commit 744742d692e37ad5c20630e57d526c8f2e2fe3c9 upstream.

The 'reqs' member of fuse_io_priv serves two purposes. First is to track
the number of oustanding async requests to the server and to signal that
the io request is completed. The second is to be a reference count on the
structure to know when it can be freed.

For sync io requests these purposes can be at odds.  fuse_direct_IO() wants
to block until the request is done, and since the signal is sent when
'reqs' reaches 0 it cannot keep a reference to the object. Yet it needs to
use the object after the userspace server has completed processing
requests. This leads to some handshaking and special casing that it
needlessly complicated and responsible for at least one race condition.

It's much cleaner and safer to maintain a separate reference count for the
object lifecycle and to let 'reqs' just be a count of outstanding requests
to the userspace server. Then we can know for sure when it is safe to free
the object without any handshaking or special cases.

The catch here is that most of the time these objects are stack allocated
and should not be freed. Initializing these objects with a single reference
that is never released prevents accidental attempts to free the objects.

Fixes: 9d5722b7777e ("fuse: handle synchronous iocbs internally")
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 7cabc61e01a0a8b663bd2b4c982aa53048218734 upstream.

There's a race in fuse_direct_IO(), whereby is_sync_kiocb() is called on an
iocb that could have been freed if async io has already completed.  The fix
in this case is simple and obvious: cache the result before starting io.

It was discovered by KASan:

kernel: ==================================================================
kernel: BUG: KASan: use after free in fuse_direct_IO+0xb1a/0xcc0 at addr ffff88036c414390

Signed-off-by: Robert Doebbelin <robert@quobyte.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: bcba24ccdc82 ("fuse: enable asynchronous processing direct IO")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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 fuse updates from Miklos Szeredi:
 "This adds SEEK_HOLE and SEEK_DATA support in lseek"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
  fuse: add support for SEEK_HOLE and SEEK_DATA in lseek

Pull fuse fixes from Miklos Szeredi:
 "Two bugfixes, both bound for -stable"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
  fuse: break infinite loop in fuse_fill_write_pages()
  cuse: fix memory leak

A useful performance improvement for accessing virtual machine images
via FUSE mount.

See https://bugzilla.redhat.com/show_bug.cgi?id=1220173 for a use-case
for glusterFS.

Signed-off-by: Ravishankar N <ravishankar@redhat.com>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>

I got a report about unkillable task eating CPU. Further
investigation shows, that the problem is in the fuse_fill_write_pages()
function. If iov's first segment has zero length, we get an infinite
loop, because we never reach iov_iter_advance() call.

Fix this by calling iov_iter_advance() before repeating an attempt to
copy data from userspace.

A similar problem is described in 124d3b7041f ("fix writev regression:
pan hanging unkillable and un-straceable"). If zero-length segmend
is followed by segment with invalid address,
iov_iter_fault_in_readable() checks only first segment (zero-length),
iov_iter_copy_from_user_atomic() skips it, fails at second and
returns zero -> goto again without skipping zero-length segment.

Patch calls iov_iter_advance() before goto again: we'll skip zero-length
segment at second iteraction and iov_iter_fault_in_readable() will detect
invalid address.

Special thanks to Konstantin Khlebnikov, who helped a lot with the commit
description.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Maxim Patlasov <mpatlasov@parallels.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Roman Gushchin <klamm@yandex-team.ru>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Fixes: ea9b9907b82a ("fuse: implement perform_write")
Cc: <stable@vger.kernel.org>

Instead of having users check for FL_POSIX or FL_FLOCK to call the correct
locks API function, use the check within locks_lock_inode_wait().  This
allows for some later cleanup.

Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>

Pull more vfs updates from Al Viro:
 "Assorted VFS fixes and related cleanups (IMO the most interesting in
  that part are f_path-related things and Eric's descriptor-related
  stuff).  UFS regression fixes (it got broken last cycle).  9P fixes.
  fs-cache series, DAX patches, Jan's file_remove_suid() work"

[ I'd say this is much more than "fixes and related cleanups".  The
  file_table locking rule change by Eric Dumazet is a rather big and
  fundamental update even if the patch isn't huge.   - Linus ]

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (49 commits)
  9p: cope with bogus responses from server in p9_client_{read,write}
  p9_client_write(): avoid double p9_free_req()
  9p: forgetting to cancel request on interrupted zero-copy RPC
  dax: bdev_direct_access() may sleep
  block: Add support for DAX reads/writes to block devices
  dax: Use copy_from_iter_nocache
  dax: Add block size note to documentation
  fs/file.c: __fget() and dup2() atomicity rules
  fs/file.c: don't acquire files->file_lock in fd_install()
  fs:super:get_anon_bdev: fix race condition could cause dev exceed its upper limitation
  vfs: avoid creation of inode number 0 in get_next_ino
  namei: make set_root_rcu() return void
  make simple_positive() public
  ufs: use dir_pages instead of ufs_dir_pages()
  pagemap.h: move dir_pages() over there
  remove the pointless include of lglock.h
  fs: cleanup slight list_entry abuse
  xfs: Correctly lock inode when removing suid and file capabilities
  fs: Call security_ops->inode_killpriv on truncate
  fs: Provide function telling whether file_remove_privs() will do anything
  ...

Pull fuse updates from Miklos Szeredi:
 "This is the start of improving fuse scalability.

  An input queue and a processing queue is split out from the monolithic
  fuse connection, each of those having their own spinlock.  The end of
  the patchset adds the ability to clone a fuse connection.  This means,
  that instead of having to read/write requests/answers on a single fuse
  device fd, the fuse daemon can have multiple distinct file descriptors
  open.  Each of those can be used to receive requests and send answers,
  currently the only constraint is that a request must be answered on
  the same fd as it was read from.

  This can be extended further to allow binding a device clone to a
  specific CPU or NUMA node.

  Based on a patchset by Srinivas Eeda and Ashish Samant.  Thanks to
  Ashish for the review of this series"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse: (40 commits)
  fuse: update MAINTAINERS entry
  fuse: separate pqueue for clones
  fuse: introduce per-instance fuse_dev structure
  fuse: device fd clone
  fuse: abort: no fc->lock needed for request ending
  fuse: no fc->lock for pqueue parts
  fuse: no fc->lock in request_end()
  fuse: cleanup request_end()
  fuse: request_end(): do once
  fuse: add req flag for private list
  fuse: pqueue locking
  fuse: abort: group pqueue accesses
  fuse: cleanup fuse_dev_do_read()
  fuse: move list_del_init() from request_end() into callers
  fuse: duplicate ->connected in pqueue
  fuse: separate out processing queue
  fuse: simplify request_wait()
  fuse: no fc->lock for iqueue parts
  fuse: allow interrupt queuing without fc->lock
  fuse: iqueue locking
  ...