Don't implement per-filesystem 'extX_permission()' functions that have
to be called for every path component operation, and instead just expose
the actual ACL checking so that the VFS layer can now do it for us.
Reviewed-by: NJames Morris <jmorris@namei.org>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch makes the error message about changing journaling mode on remount
more descriptive. Some people are going to hit this error now due to commit
bbae8bcc if they configure a kernel to default
to data=writeback mode. The problem happens if they have data=ordered set for
the root filesystem in /etc/fstab but not in the kernel command line (and they
don't use initrd). Their filesystem then gets mounted as data=writeback by
kernel but then their boot fails because init scripts won't be able to remount
the filesystem rw. Better error message will hopefully make it easier for them
to find the error in their setup and bother us less with error reports :).
Signed-off-by: NJan Kara <jack@suse.cz>

The old description for this configuration option was perhaps not
completely balanced in terms of describing the tradeoffs of using a
default of data=writeback vs. data=ordered.  Despite the fact that old
description very strongly recomended disabling this feature, all of
the major distributions have elected to preserve the existing 'legacy'
default, which is a strong hint that it perhaps wasn't telling the
whole story.

This revised description has been vetted by a number of ext3
developers as being better at informing the user about the tradeoffs
of enabling or disabling this configuration feature.

Cc: linux-ext4@vger.kernel.org
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: NJan Kara <jack@suse.cz>

Get rid of extenddisksize parameter of ext3_get_blocks_handle(). This seems to
be a relict from some old days and setting disksize in this function does not
make much sence. Currently it was set only by ext3_getblk().  Since the
parameter has some effect only if create == 1, it is easy to check that the
three callers which end up calling ext3_getblk() with create == 1 (ext3_append,
ext3_quota_write, ext3_mkdir) do the right thing and set disksize themselves.
Signed-off-by: NJan Kara <jack@suse.cz>

Contents of long symlinks is written via standard write methods. So when the
write fails, we add inode to orphan list. But symlinks don't have .truncate
method defined so nobody properly removes them from the orphan list (both on
disk and in memory).

Fix this by calling ext3_truncate() directly instead of calling vmtruncate()
(which is saner anyway since we don't need anything vmtruncate() does except
from calling .truncate in these paths).  We also add inode to orphan list only
if ext3_can_truncate() is true (currently, it can be false for symlinks when
there are no blocks allocated) - otherwise orphan list processing will complain
and ext3_truncate() will not remove inode from on-disk orphan list.
Signed-off-by: NJan Kara <jack@suse.cz>

helpers: get_cached_acl(inode, type), set_cached_acl(inode, type, acl),
forget_cached_acl(inode, type).

ubifs/xattr.c needed includes reordered, the rest is a plain switchover.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Follow-up to "block: enable by default support for large devices
and files on 32-bit archs".

Rename CONFIG_LBD to CONFIG_LBDAF to:
- allow update of existing [def]configs for "default y" change
- reflect that it is used also for large files support nowadays
Signed-off-by: NBartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

As Ted pointed out, it can happen that ext3_truncate() returns without
removing inode from orphan list.  This way we could in some rare cases
(like when we get ENOMEM from an allocation in ext3_truncate called
because of failed ext3_write_begin) leave the inode on orphan list and
that triggers assertion failure on umount.

So make ext3_truncate() always remove inode from in-memory orphan list.

Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Chain verification in ext3_get_blocks() has been hosed since it called
verify_chain(chain, NULL) which always returns success.  As a result
readers could in theory race with truncate.  On the other hand the race
probably cannot happen with the current locking scheme, since by the
time ext3_truncate() is called all the pages are already removed and
hence get_block() shouldn't be called on such pages...
Signed-off-by: NJan Kara <jack@suse.cz>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If a filesystem supports POSIX ACL's, the VFS layer expects the filesystem
to do POSIX ACL checks on any files not owned by the caller, and it does
this for every single pathname component that it looks up.

That obviously can be pretty expensive if the filesystem isn't careful
about it, especially with locking. That's doubly sad, since the common
case tends to be that there are no ACL's associated with the files in
question.

ext3 already caches the ACL data so that it doesn't have to look it up
over and over again, but it does so by taking the inode->i_lock spinlock
on every lookup. Which is a noticeable overhead even if it's a private
lock, especially on CPU's where the serialization is expensive (eg Intel
Netburst aka 'P4').

