locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE()

Please do not apply this to mainline directly, instead please re-run the
coccinelle script shown below and apply its output.

For several reasons, it is desirable to use {READ,WRITE}_ONCE() in
preference to ACCESS_ONCE(), and new code is expected to use one of the
former. So far, there's been no reason to change most existing uses of
ACCESS_ONCE(), as these aren't harmful, and changing them results in
churn.

However, for some features, the read/write distinction is critical to
correct operation. To distinguish these cases, separate read/write
accessors must be used. This patch migrates (most) remaining
ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following
coccinelle script:

----
// Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and
// WRITE_ONCE()

// $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch

virtual patch

@ depends on patch @
expression E1, E2;
@@

- ACCESS_ONCE(E1) = E2
+ WRITE_ONCE(E1, E2)

@ depends on patch @
expression E;
@@

- ACCESS_ONCE(E)
+ READ_ONCE(E)
----
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: davem@davemloft.net
Cc: linux-arch@vger.kernel.org
Cc: mpe@ellerman.id.au
Cc: shuah@kernel.org
Cc: snitzer@redhat.com
Cc: thor.thayer@linux.intel.com
Cc: tj@kernel.org
Cc: viro@zeniv.linux.org.uk
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

All users of pagevec_lookup() and pagevec_lookup_range() now pass
PAGEVEC_SIZE as a desired number of pages.

Just drop the argument.

Link: http://lkml.kernel.org/r/20170726114704.7626-11-jack@suse.czSigned-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We want only pages from given range in page_cache_seek_hole_data().  Use
pagevec_lookup_range() instead of pagevec_lookup() and remove
unnecessary code.

Note that the check for getting less pages than desired can be removed
because index gets updated by pagevec_lookup_range().

Link: http://lkml.kernel.org/r/20170726114704.7626-9-jack@suse.czSigned-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit e64855c6 ("fs: Add helper to clean bdev aliases under a bh
and use it") added a wrapper for clean_bdev_aliases() that invalidates
bdev aliases underlying a single buffer head.

However this has caused a performance regression for bonnie++ benchmark
on ext4 filesystem when delayed allocation is turned off (ext3 mode) -
average of 3 runs:

  Hmean SeqOut Char  164787.55 (  0.00%) 107189.06 (-34.95%)
  Hmean SeqOut Block 219883.89 (  0.00%) 168870.32 (-23.20%)

The reason for this regression is that clean_bdev_aliases() is slower
when called for a single block because pagevec_lookup() it uses will end
up iterating through the radix tree until it finds a page (which may
take a while) but we are only interested whether there's a page at a
particular index.

Fix the problem by using pagevec_lookup_range() instead which avoids the
needless iteration.

Fixes: e64855c6 ("fs: Add helper to clean bdev aliases under a bh and use it")
Link: http://lkml.kernel.org/r/20170726114704.7626-5-jack@suse.czSigned-off-by: NJan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@fb.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make pagevec_lookup() (and underlying find_get_pages()) update index to
the next page where iteration should continue.  Most callers want this
and also pagevec_lookup_tag() already does this.

Link: http://lkml.kernel.org/r/20170726114704.7626-3-jack@suse.czSigned-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This way we don't need a block_device structure to submit I/O.  The
block_device has different life time rules from the gendisk and
request_queue and is usually only available when the block device node
is open.  Other callers need to explicitly create one (e.g. the lightnvm
passthrough code, or the new nvme multipathing code).

For the actual I/O path all that we need is the gendisk, which exists
once per block device.  But given that the block layer also does
partition remapping we additionally need a partition index, which is
used for said remapping in generic_make_request.

Note that all the block drivers generally want request_queue or
sometimes the gendisk, so this removes a layer of indirection all
over the stack.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

To install a buffer_head into the cpu's LRU queue, bh_lru_install()
would construct a new copy of the queue and then memcpy it over the real
queue.  But it's easily possible to do the update in-place, which is
faster and simpler.  Some work can also be skipped if the buffer_head
was already in the queue.

