* origin/master: (28 commits)
  nodefs: use offset for MemRegularFile reads. Test it.
  zipfs: fix and test tarfs
  nodefs: don't tweak MemRegularFile mode
  nodefs: fix builds on darwin
  example/hello: convert hello to new nodefs API
  nodefs: add MemRegularFile.Flush
  example/statfs: use new nodefs library
  example/loopback: use new nodefs library
  nodefs: document Access
  example/zipfs: use new nodefs
  nodefs: use bridge.getattr for Access calculation
  example/multizip: use new nodefs package.
  nodefs: comment ExampleNewPersistentInode
  nodefs: add Options.DefaultPermissions
  zipfs: rewrite using new nodefs API.
  nodefs: use testMount in tests
  nodefs: don't pass root into Options.OnAdd
  nodefs: add Inode.RmAllChildren
  nodefs: various fixes
  nodefs: check that default Create returns EROFS
  ...

Together with DefaultPermissions, this lets you cd into a nodefs
powered file system.

Remove memtree.

Add an example for constructing an in-memory file system

* Fix deadlock with OnAdd

* return EROFS for missing Create

* Fill Mode using Inode.setEntryOut in all namespace operations

utility classes for symlinks and regular files without backing store.

The node can always call into the file handle if necessary, but the
reverse limits options for implementors.

Instead, define InodeEmbedder, an interface that can only be satisfied
by a struct that embeds Inode.

This is the prevalent style for FUSE libraries in Go.

Thanks to Ryan Lamore (ryanlamore) for spotting this

FOPEN_CACHE_DIR was added in Linux 4.19:

	https://git.kernel.org/linus/6433b8998a

* master: (118 commits)
  nodefs: split the dual function of OperationStubs
  nodefs: regularize method naming
  nodefs: test Mknod
  nodefs: by default return input offset for Lseek
  nodefs: rename DefaultOperations to OperationStubs
  nodefs: doc nits.
  nodefs: port utimens and allocate from fuse/nodefs
  fuse: add cancel channel to Release call
  nodefs: provide Inode.Root rather than Inode.IsRoot
  nodefs: drop InodeOf
  nodefs: embed Inode directly in DefaultOperations
  nodefs: fix outdated comment
  nodefs: fix double syscall.Close
  splice: more verbose panic if discarding pipe pair fails
  nodefs: document ToErrno, NewListDirStream
  nodefs: only set default timeout if Entry/Attr does not specify a timeout
  fuse: add Timeout methods to EntryOut and AttrOut
  nodefs: return ENOTSUP rather than ENOSYS
  nodefs: make everything compile on darwin
  nodefs: use syscall.Errno instead of fuse.Status
  ...

Provide InodeLink/InodeEmbed which implements linking machinery.