Change reserve_ram_pages_type and free_ram_pages_type to use 2 page
flags to track UC_MINUS, WC, WB and default types. Previous RAM tracking
just tracked WB or NonWB, which was not complete and did not allow
tracking of RAM fully and there was no way to get the actual type
reserved by looking at the page flags.

We use the memtype_lock spinlock for atomicity in dealing with
memtype tracking in struct page.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Only IA64 was using PG_uncached as of now. We now intend to use this bit
in x86 as well, to keep track of memory type of those addresses that
have page struct for them. So, generalize the use of that bit across
ia64 and x86.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

PAT memtype tracking uses a linear link list to keep track of IO
(non-RAM) regions and their memtypes. The code used a last_accessed
pointer as a cache to speedup the lookup. As per discussions with
H. Peter Anvin a while back, having a rbtree here will avoid bad
performances in pathological cases where we may end up with huge
linked list. This may not add any noticable performance speedup
in normal case as the number of entires in PAT memtype list tend
to be ~20-30 range. The patch removes the "cached_entry" logic
as with rbtree we have more generic way of speeding up the lookup.

With this patch, we use rbtree to do the quick lookup. We still use
linked list as the memtype range tracked can be of different sizes
and can overlap in different ways. We also keep track of usage counts
with linked list.

Example:
Multiple ioremaps with different sizes
uncached-minus @ 0xfffff00000-0xfffff04000
uncached-minus @ 0xfffff02000-0xfffff03000

And one userlevel mmap and the thread forks a new process
uncached-minus @ 0xbf453000-0xbf454000
uncached-minus @ 0xbf453000-0xbf454000
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

io_mapping_* interfaces were added, mainly for graphics drivers.
Make this interface go through the PAT reserve/free, instead of
hardcoding WC mapping. This makes sure that there are no
aliases due to unconditional WC setting.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Add new routines to request memtype for IO regions. This will currently
be a backend for io_mapping_* routines. But, it can also be made available
to drivers directly in future, in case it is needed.

reserve interface reserves the memory, makes sure we have a compatible
memory type available and keeps the identity map in sync when needed.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

ioremap has this hard-coded check for new type and requested type. That
check differs from other PAT users like /dev/mem mmap, remap_pfn_range
in only one condition where requested type is UC_MINUS and new type
is WC. Under that condition, ioremap fails. But other PAT interfaces succeed
with a WC mapping.

Change to make ioremap be in sync with other PAT APIs and use the same
macro as others. Also changes the error print to KERN_ERR instead of
pr_debug.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Make reserve_memtype internally take care of pat disabled case and fallback
to default return values.

Remove the specific pat_disabled checks in track_* routines.

Change kernel_map_sync_memtype to sync identity map even when
pat_disabled.

This change ensures that, even for pat_disabled case, we take care of
keeping identity map in sync. Before this patch, in pat disabled case,
ioremap() keeps the identity maps in sync and other APIs like pci and
/dev/mem mmap don't, which is not a very consistent behavior.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

mtr_aps_delayed_init was declared u32 and made global, but it only
ever takes boolean values and is only ever used in
arch/x86/kernel/cpu/mtrr/main.c.  Declare it "static bool" and remove
external references.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>

SDM Vol 3a section titled "MTRR considerations in MP systems" specifies
the need for synchronizing the logical cpu's while initializing/updating
MTRR.

Currently Linux kernel does the synchronization of all cpu's only when
a single MTRR register is programmed/updated. During an AP online
(during boot/cpu-online/resume)  where we initialize all the MTRR/PAT registers,
we don't follow this synchronization algorithm.

This can lead to scenarios where during a dynamic cpu online, that logical cpu
is initializing MTRR/PAT with cache disabled (cr0.cd=1) etc while other logical
HT sibling continue to run (also with cache disabled because of cr0.cd=1
on its sibling).

Starting from Westmere, VMX transitions with cr0.cd=1 don't work properly
(because of some VMX performance optimizations) and the above scenario
(with one logical cpu doing VMX activity and another logical cpu coming online)
can result in system crash.

Fix the MTRR initialization by doing rendezvous of all the cpus. During
boot and resume, we delay the MTRR/PAT init for APs till all the
logical cpu's come online and the rendezvous process at the end of AP's bringup,
will initialize the MTRR/PAT for all AP's.

