linux-kernel - Re: [PATCH v5 05/78] xarray: Replace exceptional entries

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Date:   Tue, 26 Dec 2017 20:15:42 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     linux-kernel@...r.kernel.org,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        Ross Zwisler <ross.zwisler@...ux.intel.com>,
        David Howells <dhowells@...hat.com>,
        Shaohua Li <shli@...nel.org>, Jens Axboe <axboe@...nel.dk>,
        Rehas Sachdeva <aquannie@...il.com>,
        Marc Zyngier <marc.zyngier@....com>, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-nilfs@...r.kernel.org, linux-btrfs@...r.kernel.org,
        linux-xfs@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-raid@...r.kernel.org
Subject: Re: [PATCH v5 05/78] xarray: Replace exceptional entries

On Fri, Dec 15, 2017 at 02:03:37PM -0800, Matthew Wilcox wrote:
> From: Matthew Wilcox <mawilcox@...rosoft.com>
> 
> Introduce xarray value entries to replace the radix tree exceptional
> entry code.  This is a slight change in encoding to allow the use of an
> extra bit (we can now store BITS_PER_LONG - 1 bits in a value entry).
> It is also a change in emphasis; exceptional entries are intimidating
> and different.  As the comment explains, you can choose to store values
> or pointers in the xarray and they are both first-class citizens.
> 
> Signed-off-by: Matthew Wilcox <mawilcox@...rosoft.com>
> ---
>  arch/powerpc/include/asm/book3s/64/pgtable.h    |   4 +-
>  arch/powerpc/include/asm/nohash/64/pgtable.h    |   4 +-
>  drivers/gpu/drm/i915/i915_gem.c                 |  17 ++--
>  drivers/staging/lustre/lustre/mdc/mdc_request.c |   2 +-
>  fs/btrfs/compression.c                          |   2 +-
>  fs/btrfs/inode.c                                |   4 +-
>  fs/dax.c                                        | 115 ++++++++++++------------
>  fs/proc/task_mmu.c                              |   2 +-
>  include/linux/fs.h                              |  48 ++++++----
>  include/linux/radix-tree.h                      |  36 ++------
>  include/linux/swapops.h                         |  19 ++--
>  include/linux/xarray.h                          |  40 +++++++++
>  lib/idr.c                                       |  63 ++++++-------
>  lib/radix-tree.c                                |  21 ++---
>  mm/filemap.c                                    |  10 +--
>  mm/khugepaged.c                                 |   2 +-
>  mm/madvise.c                                    |   2 +-
>  mm/memcontrol.c                                 |   2 +-
>  mm/mincore.c                                    |   2 +-
>  mm/readahead.c                                  |   2 +-
>  mm/shmem.c                                      |  10 +--
>  mm/swap.c                                       |   2 +-
>  mm/truncate.c                                   |  12 +--
>  mm/workingset.c                                 |  12 ++-
>  tools/testing/radix-tree/idr-test.c             |   6 +-
>  tools/testing/radix-tree/linux/radix-tree.h     |   1 +
>  tools/testing/radix-tree/multiorder.c           |  47 +++++-----
>  tools/testing/radix-tree/test.c                 |   2 +-
>  28 files changed, 249 insertions(+), 240 deletions(-)

Everything looks fine to me after quick scan, but hat's a lot of changes for
one patch...

> @@ -565,7 +565,7 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping,
>  			if (index > end)
>  				break;
>  
> -			if (radix_tree_exceptional_entry(page)) {
> +			if (xa_is_value(page)) {
>  				invalidate_exceptional_entry(mapping, index,
>  							     page);
>  				continue;
> @@ -696,7 +696,7 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
>  			if (index > end)
>  				break;
>  
> -			if (radix_tree_exceptional_entry(page)) {
> +			if (xa_is_value(page)) {
>  				if (!invalidate_exceptional_entry2(mapping,
>  								   index, page))
>  					ret = -EBUSY;

invalidate_exceptional_entry? Are we going to leave the terminology here as is?

-- 
 Kirill A. Shutemov