While it's at its least, make a number of boring nitpicky cleanups to
shmem.c, mostly for consistency of variable naming.  Things like "swap"
instead of "entry", "pgoff_t index" instead of "unsigned long idx".

And since everything else here is prefixed "shmem_", better change
init_tmpfs() to shmem_init().
Signed-off-by: NHugh Dickins <hughd@google.com>
Acked-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The maximum size of a shmem/tmpfs file has been limited by the maximum
size of its triple-indirect swap vector.  With 4kB page size, maximum
filesize was just over 2TB on a 32-bit kernel, but sadly one eighth of
that on a 64-bit kernel.  (With 8kB page size, maximum filesize was just
over 4TB on a 64-bit kernel, but 16TB on a 32-bit kernel,
MAX_LFS_FILESIZE being then more restrictive than swap vector layout.)

It's a shame that tmpfs should be more restrictive than ramfs, and this
limitation has now been noticed.  Add another level to the swap vector?
No, it became obscure and hard to maintain, once I complicated it to
make use of highmem pages nine years ago: better choose another way.

Surely, if 2.4 had had the radix tree pagecache introduced in 2.5, then
tmpfs would never have invented its own peculiar radix tree: we would
have fitted swap entries into the common radix tree instead, in much the
same way as we fit swap entries into page tables.

And why should each file have a separate radix tree for its pages and
for its swap entries? The swap entries are required precisely where and
when the pages are not.  We want to put them together in a single radix
tree: which can then avoid much of the locking which was needed to
prevent them from being exchanged underneath us.

This also avoids the waste of memory devoted to swap vectors, first in
the shmem_inode itself, then at least two more pages once a file grew
beyond 16 data pages (pages accounted by df and du, but not by memcg).
Allocated upfront, to avoid allocation when under swapping pressure, but
pure waste when CONFIG_SWAP is not set - I have never spattered around
the ifdefs to prevent that, preferring this move to sharing the common
radix tree instead.

There are three downsides to sharing the radix tree.  One, that it binds
tmpfs more tightly to the rest of mm, either requiring knowledge of swap
entries in radix tree there, or duplication of its code here in shmem.c.
I believe that the simplications and memory savings (and probable higher
performance, not yet measured) justify that.

Two, that on HIGHMEM systems with SWAP enabled, it's the lowmem radix
nodes that cannot be freed under memory pressure - whereas before it was
the less precious highmem swap vector pages that could not be freed.
I'm hoping that 64-bit has now been accessible for long enough, that the
highmem argument has grown much less persuasive.

Three, that swapoff is slower than it used to be on tmpfs files, since
it's using a simple generic mechanism not tailored to it: I find this
noticeable, and shall want to improve, but maybe nobody else will
notice.

So...  now remove most of the old swap vector code from shmem.c.  But,
for the moment, keep the simple i_direct vector of 16 pages, with simple
accessors shmem_put_swap() and shmem_get_swap(), as a toy implementation
to help mark where swap needs to be handled in subsequent patches.
Signed-off-by: NHugh Dickins <hughd@google.com>
Acked-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Although it is used (by i915) on nothing but tmpfs, read_cache_page_gfp()
is unsuited to tmpfs, because it inserts a page into pagecache before
calling the filesystem's ->readpage: tmpfs may have pages in swapcache
which only it knows how to locate and switch to filecache.

At present tmpfs provides a ->readpage method, and copes with this by
copying pages; but soon we can simplify it by removing its ->readpage.
Provide shmem_read_mapping_page_gfp() now, ready for that transition,

Export shmem_read_mapping_page_gfp() and add it to list in shmem_fs.h,
with shmem_read_mapping_page() inline for the common mapping_gfp case.

(shmem_read_mapping_page_gfp or shmem_read_cache_page_gfp? Generally the
read_mapping_page functions use the mapping's ->readpage, and the
read_cache_page functions use the supplied filler, so I think
read_cache_page_gfp was slightly misnamed.)
Signed-off-by: NHugh Dickins <hughd@google.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

2.6.35's new truncate convention gave tmpfs the opportunity to control
its file truncation, no longer enforced from outside by vmtruncate().
We shall want to build upon that, to handle pagecache and swap together.

