One unfortunate quirk of the reference count and reverse mapping
btrees -- they can expand in size when blocks are written to *other*
allocation groups if, say, one large extent becomes a lot of tiny
extents.  Since we don't want to start throwing errors in the middle
of CoWing, we need to reserve some blocks to handle future expansion.
The transaction block reservation counters aren't sufficient here
because we have to have a reserve of blocks in every AG, not just
somewhere in the filesystem.

Therefore, create two per-AG block reservation pools.  One feeds the
AGFL so that rmapbt expansion always succeeds, and the other feeds all
other metadata so that refcountbt expansion never fails.

Use the count of how many reserved blocks we need to have on hand to
create a virtual reservation in the AG.  Through selective clamping of
the maximum length of allocation requests and of the length of the
longest free extent, we can make it look like there's less free space
in the AG unless the reservation owner is asking for blocks.

In other words, play some accounting tricks in-core to make sure that
we always have blocks available.  On the plus side, there's nothing to
clean up if we crash, which is contrast to the strategy that the rough
draft used (actually removing extents from the freespace btrees).
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

When xfs_defer_finish calls ->finish_item, it's possible that
(refcount) won't be able to finish all the work in a single
transaction.  When this happens, the ->finish_item handler should
shorten the log done item's list count, update the work item to
reflect where work should continue, and return -EAGAIN so that
defer_finish knows to retain the pending item on the pending list,
roll the transaction, and restart processing where we left off.

Plumb in the code and document how this mechanism is supposed to work.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

Provide a helper method to count the number of blocks in a short form
btree.  The refcount and rmap btrees need to know the number of blocks
already in use to set up their per-AG block reservations during mount.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

Create a helper to generate AG btree height calculator functions.
This will be used (much) later when we get to the refcount btree.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

Remove the xfs_btree_bigkey mess and simply make xfs_btree_key big enough
to hold both keys in-core.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

Use variable length array declarations for RUI log items,
and replace the open coded sizeof formulae with a single function.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

Christoph reports slab corruption when a deferred refcount update
aborts during _defer_finish().  The cause of this was broken log item
state tracking in xfs_defer_pending -- upon an abort,
_defer_trans_abort() will call abort_intent on all intent items,
including the ones that have already had a done item attached.

This is incorrect because each intent item has 2 refcount: the first
is released when the intent item is committed to the log; and the
second is released when the _done_ item is committed to the log, or
by the intent creator if there is no done item.  In other words, once
we log the done item, responsibility for releasing the intent item's
second refcount is transferred to the done item and /must not/ be
performed by anything else.

The dfp_committed flag should have been tracking whether or not we had
a done item so that _defer_trans_abort could decide if it needs to
abort the intent item, but due to a thinko this was not the case.  Rip
it out and track the done item directly so that we do the right thing
w.r.t. intent item freeing.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reported-by: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

Filesystems like XFS that use extents should not set the
FIEMAP_EXTENT_MERGED flag in the fiemap extent structures.  To allow
for both behaviors for the upcoming gfs2 usage split the iomap
type field into type and flags, and only set FIEMAP_EXTENT_MERGED if
the IOMAP_F_MERGED flag is set.  The flags field will also come in
handy for future features such as shared extents on reflink-enabled
file systems.
Reported-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

xfs_wait_buftarg() waits for all pending I/O, drains the ioend
completion workqueue and walks the LRU until all buffers in the cache
have been released. This is traditionally an unmount operation` but the
mechanism is also reused during filesystem freeze.

xfs_wait_buftarg() invokes drain_workqueue() as part of the quiesce,
which is intended more for a shutdown sequence in that it indicates to
the queue that new operations are not expected once the drain has begun.
New work jobs after this point result in a WARN_ON_ONCE() and are
otherwise dropped.

With filesystem freeze, however, read operations are allowed and can
proceed during or after the workqueue drain. If such a read occurs
during the drain sequence, the workqueue infrastructure complains about
the queued ioend completion work item and drops it on the floor. As a
result, the buffer remains on the LRU and the freeze never completes.

