Commit Graph

29244 Commits

Author SHA1 Message Date
Linus Torvalds
f57d54bab6 Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
 "The biggest change affects group scheduling: we now track the runnable
  average on a per-task entity basis, allowing a smoother, exponential
  decay average based load/weight estimation instead of the previous
  binary on-the-runqueue/off-the-runqueue load weight method.

  This will inevitably disturb workloads that were in some sort of
  borderline balancing state or unstable equilibrium, so an eye has to
  be kept on regressions.

  For that reason the new load average is only limited to group
  scheduling (shares distribution) at the moment (which was also hurting
  the most from the prior, crude weight calculation and whose scheduling
  quality wins most from this change) - but we plan to extend this to
  regular SMP balancing as well in the future, which will simplify and
  speed up things a bit.

  Other changes involve ongoing preparatory work to extend NOHZ to the
  scheduler as well, eventually allowing completely irq-free user-space
  execution."

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits)
  Revert "sched/autogroup: Fix crash on reboot when autogroup is disabled"
  cputime: Comment cputime's adjusting code
  cputime: Consolidate cputime adjustment code
  cputime: Rename thread_group_times to thread_group_cputime_adjusted
  cputime: Move thread_group_cputime() to sched code
  vtime: Warn if irqs aren't disabled on system time accounting APIs
  vtime: No need to disable irqs on vtime_account()
  vtime: Consolidate a bit the ctx switch code
  vtime: Explicitly account pending user time on process tick
  vtime: Remove the underscore prefix invasion
  sched/autogroup: Fix crash on reboot when autogroup is disabled
  cputime: Separate irqtime accounting from generic vtime
  cputime: Specialize irq vtime hooks
  kvm: Directly account vtime to system on guest switch
  vtime: Make vtime_account_system() irqsafe
  vtime: Gather vtime declarations to their own header file
  sched: Describe CFS load-balancer
  sched: Introduce temporary FAIR_GROUP_SCHED dependency for load-tracking
  sched: Make __update_entity_runnable_avg() fast
  sched: Update_cfs_shares at period edge
  ...
2012-12-11 18:21:38 -08:00
Linus Torvalds
608ff1a210 Merge branch 'akpm' (Andrew's patchbomb)
Merge misc updates from Andrew Morton:
 "About half of most of MM.  Going very early this time due to
  uncertainty over the coreautounifiednumasched things.  I'll send the
  other half of most of MM tomorrow.  The rest of MM awaits a slab merge
  from Pekka."

* emailed patches from Andrew Morton: (71 commits)
  memory_hotplug: ensure every online node has NORMAL memory
  memory_hotplug: handle empty zone when online_movable/online_kernel
  mm, memory-hotplug: dynamic configure movable memory and portion memory
  drivers/base/node.c: cleanup node_state_attr[]
  bootmem: fix wrong call parameter for free_bootmem()
  avr32, kconfig: remove HAVE_ARCH_BOOTMEM
  mm: cma: remove watermark hacks
  mm: cma: skip watermarks check for already isolated blocks in split_free_page()
  mm, oom: fix race when specifying a thread as the oom origin
  mm, oom: change type of oom_score_adj to short
  mm: cleanup register_node()
  mm, mempolicy: remove duplicate code
  mm/vmscan.c: try_to_freeze() returns boolean
  mm: introduce putback_movable_pages()
  virtio_balloon: introduce migration primitives to balloon pages
  mm: introduce compaction and migration for ballooned pages
  mm: introduce a common interface for balloon pages mobility
  mm: redefine address_space.assoc_mapping
  mm: adjust address_space_operations.migratepage() return code
  arch/sparc/kernel/sys_sparc_64.c: s/COLOUR/COLOR/
  ...
2012-12-11 18:05:37 -08:00
David Rientjes
a9c58b907d mm, oom: change type of oom_score_adj to short
The maximum oom_score_adj is 1000 and the minimum oom_score_adj is -1000,
so this range can be represented by the signed short type with no
functional change.  The extra space this frees up in struct signal_struct
will be used for per-thread oom kill flags in the next patch.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Anton Vorontsov <anton.vorontsov@linaro.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-11 17:22:27 -08:00
Rafael Aquini
252aa6f5be mm: redefine address_space.assoc_mapping
Overhaul struct address_space.assoc_mapping renaming it to
address_space.private_data and its type is redefined to void*.  By this
approach we consistently name the .private_* elements from struct
address_space as well as allow extended usage for address_space
association with other data structures through ->private_data.

Also, all users of old ->assoc_mapping element are converted to reflect
its new name and type change (->private_data).

Signed-off-by: Rafael Aquini <aquini@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-11 17:22:26 -08:00
Rafael Aquini
78bd52097d mm: adjust address_space_operations.migratepage() return code
Memory fragmentation introduced by ballooning might reduce significantly
the number of 2MB contiguous memory blocks that can be used within a
guest, thus imposing performance penalties associated with the reduced
number of transparent huge pages that could be used by the guest workload.

This patch-set follows the main idea discussed at 2012 LSFMMS session:
"Ballooning for transparent huge pages" -- http://lwn.net/Articles/490114/
to introduce the required changes to the virtio_balloon driver, as well as
the changes to the core compaction & migration bits, in order to make
those subsystems aware of ballooned pages and allow memory balloon pages
become movable within a guest, thus avoiding the aforementioned
fragmentation issue

Following are numbers that prove this patch benefits on allowing
compaction to be more effective at memory ballooned guests.

