* y/lookup-parallel:
  nodefs: Allow for several Lookup requests to be served simultaneously

Commit d0fca860 introduced big lookup lock with the idea to "make sure
we don't return forgotten nodes to the kernel". However this way it also
started to prevent several Lookup handlers to be running simultaneously,
which can deadlock if e.g. Lookup handler somehow synchronizes with
other thread which caused the lookup:

https://github.com/hanwen/go-fuse/commit/d0fca860#commitcomment-37772099

On the surface the fix is easy: if we need to prevent lookups running in
parallel to forget, we can turn lookupLock into shared one wrt Lookup,
but exclusive wrt Forget.

However a more correct fix would be to review nodefs locking completely:
there is already per-filesystem treeLock RWMutex, which is _already_
used to synchronize for forgets and lookups. From this point of view
lookupLock is unneeded and the correct fix that d0fca860 should have been
doing is to correct the scope of treeLock to be used more precisely.

However that would be a more intrusive change, and given that nodefs is
considered deprecated today, imho it is better to proceed with making
lookupLock a shared one.

The test that is added deadlocks without provided fix.

I suggest not to reject this patch based on rationale that "nodefs is
deprecated" as there still are real filesystems that use nodefs.

I had not reviewed v2 go-fuse/fs locking yet.

Change-Id: I18e01457f474dea31dc17186dfe6db582c2e6337

* y/nodefs-cancel:
  Y nodefs: Propagate context to File methods

* master: (60 commits)
  fuse: increment loops WaitGroup on Server creation
  loopback: enable diagnostics logging
  fs: detect Inode.Path() hitting an orphaned inode
  tests: make RenameOpenDir more sensitive
  fs: add Options.Logger, and use throughout
  fs: fix FileAllocater type assertion
  loopback: leave file permissions on "000" files as-is
  example/loopback: make -allow-other imply default_permissions
  fuse: implement GETATTR for pollHack
  loopback: preserve owner when running as root
  tests: posixtest: add FstatDeleted
  loopback: use Lgetxattr and friends
  fs: remove typeChangeDebug code
  fs: don't log error failing MvChild
  posixtest: fix some lint errors
  fs: fix lint errors
  fs: failure to unmount on cleanup is a fatal error
  fs: plug fd leak in bridge_test.go
  fs: don't enforce dirent ordering.
  internal: skip test with other group if user is only 1 group
  ...

So that e.g. File.Read could be canceled.

This is already so in fs/ package. However WCFS in Wendelin.core still
uses older nodefs package, and for now it was faster to teach old
nodefs.File about cancel propagation.

References:

kirr/wendelin.core@b17aeb8c
kirr/wendelin.core@f05271b1
kirr/wendelin.core@5ba816da
kirr/go123@7ad867a3
kirr/go123@0bdac628
kirr/go123@d2dc6c09

The server.Serve routine can be called both inline and as
goroutine. In the latter case, it is a synchronization error for Serve
to call serve.loops.Add() by itself, leading to a detected race.

Change-Id: I36f24bd36d1ae77d71e7d69a54ebdf5dbee9bd62

The loopback example is usually used to debug and develop.
Enable the new diagnostics logging facility, unless -q (quiet)
is passed.

Change-Id: I9ae5214fc33616656832a219fc1470f421786b8c

Some ".deleted" logic was in place, but did not work
properly when the Inode was in the root directory.

Fix that by introducing the `found` variable and
add a test that verifies that it works.

Also, return `.go-fuse.$RANDOM/deleted` to make it
very unlikely that the placeholder name matches an
actual file or directory. Introducing the `/deleted`
subdir makes sure operations creating a file or
directory fail reliably with ENOENT.

Tests now look like this:

  $ go test ./fs -run TestPosix/RenameOpenDir -count 1  -v
  === RUN   TestPosix
  === RUN   TestPosix/RenameOpenDir
  [...]
  --- PASS: TestPosix (0.01s)
      --- SKIP: TestPosix/RenameOpenDir (0.01s)
          test.go:383: Fstat failed: no such file or directory. Known limitation - see https://github.com/hanwen/go-fuse/issues/55
  PASS
  ok    github.com/hanwen/go-fuse/v2/fs 0.014s

Change-Id: I2eb6fd48a11df543c9b7daf62647cb9d8a892568

The test seemed to pass because the inode number is overridden
in rawBridge.getattr, but looking at the permissions shows that
the wrong directory is stat()ed:

  $ go test ./fs -run TestPosix/RenameOpenDir -count 1  -v
  [...]
  17:49:46.454077 received ENODEV (unmount request), thread exiting
  17:49:46.454343 received ENODEV (unmount request), thread exiting
  --- PASS: TestPosix (0.01s)
      --- SKIP: TestPosix/RenameOpenDir (0.01s)
          test.go:392: got permissions 0755, want 0700. Known limitation - see https://github.com/hanwen/go-fuse/issues/55
  PASS
  ok    github.com/hanwen/go-fuse/v2/fs 0.016s

Also, add a log message whenever the inode number is overridden,
this should (probably) not happen during normal operation. And
it actually only happens once in the test suite (in RenameOpenDir):

  $ go test ./... -count 1 -v 2>&1 | grep "overriding ino"
  14:48:44.143694 warning: rawBridge.getattr: overriding ino 188663 with 186314

See https://github.com/hanwen/go-fuse/issues/55

Change-Id: I8b2ddb84c35a3b28b4f5e032e7113f8d484a5981

Change-Id: I4fabf222a306e5d3abdfda28422b046cd75c9a8c

The type assertion was meant to operate on `f.file`,
not on `n.ops` again.

