kcalloc manages count*sizeof overflow.
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

tmp_page to be freed if fuse_write_file_get() returns NULL.
Signed-off-by: NMaxim Patlasov <mpatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

The patch extends fuse_setattr_in, and extends the flush procedure
(fuse_flush_times()) called on ->write_inode() to send the ctime as well as
mtime.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

...and flush mtime from this.  This allows us to use the kernel
infrastructure for writing out dirty metadata (mtime at this point, but
ctime in the next patches and also maybe atime).
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Don't need to start I/O twice (once without i_mutex and one within).

Also make sure that even if the userspace filesystem doesn't support FSYNC
we do all the steps other than sending the message.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

in preparation for getting rid of FUSE_I_MTIME_DIRTY.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

In case of fc->atomic_o_trunc is set, fuse does nothing in
fuse_do_setattr() while handling open(O_TRUNC). Hence, i_mtime must be
updated explicitly in fuse_finish_open(). The patch also adds extra locking
encompassing open(O_TRUNC) operation to avoid races between the truncation
and updating i_mtime.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Bad case of shadowing.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Don't allow new fallocate modes until we figure out what (if anything) that
takes.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

filemap_map_pages() is generic implementation of ->map_pages() for
filesystems who uses page cache.

It should be safe to use filemap_map_pages() for ->map_pages() if
filesystem use filemap_fault() for ->fault().
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ning Qu <quning@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix the following warning:

In file included from include/linux/fs.h:16:0,
                 from fs/fuse/fuse_i.h:13,
                 from fs/fuse/file.c:9:
fs/fuse/file.c: In function 'fuse_file_poll':
include/linux/rbtree.h:82:28: warning: 'parent' may be used
uninitialized in this function [-Wmaybe-uninitialized]
fs/fuse/file.c:2592:27: note: 'parent' was declared here
Signed-off-by: NRajat Jain <rajatxjain@gmail.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Introduce a bit kernel and userspace exchange between each-other on
the init stage and turn writeback on if the userspace want this and
mount option 'allow_wbcache' is present (controlled by fusermount).

Also add each writable file into per-inode write list and call the
generic_file_aio_write to make use of the Linux page cache engine.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

The problem is:

1. write cached data to a file
2. read directly from the same file (via another fd)

The 2nd operation may read stale data, i.e. the one that was in a file
before the 1st op. Problem is in how fuse manages writeback.

When direct op occurs the core kernel code calls filemap_write_and_wait
to flush all the cached ops in flight. But fuse acks the writeback right
after the ->writepages callback exits w/o waiting for the real write to
happen. Thus the subsequent direct op proceeds while the real writeback
is still in flight. This is a problem for backends that reorder operation.

Fix this by making the fuse direct IO callback explicitly wait on the
in-flight writeback to finish.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

The aim of .flush fop is to hint file-system that flushing its state or caches
or any other important data to reliable storage would be desirable now.
fuse_flush() passes this hint by sending FUSE_FLUSH request to userspace.
However, dirty pages and pages under writeback may be not visible to userspace
yet if we won't ensure it explicitly.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

The .write_begin and .write_end are requiered to use generic routines
(generic_file_aio_write --> ... --> generic_perform_write) for buffered
writes.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Move the code filling and sending read request to a separate function. Future
patches will use it for .write_begin -- partial modification of a page
requires reading the page from the storage very similarly to what fuse_readpage
does.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Any write request requires a file handle to report to the userspace. Thus
when we close a file (and free the fuse_file with this info) we have to
flush all the outstanding dirty pages.

filemap_write_and_wait() is enough because every page under fuse writeback
is accounted in ff->count. This delays actual close until all fuse wb is
completed.

In case of "write cache" turned off, the flush is ensured by fuse_vma_close().
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Let the kernel maintain i_mtime locally:
 - clear S_NOCMTIME
 - implement i_op->update_time()
 - flush mtime on fsync and last close
 - update i_mtime explicitly on truncate and fallocate

Fuse inode flag FUSE_I_MTIME_DIRTY serves as indication that local i_mtime
should be flushed to the server eventually.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Make fuse think that when writeback is on the inode's i_size is always
up-to-date and not update it with the value received from the userspace.
This is done because the page cache code may update i_size without letting
the FS know.