Results for STRESS-HIGHALLOC benchmark, from Mel Gorman's mmtests suite,
running on a 4gB RAM KVM guest which was ballooning 512mB RAM in 64mB
chunks, at every minute (inflating/deflating), while test was running:

===BEGIN stress-highalloc

STRESS-HIGHALLOC
                 highalloc-3.7     highalloc-3.7
                     rc4-clean         rc4-patch
Pass 1          55.00 ( 0.00%)    62.00 ( 7.00%)
Pass 2          54.00 ( 0.00%)    62.00 ( 8.00%)
while Rested    75.00 ( 0.00%)    80.00 ( 5.00%)

MMTests Statistics: duration
                 3.7         3.7
           rc4-clean   rc4-patch
User         1207.59     1207.46
System       1300.55     1299.61
Elapsed      2273.72     2157.06

MMTests Statistics: vmstat
                                3.7         3.7
                          rc4-clean   rc4-patch
Page Ins                    3581516     2374368
Page Outs                  11148692    10410332
Swap Ins                         80          47
Swap Outs                      3641         476
Direct pages scanned          37978       33826
Kswapd pages scanned        1828245     1342869
Kswapd pages reclaimed      1710236     1304099
Direct pages reclaimed        32207       31005
Kswapd efficiency               93%         97%
Kswapd velocity             804.077     622.546
Direct efficiency               84%         91%
Direct velocity              16.703      15.682
Percentage direct scans          2%          2%
Page writes by reclaim        79252        9704
Page writes file              75611        9228
Page writes anon               3641         476
Page reclaim immediate        16764       11014
Page rescued immediate            0           0
Slabs scanned               2171904     2152448
Direct inode steals             385        2261
Kswapd inode steals          659137      609670
Kswapd skipped wait               1          69
THP fault alloc                 546         631
THP collapse alloc              361         339
THP splits                      259         263
THP fault fallback               98          50
THP collapse fail                20          17
Compaction stalls               747         499
Compaction success              244         145
Compaction failures             503         354
Compaction pages moved       370888      474837
Compaction move failure       77378       65259

===END stress-highalloc

This patch:

Introduce MIGRATEPAGE_SUCCESS as the default return code for
address_space_operations.migratepage() method and documents the expected
return code for the same method in failure cases.

Signed-off-by: Rafael Aquini <aquini@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-11 17:22:26 -08:00
Michel Lespinasse
0865935598 mm: use vm_unmapped_area() in hugetlbfs
Update the hugetlb_get_unmapped_area function to make use of
vm_unmapped_area() instead of implementing a brute force search.

Signed-off-by: Michel Lespinasse <walken@google.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-11 17:22:25 -08:00
Andi Kleen
42d7395feb mm: support more pagesizes for MAP_HUGETLB/SHM_HUGETLB
There was some desire in large applications using MAP_HUGETLB or
SHM_HUGETLB to use 1GB huge pages on some mappings, and stay with 2MB on
others.  This is useful together with NUMA policy: use 2MB interleaving
on some mappings, but 1GB on local mappings.

This patch extends the IPC/SHM syscall interfaces slightly to allow
specifying the page size.

It borrows some upper bits in the existing flag arguments and allows
encoding the log of the desired page size in addition to the *_HUGETLB
flag.  When 0 is specified the default size is used, this makes the
change fully compatible.

Extending the internal hugetlb code to handle this is straight forward.
Instead of a single mount it just keeps an array of them and selects the
right mount based on the specified page size.  When no page size is
specified it uses the mount of the default page size.

The change is not visible in /proc/mounts because internal mounts don't
appear there.  It also has very little overhead: the additional mounts
just consume a super block, but not more memory when not used.

I also exported the new flags to the user headers (they were previously
under __KERNEL__).  Right now only symbols for x86 and some other
architecture for 1GB and 2MB are defined.  The interface should already
work for all other architectures though.  Only architectures that define
multiple hugetlb sizes actually need it (that is currently x86, tile,
powerpc).  However tile and powerpc have user configurable hugetlb
sizes, so it's not easy to add defines.  A program on those
architectures would need to query sysfs and use the appropiate log2.

[akpm@linux-foundation.org: cleanups]
[rientjes@google.com: fix build]
[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hillf Danton <dhillf@gmail.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-11 17:22:25 -08:00
Namjae Jeon
d0e1d66b5a writeback: remove nr_pages_dirtied arg from balance_dirty_pages_ratelimited_nr()
There is no reason to pass the nr_pages_dirtied argument, because
nr_pages_dirtied value from the caller is unused in
balance_dirty_pages_ratelimited_nr().

Signed-off-by: Namjae Jeon <linkinjeon@gmail.com>
Signed-off-by: Vivek Trivedi <vtrivedi018@gmail.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-11 17:22:21 -08:00
Linus Torvalds
c6bd5bcc49 Merge tag 'tty-3.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull TTY/Serial merge from Greg Kroah-Hartman:
 "Here's the big tty/serial tree set of changes for 3.8-rc1.

  Contained in here is a bunch more reworks of the tty port layer from
  Jiri and bugfixes from Alan, along with a number of other tty and
  serial driver updates by the various driver authors.

  Also, Jiri has been coerced^Wconvinced to be the co-maintainer of the
  TTY layer, which is much appreciated by me.

  All of these have been in the linux-next tree for a while.

  Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>"

Fixed up some trivial conflicts in the staging tree, due to the fwserial
driver having come in both ways (but fixed up a bit in the serial tree),
and the ioctl handling in the dgrp driver having been done slightly
differently (staging tree got that one right, and removed both
TIOCGSOFTCAR and TIOCSSOFTCAR).

