axboe <axboe@suse.de>