Despite the fact that the overall buffer cache cleanup is not necessary
during freeze, fix up this operation such that it is safe to invoke
during non-unmount quiesce operations. Replace the drain_workqueue()
call with flush_workqueue(), which runs a similar serialization on
pending workqueue jobs without causing new jobs to be dropped. This is
safe for unmount as unmount independently locks out new operations by
the time xfs_wait_buftarg() is invoked.

cc: <stable@vger.kernel.org>
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

From inspection, the superblock sb_inprogress check is done in the
verifier and triggered only for the primary superblock via a
"bp->b_bn == XFS_SB_DADDR" check.

Unfortunately, the primary superblock is an uncached buffer, and
hence it is configured by xfs_buf_read_uncached() with:

	bp->b_bn = XFS_BUF_DADDR_NULL;  /* always null for uncached buffers */

And so this check never triggers. Fix it.

cc: <stable@vger.kernel.org>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

If the initial LOOKUP_LE in the simple query range fails to find
anything, we should attempt to increment the btree cursor to see
if there actually /are/ records for what we're trying to find.
Without this patch, a bnobt range query of (0, $agsize) returns
no results because the leftmost record never has a startblock
of zero.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

We only need the record's high key for the first record that we look
at; for all records, we /definitely/ need the regular record key.
Therefore, fix how the simple range query function gets its keys.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

When we're logging the last non-spare field in the AGF, we don't
need to log the spare fields, so plumb in a new AGF logging flag
to help us avoid that.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

Since the kernel doesn't currently support the realtime rmapbt,
don't allow such filesystems to be mounted.  Support will appear
in a future release.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

If the caller passes in a cursor to a zero-height btree (which is
impossible), we never set block to anything but NULL, which causes the
later dereference of it to crash.  Instead, just return -EFSCORRUPTED.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

When we're really tight on space, xfs_alloc_ag_vextent_small() can
allocate a block from the AGFL and give it to the caller.  Since the
caller is never the AGFL-fixing method, we must remove the OWN_AG
reverse mapping because it will clash with whatever rmap the caller
wants to set up.  This bug was discovered by running generic/299
repeatedly.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

Use a special read-only iomap_ops implementation to support fiemap on
the attr fork.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

We'll never get nimap == 0 for a successful return from xfs_bmapi_read,
so don't try to handle it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

No need to implement it for read-only mappings.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

By bassing through an -ENOENT, similar to the old XFS implementation of
FIEMAP_FLAG_XATTR.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
[hch: split from a larger patch]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

The flag is checked as supported, but then we do an unconditional
sync of the file, regardless of whether the flag is set or not. Make
the sync conditional on having the FIEMAP_FLAG_SYNC flag set.
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

iov_iter_copy_from_user_atomic disables page faults internally, no need to
do it around the call.  This also brings the iomap code in line with
the original filemap version.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

This catches up with commit  2457ae ("mm: non-atomically mark page
accessed during page cache allocation where possible"), which
moved the initial access marking into the pagecache allocator.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

Track the number of blocks used for the rmapbt in the AGF.  When we
get to the AG reservation code we need this counter to quickly
make our reservation during mount.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

When we do DAX IO, we try to invalidate the entire page cache held
on the file. This is incorrect as it will trash the entire mapping
tree that now tracks dirty state in exceptional entries in the radix
tree slots.

What we are trying to do is remove cached pages (e.g from reads
into holes) that sit in the radix tree over the range we are about
to write to. Hence we should just limit the invalidation to the
range we are about to overwrite.
Reported-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

The space reservations was without an explaination in commit

    "Add error reporting calls in error paths that return EFSCORRUPTED"

back in 2003.  There is no reason to reserve disk blocks in the
transaction when allocating blocks for delalloc space as we already
reserved the space when creating the delalloc extent.

With this fix we stop running out of the reserved pool in
generic/229, which has happened for long time with small blocksize
file systems, and has increased in severity with the new buffered
write path.

[ dchinner: we still need to pass the block reservation into
  xfs_bmapi_write() to ensure we don't deadlock during AG selection.
  See commit dbd5c8c9 ("xfs: pass total block res. as total
  xfs_bmapi_write() parameter") for more details on why this is
  necessary. ]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

The buffer I/O accounting mechanism tracks async buffers under I/O.  As
an optimization, the buffer I/O count is incremented only once on the
first async I/O for a given hold cycle of a buffer and decremented once
the buffer is released to the LRU (or freed).

xfs_buf_ioacct_dec() has an ASSERT() check for an XBF_ASYNC buffer, but
we have one or two corner cases where a buffer can be submitted for I/O
multiple times via different methods in a single hold cycle. If an async
I/O occurs first, the I/O count is incremented. If a sync I/O occurs
before the hold count drops, XBF_ASYNC is cleared by the time the I/O
count is decremented.

