Since all verification errors also mark the buffer as having an error,
we can combine these two calls.  Later we'll add a xfs_failaddr_t
parameter to promote the idea of reporting corruption errors and the
address of the failing check to enable better debugging reports.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

Since __xfs_dir3_data_check verifies on-disk metadata, we can't have it
noisily blowing asserts and hanging the system on corrupt data coming in
off the disk.  Instead, have it return a boolean like all the other
checker functions, and only have it noisily fail if we fail in debug
mode.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

Now that we have xfs_verify_agbno, use it to verify short form btree
pointers instead of open-coding them.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

Create two helper functions to verify the headers of a long format
btree block.  We'll use this later for the realtime rmapbt.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

We already have a function to verify fsb pointers, so get rid of the
last users of the (less robust) macro.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

In xfs_scrub_get_inode, we don't do a good enough job distinguishing
EINVAL returns from xfs_iget w/ IGET_UNTRUSTED -- this can happen if the
passed in inode number is invalid (past eofs, inobt says it isn't an
inode) or if the inum is actually valid but the inode buffer fails
verifier.  In the first case we still want to return ENOENT, but in the
second case we want to capture the corruption error.

Therefore, if xfs_iget returns EINVAL, try the raw imap lookup.  If that
succeeds, we conclude it's a corruption error, otherwise we just bounce
out to userspace.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

Always allocate a transaction for inode scrubbing, even if the _iget
fails.  This is something that is nice to have now for consistency with
the other scrubbers but will become critical when we get to online
repair where we'll actually use the transaction + raw buffer read to fix
the verifier errors.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

Refactor xfs_scrub_bmap to use for_each_xfs_iext now that it exists.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

The superblock validation routines return a variety of error codes to
reject a mount request.  For scrub we can assume that the mount
succeeded, so if we see these things appear when scrubbing secondary sb
X, we can treat them all like corruption.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

In xfs_scrub_ag_read_headers, if we're not scrubbing the AGFL but
hit a read error reading the AGFL, we should reset the error code
so that it doesn't propagate up into the caller.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

If two programs simultaneously try to write to the same part of a file
via direct IO and buffered IO, there's a chance that the post-diowrite
pagecache invalidation will fail on the dirty page.  When this happens,
the dio write succeeded, which means that the page cache is no longer
coherent with the disk!

Programs are not supposed to mix IO types and this is a clear case of
data corruption, so store an EIO which will be reflected to userspace
during the next fsync.  Replace the WARN_ON with a ratelimited pr_crit
so that the developers have /some/ kind of breadcrumb to track down the
offending program(s) and file(s) involved.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NLiu Bo <bo.li.liu@oracle.com>

The create transaction reservation calculation has two different
branches of code depending on whether the filesystem is a v5 format
fs or older. Each branch considers the max reservation between the
allocation case (new chunk allocation + record insert) and the
modify case (chunk exists, record modification) of inode allocation.

The modify case is the same for both superblock versions with the
exception of the finobt. The finobt helper checks the feature bit,
however, and so the modify case already shares the same code.

Now that inode chunk allocation has been refactored into a helper
that checks the superblock version to calculate the appropriate
reservation for the create transaction, the only remaining
difference between the create and icreate branches is the call to
the finobt helper. As noted above, the finobt helper is a no-op when
the feature is not enabled. Therefore, these branches are
effectively duplicate and can be condensed.

Remove the xfs_calc_create_*() branch of functions and update the
various callers to use the xfs_calc_icreate_*() variant. The latter
creates the same reservation size for v4 create transactions as the
removed branch. As such, this patch does not result in transaction
reservation changes.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

The reservation for the various forms of inode allocation is
scattered across several different functions. This includes two
variants of chunk allocation (v5 icreate transactions vs. older
create transactions) and the inode free transaction.

To clean up some of this code and clarify the purpose of specific
allocfree reservations, continue the pattern of defining helper
functions for smaller operational units of broader transactions.
Refactor the reservation into an inode chunk alloc/free helper that
considers the various conditions based on filesystem format.

An inode chunk free involves an extent free and buffer
invalidations. The latter requires reservation for log headers only.
An inode chunk allocation modifies the free space btrees and logs
the chunk on v4 supers. v5 supers initialize the inode chunk using
ordered buffers and so do not log the chunk.

