Looking at the conditional lock acquire functions in the kernel due to
the new sparse support (see commit 4a557a5d1a61 "sparse: introduce
conditional lock acquire function attribute"), it became obvious that
the lockref code has a couple of them, but they don't match the usual
naming convention for the other ones, and their return value logic is
also reversed.

In the other very similar places, the naming pattern is '*_and_lock()'
(eg 'atomic_put_and_lock()' and 'refcount_dec_and_lock()'), and the
function returns true when the lock is taken.

The lockref code is superficially very similar to the refcount code,
only with the special "atomic wrt the embedded lock" semantics. But
instead of the '*_and_lock()' naming it uses '*_or_lock()'.

And instead of returning true in case it took the lock, it returns true
if it *didn't* take the lock.

Now, arguably the reflock code is quite logical: it really is a "either
decrement _or_ lock" kind of situation - and the return value is about
whether the operation succeeded without any special care needed.

So despite the similarities, the differences do make some sense, and
maybe it's not worth trying to unify the different conditional locking
primitives in this area.

But while looking at this all, it did become obvious that the
'lockref_get_or_lock()' function hasn't actually had any users for
almost a decade.

The only user it ever had was the shortlived 'd_rcu_to_refcount()'
function, and it got removed and replaced with 'lockref_get_not_dead()'
back in 2013 in commits 0d98439ea3c6 ("vfs: use lockred 'dead' flag to
mark unrecoverably dead dentries") and e5c832d55588 ("vfs: fix dentry
RCU to refcounting possibly sleeping dput()")

In fact, that single use was removed less than a week after the whole
function was introduced in commit b3abd80250c1 ("lockref: add
'lockref_get_or_lock() helper") so this function has been around for a
decade, but only had a user for six days.

Let's just put this mis-designed and unused function out of its misery.

We can think about the naming and semantic oddities of the remaining
'lockref_put_or_lock()' later, but at least that function has users.

And while the naming is different and the return value doesn't match,
that function matches the whole '{atomic,refcount}_dec_and_test()'
pattern much better (ie the magic happens when the count goes down to
zero, not when it is incremented from zero).

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The kernel tends to try to avoid conditional locking semantics because
it makes it harder to think about and statically check locking rules,
but we do have a few fundamental locking primitives that take locks
conditionally - most obviously the 'trylock' functions.

That has always been a problem for 'sparse' checking for locking
imbalance, and we've had a special '__cond_lock()' macro that we've used
to let sparse know how the locking works:

# define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0)

so that you can then use this to tell sparse that (for example) the
spinlock trylock macro ends up acquiring the lock when it succeeds, but
not when it fails:

#define raw_spin_trylock(lock) __cond_lock(lock, _raw_spin_trylock(lock))

and then sparse can follow along the locking rules when you have code like

if (!spin_trylock(&dentry->d_lock))
return LRU_SKIP;
.. sparse sees that the lock is held here..
spin_unlock(&dentry->d_lock);

and sparse ends up happy about the lock contexts.

However, this '__cond_lock()' use does result in very ugly header files,
and requires you to basically wrap the real function with that macro
that uses '__cond_lock'. Which has made PeterZ NAK things that try to
fix sparse warnings over the years [1].

To solve this, there is now a very experimental patch to sparse that
basically does the exact same thing as '__cond_lock()' did, but using a
function attribute instead. That seems to make PeterZ happy [2].

Note that this does not replace existing use of '__cond_lock()', but
only exposes the new proposed attribute and uses it for the previously
unannotated 'refcount_dec_and_lock()' family of functions.

For existing sparse installations, this will make no difference (a
negative output context was ignored), but if you have the experimental
sparse patch it will make sparse now understand code that uses those
functions, the same way '__cond_lock()' makes sparse understand the very
similar 'atomic_dec_and_lock()' uses that have the old '__cond_lock()'
annotations.

Note that in some cases this will silence existing context imbalance
warnings. But in other cases it may end up exposing new sparse warnings
for code that sparse just didn't see the locking for at all before.

This is a trial, in other words. I'd expect that if it ends up being
successful, and new sparse releases end up having this new attribute,
we'll migrate the old-style '__cond_lock()' users to use the new-style
'__cond_acquires' function attribute.

