0day-ci / linux

Quite a lot of qgroup corruption happens due to wrong timing of calling
btrfs_qgroup_prepare_account_extents().

Since the safest timing is calling it just before
btrfs_qgroup_account_extents(), there is no need to separate these 2
function.

Merging them will make code cleaner and less bug prone.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>

For btrfs_qgroup_account_extent(), modify make it exit quicker for
non-fs extents.

This will also reduce the noise in trace_btrfs_qgroup_account_extent
event.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>

[BUG]
The easist way to reproduce the bug is:
------
 # mkfs.btrfs -f $dev -n 16K
 # mount $dev $mnt -o inode_cache
 # btrfs quota enable $mnt
 # btrfs quota rescan -w $mnt
 # btrfs qgroup show $mnt
qgroupid         rfer         excl
--------         ----         ----
0/5          32.00KiB     32.00KiB
             ^^ Twice the correct value
------

And fstests/btrfs qgroup test group can easily detect them with
inode_cache mount option.
Although some of them are false alerts since old test cases are using
fixed golden output.
While new test cases will use "btrfs check" to detect qgroup mismatch.

[CAUSE]
Inode_cache mount option will make commit_fs_roots() to call
btrfs_save_ino_cache() to update fs/subvol trees, and generate new
delayed refs.

However we call btrfs_qgroup_prepare_account_extents() too early, before
commit_fs_roots().
This makes the "old_roots" for newly generated extents are always NULL.
For freeing extent case, this makes both new_roots and old_roots to be
empty, while correct old_roots should not be empty.
This causing qgroup numbers not decreased correctly.

[FIX]
Modify the timing of calling btrfs_qgroup_prepare_account_extents() to
just before btrfs_qgroup_account_extents(), and add needed delayed_refs
handler.
So qgroup can handle inode_map mount options correctly.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

Currently we never clear dirty tags in DAX mappings and thus address
ranges to flush accumulate.  Now that we have locking of radix tree
entries, we have all the locking necessary to reliably clear the radix
tree dirty tag when flushing caches for corresponding address range.
Similarly to page_mkclean() we also have to write-protect pages to get a
page fault when the page is next written to so that we can mark the entry
dirty again.

Link: http://lkml.kernel.org/r/1479460644-25076-21-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Currently PTE gets updated in wp_pfn_shared() after dax_pfn_mkwrite() has
released corresponding radix tree entry lock.  When we want to
writeprotect PTE on cache flush, we need PTE modification to happen under
radix tree entry lock to ensure consistent updates of PTE and radix tree
(standard faults use page lock to ensure this consistency).  So move
update of PTE bit into dax_pfn_mkwrite().

Link: http://lkml.kernel.org/r/1479460644-25076-20-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Currently, flushing of caches for DAX mappings was ignoring entry lock.
So far this was ok (modulo a bug that a difference in entry lock could
cause cache flushing to be mistakenly skipped) but in the following
patches we will write-protect PTEs on cache flushing and clear dirty tags.
For that we will need more exclusion.  So do cache flushing under an
entry lock.  This allows us to remove one lock-unlock pair of
mapping->tree_lock as a bonus.

Link: http://lkml.kernel.org/r/1479460644-25076-19-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

DAX will need to implement its own version of page_check_address().  To
avoid duplicating page table walking code, export follow_pte() which does
what we need.

Link: http://lkml.kernel.org/r/1479460644-25076-18-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Currently finish_mkwrite_fault() returns 0 when PTE got changed before
we acquired PTE lock and VM_FAULT_WRITE when we succeeded in modifying
the PTE. This is somewhat confusing since 0 generally means success, it
is also inconsistent with finish_fault() which returns 0 on success.
Change finish_mkwrite_fault() to return 0 on success and VM_FAULT_NOPAGE
when PTE changed. Practically, there should be no behavioral difference
since we bail out from the fault the same way regardless whether we
return 0, VM_FAULT_NOPAGE, or VM_FAULT_WRITE. Also note that
VM_FAULT_WRITE has no effect for shared mappings since the only two
places that check it - KSM and GUP - care about private mappings only.
Generally the meaning of VM_FAULT_WRITE for shared mappings is not well
defined and we should probably clean that up.