Slightly redefine the ->truncate_range interface: let it now be called
between the unmap_mapping_range()s, with the filesystem responsible for
doing the truncate_inode_pages_range() from it - just as the filesystem
is nowadays responsible for doing that from its ->setattr.

Let's rename shmem_notify_change() to shmem_setattr().  Instead of
calling the generic truncate_setsize(), bring that code in so we can
call shmem_truncate_range() - which will later be updated to perform its
own variant of truncate_inode_pages_range().

Remove the punch_hole unmap_mapping_range() from shmem_truncate_range():
now that the COW's unmap_mapping_range() comes after ->truncate_range,
there is no need to call it a third time.

Export shmem_truncate_range() and add it to the list in shmem_fs.h, so
that i915_gem_object_truncate() can call it explicitly in future; get
this patch in first, then update drm/i915 once this is available (until
then, i915 will just be doing the truncate_inode_pages() twice).

Though introduced five years ago, no other filesystem is implementing
->truncate_range, and its only other user is madvise(,,MADV_REMOVE): we
expect to convert it to fallocate(,FALLOC_FL_PUNCH_HOLE,,) shortly,
whereupon ->truncate_range can be removed from inode_operations -
shmem_truncate_range() will help i915 across that transition too.
Signed-off-by: NHugh Dickins <hughd@google.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Before adding any more global entry points into shmem.c, gather such
prototypes into shmem_fs.h.  Remove mm's own declarations from swap.h,
but for now leave the ones in mm.h: because shmem_file_setup() and
shmem_zero_setup() are called from various places, and we should not
force other subsystems to update immediately.
Signed-off-by: NHugh Dickins <hughd@google.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Implement generic xattrs for tmpfs filesystems.  The Feodra project, while
trying to replace suid apps with file capabilities, realized that tmpfs,
which is used on the build systems, does not support file capabilities and
thus cannot be used to build packages which use file capabilities.  Xattrs
are also needed for overlayfs.

The xattr interface is a bit odd.  If a filesystem does not implement any
{get,set,list}xattr functions the VFS will call into some random LSM hooks
and the running LSM can then implement some method for handling xattrs.
SELinux for example provides a method to support security.selinux but no
other security.* xattrs.

As it stands today when one enables CONFIG_TMPFS_POSIX_ACL tmpfs will have
xattr handler routines specifically to handle acls.  Because of this tmpfs
would loose the VFS/LSM helpers to support the running LSM.  To make up
for that tmpfs had stub functions that did nothing but call into the LSM
hooks which implement the helpers.

This new patch does not use the LSM fallback functions and instead just
implements a native get/set/list xattr feature for the full security.* and
trusted.* namespace like a normal filesystem.  This means that tmpfs can
now support both security.selinux and security.capability, which was not
previously possible.

The basic implementation is that I attach a:

struct shmem_xattr {
	struct list_head list; /* anchored by shmem_inode_info->xattr_list */
	char *name;
	size_t size;
	char value[0];
};

Into the struct shmem_inode_info for each xattr that is set.  This
implementation could easily support the user.* namespace as well, except
some care needs to be taken to prevent large amounts of unswappable memory
being allocated for unprivileged users.

[mszeredi@suse.cz: new config option, suport trusted.*, support symlinks]
Signed-off-by: NEric Paris <eparis@redhat.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Acked-by: NSerge Hallyn <serge.hallyn@ubuntu.com>
Tested-by: NSerge Hallyn <serge.hallyn@ubuntu.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Acked-by: NHugh Dickins <hughd@google.com>
Tested-by: NJordi Pujol <jordipujolp@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The current implementation of tmpfs is not scalable.  We found that
stat_lock is contended by multiple threads when we need to get a new page,
leading to useless spinning inside this spin lock.

This patch makes use of the percpu_counter library to maintain local count
of used blocks to speed up getting and returning of pages.  So the
acquisition of stat_lock is unnecessary for getting and returning blocks,
improving the performance of tmpfs on system with large number of cpus.
On a 4 socket 32 core NHM-EX system, we saw improvement of 270%.