* tag 'tty-3.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (146 commits)
  staging: sb105x: fix potential NULL pointer dereference in mp_chars_in_buffer()
  staging/fwserial: Remove superfluous free
  staging/fwserial: Use WARN_ONCE when port table is corrupted
  staging/fwserial: Destruct embedded tty_port on teardown
  staging/fwserial: Fix build breakage when !CONFIG_BUG
  staging: fwserial: Add TTY-over-Firewire serial driver
  drivers/tty/serial/serial_core.c: clean up HIGH_BITS_OFFSET usage
  staging: dgrp: dgrp_tty.c: Audit the return values of get/put_user()
  staging: dgrp: dgrp_tty.c: Remove the TIOCSSOFTCAR ioctl handler from dgrp driver
  serial: ifx6x60: Add modem power off function in the platform reboot process
  serial: mxs-auart: unmap the scatter list before we copy the data
  serial: mxs-auart: disable the Receive Timeout Interrupt when DMA is enabled
  serial: max310x: Setup missing "can_sleep" field for GPIO
  tty/serial: fix ifx6x60.c declaration warning
  serial: samsung: add devicetree properties for non-Exynos SoCs
  serial: samsung: fix potential soft lockup during uart write
  tty: vt: Remove redundant null check before kfree.
  tty/8250 Add check for pci_ioremap_bar failure
  tty/8250 Add support for Commtech's Fastcom Async-335 and Fastcom Async-PCIe cards
  tty/8250 Add XR17D15x devices to the exar_handle_irq override
  ...
2012-12-11 14:08:47 -08:00
Linus Torvalds
cff2f741b8 Merge tag 'driver-core-3.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core updates from Greg Kroah-Hartman:
 "Here's the large driver core updates for 3.8-rc1.

  The biggest thing here is the various __dev* marking removals.  This
  is going to be a pain for the merge with different subsystem trees, I
  know, but all of the patches included here have been ACKed by their
  various subsystem maintainers, as they wanted them to go through here.

  If this is too much of a pain, I can pull all of them out of this tree
  and just send you one with the other fixes/updates and then, after
  3.8-rc1 is out, do the rest of the removals to ensure we catch them
  all, it's up to you.  The merges should all be trivial, and Stephen
  has been doing them all in linux-next for a few weeks now quite
  easily.

  Other than the __dev* marking removals, there's nothing major here,
  some firmware loading updates and other minor things in the driver
  core.

  All of these have (much to Stephen's annoyance), been in linux-next
  for a while.

  Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>"

Fixed up trivial conflicts in drivers/gpio/gpio-{em,stmpe}.c due to gpio
update.

* tag 'driver-core-3.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (93 commits)
  modpost.c: Stop checking __dev* section mismatches
  init.h: Remove __dev* sections from the kernel
  acpi: remove use of __devinit
  PCI: Remove __dev* markings
  PCI: Always build setup-bus when PCI is enabled
  PCI: Move pci_uevent into pci-driver.c
  PCI: Remove CONFIG_HOTPLUG ifdefs
  unicore32/PCI: Remove CONFIG_HOTPLUG ifdefs
  sh/PCI: Remove CONFIG_HOTPLUG ifdefs
  powerpc/PCI: Remove CONFIG_HOTPLUG ifdefs
  mips/PCI: Remove CONFIG_HOTPLUG ifdefs
  microblaze/PCI: Remove CONFIG_HOTPLUG ifdefs
  dma: remove use of __devinit
  dma: remove use of __devexit_p
  firewire: remove use of __devinitdata
  firewire: remove use of __devinit
  leds: remove use of __devexit
  leds: remove use of __devinit
  leds: remove use of __devexit_p
  mmc: remove use of __devexit
  ...
2012-12-11 13:13:55 -08:00
Ingo Molnar
c1ad41f1f7 Revert "sched/autogroup: Fix crash on reboot when autogroup is disabled"
This reverts commit 5258f386ea,
because the underlying autogroups bug got fixed upstream in
a better way, via:

  fd8ef11730 Revert "sched, autogroup: Stop going ahead if autogroup is disabled"

Cc: Mike Galbraith <efault@gmx.de>
Cc: Yong Zhang <yong.zhang0@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-12-11 10:23:45 +01:00
Linus Torvalds
684c9aaebb vfs: fix O_DIRECT read past end of block device
The direct-IO write path already had the i_size checks in mm/filemap.c,
but it turns out the read path did not, and removing the block size
checks in fs/block_dev.c (commit bbec0270bd: "blkdev_max_block: make
private to fs/buffer.c") removed the magic "shrink IO to past the end of
the device" code there.

Fix it by truncating the IO to the size of the block device, like the
write path already does.

NOTE! I suspect the write path would be *much* better off doing it this
way in fs/block_dev.c, rather than hidden deep in mm/filemap.c.  The
mm/filemap.c code is extremely hard to follow, and has various
conditionals on the target being a block device (ie the flag passed in
to 'generic_write_checks()', along with a conditional update of the
inode timestamp etc).

It is also quite possible that we should treat this whole block device
size as a "s_maxbytes" issue, and try to make the logic even more
generic.  However, in the meantime this is the fairly minimal targeted
fix.

Noted by Milan Broz thanks to a regression test for the cryptsetup
reencrypt tool.

Reported-and-tested-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-08 08:28:26 -08:00
Ingo Molnar
e783377e93 Merge tag 'cputime-adjustment-cleanups' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into sched/core
Pull cputime cleanups from Frederic Weisbecker:

 * Improve naming and code location

 * Consolidate adjustment code

 * Comment the adjustement code

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-12-08 15:31:07 +01:00
Dan Carpenter
27d7c2a006 vfs: clear to the end of the buffer on partial buffer reads
READ is zero so the "rw & READ" test is always false.  The intended test
was "((rw & RW_MASK) == READ)".

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-05 10:32:59 -08:00
Linus Torvalds
57302e0ddf vfs: avoid "attempt to access beyond end of device" warnings
The block device access simplification that avoided accessing the (racy)
block size information (commit bbec0270bd: "blkdev_max_block: make
private to fs/buffer.c") no longer checks the maximum block size in the
block mapping path.

That was _almost_ as simple as just removing the code entirely, because
the readers and writers all check the size of the device anyway, so
under normal circumstances it "just worked".

However, the block size may be such that the end of the device may
straddle one single buffer_head.  At which point we may still want to
access the end of the device, but the buffer we use to access it
partially extends past the end.

The 'bd_set_size()' function intentionally sets the block size to avoid
this, but mounting the device - or setting the block size by hand to
some other value - can modify that block size.

So instead, teach 'submit_bh()' about the special case of the buffer
head straddling the end of the device, and turning such an access into a
smaller IO access, avoiding the problem.

This, btw, also means that unlike before, we can now access the whole
device regardless of device block size setting.  So now, even if the
device size is only 512-byte aligned, we can read and write even the
last sector even when having a much bigger block size for accessing the
rest of the device.

So with this, we could now get rid of the 'bd_set_size()' block size
code entirely - resulting in faster IO for the common case - but that
would be a separate patch.

Reported-and-tested-by: Romain Francoise <romain@orebokech.com>
Reporeted-and-tested-by: Meelis Roos <mroos@linux.ee>
Reported-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-12-04 08:25:11 -08:00
Linus Torvalds
d3594ea2b3 Merge branch 'block-dev'
Merge 'block-dev' branch.

I was going to just mark everything here for stable and leave it to the
3.8 merge window, but having decided on doing another -rc, I migth as
well merge it now.

This removes the bd_block_size_semaphore semaphore that was added in
this release to fix a race condition between block size changes and
block IO, and replaces it with atomicity guaratees in fs/buffer.c
instead, along with simplifying fs/block-dev.c.

This removes more lines than it adds, makes the code generally simpler,
and avoids the latency/rt issues that the block size semaphore
introduced for mount.

I'm not happy with the timing, but it wouldn't be much better doing this
during the merge window and then having some delayed back-port of it
into stable.

* block-dev:
  blkdev_max_block: make private to fs/buffer.c
  direct-io: don't read inode->i_blkbits multiple times
  blockdev: remove bd_block_size_semaphore again
  fs/buffer.c: make block-size be per-page and protected by the page lock
2012-12-03 10:53:25 -08:00
Linus Torvalds
331fee3cd3 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs fixes from Al Viro:
 "A bunch of fixes; the last one is this cycle regression, the rest are
  -stable fodder."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  fix off-by-one in argument passed by iterate_fd() to callbacks
  lookup_one_len: don't accept . and ..
  cifs: get rid of blind d_drop() in readdir
  nfs_lookup_revalidate(): fix a leak
  don't do blind d_drop() in nfs_prime_dcache()
2012-12-01 13:29:55 -08:00
Linus Torvalds
086486e46e Merge branch 'for-linus' of git://git.samba.org/sfrench/cifs-2.6
Pull CIFS fixes from Steve French:
 "Two low risk, small fixes, that fix cifs regressions introduced in
  3.7."

* 'for-linus' of git://git.samba.org/sfrench/cifs-2.6:
  CIFS: Fix wrong buffer pointer usage in smb_set_file_info
  cifs: fix writeback race with file that is growing
2012-11-30 16:57:18 -08:00
Al Viro
a77cfcb429 fix off-by-one in argument passed by iterate_fd() to callbacks
Noticed by Pavel Roskin; the thing in his patch I disagree with
was compensating for that shite in callbacks instead of fixing
it once in the iterator itself.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-11-29 23:01:30 -05:00
Al Viro
21d8a15ac3 lookup_one_len: don't accept . and ..
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-11-29 22:17:21 -05:00
Al Viro
0903a0c849 cifs: get rid of blind d_drop() in readdir
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-11-29 22:11:06 -05:00
Al Viro
c44600c9d1 nfs_lookup_revalidate(): fix a leak
We are leaking fattr and fhandle if we decide that dentry is not to
be invalidated, after all (e.g. happens to be a mountpoint).  Just
free both before that...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-11-29 22:04:36 -05:00
Al Viro
696199f8cc don't do blind d_drop() in nfs_prime_dcache()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-11-29 22:00:51 -05:00
Linus Torvalds
bbec0270bd blkdev_max_block: make private to fs/buffer.c
We really don't want to look at the block size for the raw block device
accesses in fs/block-dev.c, because it may be changing from under us.
So get rid of the max_block logic entirely, since the caller should
already have done it anyway.

That leaves the only user of this function in fs/buffer.c, so move the
whole function there and make it static.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-11-29 17:48:12 -08:00
Linus Torvalds
ab73857e35 direct-io: don't read inode->i_blkbits multiple times
Since directio can work on a raw block device, and the block size of the
device can change under it, we need to do the same thing that
fs/buffer.c now does: read the block size a single time, using
ACCESS_ONCE().

Reading it multiple times can get different results, which will then
confuse the code because it actually encodes the i_blksize in
relationship to the underlying logical blocksize.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-11-29 12:38:44 -08:00
Linus Torvalds
1e8b33328a blockdev: remove bd_block_size_semaphore again
This reverts the block-device direct access code to the previous
unlocked code, now that fs/buffer.c no longer needs external locking.