Fixes xfstests generic/228.

Change-Id: I8f8ca0cead91a512a6d7826dd7e7e5d1887ae627

Set `opts.NullPermissions = true` to stop us from falsifying
file permissions on "000" files.

Fixes xfstests generic/088.

Change-Id: Ibabbdc97b1ae2531ca093bae6bb441ae15d3238e

With -allow-other, other users can access the mountpoint.
However, without default_permissions, nobody checks file
permissions.

Make loopback behave more like a regular filesystem by
enabling default_permissions if -allow-other is passed.

Fixes xfstests generic/087:

$ sudo ./check-loopback generic/087
fuse-xfstests gocryptfs-2018-08-18/67408ac7
Thu 26 Dec 2019 03:08:54 PM UTC

loopback is /usr/local/bin/loopback
FSTYP         -- fuse.loopback
PLATFORM      -- Linux/x86_64 brikett 5.3.12-300.fc31.x86_64
MKFS_OPTIONS  -- /var/tmp/fuse-xfstests/check-loopback/scratchdev
MOUNT_OPTIONS -- -o context=system_u:object_r:root_t:s0 /var/tmp/fuse-xfstests/check-loopback/scratchdev /var/tmp/fuse-xfstests/check-loopback/scratchdir

generic/087	 1s
Ran: generic/087
Passed all 1 tests

Runtime was 1 seconds, exit code 0

Change-Id: Ifa8ac38a3775c3cacf20d37638a95887c9c24f93

When the default_permissions option is passed to the kernel,
it issues a extra GETATTR on the .go-fuse-epoll-hack node.

Rejecting that with EIO makes `syscall.Creat` in `pollHack` fail,
ultimately erroring out during mount.

$ loopback -allow-other -debug b a
16:06:39.576856 rx 2: INIT i0 {7.31 Ra 0x20000 NO_OPEN_SUPPORT,PARALLEL_DIROPS,ABORT_ERROR,EXPLICIT_INVAL_DATA,SPLICE_WRITE,READDIRPLUS,ASYNC_DIO,DONT_MASK,NO_OPENDIR_SUPPORT,AUTO_INVAL_DATA,READDIRPLUS_AUTO,POSIX_ACL,HANDLE_KILLPRIV,MAX_PAGES,ATOMIC_O_TRUNC,EXPORT_SUPPORT,SPLICE_MOVE,BIG_WRITES,SPLICE_READ,FLOCK_LOCKS,IOCTL_DIR,WRITEBACK_CACHE,ASYNC_READ,POSIX_LOCKS,CACHE_SYMLINKS}
16:06:39.576999 tx 2:     OK, {7.28 Ra 0x20000 AUTO_INVAL_DATA,BIG_WRITES,ASYNC_READ,NO_OPEN_SUPPORT,PARALLEL_DIROPS,READDIRPLUS 0/0 Wr 0x10000 Tg 0x0}
16:06:39.578670 rx 4: GETATTR i1 {Fh 0}
16:06:39.578717 rx 6: GETATTR i1 {Fh 0}
16:06:39.578735 tx 4:     OK, {tA=1s {M040755 SZ=40 L=2 1026:1026 B0*4096 i0:1 A 1577370827.990394 M 1577370827.990394 C 1577370827.990394}}
16:06:39.578765 tx 6:     OK, {tA=1s {M040755 SZ=40 L=2 1026:1026 B0*4096 i0:1 A 1577370827.990394 M 1577370827.990394 C 1577370827.990394}}
16:06:39.579028 rx 8: LOOKUP i1 [".go-fuse-epoll-hack"] 20b
16:06:39.579053 tx 8:     2=no such file or directory, {i0 g0 tE=0s tA=0s {M00 SZ=0 L=0 0:0 B0*0 i0:0 A 0.000000 M 0.000000 C 0.000000}}
16:06:39.579087 rx 10: CREATE i1 {0100100 [WRONLY,TRUNC,CREAT,0x8000] (022)} [".go-fuse-epoll-hack"] 20b
16:06:39.579113 tx 10:     OK, {i18446744073709551615 g0 {M0100644 SZ=0 L=1 0:0 B0*0 i0:18446744073709551615 A 0.000000 M 0.000000 C 0.000000} &{18446744073709551615 0 0}}
16:06:39.579199 rx 14: GETATTR i1 {Fh 0}
16:06:39.579205 rx 12: GETATTR i18446744073709551615 {Fh 0}
16:06:39.579216 tx 14:     OK, {tA=1s {M040755 SZ=40 L=2 1026:1026 B0*4096 i0:1 A 1577370827.990394 M 1577370827.990394 C 1577370827.990394}}
16:06:39.579237 rx 16: LOOKUP i1 [".go-fuse-epoll-hack"] 20b
16:06:39.579242 tx 12:     5=input/output error, {tA=0s {M00 SZ=0 L=0 0:0 B0*0 i0:0 A 0.000000 M 0.000000 C 0.000000}}
16:06:39.579247 tx 16:     2=no such file or directory, {i0 g0 tE=0s tA=0s {M00 SZ=0 L=0 0:0 B0*0 i0:0 A 0.000000 M 0.000000 C 0.000000}}
16:06:39.579270 Mount fail: input/output error
16:06:39.579271 rx 20: LOOKUP i1 [".Trash"] 7b

Change-Id: I20024baf2e8f386b637abbd236b188bfdfa8579f

If we are running as root have caller information from
the context, try to set the owner of newly created files
and directories.

