ofs->upper_mnt is copied to ->layers[0].mnt and ->layers[0].trap could be
used instead of a separate ->upperdir_trap.

Split the lowerdir option early to get the number of layers, then allocate
the ->layers array, and finally fill the upper and lower layers, as before.

Get rid of path_put_init() in ovl_lower_dir(), since the only caller will
take care of that.

[Colin Ian King] Fix null pointer dereference on null stack pointer on
error return found by Coverity.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Next patch will remove ofs->upper_mnt, so add an accessor function for this
field.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

In ovl_copy_xattr, if all the xattrs to be copied are overlayfs private
xattrs, the copy loop will terminate without assigning anything to the
error variable, thus returning an uninitialized value.

If ovl_copy_xattr is called from ovl_clear_empty, this uninitialized error
value is put into a pointer by ERR_PTR(), causing potential invalid memory
accesses down the line.

This commit initialize error with 0. This is the correct value because when
there's no xattr to copy, because all xattrs are private, ovl_copy_xattr
should succeed.

This bug is discovered with the help of INIT_STACK_ALL and clang.
Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
Link: https://bugs.chromium.org/p/chromium/issues/detail?id=1050405
Fixes: 0956254a ("ovl: don't copy up opaqueness")
Cc: stable@vger.kernel.org # v4.8
Signed-off-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Negative dentries of upper layer are useless after construction of
overlayfs' own dentry and may keep in the memory long time even after
unmount of overlayfs instance. This patch tries to drop unnecessary
negative dentry of upper layer to effectively reclaim memory.
Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Call inode_permission() on real inode before opening regular file on one of
the underlying layers.

In some cases ovl_permission() already checks access to an underlying file,
but it misses the metacopy case, and possibly other ones as well.

Removing the redundant permission check from ovl_permission() should be
considered later.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Verify LSM permissions for underlying file, since vfs_ioctl() doesn't do
it.

[Stephen Rothwell] export security_file_ioctl
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Check permission before opening a real file.

ovl_path_open() is used by readdir and copy-up routines.

ovl_permission() theoretically already checked copy up permissions, but it
doesn't hurt to re-do these checks during the actual copy-up.

For directory reading ovl_permission() only checks access to topmost
underlying layer.  Readdir on a merged directory accesses layers below the
topmost one as well.  Permission wasn't checked for these layers.

Note: modifying ovl_permission() to perform this check would be far more
complex and hence more bug prone.  The result is less precise permissions
returned in access(2).  If this turns out to be an issue, we can revisit
this bug.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

In preparation for more permission checking, override credentials for
directory operations on the underlying filesystems.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

The three instances of ovl_path_open() in overlayfs/readdir.c do three
different things:

 - pass f_flags from overlay file
 - pass O_RDONLY | O_DIRECTORY
 - pass just O_RDONLY

The value of f_flags can be (other than O_RDONLY):

O_WRONLY	- not possible for a directory
O_RDWR		- not possible for a directory
O_CREAT		- masked out by dentry_open()
O_EXCL		- masked out by dentry_open()
O_NOCTTY	- masked out by dentry_open()
O_TRUNC		- masked out by dentry_open()
O_APPEND	- no effect on directory ops
O_NDELAY	- no effect on directory ops
O_NONBLOCK	- no effect on directory ops
__O_SYNC	- no effect on directory ops
O_DSYNC		- no effect on directory ops
FASYNC		- no effect on directory ops
O_DIRECT	- no effect on directory ops
O_LARGEFILE	- ?
O_DIRECTORY	- only affects lookup
O_NOFOLLOW	- only affects lookup
O_NOATIME	- overlay sets this unconditionally in ovl_path_open()
O_CLOEXEC	- only affects fd allocation
O_PATH		- no effect on directory ops
__O_TMPFILE	- not possible for a directory


Fon non-merge directories we use the underlying filesystem's iterate; in
this case honor O_LARGEFILE from the original file to make sure that open
doesn't get rejected.

For merge directories it's safe to pass O_LARGEFILE unconditionally since
userspace will only see the artificial offsets created by overlayfs.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Amir pointed me to metacopy test cases in unionmount-testsuite and I
decided to run "./run --ov=10 --meta" and it failed while running test
"rename-mass-5.py".