As a microbenchmark I timed how long it takes to run sb_getblk()
10,000,000 times alternating between BH_LRU_SIZE + 1 blocks.
Effectively, this benchmarks looking up buffer_heads that are in the
page cache but not in the LRU:

	Before this patch: 1.758s
	After this patch: 1.653s

This patch also removes about 350 bytes of compiled code (on x86_64),
partly due to removal of the memcpy() which was being inlined+unrolled.

Link: http://lkml.kernel.org/r/20161229193445.1913-1-ebiggers3@gmail.comSigned-off-by: NEric Biggers <ebiggers@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

I noticed on xfs that I could still sometimes get back an error on fsync
on a fd that was opened after the error condition had been cleared.

The problem is that the buffer code sets the write_io_error flag and
then later checks that flag to set the error in the mapping. That flag
perisists for quite a while however. If the file is later opened with
O_TRUNC, the buffers will then be invalidated and the mapping's error
set such that a subsequent fsync will return error. I think this is
incorrect, as there was no writeback between the open and fsync.

Add a new mark_buffer_write_io_error operation that sets the flag and
the error in the mapping at the same time. Replace all calls to
set_buffer_write_io_error with mark_buffer_write_io_error, and remove
the places that check this flag in order to set the error in the
mapping.

This sets the error in the mapping earlier, at the time that it's first
detected.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Reviewed-by: NJan Kara <jack@suse.cz>
Reviewed-by: NCarlos Maiolino <cmaiolino@redhat.com>

Signed-off-by: NJeff Layton <jlayton@redhat.com>
Reviewed-by: NJan Kara <jack@suse.cz>
Reviewed-by: NMatthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

KMSAN (KernelMemorySanitizer, a new error detection tool) reports the
use of uninitialized memory in ext4_update_bh_state():

==================================================================
BUG: KMSAN: use of unitialized memory
CPU: 3 PID: 1 Comm: swapper/0 Tainted: G    B           4.8.0-rc6+ #597
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs
01/01/2011
 0000000000000282 ffff88003cc96f68 ffffffff81f30856 0000003000000008
 ffff88003cc96f78 0000000000000096 ffffffff8169742a ffff88003cc96ff8
 ffffffff812fc1fc 0000000000000008 ffff88003a1980e8 0000000100000000
Call Trace:
 [<     inline     >] __dump_stack lib/dump_stack.c:15
 [<ffffffff81f30856>] dump_stack+0xa6/0xc0 lib/dump_stack.c:51
 [<ffffffff812fc1fc>] kmsan_report+0x1ec/0x300 mm/kmsan/kmsan.c:?
 [<ffffffff812fc33b>] __msan_warning+0x2b/0x40 ??:?
 [<     inline     >] ext4_update_bh_state fs/ext4/inode.c:727
 [<ffffffff8169742a>] _ext4_get_block+0x6ca/0x8a0 fs/ext4/inode.c:759
 [<ffffffff81696d4c>] ext4_get_block+0x8c/0xa0 fs/ext4/inode.c:769
 [<ffffffff814a2d36>] generic_block_bmap+0x246/0x2b0 fs/buffer.c:2991
 [<ffffffff816ca30e>] ext4_bmap+0x5ee/0x660 fs/ext4/inode.c:3177
...
origin description: ----tmp@generic_block_bmap
==================================================================

(the line numbers are relative to 4.8-rc6, but the bug persists
upstream)

The local |tmp| is created in generic_block_bmap() and then passed into
ext4_bmap() => ext4_get_block() => _ext4_get_block() =>
ext4_update_bh_state(). Along the way tmp.b_page is never initialized
before ext4_update_bh_state() checks its value.