For the special case of not actually having any ACL's, all that locking is
unnecessary. Even if somebody else were to be changing the ACL's on
another CPU, we simply don't care - if we've seen a NULL ACL, we might as
well use it.

So just load the ACL speculatively without any locking, and if it was
NULL, just use it. If it's non-NULL (either because we had a cached
entry, or because the cache hasn't been filled in at all), it means that
we'll need to get the lock and re-load it properly.

This is noticeable even on Nehalem, which does locking quite well (much
better than P4). From lmbench:

	Processor, Processes - times in microseconds - smaller is better
	--------------------------------------------------------------------
	Host                 OS  Mhz null null      open slct fork exec sh
	                             call  I/O stat clos TCP  proc proc proc
	--------- ------------- ---- ---- ---- ---- ---- ---- ---- ---- ----
 - before:
	nehalem.l Linux 2.6.30- 3193 0.04 0.09 0.95 1.45 2.18 69.1 273. 1141
	nehalem.l Linux 2.6.30- 3193 0.04 0.09 0.95 1.48 2.28 69.9 253. 1140
	nehalem.l Linux 2.6.30- 3193 0.04 0.10 0.95 1.42 2.19 68.6 284. 1141
 - after:
	nehalem.l Linux 2.6.30- 3193 0.04 0.09 0.92 1.44 2.12 68.3 282. 1094
	nehalem.l Linux 2.6.30- 3193 0.04 0.09 0.92 1.39 2.20 67.0 308. 1123
	nehalem.l Linux 2.6.30- 3193 0.04 0.09 0.92 1.39 2.36 67.4 293. 1148

where you can see what appears to be a roughly 3% improvement in stat
and open/close latencies from just the removal of the locking overhead.

Of course, this only matters for files you don't own (the owner never
needs to do the ACL checks), but that's the common case for libraries,
header files, and executables. As well as for the base components of any
absolute pathname, even if you are the owner of the final file.

[ At some point we probably want to move this ACL caching logic entirely
  into the VFS layer (and only call down to the filesystem when
  uncached), but in the meantime this improves ext3 a bit.

  A similar fix to btrfs makes a much bigger difference (15x improvement
  in lmbench) due to broken caching. ]
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Acked-by: NJan Kara <jack@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

[xfs, btrfs, capifs, shmem don't need BKL, exempt]
Signed-off-by: NAlessio Igor Bogani <abogani@texware.it>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Note that since we can't run into contention between remount_fs and write_super
(due to exclusion on s_umount), we have to care only about filesystems that
touch lock_super() on their own.  Out of those ext3, ext4, hpfs, sysv and ufs
do need it; fat doesn't since its ->remount_fs() only accesses assign-once
data (basically, it's "we have no atime on directories and only have atime on
files for vfat; force nodiratime and possibly noatime into *flags").

[folded a build fix from hch]
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Move BKL into ->put_super from the only caller.  A couple of
filesystems had trivial enough ->put_super (only kfree and NULLing of
s_fs_info + stuff in there) to not get any locking: coda, cramfs, efs,
hugetlbfs, omfs, qnx4, shmem, all others got the full treatment.  Most
of them probably don't need it, but I'd rather sort that out individually.
Preferably after all the other BKL pushdowns in that area.

[AV: original used to move lock_super() down as well; these changes are
removed since we don't do lock_super() at all in generic_shutdown_super()
now]
[AV: fuse, btrfs and xfs are known to need no damn BKL, exempt]
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Until now we have had a 1:1 mapping between storage device physical
block size and the logical block sized used when addressing the device.
With SATA 4KB drives coming out that will no longer be the case.  The
sector size will be 4KB but the logical block size will remain
512-bytes.  Hence we need to distinguish between the physical block size
and the logical ditto.

This patch renames hardsect_size to logical_block_size.
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Signed-off-by: NManish Katiyar <mkatiyar@gmail.com>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

If a filesystem supports POSIX ACL's, the VFS layer expects the filesystem 
to do POSIX ACL checks on any files not owned by the caller, and it does 
this for every single pathname component that it looks up.