For dynamic single cpu online, we synchronize all the logical cpus and
do the MTRR/PAT init on the AP that is coming online.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Because of deadlock possiblities smp_call_function() is not allowed to
be called with interrupts disabled. Add an exception for the cpu not
yet online, as no one else can send smp call function interrupt to this
cpu that is not yet online and as such deadlock condition is not possible.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
LKML-Reference: <1249847649-11631-6-git-send-email-marcin.slusarz@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

No code changes except printk levels (although some of the K6
mtrr code might be clearer if there were a few as would
splitting out some of the intel cache code).
Signed-off-by: Alan Cox <alan@linux.intel.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Remove duplicated #include in:

  arch/x86/kernel/dumpstack.c
Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

We already use a lot of cpu_has_ helpers.
Lets do here the same for consistency.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <20090705160154.GB4791@lenovo>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <20090708180353.GH5301@lenovo>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Yinghai noticed that i defined BIOS_BUG_MSG but added no
usage for it. The usage is to clean up this turd in generic.c:

			printk(KERN_WARNING "WARNING: BIOS bug: VAR MTRR %d "
				"contains strange UC entry under 1M, check "
				"with your system vendor!\n", i);

Breaking printk lines in the middle looks ugly, is hard to read
and breaks 'git grep'. Use the BIOS_BUG_MSG instead.

Also complete the moving of structure definitions and variables
to the top of the file.
Reported-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <20090703164225.GA21447@elte.hu>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Fix following trivial style problems:

  ERROR: trailing whitespace X 25
  WARNING: Use #include <linux/uaccess.h> instead of <asm/uaccess.h>
  WARNING: Use #include <linux/kvm_para.h> instead of <asm/kvm_para.h>
  ERROR: do not initialise externals to 0 or NULL X 2
  ERROR: "foo * bar" should be "foo *bar" X 5
  ERROR: do not use assignment in if condition X 2
  WARNING: line over 80 characters X 8
  ERROR: return is not a function, parentheses are not required
  WARNING: braces {} are not necessary for any arm of this statement
  ERROR: space required before the open parenthesis '(' X 2
  ERROR: open brace '{' following function declarations go on the next line
  ERROR: space required after that ',' (ctx:VxV) X 8
  ERROR: space required before the open parenthesis '(' X 3
  ERROR: else should follow close brace '}'
  WARNING: space prohibited between function name and open parenthesis '('
  WARNING: EXPORT_SYMBOL(foo); should immediately follow its function/variable X 2

Also use pr_debug and pr_warning where possible.

total: 50 errors, 14 warnings

arch/x86/kernel/cpu/mtrr/main.o:

   text	   data	    bss	    dec	    hex	filename
   3668	    116	   4156	   7940	   1f04	main.o.before
   3668	    116	   4156	   7940	   1f04	main.o.after

md5:
   e01af2fd28deef77c8d01e71acfbd365  main.o.before.asm
   e01af2fd28deef77c8d01e71acfbd365  main.o.after.asm
Suggested-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <20090703164225.GA21447@elte.hu>
Cc: Avi Kivity <avi@redhat.com> # Avi, please have a look at the kvm_para.h bit
[ More cleanups ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Fix:

  WARNING: Use #include <linux/io.h> instead of <asm/io.h>
  WARNING: line over 80 characters X 4

arch/x86/kernel/cpu/mtrr/state.o:

   text	   data	    bss	    dec	    hex	filename
    864	      0	      0	    864	    360	state.o.before
    864	      0	      0	    864	    360	state.o.after

md5:
   c5c4364b9aeac74d70111e1e49667a2c  state.o.before.asm
   c5c4364b9aeac74d70111e1e49667a2c  state.o.after.asm
Suggested-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <20090703164225.GA21447@elte.hu>
[ More cleanups ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Fix:

  ERROR: do not use C99 // comments
  ERROR: "foo * bar" should be "foo *bar" X 2
Suggested-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <20090703164225.GA21447@elte.hu>
[ More tidyups ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Fix:

  WARNING: Use #include <linux/uaccess.h> instead of <asm/uaccess.h>
  ERROR: trailing whitespace X 7
  ERROR: trailing statements should be on next line X 3
  WARNING: line over 80 characters X 5
  ERROR: space required before the open parenthesis '('

arch/x86/kernel/cpu/mtrr/if.o:

   text	   data	    bss	    dec	    hex	filename
   2239	      4	      0	   2243	    8c3	if.o.before
   2239	      4	      0	   2243	    8c3	if.o.after

md5:
   78d1f2aa4843ec6509c18e2dee54bc7f  if.o.before.asm
   78d1f2aa4843ec6509c18e2dee54bc7f  if.o.after.asm
Suggested-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <20090703164225.GA21447@elte.hu>
[ More cleanups to make the code more consistent. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Fix following trivial style problems:

  ERROR: trailing whitespace X 4
  WARNING: Use #include <linux/io.h> instead of <asm/io.h>
  WARNING: braces {} are not necessary for single statement blocks X 3
  ERROR: "foo * bar" should be "foo *bar"
  WARNING: line over 80 characters X 6
  ERROR: "foo * bar" should be "foo *bar"
  ERROR: spaces required around that '=' (ctx:VxO)
  ERROR: space required before that '-' (ctx:OxV)
  WARNING: suspect code indent for conditional statements (8, 12)
  ERROR: spaces required around that '=' (ctx:VxV)
  ERROR: do not initialise statics to 0 or NULL
  ERROR: space prohibited after that open parenthesis '(' X 2
  ERROR: space prohibited before that close parenthesis ')' X 2
  ERROR: trailing statements should be on next line
  ERROR: return is not a function, parentheses are not required

