Just nail the oddments now while this code is being touched
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

To support containers, allow multiple instances of devpts filesystem, such
that indices of ptys allocated in one instance are independent of ptys
allocated in other instances of devpts.

But to preserve backward compatibility, enable this support for multiple
instances only if:

	- CONFIG_DEVPTS_MULTIPLE_INSTANCES is set to Y, and
	- '-o newinstance' mount option is specified while mounting devpts

To use multi-instance mount, a container startup script could:

	$ ns_exec -cm /bin/bash
	$ umount /dev/pts
	$ mount -t devpts -o newinstance lxcpts /dev/pts
	$ mount -o bind /dev/pts/ptmx /dev/ptmx
	$ /usr/sbin/sshd -p 1234

where 'ns_exec -cm /bin/bash' is calls clone() with CLONE_NEWNS flag and execs
/bin/bash in the child process. A pty created by the sshd is not visible in
the original mount of /dev/pts.

USER-SPACE-IMPACT:
	- See Documentation/fs/devpts.txt (included in next patch) for user-
	  space impact in multi-instance and mixed-mode operation.
TODO:
	- Update mount(8), pts(4) man pages. Highlight impact of not
	  redirecting /dev/ptmx to /dev/pts/ptmx after a multi-instance mount.

Changelog[v6]:
	- [Dave Hansen] Use new get_init_pts_sb() interface
	- [Serge Hallyn] Don't bother displaying 'newinstance' in show_options
	- [Serge Hallyn] Use macros (PARSE_REMOUNT/PARSE_MOUNT) instead of 0/1.
	- [Serge Hallyn] Check error return from get_sb_single() (now
	  get_init_pts_sb())
	- devpts_pty_kill(): don't dput error dentries

Changelog[v5]:
	- Move get_sb_ref() definition to earlier patch
	- Move usage info to Documentation/filesystems/devpts.txt (next patch)
	- Make ptmx node even in init_pts_ns, now that default mode is 0000
	  (defined in earlier patch, enabled here).
	- Cache ptmx dentry and use to update mode during remount
	  (defined in earlier patch, enabled here).
	- Bugfix: explicitly ignore newinstance on remount (if newinstance was
	  specified on remount of initial mount, it would be ignored but
	  /proc/mounts would imply that the option was set)

Changelog[v4]:

	- Update patch description to address H. Peter Anvin's comments
	- Consolidate multi-instance mode code under new config token,
	  CONFIG_DEVPTS_MULTIPLE_INSTANCE.
	- Move usage-details from patch description to
	  Documentation/fs/devpts.txt

Changelog[v3]:
	- Rename new mount option to 'newinstance'
	- Create ptmx nodes only in 'newinstance' mounts
	- Bugfix: parse_mount_options() modifies @data but since we need to
	  parse the @data twice (once in devpts_get_sb() and once during
	  do_remount_sb()), parse a local copy of @data in devpts_get_sb().
	  (restructured code in devpts_get_sb() to fix this)

Changelog[v2]:
	- Support both single-mount and multiple-mount semantics and
	  provide '-onewmnt' option to select the semantics.
Signed-off-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

See comments in the function header for details. The new interface will
be used in a follow-on patch.

Changelog [v2]:
	[Dave Hansen] Replace get_sb_ref() in fs/super.c with get_init_pts_sb()
	and make the new interface private to devpts
Signed-off-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

/dev/ptmx is closely tied to the devpts filesystem. An open of /dev/ptmx,
allocates the next pty index and the associated device shows up in the
devpts fs as /dev/pts/n.

Wih multiple instancs of devpts filesystem, during an open of /dev/ptmx
we would be unable to determine which instance of the devpts is being
accessed.

So we move the 'ptmx' node into /dev/pts and use the inode of the 'ptmx'
node to identify the superblock and hence the devpts instance.  This patch
adds ability for the kernel to internally create the [ptmx, c, 5:2] device
when mounting devpts filesystem.  Since the ptmx node in devpts is new and
may surprise some userspace scripts, the default permissions for the new
node is 0000.  These permissions can be changed either using chmod or by
remounting with the new '-o ptmxmode=0666' mount option.

Changelog[v5]:
	- [Serge Hallyn bugfix]: Letting new_inode() assign inode number to
	  ptmx can collide with hand-assigning inode numbers to ptys. So,
	  hand-assign specific inode number to ptmx node also.
	- [Serge Hallyn]: Maybe safer to grab root dentry mutex while creating
	  ptmx node
	- [Bugfix with Serge Hallyn] Replace lookup_one_len() in mknod_ptmx()
	  wih d_alloc_name() (lookup during ->get_sb() locks up system). To
	  simplify patchset, fold the ptmx_dentry patch into this.

Changelog[v4]:
	- Change default permissions of pts/ptmx node to 0000.
	- Move code for ptmxmode under #ifdef CONFIG_DEVPTS_MULTIPLE_INSTANCES.

Changelog[v3]:
	- Rename ptmx_mode to ptmxmode (for consistency with 'newinstance')

Changelog[v2]:
	- [H. Peter Anvin] Remove mknod() system call support and create the
	  ptmx node internally.

Changelog[v1]:
	- Earlier version of this patch enabled creating /dev/pts/tty as
	  well. As pointed out by Al Viro and H. Peter Anvin, that is not
	  really necessary.
Signed-off-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Move code to parse mount options into a separate function so it can
(later) be shared between mount and remount operations.
Signed-off-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

With support for multiple mounts of devpts, the 'config' structure really
represents per-mount options rather than config parameters. Rename 'config'
structure to 'pts_mount_opts' and store it in the super-block.
Signed-off-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

To enable multiple mounts of devpts, 'allocated_ptys' must be a per-mount
variable rather than a global variable.  Move 'allocated_ptys' into the
super_block's s_fs_info.

Changelog[v2]:
	Define and use DEVPTS_SB() wrapper.
Signed-off-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Remove the 'devpts_root' global variable and find the root dentry using
the super_block. The super-block can be found from the device inode, using
the new wrapper, pts_sb_from_inode().

Changelog: This patch is based on an earlier patchset from Serge Hallyn
	   and Matt Helsley.
Signed-off-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

jfs version of Al Viro's nfsd race patches
Signed-off-by: NDave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

... and the same for reiserfs.  The difference here is that we need
insert_inode_locked4() to match iget5_locked().
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

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

ext3 analog of the previous patch
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

* make ext2_new_inode() put the inode into icache in locked state
* do not unlock until the inode is fully set up; otherwise nfsd
might pick it in half-baked state.
* make sure that ext2_new_inode() does *not* lead to two inodes with the
same inumber hashed at the same time; otherwise a bogus fhandle coming
from nfsd might race with inode creation:

nfsd: iget_locked() creates inode
nfsd: try to read from disk, block on that.
ext2_new_inode(): allocate inode with that inumber
ext2_new_inode(): insert it into icache, set it up and dirty
ext2_write_inode(): get the relevant part of inode table in cache,
set the entry for our inode (and start writing to disk)
nfsd: get CPU again, look into inode table, see nice and sane on-disk
inode, set the in-core inode from it

oops - we have two in-core inodes with the same inumber live in icache,
both used for IO.  Welcome to fs corruption...
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

new helpers - insert_inode_locked() and insert_inode_locked4().
Hash new inode, making sure that there's no such inode in icache
already.  If there is and it does not end up unhashed (as would
happen if we have nfsd trying to resolve a bogus fhandle), fail.
Otherwise insert our inode into hash and succeed.

In either case have i_state set to new+locked; cleanup ends up
being simpler with such calling conventions.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Creating a generic filesystem notification interface, fsnotify, which will be
used by inotify, dnotify, and eventually fanotify is really starting to
clutter the fs directory.  This patch simply moves inotify and dnotify into
fs/notify/inotify and fs/notify/dnotify respectively to make both current fs/
and future notification tidier.
Signed-off-by: NEric Paris <eparis@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

- iget5_locked in bdget really needs blockdev_superblock, instead of
  bd_mnt, so bd_mnt could be just a local variable;

- blockdev_superblock really needs __read_mostly, while local var bd_mnt
  not;

- make use of sb_is_blkdev_sb in bd_forget, instead of direct reference
  to blockdev_superblock.
Signed-off-by: NDenis ChengRq <crquan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Remove the hopelessly misguided ->dir_notify().  The only instance (cifs)
has been broken by design from the very beginning; the objects it creates
are never destroyed, keep references to struct file they can outlive, nothing
that could possibly evict them exists on close(2) path *and* no locking
whatsoever is done to prevent races with close(), should the previous, er,
deficiencies someday be dealt with.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Instead of creating the "filp" kmem_cache in vfs_caches_init(),
we can do it a litle be later in files_init(), so that filp_cachep
is static to fs/file_table.c
Acked-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NEric Dumazet <dada1@cosmosbay.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

[AV: rediffed on top of unification of init_fs]
Initialization of init_fs still uses the deprecated RW_LOCK_UNLOCKED macro.
This patch updates it to use the __RW_LOCK_UNLOCKED(lock) macro.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

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

With all the nameidata removal there's no point anymore for this helper.
Of the three callers left two will go away with the next lookup series
anyway.

Also add proper kerneldoc to inode_permission as this is the main
permission check routine now.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

No need for the nameidata in may_open - a struct path is enough.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

walk_init_root is a tiny helper that is marked __always_inline, has just
one caller and an unused argument.  Just merge it into the caller.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

We now pass on all MAY_ flags to the filesystems permission routines,
so remove the comment stating the contrary.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Explain that you really need to use the return value of d_path rather than
the buffer you passed into it.

Also fix the comment for seq_path(), the function arguments changed
recently but the comment hadn't been updated in sync.
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

no function named d_put(), it should be dput().

Impact: fix document and comment, no functionality changed
Signed-off-by: NZhao Lei <zhaolei@cn.fuijtsu.com>
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

We want ->name.len to match the resulting name on *both*
source and target
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Ensure fast symlink targets are NUL-terminated, even if corrupted
on-disk.

Cc: Sergey S. Kostyliov <rathamahata@php4.ru>
Signed-off-by: NDuane Griffin <duaneg@dghda.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Ensure fast symlink targets are NUL-terminated, even if corrupted
on-disk.

Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: NDuane Griffin <duaneg@dghda.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Ensure fast symlink targets are NUL-terminated, even if corrupted
on-disk.

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NDuane Griffin <duaneg@dghda.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Ensure fast symlink targets are NUL-terminated, even if corrupted
on-disk.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: adilger@sun.com
Cc: linux-ext4@vger.kernel.org
Signed-off-by: NDuane Griffin <duaneg@dghda.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Ensure fast symlink targets are NUL-terminated, even if corrupted
on-disk.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: linux-ext4@vger.kernel.org
Signed-off-by: NDuane Griffin <duaneg@dghda.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Ensure fast symlink targets are NUL-terminated, even if corrupted
on-disk.

Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NDuane Griffin <duaneg@dghda.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

On-disk data corruption could cause a page link to have its i_size set
to PAGE_SIZE (or a multiple thereof) and its contents all non-NUL.
NUL-terminate the link name to ensure this doesn't cause further
problems for the kernel.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NDuane Griffin <duaneg@dghda.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The result from readlink is being used to index into the link name
buffer without checking whether it is a valid length. If readlink
returns an error this will fault or cause memory corruption.

Cc: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
Cc: Dustin Kirkland <kirkland@canonical.com>
Cc: ecryptfs-devel@lists.launchpad.net
Signed-off-by: NDuane Griffin <duaneg@dghda.com>
Acked-by: NMichael Halcrow <mhalcrow@us.ibm.com>
Acked-by: NTyler Hicks <tyhicks@linux.vnet.ibm.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The extra semicolon serves no purpose.
Signed-off-by: NJulia Lawall <julia@diku.dk>
Reviewed-by: NRichard Genoud <richard.genoud@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

struct dentry is one of the most critical structures in the kernel. So it's
sad to see it going neglected.

With CONFIG_PROFILING turned on (which is probably the common case at least
for distros and kernel developers), sizeof(struct dcache) == 208 here
(64-bit). This gives 19 objects per slab.

I packed d_mounted into a hole, and took another 4 bytes off the inline
name length to take the padding out from the end of the structure. This
shinks it to 200 bytes. I could have gone the other way and increased the
length to 40, but I'm aiming for a magic number, read on...

I then got rid of the d_cookie pointer. This shrinks it to 192 bytes. Rant:
why was this ever a good idea? The cookie system should increase its hash
size or use a tree or something if lookups are a problem. Also the "fast
dcookie lookups" in oprofile should be moved into the dcookie code -- how
can oprofile possibly care about the dcookie_mutex? It gets dropped after
get_dcookie() returns so it can't be providing any sort of protection.

At 192 bytes, 21 objects fit into a 4K page, saving about 3MB on my system
with ~140 000 entries allocated. 192 is also a multiple of 64, so we get
nice cacheline alignment on 64 and 32 byte line systems -- any given dentry
will now require 3 cachelines to touch all fields wheras previously it
would require 4.

I know the inline name size was chosen quite carefully, however with the
reduction in cacheline footprint, it should actually be just about as fast
to do a name lookup for a 36 character name as it was before the patch (and
faster for other sizes). The memory footprint savings for names which are
<= 32 or > 36 bytes long should more than make up for the memory cost for
33-36 byte names.

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

Reorder struct inotify_device to remove 8 bytes of padding on 64bit
builds, reducing size to 128 bytes . Therefore allocating from a smaller
slab & using one fewer cachelines.
Signed-off-by: NRichard Kennedy <richard@rsk.demon.co.uk>

----
Hi,
patch against 2.6.28-rc7.
built & tested on AMDX2 desktop.

I've not been able to send this to the listed inotify maintainers, I
just get mail failures. So I guessed filesystem was the best home for
it, hope that's ok.

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

Add new LSM hooks for path-based checks.  Call them on directory-modifying
operations at the points where we still know the vfsmount involved.
Signed-off-by: NKentaro Takeda <takedakn@nttdata.co.jp>
Signed-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: NToshiharu Harada <haradats@nttdata.co.jp>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

nfs4_map_errors() can become static.
Signed-off-by: NWANG Cong <wangcong@zeuux.org>
Cc: J. Bruce Fields <bfields@fieldses.org>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>