Problem is w.r.t absolute redirect traversal on intermediate metacopy
dentry.  We do not store intermediate metacopy dentries and also skip
current loop/layer and move onto lookup in next layer.  But at the end of
loop, we have logic to reset "poe" and layer index if currnently looked up
dentry has absolute redirect.  We skip all that and that means lookup in
next layer will fail.

Following is simple test case to reproduce this.

- mkdir -p lower upper work merged lower/a lower/b
- touch lower/a/foo.txt
- mount -t overlay -o lowerdir=lower,upperdir=upper,workdir=work,metacopy=on none merged

# Following will create absolute redirect "/a/foo.txt" on upper/b/bar.txt.
- mv merged/a/foo.txt merged/b/bar.txt

# unmount overlay and use upper as lower layer (lower2) for next mount.
- umount merged
- mv upper lower2
- rm -rf work; mkdir -p upper work
- mount -t overlay -o lowerdir=lower2:lower,upperdir=upper,workdir=work,metacopy=on none merged

# Force a metacopy copy-up
- chown bin:bin merged/b/bar.txt

# unmount overlay and use upper as lower layer (lower3) for next mount.
- umount merged
- mv upper lower3
- rm -rf work; mkdir -p upper work
- mount -t overlay -o lowerdir=lower3:lower2:lower,upperdir=upper,workdir=work,metacopy=on none merged

# ls merged/b/bar.txt
ls: cannot access 'bar.txt': Input/output error

Intermediate lower layer (lower2) has metacopy dentry b/bar.txt with
absolute redirect "/a/foo.txt".  We skipped redirect processing at the end
of loop which sets poe to roe and sets the appropriate next lower layer
index.  And that means lookup failed in next layer.

Fix this by continuing the loop for any intermediate dentries.  We still do
not save these at lower stack.  With this fix applied unionmount-testsuite,
"./run --ov-10 --meta" now passes.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Currently ovl_get_inode() initializes OVL_UPPERDATA flag and for that it
has to call ovl_check_metacopy_xattr() and check if metacopy xattr is
present or not.

yangerkun reported sometimes underlying filesystem might return -EIO and in
that case error handling path does not cleanup properly leading to various
warnings.

Run generic/461 with ext4 upper/lower layer sometimes may trigger the bug
as below(linux 4.19):

[  551.001349] overlayfs: failed to get metacopy (-5)
[  551.003464] overlayfs: failed to get inode (-5)
[  551.004243] overlayfs: cleanup of 'd44/fd51' failed (-5)
[  551.004941] overlayfs: failed to get origin (-5)
[  551.005199] ------------[ cut here ]------------
[  551.006697] WARNING: CPU: 3 PID: 24674 at fs/inode.c:1528 iput+0x33b/0x400
...
[  551.027219] Call Trace:
[  551.027623]  ovl_create_object+0x13f/0x170
[  551.028268]  ovl_create+0x27/0x30
[  551.028799]  path_openat+0x1a35/0x1ea0
[  551.029377]  do_filp_open+0xad/0x160
[  551.029944]  ? vfs_writev+0xe9/0x170
[  551.030499]  ? page_counter_try_charge+0x77/0x120
[  551.031245]  ? __alloc_fd+0x160/0x2a0
[  551.031832]  ? do_sys_open+0x189/0x340
[  551.032417]  ? get_unused_fd_flags+0x34/0x40
[  551.033081]  do_sys_open+0x189/0x340
[  551.033632]  __x64_sys_creat+0x24/0x30
[  551.034219]  do_syscall_64+0xd5/0x430
[  551.034800]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

One solution is to improve error handling and call iget_failed() if error
is encountered.  Amir thinks that this path is little intricate and there
is not real need to check and initialize OVL_UPPERDATA in ovl_get_inode().
Instead caller of ovl_get_inode() can initialize this state.  And this will
avoid double checking of metacopy xattr lookup in ovl_lookup() and
ovl_get_inode().