Also use pr_debug and pr_warning where possible.

arch/x86/kernel/cpu/mtrr/generic.o:

   text	   data	    bss	    dec	    hex	filename
   5652	     77	   4224	   9953	   26e1	generic.o.before
   5652	     77	   4220	   9949	   26dd	generic.o.after

The md5 changed:
   b34d6c045f06daa4ed092b90cc760e8f  generic.o.before.asm
   a490c6251cfd8442fbffecc0e09a573d  generic.o.after.asm

Because mtrr_state moved from data to bss, changing its
offsets - and also because __LINE__ numbers changed.
Suggested-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <20090703164225.GA21447@elte.hu>
[ Further cleanups to make the code more consistent ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Fix trivial style problems:

  WARNING: Use #include <linux/io.h> instead of <asm/io.h>
  WARNING: line over 80 characters
  ERROR: do not initialise statics to 0 or NULL
  ERROR: space prohibited after that open parenthesis '(' X 2
  ERROR: space prohibited before that close parenthesis ')' X 2
  ERROR: trailing whitespace X 2
  ERROR: trailing statements should be on next line
  ERROR: do not use C99 // comments X 2

arch/x86/kernel/cpu/mtrr/cyrix.o:

   text	   data	    bss	    dec	    hex	filename
   1637	     32	      8	   1677	    68d	cyrix.o.before
   1637	     32	      8	   1677	    68d	cyrix.o.after

md5:
   6f52abd06905be3f4cabb5239f9b0ff0  cyrix.o.before.asm
   6f52abd06905be3f4cabb5239f9b0ff0  cyrix.o.after.asm
Suggested-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <20090703164225.GA21447@elte.hu>
[ Made the code more consistent ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Fix trivial style problems:

  WARNING: Use #include <linux/uaccess.h> instead of <asm/uaccess.h>
  WARNING: Use #include <linux/kvm_para.h> instead of <asm/kvm_para.h>

Also, nr_mtrr_spare_reg should be unsigned long.

arch/x86/kernel/cpu/mtrr/cleanup.o:

   text	   data	    bss	    dec	    hex	filename
   6241	   8992	   2056	  17289	   4389	cleanup.o.before
   6241	   8992	   2056	  17289	   4389	cleanup.o.after

The md5 has changed:
   1a7a27513aef1825236daf29110fe657  cleanup.o.before.asm
   bcea358efa2532b6020e338e158447af  cleanup.o.after.asm

Because a WARN_ON()'s __LINE__ value changed by 3 lines.
Suggested-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <20090703164225.GA21447@elte.hu>
[ Did lots of other cleanups to make the code look more consistent. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Remove dead code and fix trivial style problems:

  ERROR: trailing whitespace X 2
  WARNING: line over 80 characters X 3
  ROR: trailing whitespace
  ERROR: do not use C99 // comments X 2

arch/x86/kernel/cpu/mtrr/centaur.o:

   text	   data	    bss	    dec	    hex	filename
    605	     32	     68	    705	    2c1	centaur.o.before
    605	     32	     68	    705	    2c1	centaur.o.after

md5:
   a4865ea98ce3c163bb1d376a3949b3e3  centaur.o.before.asm
   a4865ea98ce3c163bb1d376a3949b3e3  centaur.o.after.asm
Suggested-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <20090703164225.GA21447@elte.hu>
[ Standardized comments, DocBook, curly braces, newlines. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Fix trivial style problems :

  ERROR: trailing whitespace
  WARNING: line over 80 characters
  ERROR: do not use C99 // comments

arch/x86/kernel/cpu/mtrr/amd.o:

   text	   data	    bss	    dec	    hex	filename
    501	     32	      0	    533	    215	amd.o.before
    501	     32	      0	    533	    215	amd.o.after

md5:
   62f795eb840ee2d17b03df89e789e76c  amd.o.before.asm
   62f795eb840ee2d17b03df89e789e76c  amd.o.after.asm
Suggested-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <20090703164225.GA21447@elte.hu>
[ Also restructured comments to be standard, removed stray return,
  converted function description to DocBook style, etc. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Merge reason: We were on an older pre-rc1 base, move to almost-rc2.
Signed-off-by: Ingo Molnar <mingo@elte.hu>

* 'for-linus' of git://git.infradead.org/users/eparis/notify:
  fs/notify/inotify: decrement user inotify count on close