Lays the foundation for fixing xfstests generic/087
(xfstests always run as root).

Change-Id: Ib8d768153f3ec82ce572021a433a6398560efd44

Excercises the fd-finding logic in rawBridge.GetAttr.
No issues found, tests pass, logic works fine.

Change-Id: I49731b8ec5b41344d58409c8ca615f466bd95f29

Stop following symlinks when working with extended
attributes, and add a test for it.

Problem found by xfstests generic/062.

Change-Id: I67f94451322cdfebdcbcc3af21679ccd4e2800d7

Change-Id: I87f5ff47daeb64412ff877038619d6cdf5e6ec92

Document MvChild failure condition.

Change-Id: I928335eb79c73bdedb14c9f7544c3b15e3862af8

Change-Id: I15d31de59b4c34caff132bdc7d09ad520d0e68cb

Change-Id: I3bce0eee02e0f8d1a2d02c4a4f065bb023179ab1

Any subsequent attempt to remove the mountdir will fail if the unmount
does not succeed.

Use syscall.Rmdir rather than os.Remove. We know the mount point is a
directory, and Go's cleverness can only complicate matters here.

Change-Id: I62cfad63f34af17b78c3184884a2972673f631a3

Change-Id: I4d77ac9194ca9caedf7b0418386e22ae57b90b9b

In TestBridgeReaddirPlusVirtualEntries we test that "." comes first,
and then "..". This ordering is not reliable. On
4.19.67-2rodete2-amd64, I see ".." before "."

Adapt the test to accept either ordering.

Change-Id: Ifc003dca6c2b19d9df3045ac30569ee27f78fc52

Change-Id: I59a1f187ff4c88bcefdb1e70c6461ca4b2a79c3b

After running the test suite, `df` used to report this:

  df: /tmp/TestReaddirTypeFixup090721515: Transport endpoint is not connected

To catch problems like this earlier, testMount() now reports failures to umount
cleanly, and catches the problem with TestReaddirTypeFixup:

  $ go test ./fs -run TestReaddirTypeFixup
  [...]
      mem_test.go:37: testMount: Unmount failed: /usr/bin/fusermount: failed to unmount /tmp/TestReaddirTypeFixup175482633: Device or resource busy

TestReaddirTypeFixup was missing ds.Close(), which was also added,
tests pass now and don't leave broken mounts behind.

Change-Id: Ib5d96c8531b11080cf8da526b917446388537956

Tests that openat(2) works as expected when the parent
directory is renamed (it does).

Originally written to get a FUSE log about what happens
when userspace calls openat, but it might make sense to
just keep it as a test.

Change-Id: I3fac815a7c0f713b4f859f6876d60380df9bc953

I have suddenly seen TestTypeChange hang forever, waiting for the
FORGET that never arrives. The first concern was that the assumption
that the FORGET always follows the delete was wrong. Checking the
kernel source code, the FORGET should really, actually always follow
the delete.

Looking more closely on the debug trace showed this:

        LOOKUP i1 [".Trash-1026"] 12b
             OK, {i1234 g0 tE=0s tA=0s {M0100644 SZ=0 L=0 0:0 B0*4096 i0:1234 A 0.000000 M 0.000000 C 0.000000}}

This is the desktop environment looking for the trash folder.
And because the test is stupid, it returned the same dummy
inode i1234. This means the kernel had one extra reference
to this inode and, of course, did not send a FORGET when
"file" was deleted.

I made testTypeChangeIno only react to expected file names
now, and added a log output should we wait more than ~5
seconds for the FORGET. The log message then repeats indefinitely
every 5 seconds.