[ Use the approach suggested by Kees Cook of initializing the whole bh
  structure.]
Signed-off-by: NAlexander Potapenko <glider@google.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>

Both ext4 and xfs implement seeking for the next hole or piece of data
in unwritten extents by scanning the page cache, and both versions share
the same bug when iterating the buffers of a page: the start offset into
the page isn't taken into account, so when a page fits more than two
filesystem blocks, things will go wrong.  For example, on a filesystem
with a block size of 1k, the following command will fail:

  xfs_io -f -c "falloc 0 4k" \
            -c "pwrite 1k 1k" \
            -c "pwrite 3k 1k" \
            -c "seek -a -r 0" foo

In this example, neither lseek(fd, 1024, SEEK_HOLE) nor lseek(fd, 2048,
SEEK_DATA) will return the correct result.

Introduce a generic vfs helper for seeking in the page cache that gets
this right.  The next commits will replace the filesystem specific
implementations.
Signed-off-by: NAndreas Gruenbacher <agruenba@redhat.com>
[hch: dropped the export]
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NDarrick J. Wong <darrick.wong@oracle.com>

Reviewed-by: NAndreas Dilger <adilger@dilger.ca>
Reviewed-by: NMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Replace bi_error with a new bi_status to allow for a clear conversion.
Note that device mapper overloaded bi_error with a private value, which
we'll have to keep arround at least for now and thus propagate to a
proper blk_status_t value.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

Commit afddba49 ("fs: introduce write_begin, write_end, and
perform_write aops") introduced AOP_FLAG_UNINTERRUPTIBLE flag which was
checked in pagecache_write_begin(), but that check was removed by
4e02ed4b ("fs: remove prepare_write/commit_write").

Between these two commits, commit d9414774 ("cifs: Convert cifs to
new aops.") added a check in cifs_write_begin(), but that check was soon
removed by commit a98ee8c1 ("[CIFS] fix regression in
cifs_write_begin/cifs_write_end").

Therefore, AOP_FLAG_UNINTERRUPTIBLE flag is checked nowhere.  Let's
remove this flag.  This patch has no functionality changes.

Link: http://lkml.kernel.org/r/1489294781-53494-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jpSigned-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: NJeff Layton <jlayton@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Cc: Nick Piggin <npiggin@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

_submit_bh() allowed submitting a buffer_head for I/O using custom
bio_flags.  It used to be used by jbd to set BIO_SNAP_STABLE, introduced
by commit 71368511 ("mm: make snapshotting pages for stable writes a
per-bio operation").  However, the code and flag has since been removed
and no _submit_bh() users remain.

These days, bio_flags are mostly used internally by the block layer to
track the state of bio's.  As such, it doesn't really make sense for
filesystems to use them instead of op_flags when wanting special
behavior for block requests.

Therefore, remove _submit_bh() and trim the bio_flags argument from
submit_bh_wbc().

Cc: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Instead of including the full <linux/signal.h>, we are going to include the
types-only <linux/signal_types.h> header in <linux/sched.h>, to further
decouple the scheduler header from the signal headers.

This means that various files which relied on the full <linux/signal.h> need
to be updated to gain an explicit dependency on it.

Update the code that relies on sched.h's inclusion of the <linux/signal.h> header.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Replace all 1 << inode->i_blkbits and (1 << inode->i_blkbits) in fs
branch.

This patch also fixes multiple checkpatch warnings: WARNING: Prefer
'unsigned int' to bare use of 'unsigned'

Thanks to Andrew Morton for suggesting more appropriate function instead
of macro.