As a side effect of this refactoring, add one more allocfree res to
the ifree transaction. Technically this does not serve a specific
purpose because inode chunks are freed via deferred operations and
thus occur after a transaction roll. tr_ifree has a bit of a history
of tx overruns caused by too many agfl fixups during sustained file
deletion workloads, so add this extra reservation as a form of
padding nonetheless.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

Analysis of recent reports of log reservation overruns and code
inspection has uncovered that the reservations associated with inode
operations may not cover the worst case scenarios. In particular,
many cases only include one allocfree res. for a particular
operation even though said operations may also entail AGFL fixups
and inode btree block allocations in addition to the actual inode
chunk allocation. This can easily turn into two or three block
allocations (or frees) per operation.

In theory, the only way to define the worst case reservation is to
include an allocfree res for each individual allocation in a
transaction. Since that is impractical (we can perform multiple agfl
fixups per tx and not every allocation results in a full tree
operation), we need to find a reasonable compromise that addresses
the deficiency in practice without blowing out the size of the
transactions.

Since the inode btrees are not filled by the AGFL, record insertion
and removal can directly result in block allocations and frees
depending on the shape of the tree. These allocations and frees
occur in the same transaction context as the inobt update itself,
but are separate from the allocation/free that might be required for
an inode chunk. Therefore, it makes sense to assume that an [f]inobt
insert/remove can directly result in one or more block allocations
on behalf of the tree.

Refactor the inode transaction reservations to include one allocfree
res. per inode btree modification to cover allocations required by
the tree itself. This separates the reservation required to allocate
the inode chunk from the reservation required for inobt record
insertion/removal. Apply the same logic to the finobt. This results
in killing off the finobt modify condition because we no longer
assume that the broader transaction reservation will cover finobt
block allocations and finobt shape changes can occur in either of
the inobt allocation or modify situations.
Suggested-by: NDave Chinner <david@fromorbit.com>
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

The truncate transaction does not ever modify the inode btree, but
includes an associated log reservation. Update
xfs_calc_itruncate_reservation() to remove the reservation
associated with inobt updates.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

The current AGI unlinked list addition and removal reservations do
not reflect the worst case log usage. An unlinked list removal can
log up to two on-disk inode clusters but only includes reservation
for one. An unlinked list addition logs the on-disk cluster but
includes reservation for an in-core inode.

Update the AGI unlinked list reservation helpers to calculate the
correct worst case reservation for the associated operations.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

The tr_ifree transaction handles inode unlinks and inode chunk
frees. The current transaction calculation does not accurately
reflect worst case changes to the inode btree, however. The inobt
portion of the current transaction reservation only covers
modification of a single inobt buffer (for the particular inode
record). This is a historical artifact from the days before XFS
supported full inode chunk removal.

When support for inode chunk removal was added in commit
254f6311ed1b ("Implement deletion of inode clusters in XFS."), the
additional log reservation required for chunk removal was not added
correctly. The new reservation only considered the header overhead
of associated buffers rather than the full contents of the btrees
and AGF and AGFL buffers affected by the transaction. The
reservation for the free space btrees was subsequently fixed up in
commit 5fe6abb82f76 ("Add space for inode and allocation btrees to
ITRUNCATE log reservation"), but the res. for full inobt joins has
never been added.

Further review of the ifree reservation uncovered a couple more
problems:

- The undocumented +2 blocks are intended for the AGF and AGFL, but
  are also not sized correctly and should be logged as full sectors
  (not FSBs).
- The additional single block header is undocumented and serves no
  apparent purpose.

Update xfs_calc_ifree_reservation() to include a full inobt join in
the reservation calculation. Refactor the undocumented blocks
appropriately and fix up the comments to reflect the current
calculation.
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

The transaction dump code displays the content and reservation
consumption of a particular transaction in the event of an overrun.
It currently displays the reservation associated with the
transaction ticket, but not the original reservation attached to the
transaction.

The latter value reflects the original transaction reservation
calculation before additional reservation overhead is assigned, such
as for the CIL context header and potential split region headers.

Update xlog_print_trans() to also print the original transaction
reservation in the event of overrun. This provides a reference point
to identify how much reservation overhead was added to a particular
ticket by xfs_log_calc_unit_res().
Signed-off-by: NBrian Foster <bfoster@redhat.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

Check that the nanosecond fields in each timestamp aren't larger
than a billion.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

There were ad-hoc checks for some scrub types but not others;
mark each scrub type with ... it's type, and use that to validate
the allowed and/or required input fields.

Moving these checks out of xfs_scrub_setup_ag_header makes it
a thin wrapper, so unwrap it in the process.
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
[darrick: add xfs_ prefix to enum, check scrub args after checking type]
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

Do this before adding more core checks.
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

An implicit mapping to type by order of initialization seems
error-prone, and doesn't lend itself to cscope-ing.