This assumption implies fixing the previously introduced short-read helper --
when a short read occurs the 'hole' is filled with zeroes.

fuse_file_fallocate() is also fixed because now we should keep i_size up to
date, so it must be updated if FUSE_FALLOCATE request succeeded.
Signed-off-by: NMaxim V. Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

A helper which gets called when read reports less bytes than was requested.
See patch "trust kernel i_size only" for details.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

When writeback is ON every writeable file should be in per-inode write list,
not only mmap-ed ones. Thus introduce a helper for this linkage.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

always equal to &iocb->ki_pos.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

... it does that itself (via kmap_atomic())
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

So far I've had one ACK for this, and no other comments. So I think it
is probably time to send this via some suitable tree. I'm guessing that
the vfs tree would be the most appropriate route, but not sure that
there is one at the moment (don't see anything recent at kernel.org)
so in that case I think -mm is the "back up plan". Al, please let me
know if you will take this?

Steve.

---------------------

Following on from the "Re: [PATCH v3] vfs: fix a bug when we do some dio
reads with append dio writes" thread on linux-fsdevel, this patch is my
current version of the fix proposed as option (b) in that thread.

Removing the i_size test from the direct i/o read path at vfs level
means that filesystems now have to deal with requests which are beyond
i_size themselves. These I've divided into three sets:

 a) Those with "no op" ->direct_IO (9p, cifs, ceph)
These are obviously not going to be an issue

 b) Those with "home brew" ->direct_IO (nfs, fuse)
I've been told that NFS should not have any problem with the larger
i_size, however I've added an extra test to FUSE to duplicate the
original behaviour just to be on the safe side.

 c) Those using __blockdev_direct_IO()
These call through to ->get_block() which should deal with the EOF
condition correctly. I've verified that with GFS2 and I believe that
Zheng has verified it for ext4. I've also run the test on XFS and it
passes both before and after this change.

The part of the patch in filemap.c looks a lot larger than it really is
- there are only two lines of real change. The rest is just indentation
of the contained code.

There remains a test of i_size though, which was added for btrfs. It
doesn't cause the other filesystems a problem as the test is performed
after ->direct_IO has been called. It is possible that there is a race
that does matter to btrfs, however this patch doesn't change that, so
its still an overall improvement.
Signed-off-by: NSteven Whitehouse <swhiteho@redhat.com>
Reported-by: NZheng Liu <gnehzuil.liu@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Acked-by: NMiklos Szeredi <miklos@szeredi.hu>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

open/release operations require userspace transitions to keep track
of the open count and to perform any FS-specific setup.  However,
for some purely read-only FSs which don't need to perform any setup
at open/release time, we can avoid the performance overhead of
calling into userspace for open/release calls.

This patch adds the necessary support to the fuse kernel modules to prevent
open/release operations from hitting in userspace. When the client returns
ENOSYS, we avoid sending the subsequent release to userspace, and also
remember this so that future opens also don't trigger a userspace
operation.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Various read operations (e.g. readlink, readdir) invalidate the cached
attrs for atime changes.  This patch adds a new function
'fuse_invalidate_atime', which checks for a read-only super block and
avoids the attr invalidation in that case.
Signed-off-by: NAndrew Gallagher <andrewjcg@fb.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

All async fuse requests must be supplied with extra reference to a fuse
file.  This is necessary to ensure that the fuse file is not released until
all in-flight requests are completed.  Fuse secondary writeback requests
must obey this rule as well.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

BDI_WRITTEN counter is used to estimate bdi bandwidth.  It must be
incremented every time as bdi ends page writeback.  No matter whether it
was fulfilled by actual write or by discarding the request (e.g. due to
shrunk i_size).

Note that even before writepages patches, the case "Got truncated off
completely" was handled in fuse_send_writepage() by calling
fuse_writepage_finish() which updated BDI_WRITTEN unconditionally.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

If writeback happens while fuse is in FUSE_NOWRITE condition, the request
will be queued but not processed immediately (see fuse_flush_writepages()).
Until FUSE_NOWRITE becomes relaxed, more writebacks can happen.  They will
be queued as "secondary" requests to that first ("primary") request.

Existing implementation crops only primary request.  This is not correct
because a subsequent extending write(2) may increase i_size and then
secondary requests won't be cropped properly.  The result would be stale
data written to the server to a file offset where zeros must be.