[geliangtang@gmail.com: truncate: use i_blocksize()]
  Link: http://lkml.kernel.org/r/9c8b2cd83c8f5653805d43debde9fa8817e02fc4.1484895804.git.geliangtang@gmail.com
Link: http://lkml.kernel.org/r/1481319905-10126-1-git-send-email-fabf@skynet.beSigned-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NGeliang Tang <geliangtang@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The first block to be cleaned may start at a non-zero page offset. In
such a scenario clean_bdev_aliases() will end up cleaning blocks that
do not fall in the range of blocks to be cleaned. This commit fixes the
issue by skipping blocks that do not fall in valid block range.
Signed-off-by: NChandan Rajendra <chandan@linux.vnet.ibm.com>
Reviewed-by: NJan Kara <jack@suse.cz>
Reviewed-by: NEryu Guan <eguan@redhat.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

Install the callbacks via the state machine.
Signed-off-by: NSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Cc: linux-fsdevel@vger.kernel.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20161103145021.28528-2-bigeasy@linutronix.deSigned-off-by: NThomas Gleixner <tglx@linutronix.de>

Nobody is using this function anymore. Remove it.
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NJens Axboe <axboe@fb.com>

Add a helper function that clears buffer heads from a block device
aliasing passed bh. Use this helper function from filesystems instead of
the original unmap_underlying_metadata() to save some boiler plate code
and also have a better name for the functionalily since it is not
unmapping anything for a *long* time.
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NJens Axboe <axboe@fb.com>

Provide function equivalent to unmap_underlying_metadata() for a range
of blocks. We somewhat optimize the function to use pagevec lookups
instead of looking up buffer heads one by one and use page lock to pin
buffer heads instead of mapping's private_lock to improve scalability.
Signed-off-by: NJan Kara <jack@suse.cz>
Signed-off-by: NJens Axboe <axboe@fb.com>

Add wbc_to_write_flags(), which returns the write modifier flags to use,
based on a struct writeback_control. No functional changes in this
patch, but it prepares us for factoring other wbc fields for write type.
Signed-off-by: NJens Axboe <axboe@fb.com>
Reviewed-by: NJan Kara <jack@suse.cz>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

Remove the WRITE_* and READ_SYNC wrappers, and just use the flags
directly.  Where applicable this also drops usage of the
bio_set_op_attrs wrapper.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

Now that we don't need the common flags to overflow outside the range
of a 32-bit type we can encode them the same way for both the bio and
request fields.  This in addition allows us to place the operation
first (and make some room for more ops while we're at it) and to
stop having to shift around the operation values.

In addition this allows passing around only one value in the block layer
instead of two (and eventuall also in the file systems, but we can do
that later) and thus clean up a lot of code.

Last but not least this allows decreasing the size of the cmd_flags
field in struct request to 32-bits.  Various functions passing this
value could also be updated, but I'd like to avoid the churn for now.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NJens Axboe <axboe@fb.com>

The mapping_set_error() helper sets the correct AS_ flag for the mapping
so there is no reason to open code it.  Use the helper directly.

[akpm@linux-foundation.org: be honest about conversion from -ENXIO to -EIO]
Link: http://lkml.kernel.org/r/20160912111608.2588-2-mhocko@kernel.orgSigned-off-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

__getblk_slow() was exported to modules in commit 3b5e6454
("fs/buffer.c: support buffer cache allocations with gfp modifiers").
This seems to have been a mistake, as no users were introduced nor was
the function declared in a header.  Change it back to 'static'.
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

These two are confusing leftover of the old world order, combining
values of the REQ_OP_ and REQ_ namespaces.  For callers that don't
special case we mostly just replace bi_rw with bio_data_dir or
op_is_write, except for the few cases where a switch over the REQ_OP_
values makes more sense.  Any check for READA is replaced with an
explicit check for REQ_RAHEAD.  Also remove the READA alias for
REQ_RAHEAD.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: NMike Christie <mchristi@redhat.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

gfs2 needs to be able to skip the check to see if a page is outside of
the file size when writing it out. gfs2 can get into a situation where
it needs to flush its in-memory log to disk while a truncate is in
progress. If the file being trucated has data journaling enabled, it is
possible that there are data blocks in the log that are past the end of
the file. gfs can't finish the log flush without either writing these
blocks out or revoking them. Otherwise, if the node crashed, it could
overwrite subsequent changes made by other nodes in the cluster when
it's journal was replayed.