Also add sanity checks about size of array vs. max types,
and a defensive check that ->scrub exists before using it.
Signed-off-by: NEric Sandeen <sandeen@redhat.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

- Reports realtime device free blocks in statfs calls if (realtime)
  inheritance bit is set on the inode of directory, or realtime flag
  in the case of files.  This is a bit more intuitive, especially for
  use-cases which are using a much larger device for the realtime device.
- Add XFS_IS_REALTIME_MOUNT option to gate based on the existence of a
  realtime device on the mount, similar to the XFS_IS_REALTIME_INODE
  option.
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Signed-off-by: NRichard Wareing <rwareing@fb.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

The previous fix in commit 384632e6 ("userfaultfd: non-cooperative:
fix fork use after free") corrected the refcounting in case of
UFFD_EVENT_FORK failure for the fork userfault paths.

That still didn't clear the vma->vm_userfaultfd_ctx of the vmas that
were set to point to the aborted new uffd ctx earlier in
dup_userfaultfd.

Link: http://lkml.kernel.org/r/20171223002505.593-2-aarcange@redhat.comSigned-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Reported-by: Nsyzbot <syzkaller@googlegroups.com>
Reviewed-by: NMike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This is a logical revert of commit e37fdb78 ("exec: Use secureexec
for setting dumpability")

This weakens dumpability back to checking only for uid/gid changes in
current (which is useless), but userspace depends on dumpability not
being tied to secureexec.

  https://bugzilla.redhat.com/show_bug.cgi?id=1528633Reported-by: NTom Horsley <horsley1953@gmail.com>
Fixes: e37fdb78 ("exec: Use secureexec for setting dumpability")
Cc: stable@vger.kernel.org
Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix some integer overflow problems if offset + count happen to be large
enough to cause an integer overflow.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

xfs_qm_init_quotainfo() does not check result of register_shrinker()
which was tagged as __must_check recently, reported by sparse.
Signed-off-by: NAliaksei Karaliou <akaraliou.dev@gmail.com>
[darrick: move xfs_qm_destroy_quotainos nearer xfs_qm_init_quotainos]
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

xfs_qm_destroy_quotainfo() does not destroy quotainfo->qi_tree_lock
while destroys quotainfo->qi_quotaofflock.
Signed-off-by: NAliaksei Karaliou <akaraliou.dev@gmail.com>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

refcounts have a generic implementation and an asm optimized one.  The
generic version has extra debugging to make sure that once a refcount
goes to zero, refcount_inc won't increase it.

The btrfs delayed inode code wasn't expecting this, and we're tripping
over the warnings when the generic refcounts are used.  We ended up with
this race:

Process A                                         Process B
                                                  btrfs_get_delayed_node()
						  spin_lock(root->inode_lock)
						  radix_tree_lookup()
__btrfs_release_delayed_node()
refcount_dec_and_test(&delayed_node->refs)
our refcount is now zero
						  refcount_add(2) <---
						  warning here, refcount
                                                  unchanged

spin_lock(root->inode_lock)
radix_tree_delete()

With the generic refcounts, we actually warn again when process B above
tries to release his refcount because refcount_add() turned into a
no-op.

We saw this in production on older kernels without the asm optimized
refcounts.

The fix used here is to use refcount_inc_not_zero() to detect when the
object is in the middle of being freed and return NULL.  This is almost
always the right answer anyway, since we usually end up pitching the
delayed_node if it didn't have fresh data in it.

This also changes __btrfs_release_delayed_node() to remove the extra
check for zero refcounts before radix tree deletion.
btrfs_get_delayed_node() was the only path that was allowing refcounts
to go from zero to one.

Fixes: 6de5f18e ("btrfs: fix refcount_t usage when deleting btrfs_delayed_node")
CC: <stable@vger.kernel.org> # 4.12+
Signed-off-by: NChris Mason <clm@fb.com>
Reviewed-by: NLiu Bo <bo.li.liu@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Commit e0ae9994 ("btrfs: preallocate device flush bio") reworked
the way the flush bio is allocated and used. Concretely it allocates
the bio in __alloc_device and then re-uses it multiple times with a
very simple endio routine that just calls complete() without consuming
a reference. Allocated bios by default come with a ref count of 1,
which is then consumed by the endio routine (or not, in which case they
should be bio_put by the caller). The way the impleementation works now
is that the flush bio has a refcount of 2 and we only ever bio_put it
once, leaving it to hang indefinitely. Fix this by removing the extra
bio_get in __alloc_device.