That obviously can be pretty expensive if the filesystem isn't careful 
about it, especially with locking. That's doubly sad, since the common 
case tends to be that there are no ACL's associated with the files in 
question.

ext3 already caches the ACL data so that it doesn't have to look it up 
over and over again, but it does so by taking the inode->i_lock spinlock 
on every lookup. Which is a noticeable overhead even if it's a private 
lock, especially on CPU's where the serialization is expensive (eg Intel 
Netburst aka 'P4').

For the special case of not actually having any ACL's, all that locking is 
unnecessary. Even if somebody else were to be changing the ACL's on 
another CPU, we simply don't care - if we've seen a NULL ACL, we might as 
well use it.

So just load the ACL speculatively without any locking, and if it was 
NULL, just use it. If it's non-NULL (either because we had a cached 
entry, or because the cache hasn't been filled in at all), it means that 
we'll need to get the lock and re-load it properly.

This is noticeable even on Nehalem, which does locking quite well (much 
better than P4). From lmbench:

	Processor, Processes - times in microseconds - smaller is better
	--------------------------------------------------------------------
	Host                 OS  Mhz null null      open slct fork exec sh  
	                             call  I/O stat clos TCP  proc proc proc
	--------- ------------- ---- ---- ---- ---- ---- ---- ---- ---- ----
 - before:
	nehalem.l Linux 2.6.30- 3193 0.04 0.09 0.95 1.45 2.18 69.1 273. 1141
	nehalem.l Linux 2.6.30- 3193 0.04 0.09 0.95 1.48 2.28 69.9 253. 1140
	nehalem.l Linux 2.6.30- 3193 0.04 0.10 0.95 1.42 2.19 68.6 284. 1141
 - after:
	nehalem.l Linux 2.6.30- 3193 0.04 0.09 0.92 1.44 2.12 68.3 282. 1094
	nehalem.l Linux 2.6.30- 3193 0.04 0.09 0.92 1.39 2.20 67.0 308. 1123
	nehalem.l Linux 2.6.30- 3193 0.04 0.09 0.92 1.39 2.36 67.4 293. 1148

where you can see what appears to be a roughly 3% improvement in stat
and open/close latencies from just the removal of the locking overhead. 

Of course, this only matters for files you don't own (the owner never 
needs to do the ACL checks), but that's the common case for libraries, 
header files, and executables. As well as for the base components of any 
absolute pathname, even if you are the owner of the final file.

[ At some point we probably want to move this ACL caching logic entirely
  into the VFS layer (and only call down to the filesystem when
  uncached), but in the meantime this improves ext3 a bit.

  A similar fix to btrfs makes a much bigger difference (15x improvement
  in lmbench) due to broken caching. ]
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Acked-by: NJan Kara <jack@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>

This does the same as commit 9e80d407
(avoid starting a transaction when no block allocation is needed)
but for data=writeback mode of ext3. We also cleanup the data=ordered
case a bit to stick to coding style...
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

This makes the defautl ext3 data ordering mode (when no explicit
ordering is set) configurable, so as to allow people to default to
'data=writeback' and get the resulting latency improvements.

This is a non-issue if a filesystem has been explicitly set to some
ordering (with 'tune2fs').
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In data=writeback mode, start an asynchronous flush when renaming a
file on top of an already-existing file.  This lowers the probability
of data loss in the case of applications that attempt to replace a
file via using rename().
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

In data=writeback mode, start an asynchronous flush when closing a
file which had been previously truncated down to zero.  This lowers
the probability of data loss in the case of applications that attempt
to replace a file using truncate.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

Sometimes block_write_begin() can map buffers in a page but later we
fail to copy data into those buffers (because the source page has been
paged out in the mean time).  We then end up with !uptodate mapped
buffers.  To add a bit more to the confusion, block_write_end() does
not commit any data (and thus does not any mark buffers as uptodate) if
we didn't succeed with copying all the data.

Commit f4fc66a8 (ext3: convert to new
aops) missed these cases and thus we were inserting non-uptodate
buffers to transaction's list which confuses JBD code and it reports IO
errors, aborts a transaction and generally makes users afraid about
their data ;-P.

