linux-ext4 - Re: [PATCH v4 4/5] dax: remove DAX code from page_cache_tree

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Date:   Mon, 24 Jul 2017 13:47:38 +0200
From:   Jan Kara <jack@...e.cz>
To:     Ross Zwisler <ross.zwisler@...ux.intel.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org,
        "Darrick J. Wong" <darrick.wong@...cle.com>,
        Theodore Ts'o <tytso@....edu>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Christoph Hellwig <hch@....de>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Chinner <david@...morbit.com>,
        David Airlie <airlied@...ux.ie>,
        Ingo Molnar <mingo@...hat.com>,
        Inki Dae <inki.dae@...sung.com>, Jan Kara <jack@...e.cz>,
        Jonathan Corbet <corbet@....net>,
        Joonyoung Shim <jy0922.shim@...sung.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Kukjin Kim <kgene@...nel.org>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        Patrik Jakobsson <patrik.r.jakobsson@...il.com>,
        Rob Clark <robdclark@...il.com>,
        Seung-Woo Kim <sw0312.kim@...sung.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Tomi Valkeinen <tomi.valkeinen@...com>,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, linux-doc@...r.kernel.org,
        linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org, linux-nvdimm@...ts.01.org,
        linux-samsung-soc@...r.kernel.org, linux-xfs@...r.kernel.org
Subject: Re: [PATCH v4 4/5] dax: remove DAX code from page_cache_tree_insert()

On Fri 21-07-17 16:39:54, Ross Zwisler wrote:
> Now that we no longer insert struct page pointers in DAX radix trees we can
> remove the special casing for DAX in page_cache_tree_insert().  This also
> allows us to make dax_wake_mapping_entry_waiter() local to fs/dax.c,
> removing it from dax.h.
> 
> Signed-off-by: Ross Zwisler <ross.zwisler@...ux.intel.com>
> Suggested-by: Jan Kara <jack@...e.cz>

Looks good. You can add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza


> ---
>  fs/dax.c            |  2 +-
>  include/linux/dax.h |  2 --
>  mm/filemap.c        | 13 ++-----------
>  3 files changed, 3 insertions(+), 14 deletions(-)
> 
> diff --git a/fs/dax.c b/fs/dax.c
> index fb0e4c1..0e27d90 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -127,7 +127,7 @@ static int wake_exceptional_entry_func(wait_queue_entry_t *wait, unsigned int mo
>   * correct waitqueue where tasks might be waiting for that old 'entry' and
>   * wake them.
>   */
> -void dax_wake_mapping_entry_waiter(struct address_space *mapping,
> +static void dax_wake_mapping_entry_waiter(struct address_space *mapping,
>  		pgoff_t index, void *entry, bool wake_all)
>  {
>  	struct exceptional_entry_key key;
> diff --git a/include/linux/dax.h b/include/linux/dax.h
> index 29cced8..afa99bb 100644
> --- a/include/linux/dax.h
> +++ b/include/linux/dax.h
> @@ -122,8 +122,6 @@ int dax_iomap_fault(struct vm_fault *vmf, enum page_entry_size pe_size,
>  int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index);
>  int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
>  				      pgoff_t index);
> -void dax_wake_mapping_entry_waiter(struct address_space *mapping,
> -		pgoff_t index, void *entry, bool wake_all);
>  
>  #ifdef CONFIG_FS_DAX
>  int __dax_zero_page_range(struct block_device *bdev,
> diff --git a/mm/filemap.c b/mm/filemap.c
> index a497024..1bf1265 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -130,17 +130,8 @@ static int page_cache_tree_insert(struct address_space *mapping,
>  			return -EEXIST;
>  
>  		mapping->nrexceptional--;
> -		if (!dax_mapping(mapping)) {
> -			if (shadowp)
> -				*shadowp = p;
> -		} else {
> -			/* DAX can replace empty locked entry with a hole */
> -			WARN_ON_ONCE(p !=
> -				dax_radix_locked_entry(0, RADIX_DAX_EMPTY));
> -			/* Wakeup waiters for exceptional entry lock */
> -			dax_wake_mapping_entry_waiter(mapping, page->index, p,
> -						      true);
> -		}
> +		if (shadowp)
> +			*shadowp = p;
>  	}
>  	__radix_tree_replace(&mapping->page_tree, node, slot, page,
>  			     workingset_update_node, mapping);
> -- 
> 2.9.4
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR