A gc-inode is a pseudo inode used to buffer the blocks to be moved by
garbage collection.

Block caches of gc-inodes must be cleared every time a garbage collection
function (nilfs_clean_segments) completes.  Otherwise, stale blocks
buffered in the caches may be wrongly reused in successive calls of the GC
function.

For user files, this is not a problem because their gc-inodes are
distinguished by a checkpoint number as well as an inode number.  They
never buffer different blocks if either an inode number, a checkpoint
number, or a block offset differs.

However, gc-inodes of sufile, cpfile and DAT file can store different data
for the same block offset.  Thus, the nilfs_clean_segments function can
move incorrect block for these meta-data files if an old block is cached.
I found this is really causing meta-data corruption in nilfs.

This fixes the issue by ensuring cache clear of gc-inodes and resolves
reported GC problems including checkpoint file corruption, b-tree
corruption, and the following warning during GC.

  nilfs_palloc_freev: entry number 307234 already freed.
  ...
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Tested-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: <stable@vger.kernel.org>	[2.6.37+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

In the x86 32bit PAE CONFIG_TRANSPARENT_HUGEPAGE=y case while holding the
mmap_sem for reading, cmpxchg8b cannot be used to read pmd contents under
Xen.

So instead of dealing only with "consistent" pmdvals in
pmd_none_or_trans_huge_or_clear_bad() (which would be conceptually
simpler) we let pmd_none_or_trans_huge_or_clear_bad() deal with pmdvals
where the low 32bit and high 32bit could be inconsistent (to avoid having
to use cmpxchg8b).

The only guarantee we get from pmd_read_atomic is that if the low part of
the pmd was found null, the high part will be null too (so the pmd will be
considered unstable).  And if the low part of the pmd is found "stable"
later, then it means the whole pmd was read atomically (because after a
pmd is stable, neither MADV_DONTNEED nor page faults can alter it anymore,
and we read the high part after the low part).

In the 32bit PAE x86 case, it is enough to read the low part of the pmdval
atomically to declare the pmd as "stable" and that's true for THP and no
THP, furthermore in the THP case we also have a barrier() that will
prevent any inconsistent pmdvals to be cached by a later re-read of the
*pmd.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Jonathan Nieder <jrnieder@gmail.com>
Cc: Ulrich Obergfell <uobergfe@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Petr Matousek <pmatouse@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Tested-by: Andrew Jones <drjones@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

On arches that do not support this_cpu_cmpxchg_double() slab_lock is used
to do atomic cmpxchg() on double word which contains page->_count.  The
page count can be changed from get_page() or put_page() without taking
slab_lock.  That corrupts page counter.

Fix it by moving page->_count out of cmpxchg_double data.  So that slub
does no change it while updating slub meta-data in struct page.

[akpm@linux-foundation.org: use standard comment layout, tweak comment text]
Reported-by: Amey Bhide <abhide@nicira.com>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull btrfs compile warning fixes from Chris Mason.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  Btrfs: cast devid to unsigned long long for printk %llu
  Btrfs: init old_generation in get_old_root

Pull arch/tile update from Chris Metcalf:
 "This one-line bug fix unbreaks glibc robust mutexes (among other
  things no doubt), from code merged in during the 3.5 merge window but
  which we had been running internally at Tilera for almost a year."

* 'stable' of git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile:
  tile: fix bug in get_user() for 4-byte values

Pull fbdev fixes from Florian Tobias Schandinat:

 - two fixes for s3c-fb by Jingoo Han (including a fix for a potential
   division by zero)

 - a couple of randconfig fixes by Arnd Bergmann

 - a cleanup for bfin_adv7393fb by Emil Goode

* tag 'fbdev-fixes-for-3.5-1' of git://github.com/schandinat/linux-2.6:
  video: s3c-fb: fix possible division by zero in s3c_fb_calc_pixclk
  video: s3c-fb: clear SHADOWCON register when clearing hardware window registers
  drivers/tosa: driver needs I2C and SPI to compile
  drivers/savagefb: use mdelay instead of udelay
  video/console: automatically select a font
  video/ili9320: do not mark exported functions __devexit
  drivers/video: use correct __devexit_p annotation
  video: bfin_adv7393fb: Convert to kstrtouint_from_user

The definition of 32-bit values in the 64-bit tilegx architecture is that
they should be sign-extended regardless of whether they are considered
signed or unsigned by the compiler.  Accordingly, we need to use an
"ld4s" rather than "ld4u" to load and sign-extend for get_user().