The actual experimental sparse patch was posted in [3].

Link: https://lore.kernel.org/all/20130930134434.GC12926@twins.programming.kicks-ass.net/ [1]
Link: https://lore.kernel.org/all/Yr60tWxN4P568x3W@worktop.programming.kicks-ass.net/ [2]
Link: https://lore.kernel.org/all/CAHk-=wjZfO9hGqJ2_hGQG3U_XzSh9_XaXze=HgPdvJbgrvASfA@mail.gmail.com/ [3]
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Alexander Aring <aahringo@redhat.com>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull xfs fixes from Darrick Wong:
"This fixes some stalling problems and corrects the last of the
problems (I hope) observed during testing of the new atomic xattr
update feature.

- Fix statfs blocking on background inode gc workers

- Fix some broken inode lock assertion code

- Fix xattr leaf buffer leaks when cancelling a deferred xattr update
operation

- Clean up xattr recovery to make it easier to understand.

- Fix xattr leaf block verifiers tripping over empty blocks.

- Remove complicated and error prone xattr leaf block bholding mess.

- Fix a bug where an rt extent crossing EOF was treated as "posteof"
blocks and cleaned unnecessarily.

- Fix a UAF when log shutdown races with unmount"

* tag 'xfs-5.19-fixes-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
xfs: prevent a UAF when log IO errors race with unmount
xfs: dont treat rt extents beyond EOF as eofblocks to be cleared
xfs: don't hold xattr leaf buffers across transaction rolls
xfs: empty xattr leaf header blocks are not corruption
xfs: clean up the end of xfs_attri_item_recover
xfs: always free xattri_leaf_bp when cancelling a deferred op
xfs: use invalidate_lock to check the state of mmap_lock
xfs: factor out the common lock flags assert
xfs: introduce xfs_inodegc_push()
xfs: bound maximum wait time for inodegc work

Pull nfsd fixes from Chuck Lever:
"Notable regression fixes:

- Fix NFSD crash during NFSv4.2 READ_PLUS operation

- Fix incorrect status code returned by COMMIT operation"

* tag 'nfsd-5.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux:
SUNRPC: Fix READ_PLUS crasher
NFSD: restore EINVAL error translation in nfsd_commit()

KASAN reported the following use after free bug when running
generic/475:

XFS (dm-0): Mounting V5 Filesystem
XFS (dm-0): Starting recovery (logdev: internal)
XFS (dm-0): Ending recovery (logdev: internal)
Buffer I/O error on dev dm-0, logical block 20639616, async page read
Buffer I/O error on dev dm-0, logical block 20639617, async page read
XFS (dm-0): log I/O error -5
XFS (dm-0): Filesystem has been shut down due to log error (0x2).
XFS (dm-0): Unmounting Filesystem
XFS (dm-0): Please unmount the filesystem and rectify the problem(s).
==================================================================
BUG: KASAN: use-after-free in do_raw_spin_lock+0x246/0x270
Read of size 4 at addr ffff888109dd84c4 by task 3:1H/136

CPU: 3 PID: 136 Comm: 3:1H Not tainted 5.19.0-rc4-xfsx #rc4 8e53ab5ad0fddeb31cee5e7063ff9c361915a9c4
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014
Workqueue: xfs-log/dm-0 xlog_ioend_work [xfs]
Call Trace:
<TASK>
dump_stack_lvl+0x34/0x44
print_report.cold+0x2b8/0x661
? do_raw_spin_lock+0x246/0x270
kasan_report+0xab/0x120
? do_raw_spin_lock+0x246/0x270
do_raw_spin_lock+0x246/0x270
? rwlock_bug.part.0+0x90/0x90
xlog_force_shutdown+0xf6/0x370 [xfs 4ad76ae0d6add7e8183a553e624c31e9ed567318]
xlog_ioend_work+0x100/0x190 [xfs 4ad76ae0d6add7e8183a553e624c31e9ed567318]
process_one_work+0x672/0x1040
worker_thread+0x59b/0xec0
? __kthread_parkme+0xc6/0x1f0
? process_one_work+0x1040/0x1040
? process_one_work+0x1040/0x1040
kthread+0x29e/0x340
? kthread_complete_and_exit+0x20/0x20
ret_from_fork+0x1f/0x30
</TASK>