Unfortunately, there is no way to add log entries to the log during a
flush. So gfs2 simply writes out the page instead. This situation can
only occur when the truncate code still has the file locked exclusively,
and hasn't marked this block as free in the metadata (which happens
later in truc_dealloc).  After gfs2 writes this page out, the truncation
code will shortly invalidate it and write out any revokes if necessary.

In order to make this work, gfs2 needs to be able to skip the check for
writes outside the file size. Since the check exists in
block_write_full_page, this patch exports __block_write_full_page, which
doesn't have the check.
Signed-off-by: NBenjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: NBob Peterson <rpeterso@redhat.com>

Add infrastructure for multipage buffered writes.  This is implemented
using an main iterator that applies an actor function to a range that
can be written.

This infrastucture is used to implement a buffered write helper, one
to zero file ranges and one to implement the ->page_mkwrite VM
operations.  All of them borrow a fair amount of code from fs/buffers.
for now by using an internal version of __block_write_begin that
gets passed an iomap and builds the corresponding buffer head.

The file system is gets a set of paired ->iomap_begin and ->iomap_end
calls which allow it to map/reserve a range and get a notification
once the write code is finished with it.

Based on earlier code from Dave Chinner.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NBob Peterson <rpeterso@redhat.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>

This has ll_rw_block users pass in the operation and flags separately,
so ll_rw_block can setup the bio op and bi_rw flags on the bio that
is submitted.
Signed-off-by: NMike Christie <mchristi@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

This has submit_bh users pass in the operation and flags separately,
so submit_bh_wbc can setup the bio op and bi_rw flags on the bio that
is submitted.
Signed-off-by: NMike Christie <mchristi@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NHannes Reinecke <hare@suse.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

This has callers of submit_bio/submit_bio_wait set the bio->bi_rw
instead of passing it in. This makes that use the same as
generic_make_request and how we set the other bio fields.
Signed-off-by: NMike Christie <mchristi@redhat.com>

Fixed up fs/ext4/crypto.c
Signed-off-by: NJens Axboe <axboe@fb.com>

The allocator fast path looks up the first usable zone in a zonelist and
then get_page_from_freelist does the same job in the zonelist iterator.
This patch preserves the necessary information.

                                             4.6.0-rc2                  4.6.0-rc2
                                        fastmark-v1r20             initonce-v1r20
  Min      alloc-odr0-1               364.00 (  0.00%)           359.00 (  1.37%)
  Min      alloc-odr0-2               262.00 (  0.00%)           260.00 (  0.76%)
  Min      alloc-odr0-4               214.00 (  0.00%)           214.00 (  0.00%)
  Min      alloc-odr0-8               186.00 (  0.00%)           186.00 (  0.00%)
  Min      alloc-odr0-16              173.00 (  0.00%)           173.00 (  0.00%)
  Min      alloc-odr0-32              165.00 (  0.00%)           165.00 (  0.00%)
  Min      alloc-odr0-64              161.00 (  0.00%)           162.00 ( -0.62%)
  Min      alloc-odr0-128             159.00 (  0.00%)           161.00 ( -1.26%)
  Min      alloc-odr0-256             168.00 (  0.00%)           170.00 ( -1.19%)
  Min      alloc-odr0-512             180.00 (  0.00%)           181.00 ( -0.56%)
  Min      alloc-odr0-1024            190.00 (  0.00%)           190.00 (  0.00%)
  Min      alloc-odr0-2048            196.00 (  0.00%)           196.00 (  0.00%)
  Min      alloc-odr0-4096            202.00 (  0.00%)           202.00 (  0.00%)
  Min      alloc-odr0-8192            206.00 (  0.00%)           205.00 (  0.49%)
  Min      alloc-odr0-16384           206.00 (  0.00%)           205.00 (  0.49%)

The benefit is negligible and the results are within the noise but each
cycle counts.
Signed-off-by: NMel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time
ago with promise that one day it will be possible to implement page
cache with bigger chunks than PAGE_SIZE.