OVL_UPPERDATA is inode flag.  So I was little concerned that initializing
it outside ovl_get_inode() might have some races.  But this is one way
transition.  That is once a file has been fully copied up, it can't go back
to metacopy file again.  And that seems to help avoid races.  So as of now
I can't see any races w.r.t OVL_UPPERDATA being set wrongly.  So move
settingof OVL_UPPERDATA inside the callers of ovl_get_inode().
ovl_obtain_alias() already does it.  So only two callers now left are
ovl_lookup() and ovl_instantiate().
Reported-by: yangerkun <yangerkun@huawei.com>
Suggested-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Currently we use a variable "metacopy" which signifies that dentry could be
either uppermetacopy or lowermetacopy.  Amir suggested that we can move
code around and use d.metacopy in such a way that we don't need
lowermetacopy and just can do away with uppermetacopy.

So this patch replaces "metacopy" with "uppermetacopy".

It also moves some code little higher to keep reading little simpler.
Suggested-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

overlayfs can keep index of copied up files and directories and it seems to
serve two primary puroposes.  For regular files, it avoids breaking lower
hardlinks over copy up.  For directories it seems to be used for various
error checks.

During ovl_lookup(), we lookup for index using lower dentry in many a
cases.  That lower dentry is called "origin" and following is a summary of
current logic.

If there is no upperdentry, always lookup for index using lower dentry.
For regular files it helps avoiding breaking hard links over copyup and for
directories it seems to be just error checks.

If there is an upperdentry, then there are 3 possible cases.

 - For directories, lower dentry is found using two ways.  One is regular
  path based lookup in lower layers and second is using ORIGIN xattr on
  upper dentry.  First verify that path based lookup lower dentry matches
  the one pointed by upper ORIGIN xattr.  If yes, use this verified origin
  for index lookup.

 - For regular files (non-metacopy), there is no path based lookup in lower
  layers as lookup stops once we find upper dentry.  So there is no origin
  verification.  If there is ORIGIN xattr present on upper, use that to
  lookup index otherwise don't.

 - For regular metacopy files, again lower dentry is found using path based
  lookup as well as ORIGIN xattr on upper.  Path based lookup is continued
  in this case to find lower data dentry for metacopy upper.  So like
  directories we only use verified origin.  If ORIGIN xattr is not present
  (Either because lower did not support file handles or because this is
  hardlink copied up with index=off), then don't use path lookup based
  lower dentry as origin.  This is same as regular non-metacopy file case.
Suggested-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

syzbot reported out of bounds memory access from open_by_handle_at()
with a crafted file handle that looks like this:

  { .handle_bytes = 2, .handle_type = OVL_FILEID_V1 }

handle_bytes gets rounded down to 0 and we end up calling:
  ovl_check_fh_len(fh, 0) => ovl_check_fb_len(fh + 3, -3)

But fh buffer is only 2 bytes long, so accessing struct ovl_fb at
fh + 3 is illegal.

Fixes: cbe7fba8 ("ovl: make sure that real fid is 32bit aligned in memory")
Reported-and-tested-by: syzbot+61958888b1c60361a791@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org> # v5.5
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Overlayfs doesn't work well with the fanotify mechanism.

Fanotify first probes for the required buffer size for the file handle,
but overlayfs currently bails out without passing the size back.

That results in errors in the kernel log, such as:

[527944.485384] overlayfs: failed to encode file handle (/, err=-75, buflen=0, len=29, type=1)
[527944.485386] fanotify: failed to encode fid (fsid=ae521e68.a434d95f, type=255, bytes=0, err=-2)
Signed-off-by: Lubos Dolezel <lubos@dolezel.info>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

sync_filesystem() does not sync dirty data for readonly filesystem during
umount, so before changing to readonly filesystem we should sync dirty data
for data integrity.
Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Share inode with different whiteout files for saving inode and speeding up
delete operation.

If EMLINK is encountered when linking a shared whiteout, create a new one.
In case of any other error, disable sharing for this super block.

Note: ofs->whiteout is protected by inode lock on workdir.
Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Since the stacking of regular file operations [1], the overlayfs edition of
write_iter() is called when writing regular files.