Link: http://lkml.kernel.org/r/1479460644-25076-17-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Provide a helper function for finishing write faults due to PTE being
read-only.  The helper will be used by DAX to avoid the need of
complicating generic MM code with DAX locking specifics.

Link: http://lkml.kernel.org/r/1479460644-25076-16-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

wp_page_reuse() handles write shared faults which is needed only in
wp_page_shared().  Move the handling only into that location to make
wp_page_reuse() simpler and avoid a strange situation when we sometimes
pass in locked page, sometimes unlocked etc.

Link: http://lkml.kernel.org/r/1479460644-25076-15-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

So far we set vmf->page during WP faults only when we needed to pass it to
the ->page_mkwrite handler.  Set it in all the cases now and use that
instead of passing page pointer explicitly around.

Link: http://lkml.kernel.org/r/1479460644-25076-14-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

We will need more information in the ->page_mkwrite() helper for DAX to be
able to fully finish faults there.  Pass vm_fault structure to
do_page_mkwrite() and use it there so that information propagates properly
from upper layers.

Link: http://lkml.kernel.org/r/1479460644-25076-13-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Currently we duplicate handling of shared write faults in wp_page_reuse()
and do_shared_fault().  Factor them out into a common function.

Link: http://lkml.kernel.org/r/1479460644-25076-12-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Move final handling of COW faults from generic code into DAX fault
handler.  That way generic code doesn't have to be aware of peculiarities
of DAX locking so remove that knowledge and make locking functions private
to fs/dax.c.

Link: http://lkml.kernel.org/r/1479460644-25076-11-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Introduce finish_fault() as a helper function for finishing page faults.
It is rather thin wrapper around alloc_set_pte() but since we'd want to
call this from DAX code or filesystems, it is still useful to avoid some
boilerplate code.

Link: http://lkml.kernel.org/r/1479460644-25076-10-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "dax: Clear dirty bits after flushing caches", v5.

Patchset to clear dirty bits from radix tree of DAX inodes when caches for
corresponding pfns have been flushed.  In principle, these patches enable
handlers to easily update PTEs and do other work necessary to finish the
fault without duplicating the functionality present in the generic code.
I'd like to thank Kirill and Ross for reviews of the series!

This patch (of 20):

To allow full handling of COW faults add memcg field to struct vm_fault
and a return value of ->fault() handler meaning that COW fault is fully
handled and memcg charge must not be canceled.  This will allow us to
remove knowledge about special DAX locking from the generic fault code.

Link: http://lkml.kernel.org/r/1479460644-25076-9-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Add orig_pte field to vm_fault structure to allow ->page_mkwrite handlers
to fully handle the fault.  This also allows us to save some passing of
extra arguments around.

Link: http://lkml.kernel.org/r/1479460644-25076-8-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Instead of creating another vm_fault structure, use the one passed to
wp_pfn_shared() for passing arguments into pfn_mkwrite handler.

Link: http://lkml.kernel.org/r/1479460644-25076-7-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Use vm_fault structure to pass cow_page, page, and entry in and out of the
function.  That reduces number of __do_fault() arguments from 4 to 1.

Link: http://lkml.kernel.org/r/1479460644-25076-6-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Instead of creating another vm_fault structure, use the one passed to
__do_fault() for passing arguments into fault handler.

Link: http://lkml.kernel.org/r/1479460644-25076-5-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

struct vm_fault has already pgoff entry.  Use it instead of passing pgoff
as a separate argument and then assigning it later.

Link: http://lkml.kernel.org/r/1479460644-25076-4-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Every single user of vmf->virtual_address typed that entry to unsigned
long before doing anything with it so the type of virtual_address does not
really provide us any additional safety.  Just use masked vmf->address
which already has the appropriate type.

