Adding bd_claim_by_kobject() function which takes kobject as additional
signature of holder device and creates sysfs symlinks between holder device
and claimed device.  bd_release_from_kobject() is a counterpart of
bd_claim_by_kobject.
Signed-off-by: NJun'ichi Nomura <j-nomura@ce.jp.nec.com>
Cc: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Now that get_block() can handle mapping multiple disk blocks, no need to have
->get_blocks().  This patch removes fs specific ->get_blocks() added for DIO
and makes it users use get_block() instead.
Signed-off-by: NBadari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add blkcnt_t as the type of inode.i_blocks.  This enables you to make the size
of blkcnt_t either 4 bytes or 8 bytes on 32 bits architecture with CONFIG_LSF.

- CONFIG_LSF
  Add new configuration parameter.
- blkcnt_t
  On h8300, i386, mips, powerpc, s390 and sh that define sector_t,
  blkcnt_t is defined as u64 if CONFIG_LSF is enabled; otherwise it is
  defined as unsigned long.
  On other architectures, it is defined as unsigned long.
- inode.i_blocks
  Change the type from sector_t to blkcnt_t.
Signed-off-by: NTakashi Sato <sho@tnes.nec.co.jp>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch series fixes the following problems on 32 bits architecture.

o stat64 returns the lower 32 bits of blocks, although userland st_blocks
  has 64 bits, because i_blocks has only 32 bits.  The ioctl with FIOQSIZE has
  the same problem.

o As Dave Kleikamp said, making >2TB file on JFS results in writing an
  invalid block number to disk inode.  The cause is the same as above too.

o In generic quota code dquot_transfer(), the file usage is calculated from
  i_blocks via inode_get_bytes().  If the file is over 2TB, the change of
  usage is less than expected.  The cause is the same as above too.

o As Trond Myklebust said, statfs64's entries related to blocks are invalid
  on statfs64 for a network filesystem which has more than 2^32-1 blocks with
  CONFIG_LBD disabled.  [PATCH 3/3]

We made patches to fix problems that occur when handling a large filesystem
and a large file.  It was discussed on the mails titled "stat64 for over 2TB
file returned invalid st_blocks".
Signed-off-by: NTakashi Sato <sho@tnes.nec.co.jp>
Cc: Dave Kleikamp <shaggy@austin.ibm.com>
Cc: Jan Kara <jack@ucw.cz>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Lockd and the NFSv4 server both exercise a race condition where
posix_test_lock() is called either before or after posix_lock_file() to
deal with a denied lock request due to a conflicting lock.

Remove the race condition for the NFSv4 server by adding a new conflicting
lock parameter to __posix_lock_file() , changing the name to
__posix_lock_file_conf().

Keep posix_lock_file() interface, add posix_lock_conf() interface, both
call __posix_lock_file_conf().

[akpm@osdl.org: Put the EXPORT_SYMBOL() where it belongs]
Signed-off-by: NAndy Adamson <andros@citi.umich.edu>
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The return value of this function is never used, so let's be honest and
declare it as void.

Some places where invalidatepage returned 0, I have inserted comments
suggesting a BUG_ON.

[akpm@osdl.org: JBD BUG fix]
[akpm@osdl.org: rework for git-nfs]
[akpm@osdl.org: don't go BUG in block_invalidate_page()]
Signed-off-by: NNeil Brown <neilb@suse.de>
Acked-by: NDave Kleikamp <shaggy@austin.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The only user ignores the return value, and the only instanace
(block_sync_page) always returns 0...
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Introduce FMODE_EXEC file flag, to indicate that file is being opened for
execution.  This is useful for distributed filesystems to maintain
consistent behavior for returning ETXTBUSY when opening for write and
execution happens on different nodes.

akpm:

  Needed by Lustre at present.  I assume their objective to to work towards
  being able to install Lustre on an unmodified distro kernel, which seems
  sane.  It should have zero runtime cost.

  Trond and Chuck indicate that NFS4 can probably use this too, for the same
  thing.

  Steven says it's also on the GFS todo list.
Signed-off-by: NOleg Drokin <green@linuxhacker.ru>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Chuck Lever <cel@citi.umich.edu>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

There's no reason for iprune_mutex being global.
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Pull the guts out of do_fsync() - we can use it elsewhere.

Cc: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

We need set_page_dirty() to return true if it actually transitioned the page
from a clean to dirty state.  This wasn't right in a couple of places.  Do a
kernel-wide audit, fix things up.

