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In linux v5.7-rc2, zero-length array declarations are replaced by FAM
(flexible-array member),
	a2008395fe2e 2020-04-18 dirent.h: Replace zero-length array with flexible-array member

Aufs simply follows this trend.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit 747a01ec1835988fa20177789a6fb65c5198fcb9)

In aufs5.4, kmemleak reported several false positives in
fs/aufs/xino.c.  I don't know why, but it may be related to the
"delayed" kfree (by RCU).  So I simply replace it by direct kfree()
call.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit 03836b8128073f92b4e4a1cb54f91d0d7c290d1f)

Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit 56b4b776c84f364384971c4cdfd66b4a2f0696d4)

Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>

# Conflicts:
#	include/uapi/linux/aufs_type.h

Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit 0f5f91bda77d0690c23732fd2592ae97c908a704)

Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit 9e47f923ad8bf55c272fed3d3699fa5df14b6f72)

Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit 7555811a8741218089016a6abed15a440baca476)

Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit 75664fa01701d5f79e6cee87a800354df6e70f70)

These "+1" were left accidentally when refining the lookup routine.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit 4177c438179671556de7312107c8aa766ea3d658)

Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit 2c79658cfdc070c6fc4ea5ac3ef898f2b15fb2f3)

When a branch filesystem doesn't cache ACL, aufs should not cache
either.  Until now aufs has never met such fs, but theoretically it
could happen.  Actually, in linux-v5.1-rc1, NFSv3 changed its behaviour
by the commit
	ded52fbe7020 2019-02-20 nfs: fix xfstest generic/099 failed on nfsv3
The commit ded52fbe7020 doesn't "forget" the previous acl though.
Doesn't it mean that the obsoleted acl is kept until NFS's attribute
cache is expired?  I don't know.  I've asked it on LKML, but got no
answer.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit e448daa00228186b869356fdef8d98d9f95caf53)

A compilation -Wimplicit-fallthrough warning was enabled by commit
a035d552a93b ("Makefile: Globally enable fall-through warning")
and triggers the following warning.

fs/aufs/opts.h:78:11:
warning: this statement may fall through [-Wimplicit-fallthrough=]

This patch adds comments according GNU manual.
https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#Warning-Options

Signed-off-by: He Zhe <zhe.he@windriver.com>
See-also: https://www.mail-archive.com/aufs-users@lists.sourceforge.net/msg05685.html
(cherry picked from commit e7619996b014c5d8fd2f6ad89542c545a207667f)

Add missing break statement for case Opt_wsum in au_opt_simple.
Signed-off-by: He Zhe <zhe.he@windriver.com>
See-also: https://www.mail-archive.com/aufs-users@lists.sourceforge.net/msg05684.html
(cherry picked from commit 9e7d29356ab57fa5db7e92e51267176e50c1497c)

This is detected by the commit in v5.3-rc1,
	d6fc9fcbaa65 2019-07-08 kbuild: compile-test exported headers to
		ensure they are self-contained
But the issue is not for v5.3-rc1 only I am afraid.  So this commit is
brought to aufs4.14 which is my current development base.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit d38615f7fef1c65e30e3cc418daa9e19c93ed98f)

Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit 4596850541ed7144f7fea951d02f0f6251c4a997)

The scenario is very similar to previous commit
"aufs: bugfix, ignore the being freed dynop object".
One exception is that this commit is for sbinfo object which is managed
by kobject (instead of kref).

In order to enter the plink-maintenance mode, users write an ID to
"/proc/fs/aufs/plink_maint" (this path is defined as macros in
include/uapi/linux/aufs_type.h).  If someone else is unmounting the
aufs mount corresponding that ID, then the searcher task may find a
being freed sbinfo object.
The problem and the fix is very similar to previous commit
"aufs: bugfix, ignore the being freed dynop object".
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit 949b498ae30797b19b9e7ac9b230815f31ffe378)

Aufs DYNOP (Dynamically customizable FS operations) object is managed by
kref, and when its counter reaches zero, the callback function removes
the object from the internal list which is protected by a spinlock and
then frees the object.
Here there is a small time window between
A: the counter reaches zero, and
B: require the lock to remove the object from the list.
If someone else acquires the lock and searches the list, it may find the
counter-zero'ed object which means the object is being freed.
This commit ignores the object whose counter is already zero.
Reported-and-tested-by: Kirill Kolyshkin <kolyshkin@gmail.com>
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit b633d7b2635b9615fe294b85257d05008e3747a3)

Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit 9dbd45984201453ecebcc03a91699878aa38239d)

Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit 94c692425480664a02aaac3d6f7d496ea1d05c1f)

At the mount-time, XINO files are created and removed very soon.  When
multiple mounts with being given the same XINO file path executed in
parallel, some of them may fail in creating XINO due to EEXIST.
Introducing a local mutex, make it serialized.
By default, XINO is created at the top dir of the first writable
branch.  In this case, the new mutex won't be used.

Obviously this is an unnecessary overhead when the XINO file path is not
same, and such lock should be done by inode_lock() for the parent dir.
Actually au_xino_create2() behaves in this manner.  Then why didn't I
apply the same way to this au_xino_create()?  It is just because of my
laziness.  Calling VFS filp_open() here is easy for me.
Reported-by: Kirill Kolyshkin <kolyshkin@gmail.com>
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>
(cherry picked from commit 30d9273f2a1ce331b1a79b770bdb4c493919a673)

Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>

With a little hope to make it easier to read.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>

In mainline, by the commit
	e220140ff624 2019-02-06 fsnotify: remove dirent events from
		FS_EVENTS_POSS_ON_CHILD mask
the macro is redefined, and aufs simply follows it.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>

In mainline, by the commit
	71368af9027f 2019-01-29 x86/speculation: Add PR_SPEC_DISABLE_NOEXEC
a new flag is introduced.  And aufs simply follows it.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>

Although I am not sure module_exit is necessary for the statically
linked module, here is it.  I hope it does no harm.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>

They are historical options and a branch attribute.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>

Fuse doesn't want the callers to access the inode attributes without
issuing stat, and it is not assured that they are valid after lookup or
iget().
The inode attribute is critical for aufs, and aufs decided to call stat
every time for fuse.
Of course, it makes aufs slow. But when the branch fs is not fuse, stat
is not called.

Currently, only FUSE implements ->poll(), and aufs supports it.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>

Basically ramfs is limited for its size, and is not suitable for aufs RW
branch. But people sometimes use it as RW branch without knowing it or
with knowing it.
This configuration is for those who knows what he is doing.
Signed-off-by: J. R. Okajima <hooanon05g@gmail.com>