Fixes: e0ae9994 ("btrfs: preallocate device flush bio")
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NLiu Bo <bo.li.liu@oracle.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

afs_write_end() is missing page unlock and put if afs_fill_page() fails.
Reported-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NDavid Howells <dhowells@redhat.com>

Repeating creation and deletion of a file on an afs mount will run the box
out of memory, e.g.:

	dd if=/dev/zero of=/afs/scratch/m0 bs=$((1024*1024)) count=512
	rm /afs/scratch/m0

The problem seems to be that it's not properly decrementing the nlink count
so that the inode can be scrapped.

Note that this doesn't fix local creation followed by remote deletion.
That's harder to handle and will require a separate patch as we're not told
that the file has been deleted - only that the directory has changed.
Reported-by: NMarc Dionne <marc.dionne@auristor.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>

Smatch warns that:

    fs/afs/rxrpc.c:922 afs_extract_data()
    error: uninitialized symbol 'remote_abort'.

Smatch is right that "remote_abort" might be uninitialized when we pass
it to afs_set_call_complete().  I don't know if that function uses the
uninitialized variable.  Anyway, the comment for rxrpc_kernel_recv_data(),
says that "*_abort should also be initialised to 0." and this patch does
that.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>

For rmap removal, refactor the rmap owner checks into a separate
function, then skip the checks if we are performing an unknown-owner
removal.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

Calling xfs_rmap_free with an unknown owner is supposed to remove any
rmaps covering that range regardless of owner.  This is used by the EFI
recovery code to say "we're freeing this, it mustn't be owned by
anything anymore", but for whatever reason xfs_free_ag_extent filters
them out.

Therefore, remove the filter and make xfs_rmap_unmap actually treat it
as a wildcard owner -- free anything that's already there, and if
there's no owner at all then that's fine too.

There are two existing callers of bmap_add_free that take care the rmap
deferred ops themselves and use OWN_UNKNOWN to skip the EFI-based rmap
cleanup; convert these to use OWN_NULL (via helpers), and now we really
require that an RUI (if any) gets added to the defer ops before any EFI.

Lastly, now that xfs_free_extent filters out OWN_NULL rmap free requests,
growfs will have to consult directly with the rmap to ensure that there
aren't any rmaps in the grown region.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

Under the deferred rmap operation scheme, there's a certain order in
which the rmap deferred ops have to be queued to maintain integrity
during log replay.  For alloc/map operations that order is cui -> rui;
for free/unmap operations that order is cui -> rui -> efi.  However, the
initial refcount code got the ordering wrong in the free side of things
because it queued refcount free op and an EFI and the refcount free op
queued a rmap free op, resulting in the order cui -> efi -> rui.

If we fail before the efd finishes, the efi recovery will try to do a
wildcard rmap removal and the subsequent rui will fail to find the rmap
and blow up.  This didn't ever happen due to other screws up in handling
unknown owner rmap removals, but those other screw ups broke recovery in
other ways, so fix the ordering to follow the intended rules.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

If a user performs a direct CoW write, we end up loading the CoW fork
with preallocated extents.  Therefore, we must set the cowblocks tag so
that they can be cleared out if we run low on space.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

When we're remounting the filesystem readonly, remove all CoW
preallocations prior to going ro.  If the fs goes down after the ro
remount, we never clean up the staging extents, which means xfs_check
will trip over them on a subsequent run.  Practically speaking, the next
mount will clean them up too, so this is unlikely to be seen.  Since we
shut down the cowblocks cleaner on remount-ro, we also have to make sure
we start it back up if/when we remount-rw.

Found by adding clonerange to fsstress and running xfs/017.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

Currently, xfs_itruncate_extents clears the cowblocks tag if i_cnextents
is zero.  This is wrong, since i_cnextents only tracks real extents in
the CoW fork, which means that we could have some delayed CoW
reservations still in there that will now never get cleaned.

Fix a further bug where we /don't/ clear the reflink iflag if there are
any attribute blocks -- really, it's only safe to clear the reflink flag
if there are no data fork extents and no cow fork extents.

Found by adding clonerange to fsstress in xfs/017.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

The EOFBLOCKS/COWBLOCKS tags are totally separate things, so track them
with separate i_flags.  Right now we're abusing IEOFBLOCKS for both,
which is totally bogus because we won't tag the inode with COWBLOCKS if
IEOFBLOCKS was set by a previous tagging of the inode with EOFBLOCKS.
Found by wiring up clonerange to fsstress in xfs/017.
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>