This leaves open the possibility of returning a negative errno from
set_page_dirty() sometime in the future.  But we don't do that at present.
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add two new linux-specific fadvise extensions():

LINUX_FADV_ASYNC_WRITE: start async writeout of any dirty pages between file
offsets `offset' and `offset+len'.  Any pages which are currently under
writeout are skipped, whether or not they are dirty.

LINUX_FADV_WRITE_WAIT: wait upon writeout of any dirty pages between file
offsets `offset' and `offset+len'.

By combining these two operations the application may do several things:

LINUX_FADV_ASYNC_WRITE: push some or all of the dirty pages at the disk.

LINUX_FADV_WRITE_WAIT, LINUX_FADV_ASYNC_WRITE: push all of the currently dirty
pages at the disk.

LINUX_FADV_WRITE_WAIT, LINUX_FADV_ASYNC_WRITE, LINUX_FADV_WRITE_WAIT: push all
of the currently dirty pages at the disk, wait until they have been written.

It should be noted that none of these operations write out the file's
metadata.  So unless the application is strictly performing overwrites of
already-instantiated disk blocks, there are no guarantees here that the data
will be available after a crash.

To complete this suite of operations I guess we should have a "sync file
metadata only" operation.  This gives applications access to all the building
blocks needed for all sorts of sync operations.  But sync-metadata doesn't fit
well with the fadvise() interface.  Probably it should be a new syscall:
sys_fmetadatasync().

The patch also diddles with the meaning of `endbyte' in sys_fadvise64_64().
It is made to represent that last affected byte in the file (ie: it is
inclusive).  Generally, all these byterange and pagerange functions are
inclusive so we can easily represent EOF with -1.

As Ulrich notes, these two functions are somewhat abusive of the fadvise()
concept, which appears to be "set the future policy for this fd".

But these commands are a perfect fit with the fadvise() impementation, and
several of the existing fadvise() commands are synchronous and don't affect
future policy either.   I think we can live with the slight incongruity.

Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The meaning of MS_VERBOSE is backwards; if the bit is set, it really means,
"don't be verbose".  This is confusing and counter-intuitive.

In addition, there is also no way to set the MS_VERBOSE flag in the
mount(8) program in util-linux, but interesting, it does define options
which would do the right thing if MS_SILENT were defined, which
unfortunately we do not:

#ifdef MS_SILENT
  { "quiet",    0, 0, MS_SILENT    },   /* be quiet  */
  { "loud",     0, 1, MS_SILENT    },   /* print out messages. */
#endif

So the obvious fix is to deprecate the use of MS_VERBOSE and replace it
with MS_SILENT.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Signed-off-by: NJens Axboe <axboe@suse.de>

Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Semaphore to mutex conversion.

The conversion was generated via scripts, and the result was validated
automatically via a script as well.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Semaphore to mutex conversion.

The conversion was generated via scripts, and the result was validated
automatically via a script as well.
Signed-off-by: NArjan van de Ven <arjan@infradead.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Semaphore to mutex conversion.

The conversion was generated via scripts, and the result was validated
automatically via a script as well.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Acked-by: NRobert Love <rml@novell.com>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Semaphore to mutex conversion.

The conversion was generated via scripts, and the result was validated
automatically via a script as well.
Signed-off-by: NArjan van de Ven <arjan@infradead.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Acked-by: NJens Axboe <axboe@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Currently lockd directly access the file_lock_list from fs/locks.c.
It does so to mark locks granted or reclaimable.  This is very
suboptimal, because a) lockd needs to poke into locks.c internals, and
b) it needs to iterate over all locks in the system for marking locks
granted or reclaimable.

This patch adds lists for granted and reclaimable locks to the nlm_host
structure instead, and adds locks to those.

nlmclnt_lock:
	now adds the lock to h_granted instead of setting the
	NFS_LCK_GRANTED, still O(1)

nlmclnt_mark_reclaim:
	goes away completely, replaced by a list_splice_init.
	Complexity reduced from O(locks in the system) to O(1)

reclaimer:
	iterates over h_reclaim now, complexity reduced from
	O(locks in the system) to O(locks per nlm_host)
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Currently lockd identifies its own locks using the FL_LOCKD flag.  This
doesn't scale well to multiple lock managers--if we did this in nfsv4 too,
for example, we'd be left with only one free flag bit.

Instead, we just check whether the file manager ops (fl_lmops) set on this
lock are our own.

The only use for this is in nlm_traverse_locks, which uses it to find locks
that need cleaning up when freeing a host or a file.