This patch fixes the problem by reorganizing ext3_..._write_end() code
to first call block_write_end() to mark buffers with valid data
uptodate and after that we file only uptodate buffers to transaction's
lists.

We also fix a problem where we could leave blocks allocated beyond i_size
(i_disksize in fact) because of failed write. We now add inode to orphan
list when write fails (to be safe in case we crash) and then truncate blocks
beyond i_size in a separate transaction.
Signed-off-by: NJan Kara <jack@suse.cz>
Reviewed-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

ext3_iget() returns -ESTALE if invoked on a deleted inode, in order to
report errors to NFS properly.  However, in ext[234]_lookup(), this
-ESTALE can be propagated to userspace if the filesystem is corrupted such
that a directory entry references a deleted inode.  This leads to a
misleading error message - "Stale NFS file handle" - and confusion on the
part of the admin.

The bug can be easily reproduced by creating a new filesystem, making a
link to an unused inode using debugfs, then mounting and attempting to ls
-l said link.

This patch thus changes ext3_lookup to return -EIO if it receives -ESTALE
from ext3_iget(), as ext3 does for other filesystem metadata corruption;
and also invokes the appropriate ext*_error functions when this case is
detected.
Signed-off-by: NBryan Donlan <bdonlan@gmail.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use unsigned instead of int for the parameter which carries a blocksize.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NWei Yongjun <yjwei@cn.fujitsu.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Reformat ext3/ioctl.c to make it look more like ext4/ioctl.c and remove
the BKL around ext3_ioctl().
Signed-off-by: NCyrus Massoumi <cyrusm@gmx.net>
Cc: <linux-ext4@vger.kernel.org>
Acked-by: NJan Kara <jack@ucw.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

current->fs->umask is what most of fs_struct users are doing.
Put that into a helper function.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

We don't have to start a transaction in writepage() when all the blocks
are a properly allocated. Even in ordered mode either the data has been
written via write() and they are thus already added to transaction's list
or the data was written via mmap and then it's random in which transaction
they get written anyway.

This should help VM to pageout dirty memory without blocking on transaction
commits.
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use lowercase names of quota functions instead of old uppercase ones.
Signed-off-by: NJan Kara <jack@suse.cz>
CC: linux-ext4@vger.kernel.org

ext3_dquot_initialize() and ext3_dquot_drop() is no longer
needed because of modified quota locking.
Signed-off-by: NJan Kara <jack@suse.cz>

This reverts commit c87591b7.

Since journal_start_commit() is now fixed to return 1 when we started a
transaction commit, there's some transaction waiting to be committed or
there's a transaction already committing, we don't need to call
ext3_force_commit() in ext3_sync_fs().  Furthermore ext3_force_commit()
can unnecessarily create sync transaction which is expensive so it's
worthwhile to remove it when we can.

Cc: Eric Sandeen <sandeen@redhat.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make sure the rec_len field in the '..' entry is sane, lest we overrun
the directory block and cause a kernel oops on a purposefully
corrupted filesystem.

This fixes a bug related to a bug originally reported by Sami Liedes
for ext4 at:

http://bugzilla.kernel.org/show_bug.cgi?id=12430Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org

Currently, ext3 in mainline Linux doesn't have the freeze feature which
suspends write requests.  So, we cannot take a backup which keeps the
filesystem's consistency with the storage device's features (snapshot and
replication) while it is mounted.

In many case, a commercial filesystem (e.g.  VxFS) has the freeze feature
and it would be used to get the consistent backup.

If Linux's standard filesystem ext3 has the freeze feature, we can do it
without a commercial filesystem.

So I have implemented the ioctls of the freeze feature.
I think we can take the consistent backup with the following steps.
1. Freeze the filesystem with the freeze ioctl.
2. Separate the replication volume or create the snapshot
   with the storage device's feature.
3. Unfreeze the filesystem with the unfreeze ioctl.
4. Take the backup from the separated replication volume
   or the snapshot.