With this, fs/block_dev.c is back to the original version, apart from a
whitespace cleanup that I didn't want to revert.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-11-29 10:52:19 -08:00
Linus Torvalds
45bce8f3e3 fs/buffer.c: make block-size be per-page and protected by the page lock
This makes the buffer size handling be a per-page thing, which allows us
to not have to worry about locking too much when changing the buffer
size.  If a page doesn't have buffers, we still need to read the block
size from the inode, but we can do that with ACCESS_ONCE(), so that even
if the size is changing, we get a consistent value.

This doesn't convert all functions - many of the buffer functions are
used purely by filesystems, which in turn results in the buffer size
being fixed at mount-time.  So they don't have the same consistency
issues that the raw device access can have.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-11-29 10:47:20 -08:00
Frederic Weisbecker
e80d0a1ae8 cputime: Rename thread_group_times to thread_group_cputime_adjusted
We have thread_group_cputime() and thread_group_times(). The naming
doesn't provide enough information about the difference between
these two APIs.

To lower the confusion, rename thread_group_times() to
thread_group_cputime_adjusted(). This name better suggests that
it's a version of thread_group_cputime() that does some stabilization
on the raw cputime values. ie here: scale on top of CFS runtime
stats and bound lower value for monotonicity.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
2012-11-28 17:07:57 +01:00
Pavel Shilovsky
c772aa92b6 CIFS: Fix wrong buffer pointer usage in smb_set_file_info
Commit 6bdf6dbd66 caused a regression
in setattr codepath that leads to files with wrong attributes.

Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
2012-11-28 10:02:46 -06:00
Jeff Layton
3a98b86143 cifs: fix writeback race with file that is growing
Commit eddb079deb created a regression in the writepages codepath.
Previously, whenever it needed to check the size of the file, it did so
by consulting the inode->i_size field directly. With that patch, the
i_size was fetched once on entry into the writepages code and that value
was used henceforth.

If the file is changing size though (for instance, if someone is writing
to it or has truncated it), then that value is likely to be wrong. This
can lead to data corruption. Pages past the EOF at the time that the
writepages call was issued may be silently dropped and ignored because
cifs_writepages wrongly assumes that the file must have been truncated
in the interim.

Fix cifs_writepages to properly fetch the size from the inode->i_size
field instead to properly account for this possibility.

Original bug report is here:

    https://bugzilla.kernel.org/show_bug.cgi?id=50991

Reported-and-Tested-by: Maxim Britov <ungifted01@gmail.com>
Reviewed-by: Suresh Jayaraman <sjayaraman@suse.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
2012-11-27 13:46:12 -06:00
Linus Torvalds
2844a48706 Merge branch 'akpm' (Fixes from Andrew)
Merge misc fixes from Andrew Morton:
 "8 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (8 patches)
  futex: avoid wake_futex() for a PI futex_q
  watchdog: using u64 in get_sample_period()
  writeback: put unused inodes to LRU after writeback completion
  mm: vmscan: check for fatal signals iff the process was throttled
  Revert "mm: remove __GFP_NO_KSWAPD"
  proc: check vma->vm_file before dereferencing
  UAPI: strip the _UAPI prefix from header guards during header installation
  include/linux/bug.h: fix sparse warning related to BUILD_BUG_ON_INVALID
2012-11-26 18:33:33 -08:00
Linus Torvalds
87726c334b Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs
Pull ext3 regression fix from Jan Kara:
 "Fix an ext3 regression introduced during 3.7 merge window.  It leads
  to deadlock if you stress the filesystem in the right way (luckily
  only if blocksize < pagesize)."

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  jbd: Fix lock ordering bug in journal_unmap_buffer()
2012-11-26 17:42:07 -08:00
Jan Kara
4eff96dd52 writeback: put unused inodes to LRU after writeback completion
Commit 169ebd9013 ("writeback: Avoid iput() from flusher thread")
removed iget-iput pair from inode writeback.  As a side effect, inodes
that are dirty during iput_final() call won't be ever added to inode LRU
(iput_final() doesn't add dirty inodes to LRU and later when the inode
is cleaned there's noone to add the inode there).  Thus inodes are
effectively unreclaimable until someone looks them up again.

The practical effect of this bug is limited by the fact that inodes are
pinned by a dentry for long enough that the inode gets cleaned.  But
still the bug can have nasty consequences leading up to OOM conditions
under certain circumstances.  Following can easily reproduce the
problem:

  for (( i = 0; i < 1000; i++ )); do
    mkdir $i
    for (( j = 0; j < 1000; j++ )); do
      touch $i/$j
      echo 2 > /proc/sys/vm/drop_caches
    done
  done

then one needs to run 'sync; ls -lR' to make inodes reclaimable again.

We fix the issue by inserting unused clean inodes into the LRU after
writeback finishes in inode_sync_complete().

Signed-off-by: Jan Kara <jack@suse.cz>
Reported-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: <stable@vger.kernel.org>		[3.5+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-11-26 17:41:24 -08:00
Stanislav Kinsbursky
05f564849d proc: check vma->vm_file before dereferencing
Commit 7b540d0646 ("proc_map_files_readdir(): don't bother with
grabbing files") switched proc_map_files_readdir() to use @f_mode
directly instead of grabbing @file reference, but same time the test for
@vm_file presence was lost leading to nil dereference.  The patch brings
the test back.

The all proc_map_files feature is CONFIG_CHECKPOINT_RESTORE wrapped
(which is set to 'n' by default) so the bug doesn't affect regular
kernels.

The regression is 3.7-rc1 only as far as I can tell.

[gorcunov@openvz.org: provided changelog]
Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-11-26 17:41:24 -08:00
Josh Triplett
1f20dfdaed sysfs: Mark sysfs_attr_ns static
Nothing outside of fs/sysfs/file.c references this function, so mark it static.

Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-11-26 16:25:36 -08:00
Linus Torvalds
35f95d228e Merge tag 'for-linus-20121123' of git://git.infradead.org/mtd-2.6
Pull MTD fixes from David Woodhouse:
 "The most important part of this is that it fixes a regression in
  Samsung NAND chip detection, introduced by some rework which went into
  3.7.  The initial fix wasn't quite complete, so it's in two parts.  In
  fact the first part is committed twice (Artem committed his own copy
  of the same patch) and I've merged Artem's tree into mine which
  already had that fix.

  I'd have recommitted that to make it somewhat cleaner, but figured by
  this point in the release cycle it was better to merge *exactly* the
  commits which have been in linux-next.

  If I'd recommitted, I'd also omit the sparse warning fix.  But it's
  there, and it's harmless — just marking one function as 'static' in
  onenand code.

  This also includes a couple more fixes for stable: an AB-BA deadlock
  in JFFS2, and an invalid range check in slram."

* tag 'for-linus-20121123' of git://git.infradead.org/mtd-2.6:
  mtd: nand: fix Samsung SLC detection regression
  mtd: nand: fix Samsung SLC NAND identification regression
  jffs2: Fix lock acquisition order bug in jffs2_write_begin
  mtd: onenand: Make flexonenand_set_boundary static
  mtd: slram: invalid checking of absolute end address
  mtd: ofpart: Fix incorrect NULL check in parse_ofoldpart_partitions()
  mtd: nand: fix Samsung SLC NAND identification regression
2012-11-23 15:12:17 -10:00
Jan Kara
25389bb207 jbd: Fix lock ordering bug in journal_unmap_buffer()
Commit 09e05d48 introduced a wait for transaction commit into
journal_unmap_buffer() in the case we are truncating a buffer undergoing commit
in the page stradding i_size on a filesystem with blocksize < pagesize. Sadly
we forgot to drop buffer lock before waiting for transaction commit and thus
deadlock is possible when kjournald wants to lock the buffer.

Fix the problem by dropping the buffer lock before waiting for transaction
commit. Since we are still holding page lock (and that is OK), buffer cannot
disappear under us.

CC: stable@vger.kernel.org # Wherever commit 09e05d48 was taken
Signed-off-by: Jan Kara <jack@suse.cz>
2012-11-23 15:17:18 +01:00
Linus Torvalds
ca6215dfc7 Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs
Pull reiserfs and ext3 fixes from Jan Kara:
 "Fixes of reiserfs deadlocks when quotas are enabled (locking there was
  completely busted by BKL conversion) and also one small ext3 fix in
  the trim interface."

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  ext3: Avoid underflow of in ext3_trim_fs()
  reiserfs: Move quota calls out of write lock
  reiserfs: Protect reiserfs_quota_write() with write lock
  reiserfs: Protect reiserfs_quota_on() with write lock
  reiserfs: Fix lock ordering during remount
2012-11-20 18:48:25 -10:00
Lukas Czerner
ae49eeec78 ext3: Avoid underflow of in ext3_trim_fs()
Currently if len argument in ext3_trim_fs() is smaller than one block,
the 'end' variable underflow. Avoid that by returning EINVAL if len is
smaller than file system block.

Also remove useless unlikely().

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
2012-11-19 21:36:12 +01:00
Jan Kara
7af1168693 reiserfs: Move quota calls out of write lock
Calls into highlevel quota code cannot happen under the write lock. These
calls take dqio_mutex which ranks above write lock. So drop write lock
before calling back into quota code.

CC: stable@vger.kernel.org # >= 3.0
Signed-off-by: Jan Kara <jack@suse.cz>
2012-11-19 21:34:33 +01:00
Jan Kara
361d94a338 reiserfs: Protect reiserfs_quota_write() with write lock
Calls into reiserfs journalling code and reiserfs_get_block() need to
be protected with write lock. We remove write lock around calls to high
level quota code in the next patch so these paths would suddently become
unprotected.

CC: stable@vger.kernel.org # >= 3.0
Signed-off-by: Jan Kara <jack@suse.cz>
2012-11-19 21:34:33 +01:00
Jan Kara
b9e06ef2e8 reiserfs: Protect reiserfs_quota_on() with write lock
In reiserfs_quota_on() we do quite some work - for example unpacking
tail of a quota file. Thus we have to hold write lock until a moment
we call back into the quota code.

CC: stable@vger.kernel.org # >= 3.0
Signed-off-by: Jan Kara <jack@suse.cz>
2012-11-19 21:34:32 +01:00
Jan Kara
3bb3e1fc47 reiserfs: Fix lock ordering during remount
When remounting reiserfs dquot_suspend() or dquot_resume() can be called.
These functions take dqonoff_mutex which ranks above write lock so we have
to drop it before calling into quota code.

CC: stable@vger.kernel.org # >= 3.0
Signed-off-by: Jan Kara <jack@suse.cz>
2012-11-19 21:34:32 +01:00
Al Viro
3587b1b097 fanotify: fix FAN_Q_OVERFLOW case of fanotify_read()
If the FAN_Q_OVERFLOW bit set in event->mask, the fanotify event
metadata will not contain a valid file descriptor, but
copy_event_to_user() didn't check for that, and unconditionally does a
fd_install() on the file descriptor.

Which in turn will cause a BUG_ON() in __fd_install().

Introduced by commit 352e3b2492 ("fanotify: sanitize failure exits in
copy_event_to_user()")

Mea culpa - missed that path ;-/

Reported-by: Alex Shi <lkml.alex@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-11-18 09:30:00 -10:00
Linus Torvalds
8d938105e4 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull misc VFS fixes from Al Viro:
 "Remove a bogus BUG_ON() that can trigger spuriously + alpha bits of
  do_mount() constification I'd missed during the merge window."

This pull request came in a week ago, I missed it for some reason.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  kill bogus BUG_ON() in do_close_on_exec()
  missing const in alpha callers of do_mount()
2012-11-18 09:13:48 -10:00
Linus Torvalds
d28d3730fd Merge tag 'for-linus-v3.7-rc7' of git://oss.sgi.com/xfs/xfs
Pull xfs bugfixes from Ben Myers:

 - fix attr tree double split corruption

 - fix broken error handling in xfs_vm_writepage

 - drop buffer io reference when a bad bio is built

* tag 'for-linus-v3.7-rc7' of git://oss.sgi.com/xfs/xfs:
  xfs: drop buffer io reference when a bad bio is built
  xfs: fix broken error handling in xfs_vm_writepage
  xfs: fix attr tree double split corruption
2012-11-18 08:29:34 -10:00
Ingo Molnar
ec05a2311c Merge branch 'sched/urgent' into sched/core
Merge in fixes before we queue up dependent bits, to avoid conflicts.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-11-18 09:34:44 +01:00
Dave Chinner
d69043c42d xfs: drop buffer io reference when a bad bio is built
Error handling in xfs_buf_ioapply_map() does not handle IO reference
counts correctly. We increment the b_io_remaining count before
building the bio, but then fail to decrement it in the failure case.
This leads to the buffer never running IO completion and releasing
the reference that the IO holds, so at unmount we can leak the
buffer. This leak is captured by this assert failure during unmount:

XFS: Assertion failed: atomic_read(&pag->pag_ref) == 0, file: fs/xfs/xfs_mount.c, line: 273

This is not a new bug - the b_io_remaining accounting has had this
problem for a long, long time - it's just very hard to get a
zero length bio being built by this code...

Further, the buffer IO error can be overwritten on a multi-segment
buffer by subsequent bio completions for partial sections of the
buffer. Hence we should only set the buffer error status if the
buffer is not already carrying an error status. This ensures that a
partial IO error on a multi-segment buffer will not be lost. This
part of the problem is a regression, however.

cc: <stable@vger.kernel.org>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
2012-11-17 09:36:57 -06:00
Dave Chinner
3daed8bc3e xfs: fix broken error handling in xfs_vm_writepage
When we shut down the filesystem, it might first be detected in
writeback when we are allocating a inode size transaction. This
happens after we have moved all the pages into the writeback state
and unlocked them. Unfortunately, if we fail to set up the
transaction we then abort writeback and try to invalidate the
current page. This then triggers are BUG() in block_invalidatepage()
because we are trying to invalidate an unlocked page.

Fixing this is a bit of a chicken and egg problem - we can't
allocate the transaction until we've clustered all the pages into
the IO and we know the size of it (i.e. whether the last block of
the IO is beyond the current EOF or not). However, we don't want to
hold pages locked for long periods of time, especially while we lock
other pages to cluster them into the write.

To fix this, we need to make a clear delineation in writeback where
errors can only be handled by IO completion processing. That is,
once we have marked a page for writeback and unlocked it, we have to
report errors via IO completion because we've already started the
IO. We may not have submitted any IO, but we've changed the page
state to indicate that it is under IO so we must now use the IO
completion path to report errors.

To do this, add an error field to xfs_submit_ioend() to pass it the
error that occurred during the building on the ioend chain. When
this is non-zero, mark each ioend with the error and call
xfs_finish_ioend() directly rather than building bios. This will
immediately push the ioends through completion processing with the
error that has occurred.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
2012-11-17 09:35:42 -06:00
Dave Chinner
42e2976f13 xfs: fix attr tree double split corruption
In certain circumstances, a double split of an attribute tree is
needed to insert or replace an attribute. In rare situations, this
can go wrong, leaving the attribute tree corrupted. In this case,
the attr being replaced is the last attr in a leaf node, and the
replacement is larger so doesn't fit in the same leaf node.
When we have the initial condition of a node format attribute
btree with two leaves at index 1 and 2. Call them L1 and L2.  The
leaf L1 is completely full, there is not a single byte of free space
in it. L2 is mostly empty.  The attribute being replaced - call it X
- is the last attribute in L1.

The way an attribute replace is executed is that the replacement
attribute - call it Y - is first inserted into the tree, but has an
INCOMPLETE flag set on it so that list traversals ignore it. Once
this transaction is committed, a second transaction it run to
atomically mark Y as COMPLETE and X as INCOMPLETE, so that a
traversal will now find Y and skip X. Once that transaction is
committed, attribute X is then removed.