In the long run it might be nice to do reference counting instead of
traversing all the locks like this....
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

posix_test_lock() returns a pointer to a struct file_lock which is unprotected
and can be removed while in use by the caller.  Move the conflicting lock from
the return to a parameter, and copy the conflicting lock.

In most cases the caller ends up putting the copy of the conflicting lock on
the stack.  On i386, sizeof(struct file_lock) appears to be about 100 bytes.
We're assuming that's reasonable.
Signed-off-by: NAndy Adamson <andros@citi.umich.edu>
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

posix_lock_file() is used to add a blocked lock to Lockd's block, so
posix_block_lock() is no longer needed.
Signed-off-by: NAndy Adamson <andros@citi.umich.edu>
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

Create a new file under /proc/self, called mountstats, where mounted file
systems can export information (configuration options, performance counters,
and so on).  Use a mechanism similar to /proc/mounts and s_ops->show_options.

This mechanism does not violate namespace security, and is safe to use while
other processes are unmounting file systems.

Thanks to Mike Waychison for his review and comments.

Test-plan:
Test concurrent mount/unmount operations while cat'ing /proc/self/mountstats.
Signed-off-by: NChuck Lever <cel@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

This patch fixes illegal __GFP_FS allocation inside ext3 transaction in
ext3_symlink().  Such allocation may re-enter ext3 code from
try_to_free_pages.  But JBD/ext3 code keeps a pointer to current journal
handle in task_struct and, hence, is not reentrable.

This bug led to "Assertion failure in journal_dirty_metadata()" messages.

http://bugzilla.openvz.org/show_bug.cgi?id=115Signed-off-by: NAndrey Savochkin <saw@saw.sw.com.sg>
Signed-off-by: NKirill Korotaev <dev@openvz.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

I have benchmarked this on an x86_64 NUMA system and see no significant
performance difference on kernbench.  Tested on both x86_64 and powerpc.

The way we do file struct accounting is not very suitable for batched
freeing.  For scalability reasons, file accounting was
constructor/destructor based.  This meant that nr_files was decremented
only when the object was removed from the slab cache.  This is susceptible
to slab fragmentation.  With RCU based file structure, consequent batched
freeing and a test program like Serge's, we just speed this up and end up
with a very fragmented slab -

llm22:~ # cat /proc/sys/fs/file-nr
587730  0       758844

At the same time, I see only a 2000+ objects in filp cache.  The following
patch I fixes this problem.

This patch changes the file counting by removing the filp_count_lock.
Instead we use a separate percpu counter, nr_files, for now and all
accesses to it are through get_nr_files() api.  In the sysctl handler for
nr_files, we populate files_stat.nr_files before returning to user.

Counting files as an when they are created and destroyed (as opposed to
inside slab) allows us to correctly count open files with RCU.
Signed-off-by: NDipankar Sarma <dipankar@in.ibm.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

They aren't used (nor even really usable) outside of pipe.c anyway
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Migrate a page with buffers without requiring writeback

This introduces a new address space operation migratepage() that may be used
by a filesystem to implement its own version of page migration.

A version is provided that migrates buffers attached to pages.  Some
filesystems (ext2, ext3, xfs) are modified to utilize this feature.

The swapper address space operation are modified so that a regular
migrate_page() will occur for anonymous pages without writeback (migrate_pages
forces every anonymous page to have a swap entry).
Signed-off-by: NMike Kravetz <kravetz@us.ibm.com>
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Here is a series of patches which introduce in total 13 new system calls
which take a file descriptor/filename pair instead of a single file
name.  These functions, openat etc, have been discussed on numerous
occasions.  They are needed to implement race-free filesystem traversal,
they are necessary to implement a virtual per-thread current working
directory (think multi-threaded backup software), etc.

We have in glibc today implementations of the interfaces which use the
/proc/self/fd magic.  But this code is rather expensive.  Here are some
results (similar to what Jim Meyering posted before).

The test creates a deep directory hierarchy on a tmpfs filesystem.  Then
rm -fr is used to remove all directories.  Without syscall support I get
this:

real    0m31.921s
user    0m0.688s
sys     0m31.234s

With syscall support the results are much better:

real    0m20.699s
user    0m0.536s
sys     0m20.149s

The interfaces are for obvious reasons currently not much used.  But they'll
be used.  coreutils (and Jeff's posixutils) are already using them.
Furthermore, code like ftw/fts in libc (maybe even glob) will also start using
them.  I expect a patch to make follow soon.  Every program which is walking
the filesystem tree will benefit.
Signed-off-by: NUlrich Drepper <drepper@redhat.com>
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@ftp.linux.org.uk>
Acked-by: NIngo Molnar <mingo@elte.hu>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch adds an empty /sys/fs, which filesystems can use.
Signed-off-by: NMiklos Szeredi <miklos@szeredi.hu>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

A Christoph suggested that the /proc/devices file be converted to use the
seq_file interface.  This patch does that.

