autofs: convert autofs to use the new mount api

Convert the autofs filesystem to use the mount API.

The conversion patch was originally written by David Howells.
I have taken that patch and broken it into several patches in an effort
to make the change easier to review.

Signed-off-by: Ian Kent <raven@themaw.net>
Reviewed-by: Bill O'Donnell <bodonnel@redhat.com>
Message-Id: <20230922041215.13675-8-raven@themaw.net>
Signed-off-by: Christian Brauner <brauner@kernel.org>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 83

Based on 1 normalized pattern(s):

this file is part of the linux kernel and is made available under
the terms of the gnu general public license version 2 or at your
option any later version incorporated herein by reference

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 18 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190520075211.321157221@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

autofs: improve ioctl sbi checks

Al Viro made some suggestions to improve the implementation of commit
0633da48f0 ("fix autofs_sbi() does not check super block type").

The check is unnecessary in all cases except for ioctl usage so placing
the check in the super block accessor function adds a small overhead to
the common case where it isn't needed.

So it's sufficient to do this in the ioctl code only.

Also the check in the ioctl code is needlessly complex.

[akpm@linux-foundation.org: declare autofs_fs_type in .h, not .c]
Link: http://lkml.kernel.org/r/154296970987.9889.1597442413573683096.stgit@pluto-themaw-net
Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

autofs: rename 'autofs' module back to 'autofs4'

It turns out that systemd has a bug: it wants to load the autofs module
early because of some initialization ordering with udev, and it doesn't
do that correctly. Everywhere else it does the proper "look up module
name" that does the proper alias resolution, but in that early code, it
just uses a hardcoded "autofs4" for the module name.

The result of that is that as of commit a2225d931f75 ("autofs: remove
left-over autofs4 stubs"), you get

systemd[1]: Failed to insert module 'autofs4': No such file or directory

in the system logs, and a lack of module loading. All this despite the
fact that we had very clearly marked 'autofs4' as an alias for this
module.

What's so ridiculous about this is that literally everything else does
the module alias handling correctly, including really old versions of
systemd (that just used 'modprobe' to do this), and even all the other
systemd module loading code.

Only that special systemd early module load code is broken, hardcoding
the module names for not just 'autofs4', but also "ipv6", "unix",
"ip_tables" and "virtio_rng". Very annoying.

Instead of creating an _additional_ separate compatibility 'autofs4'
module, just rely on the fact that everybody else gets this right, and
just call the module 'autofs4' for compatibility reasons, with 'autofs'
as the alias name.

That will allow the systemd people to fix their bugs, adding the proper
alias handling, and maybe even fix the name of the module to be just
"autofs" (so that they can _test_ the alias handling). And eventually,
we can revert this silly compatibility hack.

See also

https://github.com/systemd/systemd/issues/9501
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=902946

for the systemd bug reports upstream and in the Debian bug tracker
respectively.

Fixes: a2225d931f75 ("autofs: remove left-over autofs4 stubs")
Reported-by: Ben Hutchings <ben@decadent.org.uk>
Reported-by: Michael Biebl <biebl@debian.org>
Cc: Ian Kent <raven@themaw.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

autofs: remove left-over autofs4 stubs

There's no need to retain the fs/autofs4 directory for backward
compatibility.

Adding an AUTOFS4_FS fragment to the autofs Kconfig and a module alias
for autofs4 is sufficient for almost all cases. Not keeping fs/autofs4
remnants will prevent "insmod <path>/autofs4/autofs4.ko" from working
but this shouldn't be used in automation scripts rather than
modprobe(8).

There were some comments about things to look out for with the module
rename in the fs/autofs4/Kconfig that is removed by this patch, see the
commit patch if you are interested.

One potential problem with this change is that when the
fs/autofs/Kconfig fragment for AUTOFS4_FS is removed any AUTOFS4_FS
entries will be removed from the kernel config, resulting in no autofs
file system being built if there is no AUTOFS_FS entry also.

This would have also happened if the fs/autofs4 remnants had remained
and is most likely to be a problem with automated builds.

Please check your build configurations before the removal which will
occur after the next couple of kernel releases.

Acked-by: Ian Kent <raven@themaw.net>
[ With edits and commit message from Ian Kent ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

autofs: copy autofs4 to autofs

Copy source files from the autofs4 directory to the autofs directory.

Link: http://lkml.kernel.org/r/152626705013.28589.931913083997578251.stgit@pluto.themaw.net
Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] autofs3: Make sure all dentries refs are released before calling kill_anon_super()

Make sure all dentries refs are released before calling kill_anon_super()
so that the assumption that generic_shutdown_super() can completely destroy
the dentry tree for there will be no external references holds true.

What was being done in the put_super() superblock op, is now done in the
kill_sb() filesystem op instead, prior to calling kill_anon_super().

The call to shrink_dcache_sb() is removed as it is redundant since
shrink_dcache_for_umount() will now be called after the cleanup routine.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Ian Kent <raven@themaw.net>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] VFS: Permit filesystem to override root dentry on mount

Extend the get_sb() filesystem operation to take an extra argument that
permits the VFS to pass in the target vfsmount that defines the mountpoint.

The filesystem is then required to manually set the superblock and root dentry
pointers. For most filesystems, this should be done with simple_set_mnt()
which will set the superblock pointer and then set the root dentry to the
superblock's s_root (as per the old default behaviour).

The get_sb() op now returns an integer as there's now no need to return the
superblock pointer.

This patch permits a superblock to be implicitly shared amongst several mount
points, such as can be done with NFS to avoid potential inode aliasing. In
such a case, simple_set_mnt() would not be called, and instead the mnt_root
and mnt_sb would be set directly.

The patch also makes the following changes:

(*) the get_sb_*() convenience functions in the core kernel now take a vfsmount
pointer argument and return an integer, so most filesystems have to change
very little.

(*) If one of the convenience function is not used, then get_sb() should
normally call simple_set_mnt() to instantiate the vfsmount. This will
always return 0, and so can be tail-called from get_sb().

(*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the
dcache upon superblock destruction rather than shrink_dcache_anon().

This is required because the superblock may now have multiple trees that
aren't actually bound to s_root, but that still need to be cleaned up. The
currently called functions assume that the whole tree is rooted at s_root,
and that anonymous dentries are not the roots of trees which results in
dentries being left unculled.

However, with the way NFS superblock sharing are currently set to be
implemented, these assumptions are violated: the root of the filesystem is
simply a dummy dentry and inode (the real inode for '/' may well be
inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries
with child trees.

[*] Anonymous until discovered from another tree.

(*) The documentation has been adjusted, including the additional bit of
changing ext2_* into foo_* in the documentation.

[akpm@osdl.org: convert ipath_fs, do other stuff]
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Nathan Scott <nathans@sgi.com>
Cc: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!