Link: http://lkml.kernel.org/r/1479460644-25076-3-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Currently we have two different structures for passing fault information
around - struct vm_fault and struct fault_env.  DAX will need more
information in struct vm_fault to handle its faults so the content of that
structure would become event closer to fault_env.  Furthermore it would
need to generate struct fault_env to be able to call some of the generic
functions.  So at this point I don't think there's much use in keeping
these two structures separate.  Just embed into struct vm_fault all that
is needed to use it for both purposes.

Link: http://lkml.kernel.org/r/1479460644-25076-2-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

ERROR: Please use git commit description style 'commit <12+ chars of sha1> ("<title line>")' - ie: 'commit 0123456789ab ("commit description")'
torvalds#16:
flag.  However, this flag was originally silently dropped by 1e98779

WARNING: line over 80 characters
torvalds#89: FILE: mm/nommu.c:179:
+static long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,

WARNING: line over 80 characters
torvalds#90: FILE: mm/nommu.c:180:
+				      unsigned long start, unsigned long nr_pages,

WARNING: line over 80 characters
torvalds#91: FILE: mm/nommu.c:181:
+			              struct page **pages, unsigned int gup_flags)

ERROR: code indent should use tabs where possible
torvalds#91: FILE: mm/nommu.c:181:
+^I^I^I              struct page **pages, unsigned int gup_flags)$

total: 2 errors, 3 warnings, 116 lines checked

NOTE: For some of the reported defects, checkpatch may be able to
      mechanically convert to the typical style using --fix or --fix-inplace.

NOTE: Whitespace errors detected.
      You may wish to use scripts/cleanpatch or scripts/cleanfile

./patches/mm-unexport-__get_user_pages_unlocked.patch has style problems, please review.

NOTE: If any of the errors are false positives, please report
      them to the maintainer, see CHECKPATCH in MAINTAINERS.

Please run checkpatch prior to sending patches

Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Unexport the low-level __get_user_pages_unlocked() function and replaces
invocations with calls to more appropriate higher-level functions.

In hva_to_pfn_slow() we are able to replace __get_user_pages_unlocked()
with get_user_pages_unlocked() since we can now pass gup_flags.

In async_pf_execute() and process_vm_rw_single_vec() we need to pass
different tsk, mm arguments so get_user_pages_remote() is the sane
replacement in these cases (having added manual acquisition and release of
mmap_sem.)

Additionally get_user_pages_remote() reintroduces use of the FOLL_TOUCH
flag.  However, this flag was originally silently dropped by 1e98779
("mm/gup: Introduce get_user_pages_remote()"), so this appears to have
been unintentional and reintroducing it is therefore not an issue.

Link: http://lkml.kernel.org/r/20161027095141.2569-3-lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krcmar <rkrcmar@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Link: http://lkml.kernel.org/r/20161122210511.024ec341@canb.auug.org.au
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "mm: unexport __get_user_pages_unlocked()".

This patch series continues the cleanup of get_user_pages*() functions taking
advantage of the fact we can now pass gup_flags as we please.

It firstly adds an additional 'locked' parameter to get_user_pages_remote() to
allow for its callers to utilise VM_FAULT_RETRY functionality. This is necessary
as the invocation of __get_user_pages_unlocked() in process_vm_rw_single_vec()
makes use of this and no other existing higher level function would allow it to
do so.

Secondly existing callers of __get_user_pages_unlocked() are replaced with the
appropriate higher-level replacement - get_user_pages_unlocked() if the current
task and memory descriptor are referenced, or get_user_pages_remote() if other
task/memory descriptors are referenced (having acquiring mmap_sem.)

This patch (of 2):

Add a int *locked parameter to get_user_pages_remote() to allow
VM_FAULT_RETRY faulting behaviour similar to get_user_pages_[un]locked().

Taking into account the previous adjustments to get_user_pages*()
functions allowing for the passing of gup_flags, we are now in a position
where __get_user_pages_unlocked() need only be exported for his ability to
allow VM_FAULT_RETRY behaviour, this adjustment allows us to subsequently
unexport __get_user_pages_unlocked() as well as allowing for future
flexibility in the use of get_user_pages_remote().