So, the initial condition is:

     +--------+     +--------+
     |   L1   |     |   L2   |
     | fwd: 2 |---->| fwd: 0 |
     | bwd: 0 |<----| bwd: 1 |
     | fsp: 0 |     | fsp: N |
     |--------|     |--------|
     | attr A |     | attr 1 |
     |--------|     |--------|
     | attr B |     | attr 2 |
     |--------|     |--------|
     ..........     ..........
     |--------|     |--------|
     | attr X |     | attr n |
     +--------+     +--------+

So now we go to replace X, and see that L1:fsp = 0 - it is full so
we can't insert Y in the same leaf. So we record the the location of
attribute X so we can track it for later use, then we split L1 into
L1 and L3 and reblance across the two leafs. We end with:

     +--------+     +--------+     +--------+
     |   L1   |     |   L3   |     |   L2   |
     | fwd: 3 |---->| fwd: 2 |---->| fwd: 0 |
     | bwd: 0 |<----| bwd: 1 |<----| bwd: 3 |
     | fsp: M |     | fsp: J |     | fsp: N |
     |--------|     |--------|     |--------|
     | attr A |     | attr X |     | attr 1 |
     |--------|     +--------+     |--------|
     | attr B |                    | attr 2 |
     |--------|                    |--------|
     ..........                    ..........
     |--------|                    |--------|
     | attr W |                    | attr n |
     +--------+                    +--------+

And we track that the original attribute is now at L3:0.

We then try to insert Y into L1 again, and find that there isn't
enough room because the new attribute is larger than the old one.
Hence we have to split again to make room for Y. We end up with
this:

     +--------+     +--------+     +--------+     +--------+
     |   L1   |     |   L4   |     |   L3   |     |   L2   |
     | fwd: 4 |---->| fwd: 3 |---->| fwd: 2 |---->| fwd: 0 |
     | bwd: 0 |<----| bwd: 1 |<----| bwd: 4 |<----| bwd: 3 |
     | fsp: M |     | fsp: J |     | fsp: J |     | fsp: N |
     |--------|     |--------|     |--------|     |--------|
     | attr A |     | attr Y |     | attr X |     | attr 1 |
     |--------|     + INCOMP +     +--------+     |--------|
     | attr B |     +--------+                    | attr 2 |
     |--------|                                   |--------|
     ..........                                   ..........
     |--------|                                   |--------|
     | attr W |                                   | attr n |
     +--------+                                   +--------+

And now we have the new (incomplete) attribute @ L4:0, and the
original attribute at L3:0. At this point, the first transaction is
committed, and we move to the flipping of the flags.

This is where we are supposed to end up with this:

     +--------+     +--------+     +--------+     +--------+
     |   L1   |     |   L4   |     |   L3   |     |   L2   |
     | fwd: 4 |---->| fwd: 3 |---->| fwd: 2 |---->| fwd: 0 |
     | bwd: 0 |<----| bwd: 1 |<----| bwd: 4 |<----| bwd: 3 |
     | fsp: M |     | fsp: J |     | fsp: J |     | fsp: N |
     |--------|     |--------|     |--------|     |--------|
     | attr A |     | attr Y |     | attr X |     | attr 1 |
     |--------|     +--------+     + INCOMP +     |--------|
     | attr B |                    +--------+     | attr 2 |
     |--------|                                   |--------|
     ..........                                   ..........
     |--------|                                   |--------|
     | attr W |                                   | attr n |
     +--------+                                   +--------+

But that doesn't happen properly - the attribute tracking indexes
are not pointing to the right locations. What we end up with is both
the old attribute to be removed pointing at L4:0 and the new
attribute at L4:1.  On a debug kernel, this assert fails like so:

XFS: Assertion failed: args->index2 < be16_to_cpu(leaf2->hdr.count), file: fs/xfs/xfs_attr_leaf.c, line: 2725

because the new attribute location does not exist. On a production
kernel, this goes unnoticed and the code proceeds ahead merrily and
removes L4 because it thinks that is the block that is no longer
needed. This leaves the hash index node pointing to entries
L1, L4 and L2, but only blocks L1, L3 and L2 to exist. Further, the
leaf level sibling list is L1 <-> L4 <-> L2, but L4 is now free
space, and so everything is busted. This corruption is caused by the
removal of the old attribute triggering a join - it joins everything
correctly but then frees the wrong block.

xfs_repair will report something like:

bad sibling back pointer for block 4 in attribute fork for inode 131
problem with attribute contents in inode 131
would clear attr fork
bad nblocks 8 for inode 131, would reset to 3
bad anextents 4 for inode 131, would reset to 0

The problem lies in the assignment of the old/new blocks for
tracking purposes when the double leaf split occurs. The first split
tries to place the new attribute inside the current leaf (i.e.
"inleaf == true") and moves the old attribute (X) to the new block.
This sets up the old block/index to L1:X, and newly allocated
block to L3:0. It then moves attr X to the new block and tries to
insert attr Y at the old index. That fails, so it splits again.

With the second split, the rebalance ends up placing the new attr in
the second new block - L4:0 - and this is where the code goes wrong.
What is does is it sets both the new and old block index to the
second new block. Hence it inserts attr Y at the right place (L4:0)
but overwrites the current location of the attr to replace that is
held in the new block index (currently L3:0). It over writes it with
L4:1 - the index we later assert fail on.

Hopefully this table will show this in a foramt that is a bit easier
to understand:

Split		old attr index		new attr index
		vanilla	patched		vanilla	patched
before 1st	L1:26	L1:26		N/A	N/A
after 1st	L3:0	L3:0		L1:26	L1:26
after 2nd	L4:0	L3:0		L4:1	L4:0
                ^^^^			^^^^
		wrong			wrong

The fix is surprisingly simple, for all this analysis - just stop
the rebalance on the out-of leaf case from overwriting the new attr
index - it's already correct for the double split case.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>
2012-11-17 09:34:13 -06:00