linux-toradex.git/fs/hugetlbfs, branch v3.1.10

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

Merge 'akpm' patch series

2011-07-26T04:00:19+00:00

* Merge akpm patch series: (122 commits)
  drivers/connector/cn_proc.c: remove unused local
  Documentation/SubmitChecklist: add RCU debug config options
  reiserfs: use hweight_long()
  reiserfs: use proper little-endian bitops
  pnpacpi: register disabled resources
  drivers/rtc/rtc-tegra.c: properly initialize spinlock
  drivers/rtc/rtc-twl.c: check return value of twl_rtc_write_u8() in twl_rtc_set_time()
  drivers/rtc: add support for Qualcomm PMIC8xxx RTC
  drivers/rtc/rtc-s3c.c: support clock gating
  drivers/rtc/rtc-mpc5121.c: add support for RTC on MPC5200
  init: skip calibration delay if previously done
  misc/eeprom: add eeprom access driver for digsy_mtc board
  misc/eeprom: add driver for microwire 93xx46 EEPROMs
  checkpatch.pl: update $logFunctions
  checkpatch: make utf-8 test --strict
  checkpatch.pl: add ability to ignore various messages
  checkpatch: add a "prefer __aligned" check
  checkpatch: validate signature styles and To: and Cc: lines
  checkpatch: add __rcu as a sparse modifier
  checkpatch: suggest using min_t or max_t
  ...

Did this as a merge because of (trivial) conflicts in
 - Documentation/feature-removal-schedule.txt
 - arch/xtensa/include/asm/uaccess.h
that were just easier to fix up in the merge than in the patch series.

fs/hugetlbfs/inode.c: fix pgoff alignment checking on 32-bit

2011-07-26T03:57:07+00:00

This:

    vma->vm_pgoff & ~(huge_page_mask(h) >> PAGE_SHIFT)

is incorrect on 32-bit.  It causes us to & the pgoff with something that
looks like this (for a 4m hugepage): 0xfff003ff.  The mask should be
flipped and *then* shifted, to give you 0x0000_03fff.

Signed-off-by: Becky Bruce 
Cc: Benjamin Herrenschmidt 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

VFS : mount lock scalability for internal mounts

2011-07-24T14:08:32+00:00

For a number of file systems that don't have a mount point (e.g. sockfs
and pipefs), they are not marked as long term. Therefore in
mntput_no_expire, all locks in vfs_mount lock are taken instead of just
local cpu's lock to aggregate reference counts when we release
reference to file objects.  In fact, only local lock need to have been
taken to update ref counts as these file systems are in no danger of
going away until we are ready to unregister them.

The attached patch marks file systems using kern_mount without
mount point as long term.  The contentions of vfs_mount lock
is now eliminated.  Before un-registering such file system,
kern_unmount should be called to remove the long term flag and
make the mount point ready to be freed.

Signed-off-by: Tim Chen 
Signed-off-by: Al Viro

mm: don't access vm_flags as 'int'

2011-05-26T16:20:31+00:00

The type of vma->vm_flags is 'unsigned long'. Neither 'int' nor
'unsigned int'. This patch fixes such misuse.

Signed-off-by: KOSAKI Motohiro 
[ Changed to use a typedef - we'll extend it to cover more cases
  later, since there has been discussion about making it a 64-bit
  type..                      - Linus ]
Signed-off-by: Linus Torvalds

mm: Convert i_mmap_lock to a mutex

2011-05-25T15:39:18+00:00

Straightforward conversion of i_mmap_lock to a mutex.

Signed-off-by: Peter Zijlstra 
Acked-by: Hugh Dickins 
Cc: Benjamin Herrenschmidt 
Cc: David Miller 
Cc: Martin Schwidefsky 
Cc: Russell King 
Cc: Paul Mundt 
Cc: Jeff Dike 
Cc: Richard Weinberger 
Cc: Tony Luck 
Cc: KAMEZAWA Hiroyuki 
Cc: Mel Gorman 
Cc: KOSAKI Motohiro 
Cc: Nick Piggin 
Cc: Namhyung Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: hugetlbfs: change remove_from_page_cache

2011-03-23T00:44:02+00:00

This patch series changes remove_from_page_cache()'s page ref counting
rule.  Page cache ref count is decreased in delete_from_page_cache().  So
we don't need to decrease the page reference in callers.

Signed-off-by: Minchan Kim 
Cc: William Irwin 
Acked-by: Hugh Dickins 
Acked-by: Mel Gorman 
Reviewed-by: KAMEZAWA Hiroyuki 
Reviewed-by: Johannes Weiner 
Reviewed-by: KOSAKI Motohiro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs: icache RCU free inodes

2011-01-07T06:50:26+00:00

RCU free the struct inode. This will allow:

- Subsequent store-free path walking patch. The inode must be consulted for
  permissions when walking, so an RCU inode reference is a must.
- sb_inode_list_lock to be moved inside i_lock because sb list walkers who want
  to take i_lock no longer need to take sb_inode_list_lock to walk the list in
  the first place. This will simplify and optimize locking.
- Could remove some nested trylock loops in dcache code
- Could potentially simplify things a bit in VM land. Do not need to take the
  page lock to follow page->mapping.

The downsides of this is the performance cost of using RCU. In a simple
creat/unlink microbenchmark, performance drops by about 10% due to inability to
reuse cache-hot slab objects. As iterations increase and RCU freeing starts
kicking over, this increases to about 20%.

In cases where inode lifetimes are longer (ie. many inodes may be allocated
during the average life span of a single inode), a lot of this cache reuse is
not applicable, so the regression caused by this patch is smaller.

The cache-hot regression could largely be avoided by using SLAB_DESTROY_BY_RCU,
however this adds some complexity to list walking and store-free path walking,
so I prefer to implement this at a later date, if it is shown to be a win in
real situations. I haven't found a regression in any non-micro benchmark so I
doubt it will be a problem.

Signed-off-by: Nick Piggin

hugetlbfs: lessen the impact of a deprecation warning

2010-11-12T15:55:32+00:00

WARN_ONCE is a bit strong for a deprecation warning, given that it spews a
huge backtrace.

Signed-off-by: Dave Jones 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

convert get_sb_nodev() users

2010-10-29T08:16:31+00:00

Signed-off-by: Al Viro