Allocated by task 154099:
kasan_save_stack+0x1e/0x40
__kasan_kmalloc+0x81/0xa0
kmem_alloc+0x8d/0x2e0 [xfs]
xlog_cil_init+0x1f/0x540 [xfs]
xlog_alloc_log+0xd1e/0x1260 [xfs]
xfs_log_mount+0xba/0x640 [xfs]
xfs_mountfs+0xf2b/0x1d00 [xfs]
xfs_fs_fill_super+0x10af/0x1910 [xfs]
get_tree_bdev+0x383/0x670
vfs_get_tree+0x7d/0x240
path_mount+0xdb7/0x1890
__x64_sys_mount+0x1fa/0x270
do_syscall_64+0x2b/0x80
entry_SYSCALL_64_after_hwframe+0x46/0xb0

Freed by task 154151:
kasan_save_stack+0x1e/0x40
kasan_set_track+0x21/0x30
kasan_set_free_info+0x20/0x30
____kasan_slab_free+0x110/0x190
slab_free_freelist_hook+0xab/0x180
kfree+0xbc/0x310
xlog_dealloc_log+0x1b/0x2b0 [xfs]
xfs_unmountfs+0x119/0x200 [xfs]
xfs_fs_put_super+0x6e/0x2e0 [xfs]
generic_shutdown_super+0x12b/0x3a0
kill_block_super+0x95/0xd0
deactivate_locked_super+0x80/0x130
cleanup_mnt+0x329/0x4d0
task_work_run+0xc5/0x160
exit_to_user_mode_prepare+0xd4/0xe0
syscall_exit_to_user_mode+0x1d/0x40
entry_SYSCALL_64_after_hwframe+0x46/0xb0

This appears to be a race between the unmount process, which frees the
CIL and waits for in-flight iclog IO; and the iclog IO completion. When
generic/475 runs, it starts fsstress in the background, waits a few
seconds, and substitutes a dm-error device to simulate a disk falling
out of a machine. If the fsstress encounters EIO on a pure data write,
it will exit but the filesystem will still be online.

The next thing the test does is unmount the filesystem, which tries to
clean the log, free the CIL, and wait for iclog IO completion. If an
iclog was being written when the dm-error switch occurred, it can race
with log unmounting as follows:

Thread 1 Thread 2

xfs_log_unmount
xfs_log_clean
xfs_log_quiesce
xlog_ioend_work
<observe error>
xlog_force_shutdown
test_and_set_bit(XLOG_IOERROR)
xfs_log_force
<log is shut down, nop>
xfs_log_umount_write
<log is shut down, nop>
xlog_dealloc_log
xlog_cil_destroy
<wait for iclogs>
spin_lock(&log->l_cilp->xc_push_lock)
<KABOOM>

Therefore, free the CIL after waiting for the iclogs to complete. I
/think/ this race has existed for quite a few years now, though I don't
remember the ~2014 era logging code well enough to know if it was a real
threat then or if the actual race was exposed only more recently.

Fixes: ac983517ec59 ("xfs: don't sleep in xlog_cil_force_lsn on shutdown")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

Pull parisc architecture fixes from Helge Deller:
"Two important fixes for bugs in code which was added in 5.18:

- Fix userspace signal failures on 32-bit kernel due to a bug in vDSO

- Fix 32-bit load-word unalignment exception handler which returned
wrong values"

* tag 'for-5.19/parisc-4' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
parisc: Fix vDSO signal breakage on 32-bit kernel
parisc/unaligned: Fix emulate_ldw() breakage

Looks like there are still cases when "space_left - frag1bytes" can
legitimately exceed PAGE_SIZE. Ensure that xdr->end always remains
within the current encode buffer.

Reported-by: Bruce Fields <bfields@fieldses.org>
Reported-by: Zorro Lang <zlang@redhat.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216151
Fixes: 6c254bf3b637 ("SUNRPC: Fix the calculation of xdr->end in xdr_get_next_encode_buffer()")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

On a system with a realtime volume and a 28k realtime extent,
generic/491 fails because the test opens a file on a frozen filesystem
and closing it causes xfs_release -> xfs_can_free_eofblocks to
mistakenly think that the the blocks of the realtime extent beyond EOF
are posteof blocks to be freed. Realtime extents cannot be partially
unmapped, so this is pointless. Worse yet, this triggers posteof
cleanup, which stalls on a transaction allocation, which is why the test
fails.

