parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).

Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Pull more btrfs updates from Chris Mason:
 "These are mostly fixes that we've been testing, but also we grabbed
  and tested a few small cleanups that had been on the list for a while.

  Zhao Lei's patchset also fixes some early ENOSPC buglets"

* 'for-linus-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: (21 commits)
  btrfs: raid56: Use raid_write_end_io for scrub
  btrfs: Remove unnecessary ClearPageUptodate for raid56
  btrfs: use rbio->nr_pages to reduce calculation
  btrfs: Use unified stripe_page's index calculation
  btrfs: Fix calculation of rbio->dbitmap's size calculation
  btrfs: Fix no_space in write and rm loop
  btrfs: merge functions for wait snapshot creation
  btrfs: delete unused argument in btrfs_copy_from_user
  btrfs: Use direct way to determine raid56 write/recover mode
  btrfs: Small cleanup for get index_srcdev loop
  btrfs: Enhance chunk validation check
  btrfs: Enhance super validation check
  Btrfs: fix deadlock running delayed iputs at transaction commit time
  Btrfs: fix typo in log message when starting a balance
  btrfs: remove duplicate const specifier
  btrfs: initialize the seq counter in struct btrfs_device
  Btrfs: clean up an error code in btrfs_init_space_info()
  btrfs: fix iterator with update error in backref.c
  Btrfs: fix output of compression message in btrfs_parse_options()
  Btrfs: Initialize btrfs_root->highest_objectid when loading tree root and subvolume roots
  ...

size_t write_bytes is not necessary for btrfs_copy_from_user(),
delete it.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

Pull btrfs updates from Chris Mason:
 "This has our usual assortment of fixes and cleanups, but the biggest
  change included is Omar Sandoval's free space tree.  It's not the
  default yet, mounting -o space_cache=v2 enables it and sets a readonly
  compat bit.  The tree can actually be deleted and regenerated if there
  are any problems, but it has held up really well in testing so far.

  For very large filesystems (30T+) our existing free space caching code
  can end up taking a huge amount of time during commits.  The new tree
  based code is faster and less work overall to update as the commit
  progresses.

  Omar worked on this during the summer and we'll hammer on it in
  production here at FB over the next few months"

* 'for-linus-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: (73 commits)
  Btrfs: fix fitrim discarding device area reserved for boot loader's use
  Btrfs: Check metadata redundancy on balance
  btrfs: statfs: report zero available if metadata are exhausted
  btrfs: preallocate path for snapshot creation at ioctl time
  btrfs: allocate root item at snapshot ioctl time
  btrfs: do an allocation earlier during snapshot creation
  btrfs: use smaller type for btrfs_path locks
  btrfs: use smaller type for btrfs_path lowest_level
  btrfs: use smaller type for btrfs_path reada
  btrfs: cleanup, use enum values for btrfs_path reada
  btrfs: constify static arrays
  btrfs: constify remaining structs with function pointers
  btrfs tests: replace whole ops structure for free space tests
  btrfs: use list_for_each_entry* in backref.c
  btrfs: use list_for_each_entry_safe in free-space-cache.c
  btrfs: use list_for_each_entry* in check-integrity.c
  Btrfs: use linux/sizes.h to represent constants
  btrfs: cleanup, remove stray return statements
  btrfs: zero out delayed node upon allocation
  btrfs: pass proper enum type to start_transaction()
  ...

Pull vfs copy_file_range updates from Al Viro:
 "Several series around copy_file_range/CLONE"

* 'work.copy_file_range' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  btrfs: use new dedupe data function pointer
  vfs: hoist the btrfs deduplication ioctl to the vfs
  vfs: wire up compat ioctl for CLONE/CLONE_RANGE
  cifs: avoid unused variable and label
  nfsd: implement the NFSv4.2 CLONE operation
  nfsd: Pass filehandle to nfs4_preprocess_stateid_op()
  vfs: pull btrfs clone API to vfs layer
  locks: new locks_mandatory_area calling convention
  vfs: Add vfs_copy_file_range() support for pagecache copies
  btrfs: add .copy_file_range file operation
  x86: add sys_copy_file_range to syscall tables
  vfs: add copy_file_range syscall and vfs helper

Now that the VFS encapsulates the dedupe ioctl, wire up btrfs to it.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Chris Mason <clm@fb.com>

Pull btrfs fixes from Chris Mason:
 "A couple of small fixes"

* 'for-linus-4.4' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  Btrfs: check prepare_uptodate_page() error code earlier
  Btrfs: check for empty bitmap list in setup_cluster_bitmaps
  btrfs: fix misleading warning when space cache failed to load
  Btrfs: fix transaction handle leak in balance
  Btrfs: fix unprotected list move from unused_bgs to deleted_bgs list

prepare_pages() may end up calling prepare_uptodate_page() twice if our
write only spans a single page.  But if the first call returns an error,
our page will be unlocked and its not safe to call it again.

This bug goes all the way back to 2011, and it's not something commonly
hit.

While we're here, add a more explicit check for the page being truncated
away.  The bare lock_page() alone is protected only by good thoughts and
i_mutex, which we're sure to regret eventually.

Reported-by: Dave Jones <dsj@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>

The btrfs clone ioctls are now adopted by other file systems, with NFS
and CIFS already having support for them, and XFS being under active
development.  To avoid growth of various slightly incompatible
implementations, add one to the VFS.  Note that clones are different from
file copies in several ways:

 - they are atomic vs other writers
 - they support whole file clones
 - they support 64-bit legth clones
 - they do not allow partial success (aka short writes)
 - clones are expected to be a fast metadata operation

Because of that it would be rather cumbersome to try to piggyback them on
top of the recent clone_file_range infrastructure.  The converse isn't
true and the clone_file_range system call could try clone file range as
a first attempt to copy, something that further patches will enable.

Based on earlier work from Peng Tao.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>