This patch:

VFS:
Changed the type of write_super_lockfs and unlockfs from "void"
to "int" so that they can return an error.
Rename write_super_lockfs and unlockfs of the super block operation
freeze_fs and unfreeze_fs to avoid a confusion.

ext3, ext4, xfs, gfs2, jfs:
Changed the type of write_super_lockfs and unlockfs from "void"
to "int" so that write_super_lockfs returns an error if needed,
and unlockfs always returns 0.

reiserfs:
Changed the type of write_super_lockfs and unlockfs from "void"
to "int" so that they always return 0 (success) to keep a current behavior.
Signed-off-by: NTakashi Sato <t-sato@yk.jp.nec.com>
Signed-off-by: NMasayuki Hamaguchi <m-hamaguchi@ys.jp.nec.com>
Cc: <xfs-masters@oss.sgi.com>
Cc: <linux-ext4@vger.kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Kleikamp <shaggy@austin.ibm.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Alasdair G Kergon <agk@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use the new generic implementation.
Signed-off-by: NWu Fengguang <fengguang.wu@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

At the moment there are few restrictions on which flags may be set on
which inodes.  Specifically DIRSYNC may only be set on directories and
IMMUTABLE and APPEND may not be set on links.  Tighten that to disallow
TOPDIR being set on non-directories and only NODUMP and NOATIME to be set
on non-regular file, non-directories.

Introduces a flags masking function which masks flags based on mode and
use it during inode creation and when flags are set via the ioctl to
facilitate future consistency.
Signed-off-by: NDuane Griffin <duaneg@dghda.com>
Acked-by: NAndreas Dilger <adilger@sun.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

At present INDEX is the only flag that new ext3 inodes do NOT inherit from
their parent.  In addition prevent the flags DIRTY, ECOMPR, IMAGIC and
TOPDIR from being inherited.  List inheritable flags explicitly to prevent
future flags from accidentally being inherited.

This fixes the TOPDIR flag inheritance bug reported at
http://bugzilla.kernel.org/show_bug.cgi?id=9866.
Signed-off-by: NDuane Griffin <duaneg@dghda.com>
Acked-by: NAndreas Dilger <adilger@sun.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

As spotted by kmemtrace, struct ext3_sb_info is 17152 bytes on 64-bit
which makes it a very bad fit for SLAB allocators.  The culprit of the
wasted memory is ->s_blockgroup_lock which can be as big as 16 KB when
NR_CPUS >= 32.

To fix that, allocate ->s_blockgroup_lock, which fits nicely in a order 2
page in the worst case, separately.  This shinks down struct ext3_sb_info
enough to fit a 1 KB slab cache so now we allocate 16 KB + 1 KB instead of
32 KB saving 15 KB of memory.
Acked-by: NAndreas Dilger <adilger@sun.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>

Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>

With the write_begin/write_end aops, page_symlink was broken because it
could no longer pass a GFP_NOFS type mask into the point where the
allocations happened.  They are done in write_begin, which would always
assume that the filesystem can be entered from reclaim.  This bug could
cause filesystem deadlocks.

The funny thing with having a gfp_t mask there is that it doesn't really
allow the caller to arbitrarily tinker with the context in which it can be
called.  It couldn't ever be GFP_ATOMIC, for example, because it needs to
take the page lock.  The only thing any callers care about is __GFP_FS
anyway, so turn that into a single flag.

Add a new flag for write_begin, AOP_FLAG_NOFS.  Filesystems can now act on
this flag in their write_begin function.  Change __grab_cache_page to
accept a nofs argument as well, to honour that flag (while we're there,
change the name to grab_cache_page_write_begin which is more instructive
and does away with random leading underscores).

This is really a more flexible way to go in the end anyway -- if a
filesystem happens to want any extra allocations aside from the pagecache
ones in ints write_begin function, it may now use GFP_KERNEL (rather than
GFP_NOFS) for common case allocations (eg.  ocfs2_alloc_write_ctxt, for a
random example).

[kosaki.motohiro@jp.fujitsu.com: fix ubifs]
[kosaki.motohiro@jp.fujitsu.com: fix fuse]
Signed-off-by: NNick Piggin <npiggin@suse.de>
Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: <stable@kernel.org>		[2.6.28.x]
Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
[ Cleaned up the calling convention: just pass in the AOP flags
  untouched to the grab_cache_page_write_begin() function.  That
  just simplifies everybody, and may even allow future expansion of the
  logic.   - Linus ]
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>