I've obxerved one or two installation that had sufficiently large sans that
they overran the 4k limit on /proc/devices.
Signed-off-by: NNeil Horman <nhorman@redhat.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Turn noatime and nodiratime into per-mount instead of per-sb flags.

After all the preparations this is a rather trivial patch.  The mount code
needs to treat the two options as per-mount instead of per-superblock, and
touch_atime needs to be changed to check the new MNT_ flags in addition to
the MS_ flags that are kept for filesystems that are always
noatime/nodiratime but not user settable anymore.  Besides that core code
only nfs needed an update because it's leaving atime updates to the server
and thus sets the S_NOATIME flag on every inode, but needs to know whether
it's a real noatime mount for an getattr optimization.

While we're at it I've killed the IS_NOATIME/IS_NODIRATIME macros that were
only used by touch_atime.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

All callers use touch_atime now which takes a vfsmount and allows us to
implement per-mount noatime.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

To allow various options to work per-mount instead of per-sb we need a
struct vfsmount when updating ctime and mtime.  This preparation patch
replaces the inode_update_time routine with a file_update_atime routine so
we can easily get at the vfsmount.  (and the file makes more sense in this
context anyway).  Also get rid of the unused second argument - we always
want to update the ctime when calling this routine.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Anton Altaparmakov <aia21@cantab.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch converts the superblock-lock semaphore to a mutex, affecting
lock_super()/unlock_super(). Tested on ext3 and XFS.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This patch converts the inode semaphore to a mutex. I have tested it on
XFS and compiled as much as one can consider on an ia64. Anyway your
luck with it might be different.
Modified-by: NIngo Molnar <mingo@elte.hu>

(finished the conversion)
Signed-off-by: NJes Sorensen <jes@sgi.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This patch inlines the single user of struct super_block field
s_old_blocksize and removes the field.
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Small cleanups in shared mounts code.
Signed-off-by: NMiklos Szeredi <miklos@szeredi.hu>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: <viro@parcelfarce.linux.theplanet.co.uk>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

HDIO_GETGEO is implemented in most block drivers, and all of them have to
duplicate the code to copy the structure to userspace, as well as getting
the start sector.  This patch moves that to common code [1] and adds a
->getgeo method to fill out the raw kernel hd_geometry structure.  For many
drivers this means ->ioctl can go away now.

[1] the s390 block drivers are odd in this respect.  xpram sets ->start
    to 4 always which seems more than odd, and the dasd driver shifts
    the start offset around, probably because of it's non-standard
    sector size.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@suse.de>
Cc: <mike.miller@hp.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Paolo Giarrusso <blaisorblade@yahoo.it>
Cc: Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl>
Cc: Neil Brown <neilb@cse.unsw.edu.au>
Cc: Markus Lidel <Markus.Lidel@shadowconnect.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

SUS requires that when truncating a file to the size that it currently
is:
  truncate and ftruncate should NOT modify ctime or mtime
  O_TRUNC SHOULD modify ctime and mtime.

Currently mtime and ctime are always modified on most local
filesystems (side effect of ->truncate) or never modified (on NFS).

With this patch:
  ATTR_CTIME|ATTR_MTIME are sent with ATTR_SIZE precisely when
    an update of these times is required whether size changes or not
    (via a new argument to do_truncate).  This allows NFS to do
    the right thing for O_TRUNC.
  inode_setattr nolonger forces ATTR_MTIME|ATTR_CTIME when the ATTR_SIZE
    sets the size to it's current value.  This allows local filesystems
    to do the right thing for f?truncate.

Also, the logic in inode_setattr is changed a bit so there are two return
points.  One returns the error from vmtruncate if it failed, the other
returns 0 (there can be no other failure).

Finally, if vmtruncate succeeds, and ATTR_SIZE is the only change
requested, we now fall-through and mark_inode_dirty.  If a filesystem did
not have a ->truncate function, then vmtruncate will have changed i_size,
without marking the inode as 'dirty', and I think this is wrong.
Signed-off-by: NNeil Brown <neilb@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>