Similar problem may happen if secondary requests are attached to an
in-flight request that was already cropped.

The patch solves the issue by cropping all secondary requests in
fuse_writepage_end().  Thanks to Miklos for idea.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

fuse_writepage_in_flight() returns false if it fails to find request with
given index in fi->writepages.  Then the caller proceeds with populating
data->orig_pages[] and incrementing req->num_pages.  Hence,
fuse_writepage_in_flight() must revert changes it made in request before
returning false.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

If ->writepage() tries to write back a page whose copy is still in flight,
then just skip by calling redirty_page_for_writepage().

This is OK, since now ->writepage() should never be called for data
integrity sync.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

As Maxim Patlasov pointed out, it's possible to get a dirty page while it's
copy is still under writeback, despite fuse_page_mkwrite() doing its thing
(direct IO).

This could result in two concurrent write request for the same offset, with
data corruption if they get mixed up.

To prevent this, fuse needs to check and delay such writes.  This
implementation does this by:

 1. check if page is still under writeout, if so create a new, single page
    secondary request for it

 2. chain this secondary request onto the in-flight request

 2/a. if a seconday request for the same offset was already chained to the
    in-flight request, then just copy the contents of the page and discard
    the new secondary request.  This makes sure that for each page will
    have at most two requests associated with it

 3. when the in-flight request finished, send off all secondary requests
    chained onto it
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Checking against tmp-page indexes is not very useful, and results in one
(or rarely two) page requests.  Which is not much of an improvement...
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

The patch fixes a race between ftruncate(2), mmap-ed write and write(2):

1) An user makes a page dirty via mmap-ed write.
2) The user performs shrinking truncate(2) intended to purge the page.
3) Before fuse_do_setattr calls truncate_pagecache, the page goes to
   writeback. fuse_writepages_fill attaches a new page to FUSE_WRITE request,
   then releases the original page by end_page_writeback and unlock it.
4) fuse_do_setattr completes and successfully returns. Since now, i_mutex
   is free.
5) Ordinary write(2) extends i_size back to cover the page. Note that
   fuse_send_write_pages do wait for fuse writeback, but for another
   page->index.
6) fuse_writepages_fill attaches more pages to the request (if any), then
   fuse_writepages_send is eventually called. It is supposed to crop
   inarg->size of the request, but it doesn't because i_size has already been
   extended back.

Moving end_page_writeback behind fuse_writepages_send guarantees that
__fuse_release_nowrite (called from fuse_do_setattr) will crop inarg->size
of the request before write(2) gets the chance to extend i_size.
Signed-off-by: NMaxim Patlasov <mpatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

The .writepages one is required to make each writeback request carry more than
one page on it. The patch enables optimized behaviour unconditionally,
i.e. mmap-ed writes will benefit from the patch even if fc->writeback_cache=0.

[SzM: simplify, add comments]
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Don't bug if there's no writable files found for page writeback.  If ever
this is triggered, a WARN_ON helps debugging it much better then a BUG_ON.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

Lock the page in fuse_page_mkwrite() to protect against a race with
fuse_writepage() where the page is redirtied before the actual writeback
begins.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

The .writepages callback will issue writeback requests with more than one
page aboard. Make existing end/check code be aware of this.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

There will be a .writepageS callback implementation which will need to
get a fuse_file out of a fuse_inode, thus make a helper for this.
Signed-off-by: NMaxim Patlasov <MPatlasov@parallels.com>
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>

A former patch introducing FUSE_I_SIZE_UNSTABLE flag provided detailed
description of races between ftruncate and anyone who can extend i_size:

> 1. As in the previous scenario fuse_dentry_revalidate() discovered that i_size
> changed (due to our own fuse_do_setattr()) and is going to call
> truncate_pagecache() for some  'new_size' it believes valid right now. But by
> the time that particular truncate_pagecache() is called ...
> 2. fuse_do_setattr() returns (either having called truncate_pagecache() or
> not -- it doesn't matter).
> 3. The file is extended either by write(2) or ftruncate(2) or fallocate(2).
> 4. mmap-ed write makes a page in the extended region dirty.

This patch adds necessary bits to fuse_file_fallocate() to protect from that
race.
Signed-off-by: NMaxim Patlasov <mpatlasov@parallels.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Cc: stable@vger.kernel.org