        ~/go/src/github.com/hanwen/go-fuse/fs$ go test -v -run TestTypeChange
        === RUN   TestTypeChange
        20:50:18.491584 rx 2: INIT i0 {7.31 Ra 0x20000 CACHE_SYMLINKS,POSIX_LOCKS,SPLICE_MOVE,SPLICE_READ,READDIRPLUS,READDIRPLUS_AUTO,PARALLEL_DIROPS,ABORT_ERROR,EXPLICIT_INVAL_DATA,ASYNC_READ,EXPORT_SUPPORT,DONT_MASK,NO_OPENDIR_SUPPORT,SPLICE_WRITE,FLOCK_LOCKS,AUTO_INVAL_DATA,HANDLE_KILLPRIV,MAX_PAGES,POSIX_ACL,ATOMIC_O_TRUNC,BIG_WRITES,IOCTL_DIR,ASYNC_DIO,WRITEBACK_CACHE,NO_OPEN_SUPPORT}
        20:50:18.491728 tx 2:     OK, {7.28 Ra 0x20000 NO_OPEN_SUPPORT,BIG_WRITES,PARALLEL_DIROPS,READDIRPLUS,ASYNC_READ,AUTO_INVAL_DATA 0/0 Wr 0x10000 Tg 0x0}
        20:50:18.491857 rx 4: ACCESS i1 {u=1026 g=1026 r}
        20:50:18.491873 tx 4:     OK
        20:50:18.492028 rx 6: LOOKUP i1 [".go-fuse-epoll-hack"] 20b
        20:50:18.492110 tx 6:     2=no such file or directory, {i0 g0 tE=0s tA=0s {M00 SZ=0 L=0 0:0 B0*0 i0:0 A 0.000000 M 0.000000 C 0.000000}}
        20:50:18.492147 rx 8: CREATE i1 {0100100 [TRUNC,WRONLY,CREAT,0x8000] (00)} [".go-fuse-epoll-hack"] 20b
        20:50:18.492207 tx 8:     OK, {i18446744073709551615 g0 {M0100644 SZ=0 L=1 0:0 B0*0 i0:18446744073709551615 A 0.000000 M 0.000000 C 0.000000} &{18446744073709551615 0 0}}
        20:50:18.492291 rx 10: LOOKUP i1 [".Trash"] 7b
        20:50:18.492340 tx 10:     OK, {i1234 g0 tE=0s tA=0s {M0100644 SZ=0 L=0 0:0 B0*4096 i0:1234 A 0.000000 M 0.000000 C 0.000000}}
        20:50:18.492354 rx 12: POLL i18446744073709551615
        20:50:18.492359 tx 12:     38=function not implemented
        20:50:18.492370 rx 14: LOOKUP i1 [".go-fuse-epoll-hack"] 20b
        20:50:18.492378 tx 14:     2=no such file or directory, {i0 g0 tE=0s tA=0s {M00 SZ=0 L=0 0:0 B0*0 i0:0 A 0.000000 M 0.000000 C 0.000000}}
        20:50:18.492389 rx 16: GETATTR i1234 {Fh 0}
        20:50:18.492398 tx 16:     OK, {tA=0s {M0100644 SZ=0 L=0 0:0 B0*4096 i0:1234 A 0.000000 M 0.000000 C 0.000000}}
        20:50:18.492412 rx 18: FLUSH i18446744073709551615 {Fh 18446744073709551615}
        20:50:18.492417 tx 18:     5=input/output error
        20:50:18.492427 rx 20: LOOKUP i1 [".go-fuse-epoll-hack"] 20b
        20:50:18.492435 tx 20:     2=no such file or directory, {i0 g0 tE=0s tA=0s {M00 SZ=0 L=0 0:0 B0*0 i0:0 A 0.000000 M 0.000000 C 0.000000}}
        20:50:18.492450 rx 22: RELEASE i18446744073709551615 {Fh 18446744073709551615 WRONLY,0x8000  L0}
        20:50:18.492456 tx 22:     5=input/output error
        20:50:18.492469 rx 24: LOOKUP i1 ["file"] 5b
        20:50:18.492477 tx 24:     OK, {i1234 g0 tE=0s tA=0s {M0100644 SZ=0 L=0 0:0 B0*4096 i0:1234 A 0.000000 M 0.000000 C 0.000000}}
        20:50:18.492489 rx 26: LOOKUP i1 [".Trash-1026"] 12b
        20:50:18.492497 tx 26:     OK, {i1234 g0 tE=0s tA=0s {M0100644 SZ=0 L=0 0:0 B0*4096 i0:1234 A 0.000000 M 0.000000 C 0.000000}}
        20:50:18.492506 rx 28: GETATTR i1234 {Fh 0}
        20:50:18.492513 tx 28:     OK, {tA=0s {M0100644 SZ=0 L=0 0:0 B0*4096 i0:1234 A 0.000000 M 0.000000 C 0.000000}}
        20:50:18.492521 rx 30: GETATTR i1234 {Fh 0}
        20:50:18.492528 tx 30:     OK, {tA=0s {M0100644 SZ=0 L=0 0:0 B0*4096 i0:1234 A 0.000000 M 0.000000 C 0.000000}}
        20:50:18.492537 rx 32: LOOKUP i1 ["file"] 5b
        20:50:18.492545 tx 32:     OK, {i1234 g0 tE=0s tA=0s {M0100644 SZ=0 L=0 0:0 B0*4096 i0:1234 A 0.000000 M 0.000000 C 0.000000}}
        20:50:18.492555 rx 34: FORGET i18446744073709551615 {Nlookup=1}
        20:50:18.492575 rx 36: UNLINK i1 ["file"] 5b
        20:50:18.492588 tx 36:     OK
        20:50:18.492621 rx 38: LOOKUP i1 ["dir"] 4b
        [hangs here]

Change-Id: Ibee48faf09c5a8993dfc7bb75251551f699cd63e

Options.ServerCallbacks can set the callbacks used when not mounting
the filesystem.

Change-Id: I51bf875a816c23e587ec8b575110221bdfcdaffe

This provides more fidelity for reproducing file system behavior. Case
in point, it lets us rename a directory on top of an existing
directory

Fixes #55.

Change-Id: I82572aae32ee225b1629303c448a09f1066eb4ed

ListXAttr called with an empty buffer returns the current size of
the list but does not touch the buffer (see man 2 listxattr).