* git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable:
  Btrfs: fix error message formatting
  Btrfs: fix use after free in btrfs_start_workers fail path
  Btrfs: honor nodatacow/sum mount options for new files
  Btrfs: update backrefs while dropping snapshot
  Btrfs: account for space we may use in fallocate
  Btrfs: fix the file clone ioctl for preallocated extents
  Btrfs: don't log the inode in file_write while growing the file

* git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-rc-fixes-2.6:
  [SCSI] cxgb3i: fix connection error when vlan is enabled
  [SCSI] FC transport: Locking fix for common-code FC pass-through patch
  [SCSI] zalon: fix oops on attach failure
  [SCSI] fnic: use DMA_BIT_MASK(nn) instead of deprecated DMA_nnBIT_MASK
  [SCSI] fnic: remove redundant BUG_ONs and fix checks on unsigned
  [SCSI] ibmvscsi: Fix module load hang

* git://git.infradead.org/iommu-2.6: (38 commits)
  intel-iommu: Don't keep freeing page zero in dma_pte_free_pagetable()
  intel-iommu: Introduce first_pte_in_page() to simplify PTE-setting loops
  intel-iommu: Use cmpxchg64_local() for setting PTEs
  intel-iommu: Warn about unmatched unmap requests
  intel-iommu: Kill superfluous mapping_lock
  intel-iommu: Ensure that PTE writes are 64-bit atomic, even on i386
  intel-iommu: Make iommu=pt work on i386 too
  intel-iommu: Performance improvement for dma_pte_free_pagetable()
  intel-iommu: Don't free too much in dma_pte_free_pagetable()
  intel-iommu: dump mappings but don't die on pte already set
  intel-iommu: Combine domain_pfn_mapping() and domain_sg_mapping()
  intel-iommu: Introduce domain_sg_mapping() to speed up intel_map_sg()
  intel-iommu: Simplify __intel_alloc_iova()
  intel-iommu: Performance improvement for domain_pfn_mapping()
  intel-iommu: Performance improvement for dma_pte_clear_range()
  intel-iommu: Clean up iommu_domain_identity_map()
  intel-iommu: Remove last use of PHYSICAL_PAGE_MASK, for reserving PCI BARs
  intel-iommu: Make iommu_flush_iotlb_psi() take pfn as argument
  intel-iommu: Change aligned_size() to aligned_nrpages()
  intel-iommu: Clean up intel_map_sg(), remove domain_page_mapping()
  ...

fix hang with HIGHMEM_64G and 32bit resource.  According to hpa and
Linus, use (resource_size_t)-1 to fend off big ranges.

Analyzed by hpa
Reported-and-tested-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

These macros had two bugs:
 - the type of the mask was not correctly expanded to the full size of
   the argument being expanded, resulting in possible loss of high bits
   when mixing types.
 - the alignment argument was evaluated twice, despite the macro looking
   like a fancy function (but it really does need to be a macro, since
   it works on arbitrary integer types)

Noticed by Peter Anvin, and with a fix that is a modification of his
suggestion (bug noticed by Yinghai Lu).

Cc: Peter Anvin <hpa@zytor.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Make an error msg look nicer by inserting a space between number and word.
Signed-off-by: Hu Tao <hu.taoo@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

worker memory is already freed on one fail path in btrfs_start_workers,
but is still dereferenced. Switch the dereference and kfree.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

The btrfs attr patches unconditionally inherited the inode flags field
without honoring nodatacow and nodatasum.  This fix makes sure
we properly record the nodatacow/sum mount options in new inodes.
Signed-off-by: Chris Mason <chris.mason@oracle.com>

The new backref format has restriction on type of backref item.  If a tree
block isn't referenced by its owner tree, full backrefs must be used for the
pointers in it. When a tree block loses its owner tree's reference, backrefs
for the pointers in it should be updated to full backrefs. Current
btrfs_drop_snapshot misses the code that updates backrefs, so it's unsafe for
general use.

This patch adds backrefs update code to btrfs_drop_snapshot.  It isn't a
problem in the restricted form btrfs_drop_snapshot is used today, but for
general snapshot deletion this update is required.
Signed-off-by: Yan Zheng <zheng.yan@oracle.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

Using Eric Sandeen's xfstest for fallocate, you can easily trigger a ENOSPC
panic on btrfs.  This is because we do not account for data we may use when
doing the fallocate.  This patch fixes the problem by properly reserving space,
and then just freeing it when we are done.  The reservation stuff was made with
delalloc in mind, so its a little crude for this case, but it keeps the box
from panicing.
Signed-off-by: Josef Bacik <jbacik@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

The per-user inotify_devs value is incremented each time a new file is
allocated, but never decremented. This led to inotify_init failing after a
limited number of calls.
Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Eric Paris <eparis@redhat.com>