Marios Titas running a Haskell program noticed a problem with fuse's
readdirplus: when it is interrupted by a signal, it skips one directory
entry.

The reason is that fuse erronously updates ctx->pos after a failed
dir_emit().

The issue originates from the patch adding readdirplus support.

Reported-by: Jakob Unterwurzacher <jakobunt@gmail.com>
Tested-by: Marios Titas <redneb@gmx.com> 
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 0b05b18381ee ("fuse: implement NFS-like readdirplus support")
Cc: <stable@vger.kernel.org> # v3.9

[AV: in addition to the fix in previous commit]

Signed-off-by: Matthew Garrett <mjg59@google.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Pull fuse updates from Miklos Szeredi:
 "This fixes a regression (spotted by the Sandstorm.io folks) in the pid
  namespace handling introduced in 4.12.

  There's also a fix for honoring sync/dsync flags for pwritev2()"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
  fuse: getattr cleanup
  fuse: honor iocb sync flags on write
  fuse: allow server to run in different pid_ns

The refreshed argument isn't used by any caller, get rid of it.

Use a helper for just updating the inode (no need to fill in a kstat).

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

If the IOCB_DSYNC flag is set a sync is not being performed by
fuse_file_write_iter.

Honor IOCB_DSYNC/IOCB_SYNC by setting O_DYSNC/O_SYNC respectively in the
flags filed of the write request.

We don't need to sync data or metadata, since fuse_perform_write() does
write-through and the filesystem is responsible for updating file times.

Original patch by Vitaly Zolotusky.

Reported-by: Nate Clark <nate@neworld.us>
Cc: Vitaly Zolotusky <vitaly@unitc.com>.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Commit 0b6e9ea041e6 ("fuse: Add support for pid namespaces") broke
Sandstorm.io development tools, which have been sending FUSE file
descriptors across PID namespace boundaries since early 2014.

The above patch added a check that prevented I/O on the fuse device file
descriptor if the pid namespace of the reader/writer was different from the
pid namespace of the mounter.  With this change passing the device file
descriptor to a different pid namespace simply doesn't work.  The check was
added because pids are transferred to/from the fuse userspace server in the
namespace registered at mount time.

To fix this regression, remove the checks and do the following:

1) the pid in the request header (the pid of the task that initiated the
filesystem operation) is translated to the reader's pid namespace.  If a
mapping doesn't exist for this pid, then a zero pid is used.  Note: even if
a mapping would exist between the initiator task's pid namespace and the
reader's pid namespace the pid will be zero if either mapping from
initator's to mounter's namespace or mapping from mounter's to reader's
namespace doesn't exist.

2) The lk.pid value in setlk/setlkw requests and getlk reply is left alone.
Userspace should not interpret this value anyway.  Also allow the
setlk/setlkw operations if the pid of the task cannot be represented in the
mounter's namespace (pid being zero in that case).

Reported-by: Kenton Varda <kenton@sandstorm.io>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 0b6e9ea041e6 ("fuse: Add support for pid namespaces")
Cc: <stable@vger.kernel.org> # v4.12+
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Seth Forshee <seth.forshee@canonical.com>

Pull writeback error handling updates from Jeff Layton:
 "This pile continues the work from last cycle on better tracking
  writeback errors. In v4.13 we added some basic errseq_t infrastructure
  and converted a few filesystems to use it.

  This set continues refining that infrastructure, adds documentation,
  and converts most of the other filesystems to use it. The main
  exception at this point is the NFS client"

* tag 'wberr-v4.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
  ecryptfs: convert to file_write_and_wait in ->fsync
  mm: remove optimizations based on i_size in mapping writeback waits
  fs: convert a pile of fsync routines to errseq_t based reporting
  gfs2: convert to errseq_t based writeback error reporting for fsync
  fs: convert sync_file_range to use errseq_t based error-tracking
  mm: add file_fdatawait_range and file_write_and_wait
  fuse: convert to errseq_t based error tracking for fsync
  mm: consolidate dax / non-dax checks for writeback
  Documentation: add some docs for errseq_t
  errseq: rename __errseq_set to errseq_set

Pull file locking updates from Jeff Layton:
 "This pile just has a few file locking fixes from Ben Coddington. There
  are a couple of cleanup patches + an attempt to bring sanity to the
  l_pid value that is reported back to userland on an F_GETLK request.

  After a few gyrations, he came up with a way for filesystems to
  communicate to the VFS layer code whether the pid should be translated
  according to the namespace or presented as-is to userland"

* tag 'locks-v4.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
  locks: restore a warn for leaked locks on close
  fs/locks: Remove fl_nspid and use fs-specific l_pid for remote locks
  fs/locks: Use allocation rather than the stack in fcntl_getlk()

Pull fuse fixes from Miklos Szeredi:
 "Fix a few bugs in fuse"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
  fuse: set mapping error in writepage_locked when it fails
  fuse: Dont call set_page_dirty_lock() for ITER_BVEC pages for async_dio
  fuse: initialize the flock flag in fuse_file on allocation

This ensures that we see errors on fsync when writeback fails.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>