Fixes the xfstests generic/020 crash.
Fixes https://github.com/hanwen/go-fuse/issues/337 .

Add test
Co-authored-by: Han-Wen Nienhuys <hanwen@google.com>
Change-Id: I94c94bc56fdf506d2eb924b246336b787fa2976a

The tests sometimes hang in a way that "go test -timeout"
does not work anymore.

Example: https://travis-ci.org/hanwen/go-fuse/jobs/609260654

Use the external "timeout" command as backup, triggering
1 minute later.

Also, the test that seems to hang is "fs", run it alone
first in the hope of getting more info.

Add "set -e" so executing stops if the first step fails
( https://github.com/travis-ci/travis-ci/issues/1066 )

Also add "-failfast" to "go test" so the failures are
not buried in later output.

All failure modes are easier to analyze now in my opinion,
as you just have to scroll to the bottom to see what is
going on.

Examples:
* https://travis-ci.com/rfjakob/go-fuse/jobs/254766675
  TestStatFs failure due to non-deterministic test, stopped by -failfast)
* https://travis-ci.com/rfjakob/go-fuse/jobs/254766676
  Hang in TestParallelDiropsHang, stopped by -timeout, backtrace available
* https://travis-ci.com/rfjakob/go-fuse/jobs/254766677
  Hang somewhere in "go test ./...", killed by "timeout -k 10".
  No backtrace, unfortunately, but at least it took 6 minutes
  instead of 10.

Change-Id: I8069d22863c178b5c9c4d0c40f13dccfdfd0873d

When a inode is deleted and recreated, the inode number may
be reused, and it may appear that it has changed type.

A simple solution is to wait for the FORGET that *always*
follows the deletion. This is what this patch does.

Makes fsstress happy (tested with fsstress-loopback.bash from
gocryptfs, which is similar to xfstests generic/013).

Also fixes the test that was introduced in the last commit
(TestTypeChange).

fsstress-loopback.bash before:

    ~/go/src/github.com/rfjakob/gocryptfs/tests/stress_tests$ ./fsstress-loopback.bash
    Recompile go-fuse loopback
    Waiting for mount:  ok
    Starting fsstress loop
    1
        fsstress.1 seed = 1572931176
        fsstress.2 seed = 1572919573
        fsstress.3 seed = 1573005097
        rm
    rm: cannot remove '/var/tmp/fsstress-loopback.bash.qgK.mnt/fsstress.2/p4/d1XXXX': Is a directory
    rm: cannot remove '/var/tmp/fsstress-loopback.bash.qgK.mnt/fsstress.2/p6/d0/d44XXXXXXXXXXXX/d4cXXXX': Is a directory
    rm: cannot remove '/var/tmp/fsstress-loopback.bash.qgK.mnt/fsstress.3/p1/d11/d124/d12f/d154/d15a/d143/df1/d100/d135/d123/d3a': Is a directory
    rm: cannot remove '/var/tmp/fsstress-loopback.bash.qgK.mnt/fsstress.3/p1/d11/f22': Not a directory
    rm: cannot remove '/var/tmp/fsstress-loopback.bash.qgK.mnt/fsstress.3/p3/d0/d7e/d4b/d102/d157/d134/d12f/d14b/d17a/d130': Is a directory
    rm: cannot remove '/var/tmp/fsstress-loopback.bash.qgK.mnt/fsstress.3/p3/d0/d7e/d4b/d102/d157/d158/df2/ff5': Not a directory
    rm: cannot remove '/var/tmp/fsstress-loopback.bash.qgK.mnt/fsstress.3/p3/d0/d1c': Is a directory
    rm: cannot remove '/var/tmp/fsstress-loopback.bash.qgK.mnt/fsstress.3/p0/d0/d4': Is a directory
    rm: cannot remove '/var/tmp/fsstress-loopback.bash.qgK.mnt/fsstress.3/p2/d6/dfd/da6/df2/d124/dea/d100/d120/d131/d13e/d13b/d149/d13a/f9c': Not a directory
    rm: cannot remove '/var/tmp/fsstress-loopback.bash.qgK.mnt/fsstress.3/p2/d6/dfd/da6/df2/d124/dea/dd5/dfa/d127/d129/d14a/d117/d14c/d82': Is a directory
    ./fsstress-loopback.bash: line 1: kill: %1: no such job

After (with typechangeDebug = true):