Link: http://lkml.kernel.org/r/20161027095141.2569-2-lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krcmar <rkrcmar@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

We can avoid the idr tree lookup (albeit possibly avoiding
idr_find_fast()) when being awoken in EINTR, as the semid will not change
in this context while blocked.  Use the sma pointer directly and take the
sem_lock, then re-check for RMID races.  We continue to re-check the
queue.status with the lock held such that we can detect situations where
we where are dealing with a spurious wakeup but another task that holds
the sem_lock updated the queue.status while we were spinning for it.  Once
we take the lock it obviously won't change again.

Being the only caller, get rid of sem_obtain_lock() altogether.

Link: http://lkml.kernel.org/r/1478708774-28826-3-git-send-email-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

WARNING: line over 80 characters
torvalds#69: FILE: ipc/sem.c:1997:
+		 * fastpath: the semop has completed, either successfully or not, from

WARNING: line over 80 characters
#70: FILE: ipc/sem.c:1998:
+		 * the syscall pov, is quite irrelevant to us at this point; we're done.

WARNING: line over 80 characters
torvalds#73: FILE: ipc/sem.c:2001:
+		 * spuriously.  The queue.status is checked again in the slowpath (aka

WARNING: line over 80 characters
torvalds#74: FILE: ipc/sem.c:2002:
+		 * after taking sem_lock), such that we can detect scenarios where we

WARNING: line over 80 characters
torvalds#75: FILE: ipc/sem.c:2003:
+		 * were awakened externally, during the window between wake_q_add() and

WARNING: line over 80 characters
torvalds#84: FILE: ipc/sem.c:2009:
+			 * User space could assume that semop() is a memory barrier:

WARNING: line over 80 characters
torvalds#85: FILE: ipc/sem.c:2010:
+			 * Without the mb(), the cpu could speculatively read in user

WARNING: line over 80 characters
torvalds#86: FILE: ipc/sem.c:2011:
+			 * space stale data that was overwritten by the previous owner

total: 0 errors, 8 warnings, 127 lines checked

NOTE: For some of the reported defects, checkpatch may be able to
      mechanically convert to the typical style using --fix or --fix-inplace.

./patches/ipc-sem-simplify-wait-wake-loop.patch has style problems, please review.

NOTE: If any of the errors are false positives, please report
      them to the maintainer, see CHECKPATCH in MAINTAINERS.

Please run checkpatch prior to sending patches

Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Instead of using the reverse goto, we can simplify the flow and make it
more language natural by just doing do-while instead.  One would hope this
is the standard way (or obviously just with a while bucle) that we do
wait/wakeup handling in the kernel.  The exact same logic is kept, just
more indented.

Link: http://lkml.kernel.org/r/1478708774-28826-2-git-send-email-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

... saves some LoC and looks cleaner than re-implementing the
calls.

Link: http://lkml.kernel.org/r/1474225896-10066-6-git-send-email-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

The compiler already does this, but make it explicit.  This helper is
really small and also used in update_queue's main loop, which is O(N^2)
scanning.  Inline and avoid the function overhead.

Link: http://lkml.kernel.org/r/1474225896-10066-5-git-send-email-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

WARNING: Missing a blank line after declarations
torvalds#132: FILE: ipc/sem.c:747:
+			int undo = un->semadj[sop->sem_num] - sem_op;
+			un->semadj[sop->sem_num] = undo;

ERROR: spaces required around that '?' (ctx:VxW)
torvalds#142: FILE: ipc/sem.c:757:
+	return sop->sem_flg & IPC_NOWAIT? -EAGAIN : 1;
 	                                ^

total: 1 errors, 1 warnings, 171 lines checked

NOTE: For some of the reported defects, checkpatch may be able to
      mechanically convert to the typical style using --fix or --fix-inplace.

./patches/ipc-sem-optimize-perform_atomic_semop.patch has style problems, please review.

NOTE: If any of the errors are false positives, please report
      them to the maintainer, see CHECKPATCH in MAINTAINERS.

Please run checkpatch prior to sending patches

Cc: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>