Remove the async assert check from xfs_buf_ioacct_dec() as this is a
perfectly valid scenario. For the purposes of I/O accounting, we really
only care about the buffer async state at I/O submission time.
Discovered-and-analyzed-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

Pull thermal updates from Zhang Rui:

 - Fix a race condition when updating cooling device, which may lead to
   a situation where a thermal governor never updates the cooling
   device.  From Michele Di Giorgio.

 - Fix a zero division error when disabling the forced idle injection
   from the intel powerclamp.  From Petr Mladek.

 - Add suspend/resume callback for intel_pch_thermal thermal driver.
   From Srinivas Pandruvada.

 - Another two fixes for clocking cooling driver and hwmon sysfs I/F.
   From Michele Di Giorgio and Kuninori Morimoto.

[ Hmm.  That suspend/resume callback for intel_pch_thermal doesn't look
  like a fix, but I'm letting it slide..  - Linus ]

* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux:
  thermal: clock_cooling: Fix missing mutex_init()
  thermal: hwmon: EXPORT_SYMBOL_GPL for thermal hwmon sysfs
  thermal: fix race condition when updating cooling device
  thermal/powerclamp: Prevent division by zero when counting interval
  thermal: intel_pch_thermal: Add suspend/resume callback

Pull m68knommu fix from Greg Ungerer:
 "This contains only a single fix for a register corruption problem on
  certain types of m68k flat format binaries"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu:
  m68knommu: fix user a5 register being overwritten

Merge tag 'fixes-for-linus-4.8' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging

Pull h8300 and unicore32 architecture fixes from Guenter Roeck:
 "Two patches to fix h8300 and unicore32 builds.

  unicore32 builds have been broken since v4.6.  The fix has been
  available in -next since March of this year.

  h8300 builds have been broken since the last commit window.  The fix
  has been available in -next since June of this year"

* tag 'fixes-for-linus-4.8' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
  h8300: Add missing include file to asm/io.h
  unicore32: mm: Add missing parameter to arch_vma_access_permitted

Pull arm64 fixes from Catalin Marinas:

 - support for nr_cpus= command line argument (maxcpus was previously
   changed to allow secondary CPUs to be hot-plugged)

 - ARM PMU interrupt handling fix

 - fix potential TLB conflict in the hibernate code

 - improved handling of EL1 instruction aborts (better error reporting)

 - removal of useless jprobes code for stack saving/restoring

 - defconfig updates

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: defconfig: enable CONFIG_LOCALVERSION_AUTO
  arm64: defconfig: add options for virtualization and containers
  arm64: hibernate: handle allocation failures
  arm64: hibernate: avoid potential TLB conflict
  arm64: Handle el1 synchronous instruction aborts cleanly
  arm64: Remove stack duplicating code from jprobes
  drivers/perf: arm-pmu: Fix handling of SPI lacking "interrupt-affinity" property
  drivers/perf: arm-pmu: convert arm_pmu_mutex to spinlock
  arm64: Support hard limit of cpu count by nr_cpus

Pull KVM fixes from Radim Krčmář:
 "KVM:
   - lock kvm_device list to prevent corruption on device creation.

  PPC:
   - split debugfs initialization from creation of the xics device to
     unlock the newly taken kvm lock earlier.

  s390:
   - prevent userspace from triggering two WARN_ON_ONCE.

  MIPS:
   - fix several issues in the management of TLB faults (Cc: stable)"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  MIPS: KVM: Propagate kseg0/mapped tlb fault errors
  MIPS: KVM: Fix gfn range check in kseg0 tlb faults
  MIPS: KVM: Add missing gfn range check
  MIPS: KVM: Fix mapped fault broken commpage handling
  KVM: Protect device ops->create and list_add with kvm->lock
  KVM: PPC: Move xics_debugfs_init out of create
  KVM: s390: reset KVM_REQ_MMU_RELOAD if mapping the prefix failed
  KVM: s390: set the prefix initially properly

Pull block fixes from Jens Axboe:

