Re: [PATCH v2 2/3] fs: fold __generic_write_end back into generic_write_end

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Wed, Jun 26, 2019 at 03:23:34PM +0200, Andreas Gruenbacher wrote:
> From: Christoph Hellwig <hch@lst.de>
> 
> This effectively reverts a6d639da63ae ("fs: factor out a
> __generic_write_end helper") as we now open code what is left of that
> helper in iomap.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
>  fs/buffer.c   | 62 ++++++++++++++++++++++++---------------------------
>  fs/internal.h |  2 --
>  2 files changed, 29 insertions(+), 35 deletions(-)
> 
> diff --git a/fs/buffer.c b/fs/buffer.c
> index e450c55f6434..49a871570092 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -2086,38 +2086,6 @@ int block_write_begin(struct address_space *mapping, loff_t pos, unsigned len,
>  }
>  EXPORT_SYMBOL(block_write_begin);
>  
> -void __generic_write_end(struct inode *inode, loff_t pos, unsigned copied,
> -		struct page *page)
> -{
> -	loff_t old_size = inode->i_size;
> -	bool i_size_changed = false;
> -
> -	/*
> -	 * No need to use i_size_read() here, the i_size cannot change under us
> -	 * because we hold i_rwsem.
> -	 *
> -	 * But it's important to update i_size while still holding page lock:
> -	 * page writeout could otherwise come in and zero beyond i_size.
> -	 */
> -	if (pos + copied > inode->i_size) {
> -		i_size_write(inode, pos + copied);
> -		i_size_changed = true;
> -	}
> -
> -	unlock_page(page);
> -
> -	if (old_size < pos)
> -		pagecache_isize_extended(inode, old_size, pos);
> -	/*
> -	 * Don't mark the inode dirty under page lock. First, it unnecessarily
> -	 * makes the holding time of page lock longer. Second, it forces lock
> -	 * ordering of page lock and transaction start for journaling
> -	 * filesystems.
> -	 */
> -	if (i_size_changed)
> -		mark_inode_dirty(inode);
> -}
> -
>  int block_write_end(struct file *file, struct address_space *mapping,
>  			loff_t pos, unsigned len, unsigned copied,
>  			struct page *page, void *fsdata)
> @@ -2158,9 +2126,37 @@ int generic_write_end(struct file *file, struct address_space *mapping,
>  			loff_t pos, unsigned len, unsigned copied,
>  			struct page *page, void *fsdata)
>  {
> +	struct inode *inode = mapping->host;
> +	loff_t old_size = inode->i_size;
> +	bool i_size_changed = false;
> +
>  	copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
> -	__generic_write_end(mapping->host, pos, copied, page);
> +
> +	/*
> +	 * No need to use i_size_read() here, the i_size cannot change under us
> +	 * because we hold i_rwsem.
> +	 *
> +	 * But it's important to update i_size while still holding page lock:
> +	 * page writeout could otherwise come in and zero beyond i_size.
> +	 */
> +	if (pos + copied > inode->i_size) {
> +		i_size_write(inode, pos + copied);
> +		i_size_changed = true;
> +	}
> +
> +	unlock_page(page);
>  	put_page(page);
> +
> +	if (old_size < pos)
> +		pagecache_isize_extended(inode, old_size, pos);
> +	/*
> +	 * Don't mark the inode dirty under page lock. First, it unnecessarily
> +	 * makes the holding time of page lock longer. Second, it forces lock
> +	 * ordering of page lock and transaction start for journaling
> +	 * filesystems.
> +	 */
> +	if (i_size_changed)
> +		mark_inode_dirty(inode);
>  	return copied;
>  }
>  EXPORT_SYMBOL(generic_write_end);
> diff --git a/fs/internal.h b/fs/internal.h
> index a48ef81be37d..2f3c3de51fad 100644
> --- a/fs/internal.h
> +++ b/fs/internal.h
> @@ -40,8 +40,6 @@ static inline int __sync_blockdev(struct block_device *bdev, int wait)
>  extern void guard_bio_eod(int rw, struct bio *bio);
>  extern int __block_write_begin_int(struct page *page, loff_t pos, unsigned len,
>  		get_block_t *get_block, struct iomap *iomap);
> -void __generic_write_end(struct inode *inode, loff_t pos, unsigned copied,
> -		struct page *page);
>  
>  /*
>   * char_dev.c
> -- 
> 2.20.1
>