    $ ./fsstress-loopback.bash
    Recompile go-fuse loopback
    Waiting for mount:  ok
    Starting fsstress loop
    1
        fsstress.1 seed = 1574198874
        fsstress.2 seed = 1574016238
    17:51:25.770396 Ino:13634604 typechange 0x8000 -> 0xa000, sleep=0s
    17:51:25.890382 Ino:13899580 typechange 0xa000 -> 0x8000, sleep=0s
    17:51:25.890400 Ino:13899580 typechange 0xa000 -> 0x8000, sleep=1µs
    17:51:25.890412 Ino:13899580 typechange 0xa000 -> 0x8000, sleep=1.41µs
        fsstress.3 seed = 1574847533
    17:51:27.472057 Ino:14158985 typechange 0x4000 -> 0x8000, sleep=0s
    17:51:27.472070 Ino:14158985 typechange 0x4000 -> 0x8000, sleep=1µs
    17:51:27.472304 Ino:14158985 typechange 0x8000 -> 0x4000, sleep=0s
    17:51:27.478628 Ino:14159000 typechange 0x8000 -> 0x4000, sleep=0s
    17:51:27.478640 Ino:14159000 typechange 0x8000 -> 0x4000, sleep=1µs
    17:51:27.478700 Ino:14159000 typechange 0x8000 -> 0x4000, sleep=1.051µs
    17:51:27.478747 Ino:14159000 typechange 0x8000 -> 0x4000, sleep=1.817µs
    17:51:27.478796 Ino:14159000 typechange 0x8000 -> 0x4000, sleep=3.18µs
    17:51:27.478840 Ino:14159000 typechange 0x8000 -> 0x4000, sleep=5.718µs
    17:51:27.478884 Ino:14159000 typechange 0x8000 -> 0x4000, sleep=8.396µs
    17:51:27.478976 Ino:14159000 typechange 0x8000 -> 0x4000, sleep=10.784µs
    17:51:27.479024 Ino:14159000 typechange 0x8000 -> 0x4000, sleep=13.017µs
    17:51:27.479067 Ino:14159000 typechange 0x8000 -> 0x4000, sleep=16.065µs
    17:51:27.479108 Ino:14159000 typechange 0x8000 -> 0x4000, sleep=19.767µs
    17:51:27.479145 Ino:14159000 typechange 0x8000 -> 0x4000, sleep=27.427µs
    17:51:27.479240 Ino:14159000 typechange 0x8000 -> 0x4000, sleep=36.272µs
    17:51:27.500756 Ino:14291431 typechange 0x4000 -> 0x8000, sleep=0s
    17:51:27.500770 Ino:14291431 typechange 0x4000 -> 0x8000, sleep=1µs
    17:51:27.500779 Ino:14291431 typechange 0x4000 -> 0x8000, sleep=1.873µs
    17:51:27.521194 Ino:14291506 typechange 0x4000 -> 0x8000, sleep=0s
    17:51:27.521207 Ino:14291506 typechange 0x4000 -> 0x8000, sleep=1µs
        rm
    2
        fsstress.1 seed = 1574600636
        fsstress.2 seed = 1574203490
    17:51:29.009666 Ino:12209562 typechange 0x4000 -> 0xa000, sleep=0s
    17:51:29.010068 Ino:12209562 typechange 0x4000 -> 0xa000, sleep=1µs
    17:51:29.010078 Ino:12209562 typechange 0x4000 -> 0xa000, sleep=1.79µs
    17:51:29.010179 Ino:12209562 typechange 0x4000 -> 0xa000, sleep=3.331µs
    17:51:29.010255 Ino:12209562 typechange 0x4000 -> 0xa000, sleep=4.537µs
    17:51:29.010364 Ino:12209562 typechange 0x4000 -> 0xa000, sleep=8.354µs
    17:51:29.010416 Ino:12209562 typechange 0x4000 -> 0xa000, sleep=8.897µs
        fsstress.3 seed = 1573917850
    17:51:33.623359 Ino:14291439 typechange 0x8000 -> 0x4000, sleep=0s
    17:51:33.623378 Ino:14291439 typechange 0x8000 -> 0x4000, sleep=1µs
    17:51:33.623392 Ino:14291439 typechange 0x8000 -> 0x4000, sleep=1.378µs
    17:51:33.644130 Ino:14291494 typechange 0x8000 -> 0x4000, sleep=0s
    17:51:33.644151 Ino:14291494 typechange 0x8000 -> 0x4000, sleep=1µs
    17:51:33.644159 Ino:14291494 typechange 0x8000 -> 0x4000, sleep=1.072µs
    17:51:33.654370 Ino:14291501 typechange 0x8000 -> 0x4000, sleep=0s
    17:51:33.654384 Ino:14291501 typechange 0x8000 -> 0x4000, sleep=1µs
    17:51:33.654393 Ino:14291501 typechange 0x8000 -> 0x4000, sleep=1.588µs
    17:51:33.654399 Ino:14291501 typechange 0x8000 -> 0x4000, sleep=2.639µs
    17:51:33.655098 Ino:14291476 typechange 0x4000 -> 0x8000, sleep=0s
    17:51:33.667216 Ino:14291504 typechange 0x4000 -> 0x8000, sleep=0s
    17:51:33.667228 Ino:14291504 typechange 0x4000 -> 0x8000, sleep=1µs
    17:51:33.667236 Ino:14291504 typechange 0x4000 -> 0x8000, sleep=1.443µs
    17:51:33.667242 Ino:14291504 typechange 0x4000 -> 0x8000, sleep=2.286µs
        rm
    3
        fsstress.1 seed = 1574749722
        fsstress.2 seed = 1574328972
    17:51:35.220180 Ino:13771167 typechange 0x8000 -> 0xa000, sleep=0s
    17:51:35.220205 Ino:13771167 typechange 0x8000 -> 0xa000, sleep=1µs
    17:51:35.514144 Ino:13771355 typechange 0x4000 -> 0xa000, sleep=0s
    17:51:35.514165 Ino:13771355 typechange 0x4000 -> 0xa000, sleep=1µs
    17:51:35.514172 Ino:13771355 typechange 0x4000 -> 0xa000, sleep=1.739µs
    17:51:35.515875 Ino:13771355 typechange 0x4000 -> 0xa000, sleep=1.969µs
    17:51:35.516021 Ino:13771355 typechange 0x4000 -> 0xa000, sleep=3.744µs
    17:51:35.516094 Ino:13771355 typechange 0x4000 -> 0xa000, sleep=4.308µs
    17:51:35.516514 Ino:13771355 typechange 0x4000 -> 0xa000, sleep=5.112µs
    17:51:35.516765 Ino:13771355 typechange 0x4000 -> 0xa000, sleep=5.299µs
    17:51:35.516870 Ino:13771355 typechange 0x4000 -> 0xa000, sleep=8.169µs
    17:51:36.429950 Ino:13771381 typechange 0x8000 -> 0xa000, sleep=0s
    17:51:36.430068 Ino:13771381 typechange 0x8000 -> 0xa000, sleep=1µs
    17:51:36.430082 Ino:13771381 typechange 0x8000 -> 0xa000, sleep=1.071µs
    17:51:36.547108 Ino:13899567 typechange 0x8000 -> 0x4000, sleep=0s
    17:51:36.547121 Ino:13899567 typechange 0x8000 -> 0x4000, sleep=1µs
    17:51:36.547158 Ino:13899567 typechange 0x8000 -> 0x4000, sleep=1.907µs
    17:51:36.547181 Ino:13899567 typechange 0x8000 -> 0x4000, sleep=2.358µs
    17:51:38.112588 Ino:13771503 typechange 0x8000 -> 0xa000, sleep=0s
    17:51:38.112602 Ino:13771503 typechange 0x8000 -> 0xa000, sleep=1µs
    17:51:38.112611 Ino:13771503 typechange 0x8000 -> 0xa000, sleep=1.11µs
    17:51:38.524020 Ino:13899675 typechange 0xa000 -> 0x8000, sleep=0s
    17:51:38.524042 Ino:13899675 typechange 0xa000 -> 0x8000, sleep=1µs