Since then, xattr lookup is needed on every write since file_remove_privs()
is called from ovl_write_iter(), which would become the performance
bottleneck when writing small chunks of data. In my test case,
file_remove_privs() would consume ~15% CPU when running fstime of unixbench
(the workload is repeadly writing 1 KB to the same file) [2].

Inherit the SB_NOSEC flag from upperdir. Since then xattr lookup would be
done only once on the first write. Unixbench fstime gets a ~20% performance
gain with this patch.

[1] https://lore.kernel.org/lkml/20180606150905.GC9426@magnolia/T/
[2] https://www.spinics.net/lists/linux-unionfs/msg07153.htmlSigned-off-by: Jeffle Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Stacked filesystems like overlayfs has no own writeback, but they have to
forward syncfs() requests to backend for keeping data integrity.

During global sync() each overlayfs instance calls method ->sync_fs() for
backend although it itself is in global list of superblocks too.  As a
result one syscall sync() could write one superblock several times and send
multiple disk barriers.

This patch adds flag SB_I_SKIP_SYNC into sb->sb_iflags to avoid that.
Reported-by: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru>
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

With index=on, let index dir act as the work dir for copy up and cleanups.
This will help implementing whiteout inode sharing.

We still create the "work" dir on mount regardless of index=on and it is
used to test the features supported by upper fs.  One reason is that before
the feature tests, we do not know if index could be enabled or not.

The reason we do not use "index" directory also as workdir with index=off
is because the existence of the "index" directory acts as a simple
persistent signal that index was enabled on this filesystem and tools may
want to use that signal.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

With index=on, we copy up lower hardlinks to work dir and move them into
index dir. Fix locking to allow work dir and index dir to be the same
directory.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Teach ovl_indexdir_cleanup() to remove temp directories containing
whiteouts to prepare for using index dir instead of work dir for removing
merge directories.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Similar to the way that a conflict between metacopy=on,redirect_dir=off is
resolved, also resolve conflicts between nfs_export=on,index=off and
nfs_export=on,metacopy=on.

An explicit mount option wins over a default config value.  Both explicit
mount options result in an error.

Without this change the xfstests group overlay/exportfs are skipped if
metacopy is enabled by default.
Reported-by: Chengguang Xu <cgxu519@mykernel.net>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

The "buflen" value comes from the user and there is a potential that it
could be zero.  In do_handle_to_path() we know that "handle->handle_bytes"
is non-zero and we do:

	handle_dwords = handle->handle_bytes >> 2;

So values 1-3 become zero.  Then in ovl_fh_to_dentry() we do:

	int len = fh_len << 2;

So now len is in the "0,4-128" range and a multiple of 4.  But if
"buflen" is zero it will try to copy negative bytes when we do the
memcpy in ovl_fid_to_fh().

	memcpy(&fh->fb, fid, buflen - OVL_FH_WIRE_OFFSET);

And that will lead to a crash.  Thanks to Amir Goldstein for his help
with this patch.

Fixes: cbe7fba8 ("ovl: make sure that real fid is 32bit aligned in memory")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Cc: <stable@vger.kernel.org> # v5.5
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

As of now during open(), we don't pass bunch of flags to underlying
filesystem. O_TRUNC is one of these. Normally this is not a problem as VFS
calls ->setattr() with zero size and underlying filesystem sets file size
to 0.

But when overlayfs is running on top of virtiofs, it has an optimization
where it does not send setattr request to server if dectects that
truncation is part of open(O_TRUNC). It assumes that server already zeroed
file size as part of open(O_TRUNC).

fuse_do_setattr() {
        if (attr->ia_valid & ATTR_OPEN) {
                /*
                 * No need to send request to userspace, since actual
                 * truncation has already been done by OPEN.  But still
                 * need to truncate page cache.
                 */
        }
}

IOW, fuse expects O_TRUNC to be passed to it as part of open flags.

But currently overlayfs does not pass O_TRUNC to underlying filesystem
hence fuse/virtiofs breaks. Setup overlayfs on top of virtiofs and
following does not zero the file size of a file is either upper only or has
already been copied up.

fd = open(foo.txt, O_TRUNC | O_WRONLY);

There are two ways to fix this. Either pass O_TRUNC to underlying
filesystem or clear ATTR_OPEN from attr->ia_valid so that fuse ends up
sending a SETATTR request to server. Miklos is concerned that O_TRUNC might
have side affects so it is better to clear ATTR_OPEN for now. Hence this
patch clears ATTR_OPEN from attr->ia_valid.