 - an NVMe fix from Gabriel, fixing a suspend/resume issue on some
   setups

 - addition of a few missing entries in the block queue sysfs
   documentation, from Joe

 - a fix for a sparse shadow warning for the bvec iterator, from
   Johannes

 - a writeback deadlock involving raid issuing barriers, and not
   flushing the plug when we wakeup the flusher threads.  From
   Konstantin

 - a set of patches for the NVMe target/loop/rdma code, from Roland and
   Sagi

* 'for-linus' of git://git.kernel.dk/linux-block:
  bvec: avoid variable shadowing warning
  doc: update block/queue-sysfs.txt entries
  nvme: Suspend all queues before deletion
  mm, writeback: flush plugged IO in wakeup_flusher_threads()
  nvme-rdma: Remove unused includes
  nvme-rdma: start async event handler after reconnecting to a controller
  nvmet: Fix controller serial number inconsistency
  nvmet-rdma: Don't use the inline buffer in order to avoid allocation for small reads
  nvmet-rdma: Correctly handle RDMA device hot removal
  nvme-rdma: Make sure to shutdown the controller if we can
  nvme-loop: Remove duplicate call to nvme_remove_namespaces
  nvme-rdma: Free the I/O tags when we delete the controller
  nvme-rdma: Remove duplicate call to nvme_remove_namespaces
  nvme-rdma: Fix device removal handling
  nvme-rdma: Queue ns scanning after a sucessful reconnection
  nvme-rdma: Don't leak uninitialized memory in connect request private data

h8300 builds fail with

arch/h8300/include/asm/io.h:9:15: error: unknown type name ‘u8’
arch/h8300/include/asm/io.h:15:15: error: unknown type name ‘u16’
arch/h8300/include/asm/io.h:21:15: error: unknown type name ‘u32’

and many related errors.

Fixes: 23c82d41bdf4 ("kexec-allow-architectures-to-override-boot-mapping-fix")
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

unicore32 fails to compile with the following errors.

mm/memory.c: In function ‘__handle_mm_fault’:
mm/memory.c:3381: error:
	too many arguments to function ‘arch_vma_access_permitted’
mm/gup.c: In function ‘check_vma_flags’:
mm/gup.c:456: error:
	too many arguments to function ‘arch_vma_access_permitted’
mm/gup.c: In function ‘vma_permits_fault’:
mm/gup.c:640: error:
	too many arguments to function ‘arch_vma_access_permitted’

Fixes: d61172b4 ("mm/core, x86/mm/pkeys: Differentiate instruction fetches")
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Guan Xuetao <gxt@mprc.pku.edu.cn>

Pull VFIO fix from Alex Williamson:
 "Fix oops when dereferencing empty data (Alex Williamson)"

* tag 'vfio-v4.8-rc2' of git://github.com/awilliam/linux-vfio:
  vfio/pci: Fix NULL pointer oops in error interrupt setup handling

Pull nfsd fixes from Bruce Fields:
 "Fixes for the dentry refcounting leak I introduced in 4.8-rc1, and for
  races in the LOCK code which appear to go back to the big nfsd state
  lock removal from 3.17"

* tag 'nfsd-4.8-1' of git://linux-nfs.org/~bfields/linux:
  nfsd: don't return an unhashed lock stateid after taking mutex
  nfsd: Fix race between FREE_STATEID and LOCK
  nfsd: fix dentry refcounting on create

Pull power management fixes from Rafael Wysocki:
 "Two hibernation fixes allowing it to work with the recently added
  randomization of the kernel identity mapping base on x86-64 and one
  cpufreq driver regression fix.

  Specifics:

   - Fix the x86 identity mapping creation helpers to avoid the
     assumption that the base address of the mapping will always be
     aligned at the PGD level, as it may be aligned at the PUD level if
     address space randomization is enabled (Rafael Wysocki).

   - Fix the hibernation core to avoid executing tracing functions
     before restoring the processor state completely during resume
     (Thomas Garnier).

   - Fix a recently introduced regression in the powernv cpufreq driver
     that causes it to crash due to an out-of-bounds array access
     (Akshay Adiga)"

* tag 'pm-4.8-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  PM / hibernate: Restore processor state before using per-CPU variables
  x86/power/64: Always create temporary identity mapping correctly
  cpufreq: powernv: Fix crash in gpstate_timer_handler()