Change-Id: I6120ce76730018d22898127290f492fa9f85a957

TestTypeChange simulates inode number reuse that happens on real
filesystems. For go-fuse, inode number reuse can look like a file changing
to a directory or vice versa. Acutally, the old inode does not exist anymore,
we just have not received the FORGET yet.

The test fails reliably with iteration count 100. Will be fixed in the
next commit.

Test failure looks like this:

	~/go/src/github.com/hanwen/go-fuse/fs$ go test -run TestTypeChange -v
	=== RUN   TestTypeChange
	21:43:36.065494 rx 2: INIT i0 {7.31 Ra 0x20000 MAX_PAGES,SPLICE_READ,FLOCK_LOCKS,READDIRPLUS,READDIRPLUS_AUTO,ASYNC_DIO,WRITEBACK_CACHE,HANDLE_KILLPRIV,SPLICE_WRITE,PARALLEL_DIROPS,ABORT_ERROR,EXPLICIT_INVAL_DATA,NO_OPENDIR_SUPPORT,ASYNC_READ,BIG_WRITES,DONT_MASK,IOCTL_DIR,AUTO_INVAL_DATA,POSIX_ACL,CACHE_SYMLINKS,POSIX_LOCKS,ATOMIC_O_TRUNC,EXPORT_SUPPORT,SPLICE_MOVE,NO_OPEN_SUPPORT}
	21:43:36.065573 tx 2:     OK, {7.28 Ra 0x20000 PARALLEL_DIROPS,AUTO_INVAL_DATA,ASYNC_READ,BIG_WRITES,NO_OPEN_SUPPORT,READDIRPLUS 0/0 Wr 0x10000 Tg 0x0}
	21:43:36.065742 rx 4: LOOKUP i1 [".go-fuse-epoll-hack"] 20b
	21:43:36.065798 tx 4:     2=no such file or directory, {i0 g0 tE=0s tA=0s {M00 SZ=0 L=0 0:0 B0*0 i0:0 A 0.000000 M 0.000000 C 0.000000}}
	21:43:36.065837 rx 6: CREATE i1 {0100100 [WRONLY,CREAT,TRUNC,0x8000] (00)} [".go-fuse-epoll-hack"] 20b
	21:43:36.065861 tx 6:     OK, {i18446744073709551615 g0 {M0100644 SZ=0 L=1 0:0 B0*0 i0:18446744073709551615 A 0.000000 M 0.000000 C 0.000000} &{18446744073709551615 0 0}}
	21:43:36.065945 rx 8: POLL i18446744073709551615
	21:43:36.065954 tx 8:     38=function not implemented
	21:43:36.066009 rx 10: FLUSH i18446744073709551615 {Fh 18446744073709551615}
	21:43:36.066046 tx 10:     5=input/output error
	21:43:36.066065 rx 12: RELEASE i18446744073709551615 {Fh 18446744073709551615 WRONLY,0x8000  L0}
	21:43:36.066071 tx 12:     5=input/output error
	21:43:36.066107 rx 14: LOOKUP i1 ["file"] 5b
	21:43:36.066181 tx 14:     OK, {i1234 g0 tE=0s tA=0s {M0100644 SZ=0 L=0 0:0 B0*4096 i0:1234 A 0.000000 M 0.000000 C 0.000000}}
	21:43:36.066217 rx 16: GETATTR i1234 {Fh 0}
	21:43:36.066240 tx 16:     OK, {tA=0s {M0100644 SZ=0 L=0 0:0 B0*4096 i0:1234 A 0.000000 M 0.000000 C 0.000000}}
	21:43:36.066264 rx 18: LOOKUP i1 ["file"] 5b
	21:43:36.066285 tx 18:     OK, {i1234 g0 tE=0s tA=0s {M0100644 SZ=0 L=0 0:0 B0*4096 i0:1234 A 0.000000 M 0.000000 C 0.000000}}
	21:43:36.066301 rx 20: UNLINK i1 ["file"] 5b
	21:43:36.066321 tx 20:     OK
	21:43:36.066361 rx 24: LOOKUP i1 ["dir"] 4b
	21:43:36.066371 tx 24:     OK, {i1234 g0 tE=0s tA=0s {M0100644 SZ=0 L=0 0:0 B0*4096 i0:1234 A 0.000000 M 0.000000 C 0.000000}}
	21:43:36.066383 rx 22: FORGET i1234 {Nlookup=2}
	21:43:36.066390 rx 26: GETATTR i1234 {Fh 0}
	21:43:36.068259 tx 26:     OK, {tA=0s {M0100644 SZ=0 L=0 0:0 B0*4096 i0:1234 A 0.000000 M 0.000000 C 0.000000}}
	21:43:36.069664 received ENODEV (unmount request), thread exiting
	21:43:36.073309 received ENODEV (unmount request), thread exiting
	21:43:36.073396 received ENODEV (unmount request), thread exiting
	--- FAIL: TestTypeChange (0.01s)
	    bridge_test.go:96: should be a dir now
	FAIL
	exit status 1
	FAIL	github.com/hanwen/go-fuse/v2/fs	0.017s

Change-Id: I7a1a10303ecc0a8c008d29d5d81079868fc2cc43

As seen in debug logs like shown below, concurrent
FORGETs and inode number reuse could make use give
an Inode to the kernel that has already been deleted
from the nodes[] map.

With this change, I can no langer trigger a panic
in xfstests generic/007.

Fixes https://github.com/hanwen/go-fuse/issues/324

Nodes that appear to change type are not handled yet
(actually caused by inode number reuse), but this is
a separate problem.

Debug log:

  17:09:07.651735 rx 84444: CREATE i13632136 {0100644 [WRONLY,TRUNC,CREAT,0x8000] (022)} ["XXXXXXXXXXXX.38"] 16b
  17:09:07.651790 tx 84444:     OK, {i13632483 g1 {M0100644 SZ=0 L=1 0:0 B0*4096 i0:13632483 A 1572192547.650470 M 1572192547.650470 C 1572192547.650470} &{7 0 0}}
  [...]
  17:09:07.684439 rx 87988: CREATE i13632119 {0100644 [CREAT,TRUNC,WRONLY,0x8000] (022)} ["XXXXXXXXXXXX.37"] 16b
  [...]
  17:09:07.684472 rx 87992: FORGET i13632483 {Nlookup=1}
  17:09:07.684483 tx 87988:     OK, {i13632483 g1 {M0100644 SZ=0 L=1 0:0 B0*4096 i0:13632483 A 1572192547.683470 M 1572192547.683470 C 1572192547.683470} &{8 0 0}}
  [...]
  17:09:07.684557 rx 88006: FLUSH i13632483 {Fh 8}
  17:09:07.684560 unknown node 13632483
  17:09:07.684564 tx 88002:     OK,  "XXXXXXXXXXXX.830"
  panic: unknown node 13632483

Change-Id: Ibb1a7a6a459d2e4133a4e512e0816e8ed950a8d7

Getting rid of the "Mounted!" message makes it easier
to integrate into xfstests, which barks at all and any
unexpected output.

Used by https://github.com/rfjakob/fuse-xfstests/commit/ab1d77ccdb8cf16f79cb312bcb3aaadb23660807

Change-Id: Idff314474b4980ef6f6fc2460b338a840bb0e409

As pointed out by @slackner at
https://github.com/hanwen/go-fuse/commit/8581b7e950b2d520370eba8997ddd9493192e9c7#r35845728
FixMode() failed to take into account the length
of the file name and the padding.

To fix this without adding a lot of additional
pointer arithmetic, add the "lastDirent" field
to DirEntryList. This stores the last serialized
_Dirent, so _Dirent.Typ can be accessed easily
by FixMode().

Change-Id: I6ca3fe551e1a072779b1d5ed5293add057e55287

Add TestReaddirTypeFixup(). This test currently fails
because FixMode is broken. Will be fixed in a later commit.

Change-Id: Ie4eab9c5817ddb772b73aa22e8f75f5d4f2ad49c

Fixes issue #314

Change-Id: I6bf2d64d0e62c4881b7010c5c0421a16bd8d7db2

On OSX, Fh apparently is non-zero sometimes, even with FATTR_FH unset.

Fixes #329

Change-Id: I4d9b6a83a3a8e8fa615dfbfa4d1b132b752528da