I found this problem while running unionmount-testsuite. With this patch,
unionmount-testsuite passes with overlayfs on top of virtiofs.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Fixes: bccece1e ("ovl: allow remote upper")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

ovl_setattr() can be passed an attr which has ATTR_FILE set and
attr->ia_file is a file pointer to overlay file. This is done in
open(O_TRUNC) path.

We should either replace with attr->ia_file with underlying file object or
clear ATTR_FILE so that underlying filesystem does not end up using
overlayfs file object pointer.

There are no good use cases yet so for now clear ATTR_FILE. fuse seems to
be one user which can use this. But it can work even without this.  So it
is not mandatory to pass ATTR_FILE to fuse.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Fixes: bccece1e ("ovl: allow remote upper")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

When remapping a mapping where a portion of a VMA is remapped
into another portion of the VMA it can cause the VMA to become
split. During the copy_vma operation the VMA can actually
be remerged if it's an anonymous VMA whose pages have not yet
been faulted. This isn't normally a problem because at the end
of the remap the original portion is unmapped causing it to
become split again.

However, MREMAP_DONTUNMAP leaves that original portion in place which
means that the VMA which was split and then remerged is not actually
split at the end of the mremap. This patch fixes a bug where
we don't detect that the VMAs got remerged and we end up
putting back VM_ACCOUNT on the next mapping which is completely
unreleated. When that next mapping is unmapped it results in
incorrectly unaccounting for the memory which was never accounted,
and eventually we will underflow on the memory comittment.

There is also another issue which is similar, we're currently
accouting for the number of pages in the new_vma but that's wrong.
We need to account for the length of the remap operation as that's
all that is being added. If there was a mapping already at that
location its comittment would have been adjusted as part of
the munmap at the start of the mremap.

A really simple repro can be seen in:
https://gist.github.com/bgaff/e101ce99da7d9a8c60acc641d07f312c

Fixes: e346b381 ("mm/mremap: add MREMAP_DONTUNMAP to mremap()")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Brian Geffon <bgeffon@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull clk fixes from Stephen Boyd:
 "Two build fixes for a couple clk drivers and a fix for the Unisoc
  serial clk where we want to keep it on for earlycon"

* tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
  clk: sprd: don't gate uart console clock
  clk: mmp2: fix link error without mmp2
  clk: asm9260: fix __clk_hw_register_fixed_rate_with_accuracy typo

Pull x86 and objtool fixes from Thomas Gleixner:
 "A set of fixes for x86 and objtool:

  objtool:

   - Ignore the double UD2 which is emitted in BUG() when
     CONFIG_UBSAN_TRAP is enabled.

   - Support clang non-section symbols in objtool ORC dump

   - Fix switch table detection in .text.unlikely

   - Make the BP scratch register warning more robust.

  x86:

   - Increase microcode maximum patch size for AMD to cope with new CPUs
     which have a larger patch size.

   - Fix a crash in the resource control filesystem when the removal of
     the default resource group is attempted.

   - Preserve Code and Data Prioritization enabled state accross CPU
     hotplug.

   - Update split lock cpu matching to use the new X86_MATCH macros.

   - Change the split lock enumeration as Intel finaly decided that the
     IA32_CORE_CAPABILITIES bits are not architectural contrary to what
     the SDM claims. !@#%$^!

   - Add Tremont CPU models to the split lock detection cpu match.