The implementation below has a slight chance of race between threads
causing a slight overshoot of the maximum configured blocks.  However, any
overshoot is small, and is bounded by the number of cpus.  This happens
when the number of used blocks is slightly below the maximum configured
blocks when a thread checks the used block count, and another thread
allocates the last block before the current thread does.  This should not
be a problem for tmpfs, as the overshoot is most likely to be a few blocks
and bounded.  If a strict limit is really desired, then configured the max
blocks to be the limit less the number of cpus in system.
Signed-off-by: NTim Chen <tim.c.chen@linux.intel.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>

Now that we cache the ACL pointers in the generic inode all the generic_acl
cruft can go away and generic_acl.c can directly implement xattr handlers
dealing with the full Posix ACL semantics for in-memory filesystems.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Devtmpfs lets the kernel create a tmpfs instance called devtmpfs
very early at kernel initialization, before any driver-core device
is registered. Every device with a major/minor will provide a
device node in devtmpfs.

Devtmpfs can be changed and altered by userspace at any time,
and in any way needed - just like today's udev-mounted tmpfs.
Unmodified udev versions will run just fine on top of it, and will
recognize an already existing kernel-created device node and use it.
The default node permissions are root:root 0600. Proper permissions
and user/group ownership, meaningful symlinks, all other policy still
needs to be applied by userspace.

If a node is created by devtmps, devtmpfs will remove the device node
when the device goes away. If the device node was created by
userspace, or the devtmpfs created node was replaced by userspace, it
will no longer be removed by devtmpfs.

If it is requested to auto-mount it, it makes init=/bin/sh work
without any further userspace support. /dev will be fully populated
and dynamic, and always reflect the current device state of the kernel.
With the commonly used dynamic device numbers, it solves the problem
where static devices nodes may point to the wrong devices.

It is intended to make the initial bootup logic simpler and more robust,
by de-coupling the creation of the inital environment, to reliably run
userspace processes, from a complex userspace bootstrap logic to provide
a working /dev.
Signed-off-by: NKay Sievers <kay.sievers@vrfy.org>
Signed-off-by: NJan Blunck <jblunck@suse.de>
Tested-By: NHarald Hoyer <harald@redhat.com>
Tested-By: NScott James Remnant <scott@ubuntu.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

shmfs wants purely standard POSIX ACL semantics, so we can use the new
generic VFS layer POSIX ACL checking rather than cooking our own
'permission()' function.
Reviewed-by: NJames Morris <jmorris@namei.org>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Acked-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

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

* kill nameidata * argument; map the 3 bits in ->flags anybody cares
  about to new MAY_... ones and pass with the mask.
* kill redundant gfs2_iop_permission()
* sanitize ecryptfs_permission()
* fix remaining places where ->permission() instances might barf on new
  MAY_... found in mask.

The obvious next target in that direction is permission(9)

folded fix for nfs_permission() breakage from Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

This patch replaces the mempolicy mode, mode_flags, and nodemask in the
shmem_sb_info struct with a struct mempolicy pointer, initialized to NULL.
This removes dependency on the details of mempolicy from shmem.c and hugetlbfs
inode.c and simplifies the interfaces.

mpol_parse_str() in mempolicy.c is changed to return, via a pointer to a
pointer arg, a struct mempolicy pointer on success.  For MPOL_DEFAULT, the
returned pointer is NULL.  Further, mpol_parse_str() now takes a 'no_context'
argument that causes the input nodemask to be stored in the w.user_nodemask of
the created mempolicy for use when the mempolicy is installed in a tmpfs inode
shared policy tree.  At that time, any cpuset contextualization is applied to
the original input nodemask.  This preserves the previous behavior where the
input nodemask was stored in the superblock.  We can think of the returned
mempolicy as "context free".

Because mpol_parse_str() is now calling mpol_new(), we can remove from
mpol_to_str() the semantic checks that mpol_new() already performs.

Add 'no_context' parameter to mpol_to_str() to specify that it should format
the nodemask in w.user_nodemask for 'bind' and 'interleave' policies.

Change mpol_shared_policy_init() to take a pointer to a "context free" struct
mempolicy and to create a new, "contextualized" mempolicy using the mode,
mode_flags and user_nodemask from the input mempolicy.

  Note: we know that the mempolicy passed to mpol_to_str() or
  mpol_shared_policy_init() from a tmpfs superblock is "context free".  This
  is currently the only instance thereof.  However, if we found more uses for
  this concept, and introduced any ambiguity as to whether a mempolicy was
  context free or not, we could add another internal mode flag to identify
  context free mempolicies.  Then, we could remove the 'no_context' argument
  from mpol_to_str().

