linux-kernel - Re: [PATCH v5 12/17] dax: add dax_iomap

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Message-ID: <20161011070629.GD6952@quack2.suse.cz>
Date:   Tue, 11 Oct 2016 09:06:29 +0200
From:   Jan Kara <jack@...e.cz>
To:     Ross Zwisler <ross.zwisler@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org, Theodore Ts'o <tytso@....edu>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Hellwig <hch@....de>,
        Dan Williams <dan.j.williams@...el.com>,
        Dave Chinner <david@...morbit.com>, Jan Kara <jack@...e.com>,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org, linux-nvdimm@...ts.01.org,
        linux-xfs@...r.kernel.org
Subject: Re: [PATCH v5 12/17] dax: add dax_iomap_sector() helper function

On Fri 07-10-16 15:08:59, Ross Zwisler wrote:
> To be able to correctly calculate the sector from a file position and a
> struct iomap there is a complex little bit of logic that currently happens
> in both dax_iomap_actor() and dax_iomap_fault().  This will need to be
> repeated yet again in the DAX PMD fault handler when it is added, so break
> it out into a helper function.
> 
> Signed-off-by: Ross Zwisler <ross.zwisler@...ux.intel.com>

Looks good. You can add:

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

								Honza

> ---
>  fs/dax.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/dax.c b/fs/dax.c
> index 982ccbb..7689ab0 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -1023,6 +1023,11 @@ int dax_truncate_page(struct inode *inode, loff_t from, get_block_t get_block)
>  EXPORT_SYMBOL_GPL(dax_truncate_page);
>  
>  #ifdef CONFIG_FS_IOMAP
> +static inline sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos)
> +{
> +	return iomap->blkno + (((pos & PAGE_MASK) - iomap->offset) >> 9);
> +}
> +
>  static loff_t
>  dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
>  		struct iomap *iomap)
> @@ -1048,8 +1053,7 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
>  		struct blk_dax_ctl dax = { 0 };
>  		ssize_t map_len;
>  
> -		dax.sector = iomap->blkno +
> -			(((pos & PAGE_MASK) - iomap->offset) >> 9);
> +		dax.sector = dax_iomap_sector(iomap, pos);
>  		dax.size = (length + offset + PAGE_SIZE - 1) & PAGE_MASK;
>  		map_len = dax_map_atomic(iomap->bdev, &dax);
>  		if (map_len < 0) {
> @@ -1186,7 +1190,7 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
>  		goto unlock_entry;
>  	}
>  
> -	sector = iomap.blkno + (((pos & PAGE_MASK) - iomap.offset) >> 9);
> +	sector = dax_iomap_sector(&iomap, pos);
>  
>  	if (vmf->cow_page) {
>  		switch (iomap.type) {
> -- 
> 2.7.4
> 
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR