linux-toradex.git/include/linux/fs.h, branch T20_LinuxImageV2.0_20130305

fix apparmor dereferencing potentially freed dentry, sanitize __d_path() API

2011-12-21T20:58:28+00:00

commit 02125a826459a6ad142f8d91c5b6357562f96615 upstream.

__d_path() API is asking for trouble and in case of apparmor d_namespace_path()
getting just that.  The root cause is that when __d_path() misses the root
it had been told to look for, it stores the location of the most remote ancestor
in *root.  Without grabbing references.  Sure, at the moment of call it had
been pinned down by what we have in *path.  And if we raced with umount -l, we
could have very well stopped at vfsmount/dentry that got freed as soon as
prepend_path() dropped vfsmount_lock.

It is safe to compare these pointers with pre-existing (and known to be still
alive) vfsmount and dentry, as long as all we are asking is "is it the same
address?".  Dereferencing is not safe and apparmor ended up stepping into
that.  d_namespace_path() really wants to examine the place where we stopped,
even if it's not connected to our namespace.  As the result, it looked
at ->d_sb->s_magic of a dentry that might've been already freed by that point.
All other callers had been careful enough to avoid that, but it's really
a bad interface - it invites that kind of trouble.

The fix is fairly straightforward, even though it's bigger than I'd like:
	* prepend_path() root argument becomes const.
	* __d_path() is never called with NULL/NULL root.  It was a kludge
to start with.  Instead, we have an explicit function - d_absolute_root().
Same as __d_path(), except that it doesn't get root passed and stops where
it stops.  apparmor and tomoyo are using it.
	* __d_path() returns NULL on path outside of root.  The main
caller is show_mountinfo() and that's precisely what we pass root for - to
skip those outside chroot jail.  Those who don't want that can (and do)
use d_path().
	* __d_path() root argument becomes const.  Everyone agrees, I hope.
	* apparmor does *NOT* try to use __d_path() or any of its variants
when it sees that path->mnt is an internal vfsmount.  In that case it's
definitely not mounted anywhere and dentry_path() is exactly what we want
there.  Handling of sysctl()-triggered weirdness is moved to that place.
	* if apparmor is asked to do pathname relative to chroot jail
and __d_path() tells it we it's not in that jail, the sucker just calls
d_absolute_path() instead.  That's the other remaining caller of __d_path(),
BTW.
        * seq_path_root() does _NOT_ return -ENAMETOOLONG (it's stupid anyway -
the normal seq_file logics will take care of growing the buffer and redoing
the call of ->show() just fine).  However, if it gets path not reachable
from root, it returns SEQ_SKIP.  The only caller adjusted (i.e. stopped
ignoring the return value as it used to do).

Reviewed-by: John Johansen 
ACKed-by: John Johansen 
Signed-off-by: Al Viro 
Signed-off-by: Greg Kroah-Hartman

Merge branch 'for-linus' of git://git.kernel.dk/linux-block

2011-09-21T20:20:21+00:00

* 'for-linus' of git://git.kernel.dk/linux-block:
  floppy: use del_timer_sync() in init cleanup
  blk-cgroup: be able to remove the record of unplugged device
  block: Don't check QUEUE_FLAG_SAME_COMP in __blk_complete_request
  mm: Add comment explaining task state setting in bdi_forker_thread()
  mm: Cleanup clearing of BDI_pending bit in bdi_forker_thread()
  block: simplify force plug flush code a little bit
  block: change force plug flush call order
  block: Fix queue_flag update when rq_affinity goes from 2 to 1
  block: separate priority boosting from REQ_META
  block: remove READ_META and WRITE_META
  xen-blkback: fixed indentation and comments
  xen-blkback: Don't disconnect backend until state switched to XenbusStateClosed.

lockdep: Add helper function for dir vs file i_mutex annotation

2011-08-25T17:50:18+00:00

Purely in-memory filesystems do not use the inode hash as the dcache
tells us if an entry already exists.  As a result, they do not call
unlock_new_inode, and thus directory inodes do not get put into a
different lockdep class for i_sem.

We need the different lockdep classes, because the locking order for
i_mutex is different for directory inodes and regular inodes.  Directory
inodes can do "readdir()", which takes i_mutex *before* possibly taking
mm->mmap_sem (due to a page fault while copying the directory entry to
user space).

In contrast, regular inodes can be mmap'ed, which takes mm->mmap_sem
before accessing i_mutex.

The two cases can never happen for the same inode, so no real deadlock
can occur, but without the different lockdep classes, lockdep cannot
understand that.  As a result, if CONFIG_DEBUG_LOCK_ALLOC is set, this
can lead to false positives from lockdep like below:

    find/645 is trying to acquire lock:
     (&mm->mmap_sem){++++++}, at: [] might_fault+0x5c/0xac

    but task is already holding lock:
     (&sb->s_type->i_mutex_key#15){+.+.+.}, at: []
    vfs_readdir+0x5b/0xb4

    which lock already depends on the new lock.

    the existing dependency chain (in reverse order) is:

    -> #1 (&sb->s_type->i_mutex_key#15){+.+.+.}:
          [] lock_acquire+0xbf/0x103
          [] __mutex_lock_common+0x4c/0x361
          [] mutex_lock_nested+0x40/0x45
          [] hugetlbfs_file_mmap+0x82/0x110
          [] mmap_region+0x258/0x432
          [] do_mmap_pgoff+0x2ac/0x306
          [] sys_mmap_pgoff+0x118/0x16a
          [] sys_mmap+0x22/0x24
          [] system_call_fastpath+0x16/0x1b

    -> #0 (&mm->mmap_sem){++++++}:
          [] __lock_acquire+0xa1a/0xcf7
          [] lock_acquire+0xbf/0x103
          [] might_fault+0x89/0xac
          [] filldir+0x6f/0xc7
          [] dcache_readdir+0x67/0x205
          [] vfs_readdir+0x7b/0xb4
          [] sys_getdents+0x7e/0xd1
          [] system_call_fastpath+0x16/0x1b

This patch moves the directory vs file lockdep annotation into a helper
function that can be called by in-memory filesystems and has hugetlbfs
call it.

Signed-off-by: Josh Boyer 
Acked-by: Peter Zijlstra 
Signed-off-by: Linus Torvalds

block: remove READ_META and WRITE_META

2011-08-23T12:49:55+00:00

Replace all occurnanced of the undocumented READ_META with READ | REQ_META
and remove the unused WRITE_META define.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Jens Axboe

vfs: optimize inode cache access patterns

2011-08-07T05:53:23+00:00

The inode structure layout is largely random, and some of the vfs paths
really do care.  The path lookup in particular is already quite D$
intensive, and profiles show that accessing the 'inode->i_op->xyz'
fields is quite costly.

We already optimized the dcache to not unnecessarily load the d_op
structure for members that are often NULL using the DCACHE_OP_xyz bits
in dentry->d_flags, and this does something very similar for the inode
ops that are used during pathname lookup.

It also re-orders the fields so that the fields accessed by 'stat' are
together at the beginning of the inode structure, and roughly in the
order accessed.

The effect of this seems to be in the 1-2% range for an empty kernel
"make -j" run (which is fairly kernel-intensive, mostly in filename
lookup), so it's visible.  The numbers are fairly noisy, though, and
likely depend a lot on exact microarchitecture.  So there's more tuning
to be done.

Signed-off-by: Linus Torvalds

vfs: avoid taking inode_hash_lock on pipes and sockets

2011-08-01T05:41:17+00:00

Some inodes (pipes, sockets, ...) are not hashed, no need to take
contended inode_hash_lock at dismantle time.

nice speedup on SMP machines on socket intensive workloads.

Signed-off-by: Eric Dumazet 
Signed-off-by: Al Viro

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6

2011-07-27T01:30:20+00:00

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
  merge fchmod() and fchmodat() guts, kill ancient broken kludge
  xfs: fix misspelled S_IS...()
  xfs: get rid of open-coded S_ISREG(), etc.
  vfs: document locking requirements for d_move, __d_move and d_materialise_unique
  omfs: fix (mode & S_IFDIR) abuse
  btrfs: S_ISREG(mode) is not mode & S_IFREG...
  ima: fmode_t misspelled as mode_t...
  pci-label.c: size_t misspelled as mode_t
  jffs2: S_ISLNK(mode & S_IFMT) is pointless
  snd_msnd ->mode is fmode_t, not mode_t
  v9fs_iop_get_acl: get rid of unused variable
  vfs: dont chain pipe/anon/socket on superblock s_inodes list
  Documentation: Exporting: update description of d_splice_alias
  fs: add missing unlock in default_llseek()

vfs: dont chain pipe/anon/socket on superblock s_inodes list

2011-07-26T16:57:09+00:00

Workloads using pipes and sockets hit inode_sb_list_lock contention.

superblock s_inodes list is needed for quota, dirty, pagecache and
fsnotify management. pipe/anon/socket fs are clearly not candidates for
these.

Signed-off-by: Eric Dumazet 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Al Viro

Merge branch 'for-3.1' of git://linux-nfs.org/~bfields/linux

2011-07-26T05:49:19+00:00

* 'for-3.1' of git://linux-nfs.org/~bfields/linux:
  nfsd: don't break lease on CLAIM_DELEGATE_CUR
  locks: rename lock-manager ops
  nfsd4: update nfsv4.1 implementation notes
  nfsd: turn on reply cache for NFSv4
  nfsd4: call nfsd4_release_compoundargs from pc_release
  nfsd41: Deny new lock before RECLAIM_COMPLETE done
  fs: locks: remove init_once
  nfsd41: check the size of request
  nfsd41: error out when client sets maxreq_sz or maxresp_sz too small
  nfsd4: fix file leak on open_downgrade
  nfsd4: remember to put RW access on stateid destruction
  NFSD: Added TEST_STATEID operation
  NFSD: added FREE_STATEID operation
  svcrpc: fix list-corrupting race on nfsd shutdown
  rpc: allow autoloading of gss mechanisms
  svcauth_unix.c: quiet sparse noise
  svcsock.c: include sunrpc.h to quiet sparse noise
  nfsd: Remove deprecated nfsctl system call and related code.
  NFSD: allow OP_DESTROY_CLIENTID to be only op in COMPOUND

Fix up trivial conflicts in Documentation/feature-removal-schedule.txt

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial

2011-07-25T20:56:39+00:00

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (43 commits)
  fs: Merge split strings
  treewide: fix potentially dangerous trailing ';' in #defined values/expressions
  uwb: Fix misspelling of neighbourhood in comment
  net, netfilter: Remove redundant goto in ebt_ulog_packet
  trivial: don't touch files that are removed in the staging tree
  lib/vsprintf: replace link to Draft by final RFC number
  doc: Kconfig: `to be' -> `be'
  doc: Kconfig: Typo: square -> squared
  doc: Konfig: Documentation/power/{pm => apm-acpi}.txt
  drivers/net: static should be at beginning of declaration
  drivers/media: static should be at beginning of declaration
  drivers/i2c: static should be at beginning of declaration
  XTENSA: static should be at beginning of declaration
  SH: static should be at beginning of declaration
  MIPS: static should be at beginning of declaration
  ARM: static should be at beginning of declaration
  rcu: treewide: Do not use rcu_read_lock_held when calling rcu_dereference_check
  Update my e-mail address
  PCIe ASPM: forcedly -> forcibly
  gma500: push through device driver tree
  ...

Fix up trivial conflicts:
 - arch/arm/mach-ep93xx/dma-m2p.c (deleted)
 - drivers/gpio/gpio-ep93xx.c (renamed and context nearby)
 - drivers/net/r8169.c (just context changes)