Simplify page cache zeroing of segments of pages through 3 functions

zero_user_segments(page, start1, end1, start2, end2)

        Zeros two segments of the page. It takes the position where to
        start and end the zeroing which avoids length calculations and
	makes code clearer.

zero_user_segment(page, start, end)

        Same for a single segment.

zero_user(page, start, length)

        Length variant for the case where we know the length.

We remove the zero_user_page macro. Issues:

1. Its a macro. Inline functions are preferable.

2. The KM_USER0 macro is only defined for HIGHMEM.

   Having to treat this special case everywhere makes the
   code needlessly complex. The parameter for zeroing is always
   KM_USER0 except in one single case that we open code.

Avoiding KM_USER0 makes a lot of code not having to be dealing
with the special casing for HIGHMEM anymore. Dealing with
kmap is only necessary for HIGHMEM configurations. In those
configurations we use KM_USER0 like we do for a series of other
functions defined in highmem.h.

Since KM_USER0 is depends on HIGHMEM the existing zero_user_page
function could not be a macro. zero_user_* functions introduced
here can be be inline because that constant is not used when these
functions are called.

Also extract the flushing of the caches to be outside of the kmap.

[akpm@linux-foundation.org: fix nfs and ntfs build]
[akpm@linux-foundation.org: fix ntfs build some more]
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Steven French <sfrench@us.ibm.com>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: <linux-ext4@vger.kernel.org>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Anton Altaparmakov <aia21@cantab.net>
Cc: Mark Fasheh <mark.fasheh@oracle.com>
Cc: David Chinner <dgc@sgi.com>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Cc: Steven French <sfrench@us.ibm.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In ocfs2_read_inline_data() we should store file size in loff_t. Although
the file size should fit in 32 bits we cannot be sure in case filesystem is
corrupted.
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

Add ->readpages support to Ocfs2. This is rather trivial - all it required
is a small update to ocfs2_get_block (for mapping full extents via b_size)
and an ocfs2_readpages() function which partially mirrors ocfs2_readpage().
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

Call this the "inode_lock" now, since it covers both data and meta data.
This patch makes no functional changes.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

The meta lock now covers both meta data and data, so this just removes the
now-redundant data lock.

Combining locks saves us a round of lock mastery per inode and one less lock
to ping between nodes during read/write.

We don't lose much - since meta locks were always held before a data lock
(and at the same level) ordered writeout mode (the default) ensured that
flushing for the meta data lock also pushed out data anyways.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

This was causing us to prematurely push out inline data by one byte.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

On file systems which don't support sparse files, Ocfs2_map_page_blocks()
was reading blocks on appending writes. This caused write performance to
suffer dramatically. Fix this by detecting an appending write on a nonsparse
fs and skipping the read.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

Plug ocfs2 into the ->write_begin and ->write_end aops.

A bunch of custom code is now gone - the iovec iteration stuff during write
and the ocfs2 splice write actor.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This fixes up write, truncate, mmap, and RESVSP/UNRESVP to understand inline
inode data.

For the most part, the changes to the core write code can be relied on to do
the heavy lifting. Any code calling ocfs2_write_begin (including shared
writeable mmap) can count on it doing the right thing with respect to
growing inline data to an extent tree.

Size reducing truncates, including UNRESVP can simply zero that portion of
the inode block being removed. Size increasing truncatesm, including RESVP
have to be a little bit smarter and grow the inode to an extent tree if
necessary.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>
Reviewed-by: NJoel Becker <joel.becker@oracle.com>

This hooks up ocfs2_readpage() to populate a page with data from an inode
block. Direct IO reads from inline data are modified to fall back to
buffered I/O. Appropriate checks are also placed in the extent map code to
avoid reading an extent list when inline data might be stored.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>
Reviewed-by: NJoel Becker <joel.becker@oracle.com>

We'll want to reuse most of this when pushing inline data back out to an
extent. Keeping this part as a seperate patch helps to keep the upcoming
changes for write support uncluttered.

The core portion of ocfs2_zero_cluster_pages() responsible for making sure a
page is mapped and properly dirtied is abstracted out into it's own
function, ocfs2_map_and_dirty_page(). Actual functionality doesn't change,
though zeroing becomes optional.

We also turn part of ocfs2_free_write_ctxt() into  a common function for
unlocking and freeing a page array. This operation is very common (and
uniform) for Ocfs2 cluster sizes greater than page size, so it makes sense
to keep the code in one place.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>
Reviewed-by: NJoel Becker <joel.becker@oracle.com>

By doing this, we can remove any higher level logic which has to have
knowledge of btree functionality - any callers of ocfs2_write_begin() can
now expect it to do anything necessary to prepare the inode for new data.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>
Reviewed-by: NJoel Becker <joel.becker@oracle.com>

The target page offsets were being incorrectly set a second time in
ocfs2_prepare_page_for_write(), which was causing problems on a 16k page
size kernel. Additionally, ocfs2_write_failure() was incorrectly using those
parameters instead of the parameters for the individual page being cleaned
up.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

This was broken for file systems whose cluster size is greater than page
size. Pos needs to be incremented as we loop through the descriptors, and
len needs to be capped to the size of a single cluster.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

In ocfs2_alloc_write_write_ctxt, the written clusters length is calculated
by the byte length only. This may cause some problems if we start to write
at some position in the end of one cluster and last to a second cluster
while the "len" is smaller than a cluster size. In that case, we have to
write 2 clusters actually.
So we have to take the start position into consideration also.
Signed-off-by: NTao Ma <tao.ma@oracle.com>
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

Nonlinear mappings are (AFAIKS) simply a virtual memory concept that encodes
the virtual address -> file offset differently from linear mappings.

