Reclaim will be leaving shadow entries in the page cache radix tree upon
evicting the real page.  As those pages are found from the LRU, an
iput() can lead to the inode being freed concurrently.  At this point,
reclaim must no longer install shadow pages because the inode freeing
code needs to ensure the page tree is really empty.

Add an address_space flag, AS_EXITING, that the inode freeing code sets
under the tree lock before doing the final truncate.  Reclaim will check
for this flag before installing shadow pages.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Bob Liu <bob.liu@oracle.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Luigi Semenzato <semenzato@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Metin Doslu <metin@citusdata.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Ozgun Erdogan <ozgun@citusdata.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roman Gushchin <klamm@yandex-team.ru>
Cc: Ryan Mallon <rmallon@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The hostfs_*() callback functions are all only used within
hostfs_kern.c, so make them static.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: user-mode-linux-devel@lists.sourceforge.net
Signed-off-by: Richard Weinberger <richard@nod.at>

Rename simple_delete_dentry() to always_delete_dentry() and export it.
Export simple_dentry_operations, while we are at it, and get rid of
their duplicates

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

We have to implement ->release() and trigger writeback from it.
Otherwise we might lose dirty pages at munmap().

Signed-off-by: Richard Weinberger <richard@nod.at>

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

The inode info structure is zeroed at allocation with kzalloc, and then
all but one of the fields (including the largest, vfs_inode) are
initialised explicitly. Switch to using kmalloc and initialise the
remaining field too.

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Move HOSTFS_SUPER_MAGIC to <linux/magic.h> to be with it's magical
friends from other file systems.

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

A "will unlock" comment was added to hostfs in the following commit,
along with a spinlock:

Commit e9193059b1b3733695d5b80e667778311695aa73 ("hostfs: fix races in
dentry_name() and inode_name()").

But the spinlock was subsequently removed in the following commit:

Commit ec2447c278ee973d35f38e53ca16ba7f965ae33d ("hostfs: simplify
locking").

Since the comment is no longer applicable, remove it.

Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Pull namespace bugfixes from Eric Biederman:
 "This tree includes a partial revert for "fs: Limit sys_mount to only
  request filesystem modules." When I added the new style module aliases
  to the filesystems I deleted the old ones.  A bad move.  It turns out
  that distributions like Arch linux use module aliases when
  constructing ramdisks.  Which meant ultimately that an ext3 filesystem
  mounted with ext4 would not result in the ext4 module being put into
  the ramdisk.

  The other change in this tree adds a handful of filesystem module
  alias I simply failed to add the first time.  Which inconvinienced a
  few folks using cifs.

  I don't want to inconvinience folks any longer than I have to so here
  are these trivial fixes."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  fs: Readd the fs module aliases.
  fs: Limit sys_mount to only request filesystem modules. (Part 3)

Somehow I failed to add the MODULE_ALIAS_FS for cifs, hostfs, hpfs,
squashfs, and udf despite what I thought were my careful checks :(

Add them now.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>