Teach the predicate to account for realtime extents properly.

Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

Pull perf tools fixes from Arnaldo Carvalho de Melo:

- BPF program info linear (BPIL) data is accessed assuming 64-bit
alignment resulting in undefined behavior as the data is just byte
aligned. Fix it, Found using -fsanitize=undefined.

- Fix 'perf offcpu' build on old kernels wrt task_struct's
state/__state field.

- Fix perf_event_attr.sample_type setting on the 'offcpu-time' event
synthesized by the 'perf offcpu' tool.

- Don't bail out when synthesizing PERF_RECORD_ events for pre-existing
threads when one goes away while parsing its procfs entries.

- Don't sort the task scan result from /proc, its not needed and
introduces bugs when the main thread isn't the first one to be
processed.

- Fix uninitialized 'offset' variable on aarch64 in the unwind code.

- Sync KVM headers with the kernel sources.

* tag 'perf-tools-fixes-for-v5.19-2022-07-02' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux:
perf synthetic-events: Ignore dead threads during event synthesis
perf synthetic-events: Don't sort the task scan result from /proc
perf unwind: Fix unitialized 'offset' variable on aarch64
tools headers UAPI: Sync linux/kvm.h with the kernel sources
perf bpf: 8 byte align bpil data
tools kvm headers arm64: Update KVM headers from the kernel sources
perf offcpu: Accept allowed sample types only
perf offcpu: Fix build failure on old kernels

Addition of vDSO support for parisc in kernel v5.18 suddenly broke glibc
signal testcases on a 32-bit kernel.

The trampoline code (sigtramp.S) which is mapped into userspace includes
an offset to the context data on the stack, which is used by gdb and
glibc to get access to registers.

In a 32-bit kernel we used by mistake the offset into the compat context
(which is valid on a 64-bit kernel only) instead of the offset into the
"native" 32-bit context.

Reported-by: John David Anglin <dave.anglin@bell.net>
Tested-by: John David Anglin <dave.anglin@bell.net>
Fixes: df24e1783e6e ("parisc: Add vDSO support")
CC: stable@vger.kernel.org # 5.18
Signed-off-by: Helge Deller <deller@gmx.de>

commit 555dbf1a9aac ("nfsd: Replace use of rwsem with errseq_t")
incidentally broke translation of -EINVAL to nfserr_notsupp.
The patch restores that.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Fixes: 555dbf1a9aac ("nfsd: Replace use of rwsem with errseq_t")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Now that we've established (again!) that empty xattr leaf buffers are
ok, we no longer need to bhold them to transactions when we're creating
new leaf blocks. Get rid of the entire mechanism, which should simplify
the xattr code quite a bit.

The original justification for using bhold here was to prevent the AIL
from trying to write the empty leaf block into the fs during the brief
time that we release the buffer lock. The reason for /that/ was to
prevent recovery from tripping over the empty ondisk block.

Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Pull powerpc fixes from Michael Ellerman:

- Fix BPF uapi confusion about the correct type of bpf_user_pt_regs_t.

- Fix virt_addr_valid() when memory is hotplugged above the boot-time
high_memory value.

- Fix a bug in 64-bit Book3E map_kernel_page() which would incorrectly
allocate a PMD page at PUD level.

- Fix a couple of minor issues found since we enabled KASAN for 64-bit
Book3S.

Thanks to Aneesh Kumar K.V, Cédric Le Goater, Christophe Leroy, Kefeng
Wang, Liam Howlett, Nathan Lynch, and Naveen N. Rao.

* tag 'powerpc-5.19-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
powerpc/memhotplug: Add add_pages override for PPC
powerpc/bpf: Fix use of user_pt_regs in uapi
powerpc/prom_init: Fix kernel config grep
powerpc/book3e: Fix PUD allocation size in map_kernel_page()
powerpc/xive/spapr: correct bitmap allocation size