This promise never materialized.  And unlikely will.

We have many places where PAGE_CACHE_SIZE assumed to be equal to
PAGE_SIZE.  And it's constant source of confusion on whether
PAGE_CACHE_* or PAGE_* constant should be used in a particular case,
especially on the border between fs and mm.

Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much
breakage to be doable.

Let's stop pretending that pages in page cache are special.  They are
not.

The changes are pretty straight-forward:

 - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

 - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>;

 - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN};

 - page_cache_get() -> get_page();

 - page_cache_release() -> put_page();

This patch contains automated changes generated with coccinelle using
script below.  For some reason, coccinelle doesn't patch header files.
I've called spatch for them manually.

The only adjustment after coccinelle is revert of changes to
PAGE_CAHCE_ALIGN definition: we are going to drop it later.

There are few places in the code where coccinelle didn't reach.  I'll
fix them manually in a separate patch.  Comments and documentation also
will be addressed with the separate patch.

virtual patch

@@
expression E;
@@
- E << (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
expression E;
@@
- E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT)
+ E

@@
@@
- PAGE_CACHE_SHIFT
+ PAGE_SHIFT

@@
@@
- PAGE_CACHE_SIZE
+ PAGE_SIZE

@@
@@
- PAGE_CACHE_MASK
+ PAGE_MASK

@@
expression E;
@@
- PAGE_CACHE_ALIGN(E)
+ PAGE_ALIGN(E)

@@
expression E;
@@
- page_cache_get(E)
+ get_page(E)

@@
expression E;
@@
- page_cache_release(E)
+ put_page(E)
Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Now that migration doesn't clear page->mem_cgroup of live pages anymore,
it's safe to make lock_page_memcg() and the memcg stat functions take
pages, and spare the callers from memcg objects.

[akpm@linux-foundation.org: fix warnings]
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Suggested-by: NVladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: NVladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

These patches tag the page cache radix tree eviction entries with the
memcg an evicted page belonged to, thus making per-cgroup LRU reclaim
work properly and be as adaptive to new cache workingsets as global
reclaim already is.

This should have been part of the original thrash detection patch
series, but was deferred due to the complexity of those patches.

This patch (of 5):

So far the only sites that needed to exclude charge migration to
stabilize page->mem_cgroup have been per-cgroup page statistics, hence
the name mem_cgroup_begin_page_stat().  But per-cgroup thrash detection
will add another site that needs to ensure page->mem_cgroup lifetime.

Rename these locking functions to the more generic lock_page_memcg() and
unlock_page_memcg().  Since charge migration is a cgroup1 feature only,
we might be able to delete it at some point, and these now easy to
identify locking sites along with it.
Signed-off-by: NJohannes Weiner <hannes@cmpxchg.org>
Suggested-by: NVladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: NVladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

The function currently called "__block_page_mkwrite()" used to be called
"block_page_mkwrite()" until a wrapper for this function was added by:

commit 24da4fab ("vfs: Create __block_page_mkwrite() helper passing
	error values back")

This wrapper, the current "block_page_mkwrite()", is currently unused.
__block_page_mkwrite() is used directly by ext4, nilfs2 and xfs.

Remove the unused wrapper, rename __block_page_mkwrite() back to
block_page_mkwrite() and update the comment above block_page_mkwrite().
Signed-off-by: NRoss Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: NJan Kara <jack@suse.com>
Cc: Jan Kara <jack@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

There are many places which use mapping_gfp_mask to restrict a more
generic gfp mask which would be used for allocations which are not
directly related to the page cache but they are performed in the same
context.

Let's introduce a helper function which makes the restriction explicit and
easier to track.  This patch doesn't introduce any functional changes.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NMichal Hocko <mhocko@suse.com>
Suggested-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>