   - Add a missing static attribute to make sparse happy"

* tag 'x86-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/split_lock: Add Tremont family CPU models
  x86/split_lock: Bits in IA32_CORE_CAPABILITIES are not architectural
  x86/resctrl: Preserve CDP enable over CPU hotplug
  x86/resctrl: Fix invalid attempt at removing the default resource group
  x86/split_lock: Update to use X86_MATCH_INTEL_FAM6_MODEL()
  x86/umip: Make umip_insns static
  x86/microcode/AMD: Increase microcode PATCH_MAX_SIZE
  objtool: Make BP scratch register warning more robust
  objtool: Fix switch table detection in .text.unlikely
  objtool: Support Clang non-section symbols in ORC generation
  objtool: Support Clang non-section symbols in ORC dump
  objtool: Fix CONFIG_UBSAN_TRAP unreachable warnings

Pull time namespace fix from Thomas Gleixner:
 "An update for the proc interface of time namespaces: Use symbolic
  names instead of clockid numbers. The usability nuisance of numbers
  was noticed by Michael when polishing the man page"

* tag 'timers-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  proc, time/namespace: Show clock symbolic names in /proc/pid/timens_offsets

Pull perf tooling fixes and updates from Thomas Gleixner:

 - Fix the header line of perf stat output for '--metric-only --per-socket'

 - Fix the python build with clang

 - The usual tools UAPI header synchronization

* tag 'perf-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  tools headers: Synchronize linux/bits.h with the kernel sources
  tools headers: Adopt verbatim copy of compiletime_assert() from kernel sources
  tools headers: Update x86's syscall_64.tbl with the kernel sources
  tools headers UAPI: Sync drm/i915_drm.h with the kernel sources
  tools headers UAPI: Update tools's copy of drm.h headers
  tools headers kvm: Sync linux/kvm.h with the kernel sources
  tools headers UAPI: Sync linux/fscrypt.h with the kernel sources
  tools include UAPI: Sync linux/vhost.h with the kernel sources
  tools arch x86: Sync asm/cpufeatures.h with the kernel sources
  tools headers UAPI: Sync linux/mman.h with the kernel
  tools headers UAPI: Sync sched.h with the kernel
  tools headers: Update linux/vdso.h and grab a copy of vdso/const.h
  perf stat: Fix no metric header if --per-socket and --metric-only set
  perf python: Check if clang supports -fno-semantic-interposition
  tools arch x86: Sync the msr-index.h copy with the kernel sources

Pull irq fixes from Thomas Gleixner:
 "A set of fixes/updates for the interrupt subsystem:

   - Remove setup_irq() and remove_irq(). All users have been converted
     so remove them before new users surface.

   - A set of bugfixes for various interrupt chip drivers

   - Add a few missing static attributes to address sparse warnings"

* tag 'irq-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/irq-bcm7038-l1: Make bcm7038_l1_of_init() static
  irqchip/irq-mvebu-icu: Make legacy_bindings static
  irqchip/meson-gpio: Fix HARDIRQ-safe -> HARDIRQ-unsafe lock order
  irqchip/sifive-plic: Fix maximum priority threshold value
  irqchip/ti-sci-inta: Fix processing of masked irqs
  irqchip/mbigen: Free msi_desc on device teardown
  irqchip/gic-v4.1: Update effective affinity of virtual SGIs
  irqchip/gic-v4.1: Add support for VPENDBASER's Dirty+Valid signaling
  genirq: Remove setup_irq() and remove_irq()

Pull scheduler fixes from Thomas Gleixner:
 "Two fixes for the scheduler:

   - Work around an uninitialized variable warning where GCC can't
     figure it out.

   - Allow 'isolcpus=' to skip unknown subparameters so that older
     kernels work with the commandline of a newer kernel. Improve the
     error output while at it"

* tag 'sched-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/vtime: Work around an unitialized variable warning
  sched/isolation: Allow "isolcpus=" to skip unknown sub-parameters

Pull RCU fix from Thomas Gleixner:
 "A single bugfix for RCU to prevent taking a lock in NMI context"

* tag 'core-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rcu: Don't acquire lock in NMI handler in rcu_nmi_enter_common()

Pull ext4 fixes from Ted Ts'o:
 "Miscellaneous bug fixes and cleanups for ext4, including a fix for
  generic/388 in data=journal mode, removing some BUG_ON's, and cleaning
  up some compiler warnings"

* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: convert BUG_ON's to WARN_ON's in mballoc.c
  ext4: increase wait time needed before reuse of deleted inode numbers
  ext4: remove set but not used variable 'es' in ext4_jbd2.c
  ext4: remove set but not used variable 'es'
  ext4: do not zeroout extents beyond i_disksize
  ext4: fix return-value types in several function comments
  ext4: use non-movable memory for superblock readahead
  ext4: use matching invalidatepage in ext4_writepage