This fixes glibc bug 14238 (see http://sourceware.org/bugzilla),
introduced during the 3.5 merge window.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

Minchan Kim reports that when a system has many swap areas, and tmpfs
swaps out to the ninth or more, shmem_getpage_gfp()'s attempts to read
back the page cannot locate it, and the read fails with -ENOMEM.

Whoops.  Yes, I blindly followed read_swap_header()'s pte_to_swp_entry(
swp_entry_to_pte()) technique for determining maximum usable swap
offset, without stopping to realize that that actually depends upon the
pte swap encoding shifting swap offset to the higher bits and truncating
it there.  Whereas our radix_tree swap encoding leaves offset in the
lower bits: it's swap "type" (that is, index of swap area) that was
truncated.

Fix it by reducing the SWP_TYPE_SHIFT() in swapops.h, and removing the
broken radix_to_swp_entry(swp_to_radix_entry()) from read_swap_header().

This does not reduce the usable size of a swap area any further, it
leaves it as claimed when making the original commit: no change from 3.0
on x86_64, nor on i386 without PAE; but 3.0's 512GB is reduced to 128GB
per swapfile on i386 with PAE.  It's not a change I would have risked
five years ago, but with x86_64 supported for ten years, I believe it's
appropriate now.

Hmm, and what if some architecture implements its swap pte with offset
encoded below type? That would equally break the maximum usable swap
offset check.  Happily, they all follow the same tradition of encoding
offset above type, but I'll prepare a check on that for next.
Reported-and-Reviewed-and-Tested-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: stable@vger.kernel.org [3.1, 3.2, 3.3, 3.4]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull SCSI fixes from James Bottomley:
 "This is a couple of minor fixes, one for a preempt warning in the
  mpt2sas driver and one is a config failure with the new sd async
  domain."

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  [SCSI] Fix sd_probe_domain config problem
  [SCSI] mpt2sas: Fix unsafe using smp_processor_id() in preemptible

Pull NFS client bugfixes from Trond Myklebust:
 "Highlights include:

   - Fix a couple of mount regressions due to the recent cleanups.
   - Fix an Oops in the open recovery code
   - Fix an rpc_pipefs upcall hang that results from some of the net
     namespace work from 3.4.x (stable kernel candidate).
   - Fix a couple of write and o_direct regressions that were found at
     last weeks Bakeathon testing event in Ann Arbor."

* tag 'nfs-for-3.5-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  NFS: add an endian notation for sparse
  NFSv4.1: integer overflow in decode_cb_sequence_args()
  rpc_pipefs: allow rpc_purge_list to take a NULL waitq pointer
  NFSv4 do not send an empty SETATTR compound
  NFSv2: EOF incorrectly set on short read
  NFS: Use the NFS_DEFAULT_VERSION for v2 and v3 mounts
  NFS: fix directio refcount bug on commit
  NFSv4: Fix unnecessary delegation returns in nfs4_do_open
  NFSv4.1: Convert another trivial printk into a dprintk
  NFS4: Fix open bug when pnfs module blacklisted
  NFS: Remove incorrect BUG_ON in nfs_found_client
  NFS: Map minor mismatch error to protocol not support error.
  NFS: Fix a commit bug
  NFS4: Set parsed mount data version to 4
  NFSv4.1: Ensure we clear session state flags after a session creation
  NFSv4.1: Convert a trivial printk into a dprintk
  NFSv4: Fix up decode_attr_mdsthreshold
  NFSv4: Fix an Oops in the open recovery code
  NFSv4.1: Fix a request leak on the back channel

Pull DMA-mapping fixes from Marek Szyprowski:
 "A set of minor fixes for dma-mapping code (ARM and x86) required for
  Contiguous Memory Allocator (CMA) patches merged in v3.5-rc1."

* 'fixes-for-linus' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping:
  x86: dma-mapping: fix broken allocation when dma_mask has been provided
  ARM: dma-mapping: fix debug messages in dmabounce code
  ARM: mm: fix type of the arm_dma_limit global variable
  ARM: dma-mapping: Add missing static storage class specifier

Pull PowerPC fix from Paul Mackerras:
 "Just one commit, and a one-liner at that, but an important one;
  without it hard_irq_disable() does nothing on powerpc."

* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc:
  Make hard_irq_disable() actually hard-disable interrupts

Pull two nfsd bugfixes from J. Bruce Fields.

* 'for-3.5' of git://linux-nfs.org/~bfields/linux:
  nfsd4: BUG_ON(!is_spin_locked()) no good on UP kernels
  NFS: hard-code init_net for NFS callback transports

Merge tag 'stable/for-linus-3.5-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen

Pull five Xen bug-fixes from Konrad Rzeszutek Wilk:

 - When booting as PVHVM we would try to use PV console - but would not validate
   the parameters causing us to crash during restore b/c we re-use the wrong event
   channel.
 - When booting on machines with SR-IOV PCI bridge we didn't check for the bridge
   and tried to use it.
 - Under AMD machines would advertise the APERFMPERF resulting in needless amount
   of MSRs from the guest.
 - A global value (xen_released_pages) was not subtracted at bootup when pages
   were added back in. This resulted in the balloon worker having the wrong
   account of how many pages were truly released.
 - Fix dead-lock when xen-blkfront is run in the same domain as xen-blkback.

* tag 'stable/for-linus-3.5-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen:
  xen: mark local pages as FOREIGN in the m2p_override
  xen/setup: filter APERFMPERF cpuid feature out
  xen/balloon: Subtract from xen_released_pages the count that is populated.
  xen/pci: Check for PCI bridge before using it.
  xen/events: Add WARN_ON when quick lookup found invalid type.
  xen/hvc: Check HVM_PARAM_CONSOLE_[EVTCHN|PFN] for correctness.
  xen/hvc: Fix error cases around HVM_PARAM_CONSOLE_PFN
  xen/hvc: Collapse error logic.

Pull USB fixes from Greg Kroah-Hartman:
 "Here are a bunch of tiny fixes for the USB core and drivers for
  3.5-rc3

  A bunch of gadget fixes, and new device ids, as well as some fixes for
  a number of different regressions that have been reported recently.
  We also fixed some PCI host controllers to resolve a long-standing bug
  with a whole class of host controllers that have been plaguing people
  for a number of kernel releases, preventing their systems from
  suspending properly.

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

* tag 'usb-3.5-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (41 commits)
  USB: fix gathering of interface associations
  usb: ehci-sh: fix illegal phy_init() running when platform_data is NULL
  usb: cdc-acm: fix devices not unthrottled on open
  Fix OMAP EHCI suspend/resume failure (i693)
  USB: ohci-hub: Mark ohci_finish_controller_resume() as __maybe_unused
  usb: use usb_serial_put in usb_serial_probe errors
  USB: EHCI: Fix build warning in xilinx ehci driver
  USB: fix PS3 EHCI systems
  xHCI: Increase the timeout for controller save/restore state operation
  xhci: Don't free endpoints in xhci_mem_cleanup()
  xhci: Fix invalid loop check in xhci_free_tt_info()
  xhci: Fix error path return value.
  USB: Checking the wrong variable in usb_disable_lpm()
  usb-storage: Add 090c:1000 to unusal-devs
  USB: serial-generic: use a single set of device IDs
  USB: serial: Enforce USB driver and USB serial driver match
  USB: add NO_D3_DURING_SLEEP flag and revert 151b6128
  USB: option: add more YUGA device ids
  USB: mos7840: Fix compilation of usb serial driver
  USB: option: fix memory leak
  ...

Pull IDE fixes from David S. Miller:

1) Two fixes to icside, one for a build failure and another for a
   warning.  From Christian Dietrich.

2) Fix a bit operation that did erroneous masking, from Julia Lawall.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/ide:
  drivers/ide/ide-cs.c: adjust suspicious bit operation
  ide: icside.c: fix printk format string compile warning
  ide: icside.c: Fix compile with CONFIG_BLK_DEV_IDEDMA_ICS=n

Avoid warning in 32 bit machines
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

Pull sparc update from David S. Miller:
 "This just removes some sparc headers that were never, ever, used."

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc:
  sparc: remove two unused headers

gcc was giving an uninit variable warning here.  Strictly
speaking we don't need to init it, but this will make things
much less error prone.
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

Pull x86 fixes from Ingo Molnar.

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/smp: Fix topology checks on AMD MCM CPUs
  x86/mm: Fix some kernel-doc warnings
  x86, um: Correct syscall table type attributes breaking gcc 4.8

Pull perf fixes from Ingo Molnar.

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  watchdog: Quiet down the boot messages
  perf/x86: Fix broken LBR fixup code
  tracing: Have tracing_off() actually turn tracing off

Pull core updates (RCU and locking) from Ingo Molnar:
 "Most of the diffstat comes from the RCU slow boot regression fixes,
  but there's also a debuggability improvements/fixes."

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  memblock: Document memblock_is_region_{memory,reserved}()
  rcu: Precompute RCU_FAST_NO_HZ timer offsets
  rcu: Move RCU_FAST_NO_HZ per-CPU variables to rcu_dynticks structure
  rcu: Update RCU_FAST_NO_HZ tracing for lazy callbacks
  rcu: RCU_FAST_NO_HZ detection of callback adoption
  spinlock: Indicate that a lockup is only suspected
  kdump: Execute kmsg_dump(KMSG_DUMP_PANIC) after smp_send_stop()
  panic: Make panic_on_oops configurable

Pull target updates from Nicholas Bellinger:
 "This series contains post merge qla_target.c / tcm_qla2xxx bugfixes
  from the past weeks, including the patch to allow target-core to use
  an optional session shutdown callback to help address an active I/O
  shutdown bug in tcm_qla2xxx code (Joern).

  Also included is a target regression bugfix releated to explict ALUA
  target port group CDB emulation that is CC'ed to stable (Roland)."

* git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending:
  qla2xxx: Remove version.h header file inclusion
  tcm_qla2xxx: Handle malformed wwn strings properly
  tcm_qla2xxx: tcm_qla2xxx_handle_tmr() can be static
  qla2xxx: Don't leak commands we give up on in qlt_do_work()
  qla2xxx: Don't crash if we can't find cmd for failed CTIO
  tcm_qla2xxx: Don't insert nacls without sessions into the btree
  target: Return error to initiator if SET TARGET PORT GROUPS emulation fails
  tcm_qla2xxx: Clear session s_id + loop_id earlier during shutdown
  tcm_qla2xxx: Convert to TFO->put_session() usage
  target: Add TFO->put_session() caller for HW fabric session shutdown

Pull btrfs update from Chris Mason:
 "The dates look like I had to rebase this morning because there was a
  compiler warning for a printk arg that I had missed earlier.

  These are all fixes, including one to prevent using stale pointers for
  device names, and lots of fixes around transaction abort cleanups
  (Josef, Liu Bo).

  Jan Schmidt also sent in a number of fixes for the new reference
  number tracking code.

  Liu Bo beat me to updating the MAINTAINERS file.  Since he thought to
  also fix the git url, I kept his commit."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: (24 commits)
  Btrfs: update MAINTAINERS info for BTRFS FILE SYSTEM
  Btrfs: destroy the items of the delayed inodes in error handling routine
  Btrfs: make sure that we've made everything in pinned tree clean
  Btrfs: avoid memory leak of extent state in error handling routine
  Btrfs: do not resize a seeding device
  Btrfs: fix missing inherited flag in rename
  Btrfs: fix incompat flags setting
  Btrfs: fix defrag regression
  Btrfs: call filemap_fdatawrite twice for compression
  Btrfs: keep inode pinned when compressing writes
  Btrfs: implement ->show_devname
  Btrfs: use rcu to protect device->name
  Btrfs: unlock everything properly in the error case for nocow
  Btrfs: fix btrfs_destroy_marked_extents
  Btrfs: abort the transaction if the commit fails
  Btrfs: wake up transaction waiters when aborting a transaction
  Btrfs: fix locking in btrfs_destroy_delayed_refs
  Btrfs: pass locked_page into extent_clear_unlock_delalloc if theres an error
  Btrfs: fix race in tree mod log addition
  Btrfs: add btrfs_next_old_leaf
  ...

Update to the latest btrfs's maintainer mail and git repo.
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

the items of the delayed inodes were forgotten to be freed, this patch
fixes it.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

Since we have two trees for recording pinned extents, we need to go through
both of them to make sure that we've done everything clean.
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

We've forgotten to clear extent states in pinned tree, which will results in
space counter mismatch and memory leak:

WARNING: at fs/btrfs/extent-tree.c:7537 btrfs_free_block_groups+0x1f3/0x2e0 [btrfs]()
...
space_info 2 has 8380416 free, is not full
space_info total=12582912, used=4096, pinned=4096, reserved=0, may_use=0, readonly=4194304
btrfs state leak: start 29364224 end 29376511 state 1 in tree ffff880075f20090 refs 1
...
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

Seeding devices are not supposed to change any more.
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

When we move a file into a directory with compression flag, we need to
inherite BTRFS_INODE_COMPRESS and clear BTRFS_INODE_NOCOMPRESS as well.
But if we move a file into a directory without compression flag, we need
to clear both of them.

It is the way how our setflags deals with compression flag, so keep
the same behaviour here.
Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

At present, hard_irq_disable() does nothing on powerpc because of
this code in include/linux/interrupt.h:

    #ifndef hard_irq_disable
    #define hard_irq_disable()      do { } while(0)
    #endif

So we need to make our hard_irq_disable be a macro.  It was previously
a macro until commit 7230c564 ("powerpc: Rework lazy-interrupt
handling") changed it to a static inline function.

Cc: stable@vger.kernel.org
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
--
 arch/powerpc/include/asm/hw_irq.h |    3 +++
 1 file changed, 3 insertions(+)

It's a bug, but it happens to work, as BTRFS_COMPRESS_LZO == 2, which
has only one bit set.
Signed-off-by: Li Zefan <lizefan@huawei.com>

If a file has 3 small extents:

| ext1 | ext2 | ext3 |

Running "btrfs fi defrag" will only defrag the last two extents, if those
extent mappings hasn't been read into memory from disk.

This bug was introduced by commit 17ce6ef8
("Btrfs: add a check to decide if we should defrag the range")

The cause is, that commit looked into previous and next extents using
lookup_extent_mapping() only.

While at it, remove the code that checks the previous extent, since
it's sufficient to check the next extent.
Signed-off-by: Li Zefan <lizefan@huawei.com>

I removed this in an earlier commit and I was wrong.  Because compression
can return from filemap_fdatawrite() without having actually set any of it's
pages as writeback() it can make filemap_fdatawait() do essentially nothing,
and then we won't find any ordered extents because they may not have been
created yet.  So not only does this make fsync() completely useless, but it
will also screw up if you truncate on a non-page aligned offset since we
zero out the end and then wait on ordered extents and then call drop caches.
We can drop the cache before the io completes and then we try to unpin the
extent we just wrote we won't find it and everything goes sideways.  So fix
this by putting it back and put a giant comment there to keep me from trying
to remove it in the future.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

A user reported lots of problems using compression on the new code and it
turns out part of the problem was that igrab() was failing when we added a
new ordered extent.  This is because when writing out an inode under
compression we immediately return without actually doing anything to the
pages, and then in another thread at some point down the line actually do
the ordered dance.  The problem is between the point that we start writeback
and we actually add the ordered extent we could be trying to reclaim the
inode, which makes igrab() return NULL.  So we need to do an igrab() when we
create the async extent and then drop it when we are done with it.  This
makes sure we stay pinned in memory until the ordered extent can get a
reference on it and we are good to go.  With this patch we no longer panic
in btrfs_finish_ordered_io().  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>

Because btrfs can remove the device that was mounted we need to have a
->show_devname so that in this case we can print out some other device in
the file system to /proc/mount.  So if there are multiple devices in a btrfs
file system we will just print the device with the lowest devid that we can
find.  This will make everything consistent and deal with device removal
properly.  The drawback is if you mount with a device that is higher than
the lowest devicd it won't show up as the mounted device in /proc/mounts,
but this is a small price to pay. This was inspired by Miao Xie's patch.
Thanks,
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <josef@redhat.com>

Al pointed out that we can just toss out the old name on a device and add a
new one arbitrarily, so anybody who uses device->name in printk could
possibly use free'd memory.  Instead of adding locking around all of this he
suggested doing it with RCU, so I've introduced a struct rcu_string that
does just that and have gone through and protected all accesses to
device->name that aren't under the uuid_mutex with rcu_read_lock().  This
protects us and I will use it for dealing with removing the device that we
used to mount the file system in a later patch.  Thanks,
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <josef@redhat.com>

I was getting hung on umount when a transaction was aborted because a range
of one of the free space inodes was still locked.  This is because the nocow
stuff doesn't unlock anything on error.  This fixed the problem and I
verified that is what was happening.  Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>