->populate is a layering violation because the filesystem/pagecache code
should need to know anything about the virtual memory mapping.  The hitch here
is that the ->nopage handler didn't pass down enough information (ie.  pgoff).
 But it is more logical to pass pgoff rather than have the ->nopage function
calculate it itself anyway (because that's a similar layering violation).

Having the populate handler install the pte itself is likewise a nasty thing
to be doing.

This patch introduces a new fault handler that replaces ->nopage and
->populate and (later) ->nopfn.  Most of the old mechanism is still in place
so there is a lot of duplication and nice cleanups that can be removed if
everyone switches over.

The rationale for doing this in the first place is that nonlinear mappings are
subject to the pagefault vs invalidate/truncate race too, and it seemed stupid
to duplicate the synchronisation logic rather than just consolidate the two.

After this patch, MAP_NONBLOCK no longer sets up ptes for pages present in
pagecache.  Seems like a fringe functionality anyway.

NOPAGE_REFAULT is removed.  This should be implemented with ->fault, and no
users have hit mainline yet.

[akpm@linux-foundation.org: cleanup]
[randy.dunlap@oracle.com: doc. fixes for readahead]
[akpm@linux-foundation.org: build fix]
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Cc: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

This can now be trivially supported with re-use of our existing extend code.

ocfs2_allocate_unwritten_extents() takes a start offset and a byte length
and iterates over the inode, adding extents (marked as unwritten) until len
is reached. Existing extents are skipped over.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

Update the write code to detect when the user is asking to write to an
unwritten extent. Like writing to a hole, we must zero the region between
the write and the cluster boundaries. Most of the existing cluster zeroing
logic can be re-used with some additional checks for the unwritten flag on
extent records.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

We can easily seperate out the write descriptor setup and manipulation
into helper functions.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

We don't want to submit buffer_new blocks for read i/o. This actually won't
happen right now because those requests during an allocating write are all nicely
aligned. It's probably a good idea to provide an explicit check though.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

Implement cluster consistent shared writeable mappings using the
->page_mkwrite() callback.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

ocfs2_mkwrite() will want this so that it can add some mmap specific checks
before asking for a write.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

Use some ideas from the new-aops patch series and turn
ocfs2_buffered_write_cluster() into a 2 stage operation with the caller
copying data in between. The code now understands multiple cluster writes as
a result of having to deal with a full page write for greater than 4k pages.

This sets us up to easily call into the write path during ->page_mkwrite().
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

The write path code intends to bug if a math error (or unhandled case)
results in a write outside of the current cluster boundaries. The actual
BUG_ON() statements however are incorrect, leading to a crash on kernels
with 64k page size. Fix those by checking against the right variables.

Also, move the assertions higher up within the functions so that they trip
*before* the code starts to mark buffers.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

Use zero_user_page() instead of open-coding it.
Signed-off-by: NNate Diller <nate.diller@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

Similarly to the page lock / cluster lock inversion in ocfs2_readpage, we
can deadlock on ip_alloc_sem. We can down_read_trylock() instead and just
return AOP_TRUNCATED_PAGE if the operation fails.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

We can otherwise recurse into the file system.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

None of these are actually harmful, but the noise makes looking for real
problems difficult.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

This patch makes the following needlessly global functions static:
- aops.c: ocfs2_write_data_page()
- dlmglue.c: ocfs2_dump_meta_lvb_info()
- file.c: ocfs2_set_inode_size()
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

Cluster locking might have been redone because a direct write won't
complete, so this needs to be reflected in the iocb.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

Older file systems which didn't support holes did a dumb calculation of
i_blocks based on i_size. This is no longer accurate, so fix things up to
take actual allocation into account.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

Initially, we had wired things to return a size '1' of holes. Cook up a
small amount of code to find the next extent and calculate the number of
clusters between the virtual offset and the next allocated extent.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

Return an optional extent flags field from our lookup functions and wire up
callers to treat unwritten regions as holes for the purpose of returning
zeros to the user.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

We need to fill holes during a splice write. Provide our own splice write
actor which can call ocfs2_file_buffered_write() with a splice-specific
callback.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

Since we don't zero on extend anymore, truncate needs to be fixed up to zero
the part of a file between i_size and and end of it's cluster. Otherwise a
subsequent extend could expose bad data.

This introduced a new helper, which can be used in ocfs2_write().
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

ocfs2_get_block() didn't understand sparse files, fix that. Also remove some
code that isn't really useful anymore. We can fix up
ocfs2_direct_IO_get_blocks() at the same time.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

These are no longer used, and can't handle file systems with sparse file
allocation.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>

Unfortunately, ocfs2 can no longer make use of generic_file_aio_write_nlock()
because allocating writes will require zeroing of pages adjacent to the I/O
for cluster sizes greater than page size.

Implement a custom file write here, which can order page locks for zeroing.
This also has the advantage that cluster locks can easily be ordered outside
of the page locks.
Signed-off-by: NMark Fasheh <mark.fasheh@oracle.com>