Pull cifs fixes from Steve French:
 "Three small smb3 fixes: two debug related (helping network tracing for
  SMB2 mounts, and the other removing an unintended debug line on
  signing failures), and one fixing a performance problem with 64K
  pages"

* tag '5.7-rc-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  smb3: remove overly noisy debug line in signing errors
  cifs: improve read performance for page size 64KB & cache=strict & vers=2.1+
  cifs: dump the session id and keys also for SMB2 sessions

Merge tag 'flexible-array-member-5.7-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux

Pull flexible-array member conversion from Gustavo Silva:
 "The current codebase makes use of the zero-length array language
  extension to the C90 standard, but the preferred mechanism to declare
  variable-length types such as these ones is a flexible array
  member[1][2], introduced in C99:

    struct foo {
        int stuff;
        struct boo array[];
    };

  By making use of the mechanism above, we will get a compiler warning
  in case the flexible array does not occur last in the structure, which
  will help us prevent some kind of undefined behavior bugs from being
  inadvertently introduced[3] to the codebase from now on.

  Also, notice that, dynamic memory allocations won't be affected by
  this change:

   "Flexible array members have incomplete type, and so the sizeof
    operator may not be applied. As a quirk of the original
    implementation of zero-length arrays, sizeof evaluates to zero."[1]

  sizeof(flexible-array-member) triggers a warning because flexible
  array members have incomplete type[1]. There are some instances of
  code in which the sizeof operator is being incorrectly/erroneously
  applied to zero-length arrays and the result is zero. Such instances
  may be hiding some bugs. So, this work (flexible-array member
  convertions) will also help to get completely rid of those sorts of
  issues.

  Notice that all of these patches have been baking in linux-next for
  quite a while now and, 238 more of these patches have already been
  merged into 5.7-rc1.

  There are a couple hundred more of these issues waiting to be
  addressed in the whole codebase"

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour")

* tag 'flexible-array-member-5.7-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux: (28 commits)
  xattr.h: Replace zero-length array with flexible-array member
  uapi: linux: fiemap.h: Replace zero-length array with flexible-array member
  uapi: linux: dlm_device.h: Replace zero-length array with flexible-array member
  tpm_eventlog.h: Replace zero-length array with flexible-array member
  ti_wilink_st.h: Replace zero-length array with flexible-array member
  swap.h: Replace zero-length array with flexible-array member
  skbuff.h: Replace zero-length array with flexible-array member
  sched: topology.h: Replace zero-length array with flexible-array member
  rslib.h: Replace zero-length array with flexible-array member
  rio.h: Replace zero-length array with flexible-array member
  posix_acl.h: Replace zero-length array with flexible-array member
  platform_data: wilco-ec.h: Replace zero-length array with flexible-array member
  memcontrol.h: Replace zero-length array with flexible-array member
  list_lru.h: Replace zero-length array with flexible-array member
  lib: cpu_rmap: Replace zero-length array with flexible-array member
  irq.h: Replace zero-length array with flexible-array member
  ihex.h: Replace zero-length array with flexible-array member
  igmp.h: Replace zero-length array with flexible-array member
  genalloc.h: Replace zero-length array with flexible-array member
  ethtool.h: Replace zero-length array with flexible-array member
  ...

Pull SCSI fixes from James Bottomley:
 "Seven fixes: three in target, one on a sg error leg, two in qla2xxx
  fixing warnings introduced in the last merge window and updating
  MAINTAINERS and one in hisi_sas fixing a problem introduced by libata"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: sg: add sg_remove_request in sg_common_write
  scsi: target: tcmu: reset_ring should reset TCMU_DEV_BIT_BROKEN
  scsi: target: fix PR IN / READ FULL STATUS for FC
  scsi: target: Write NULL to *port_nexus_ptr if no ISID
  scsi: MAINTAINERS: Update qla2xxx FC-SCSI driver maintainer
  scsi: qla2xxx: Fix regression warnings
  scsi: hisi_sas: Fix build error without SATA_HOST

The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>