Added shmem_get_sbmpol() to return a reference counted superblock mempolicy,
if one exists, to pass to mpol_shared_policy_init().  We must add the
reference under the sb stat_lock to prevent races with replacement of the mpol
by remount.  This reference is removed in mpol_shared_policy_init().

[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: another build fix]
[akpm@linux-foundation.org: yet another build fix]
Signed-off-by: NLee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

With the evolution of mempolicies, it is necessary to support mempolicy mode
flags that specify how the policy shall behave in certain circumstances.  The
most immediate need for mode flag support is to suppress remapping the
nodemask of a policy at the time of rebind.

Both the mempolicy mode and flags are passed by the user in the 'int policy'
formal of either the set_mempolicy() or mbind() syscall.  A new constant,
MPOL_MODE_FLAGS, represents the union of legal optional flags that may be
passed as part of this int.  Mempolicies that include illegal flags as part of
their policy are rejected as invalid.

An additional member to struct mempolicy is added to support the mode flags:

	struct mempolicy {
		...
		unsigned short policy;
		unsigned short flags;
	}

The splitting of the 'int' actual passed by the user is done in
sys_set_mempolicy() and sys_mbind() for their respective syscalls.  This is
done by intersecting the actual with MPOL_MODE_FLAGS, rejecting the syscall of
there are additional flags, and storing it in the new 'flags' member of struct
mempolicy.  The intersection of the actual with ~MPOL_MODE_FLAGS is stored in
the 'policy' member of the struct and all current users of pol->policy remain
unchanged.

The union of the policy mode and optional mode flags is passed back to the
user in get_mempolicy().

This combination of mode and flags within the same actual does not break
userspace code that relies on get_mempolicy(&policy, ...) and either

	switch (policy) {
	case MPOL_BIND:
		...
	case MPOL_INTERLEAVE:
		...
	};

statements or

	if (policy == MPOL_INTERLEAVE) {
		...
	}

statements.  Such applications would need to use optional mode flags when
calling set_mempolicy() or mbind() for these previously implemented statements
to stop working.  If an application does start using optional mode flags, it
will need to mask the optional flags off the policy in switch and conditional
statements that only test mode.

An additional member is also added to struct shmem_sb_info to store the
optional mode flags.

[hugh@veritas.com: shmem mpol: fix build warning]
Cc: Paul Jackson <pj@sgi.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The mempolicy mode constants, MPOL_DEFAULT, MPOL_PREFERRED, MPOL_BIND, and
MPOL_INTERLEAVE, are better declared as part of an enum since they are
sequentially numbered and cannot be combined.

The policy member of struct mempolicy is also converted from type short to
type unsigned short.  A negative policy does not have any legitimate meaning,
so it is possible to change its type in preparation for adding optional mode
flags later.

The equivalent member of struct shmem_sb_info is also changed from int to
unsigned short.

For compatibility, the policy formal to get_mempolicy() remains as a pointer
to an int:

	int get_mempolicy(int *policy, unsigned long *nmask,
			  unsigned long maxnode, unsigned long addr,
			  unsigned long flags);

although the only possible values is the range of type unsigned short.

Cc: Paul Jackson <pj@sgi.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add .show_options super operation to tmpfs.
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add access control lists for tmpfs.
Signed-off-by: NAndreas Gruenbacher <agruen@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Anything that writes into a tmpfs filesystem is liable to disproportionately
decrease the available memory on a particular node.  Since there's no telling
what sort of application (e.g.  dd/cp/cat) might be dropping large files
there, this lets the admin choose the appropriate default behavior for their
site's situation.

Introduce a tmpfs mount option which allows specifying a memory policy and
a second option to specify the nodelist for that policy.  With the default
policy, tmpfs will behave as it does today.  This patch adds support for
preferred, bind, and interleave policies.

The default policy will cause pages to be added to tmpfs files on the node
which is doing the writing.  Some jobs expect a single process to create
and manage the tmpfs files.  This results in a node which has a
significantly reduced number of free pages.

With this patch, the administrator can specify the policy and nodes for
that policy where they would prefer allocations.

This patch was originally written by Brent Casavant and Hugh Dickins.  I
added support for the bind and preferred policies and the mpol_nodelist
mount option.
Signed-off-by: NBrent Casavant <bcasavan@sgi.com>
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NRobin Holt <holt@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!