linux-kernel - Re: [PATCH 4/9] iomap: Use bitmap ops to set uptodate bits

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Message-ID: <20200825205034.GI6096@magnolia>
Date:   Tue, 25 Aug 2020 13:50:34 -0700
From:   "Darrick J. Wong" <darrick.wong@...cle.com>
To:     "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc:     linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-nvdimm@...ts.01.org, linux-kernel@...r.kernel.org,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH 4/9] iomap: Use bitmap ops to set uptodate bits

On Mon, Aug 24, 2020 at 03:55:05PM +0100, Matthew Wilcox (Oracle) wrote:
> Now that the bitmap is protected by a spinlock, we can use the
> more efficient bitmap ops instead of individual test/set bit ops.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> Reviewed-by: Christoph Hellwig <hch@....de>

Yay!
Reviewed-by: Darrick J. Wong <darrick.wong@...cle.com>

--D

> ---
>  fs/iomap/buffered-io.c | 12 ++----------
>  1 file changed, 2 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index 639d54a4177e..dbf9572dabe9 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -134,19 +134,11 @@ iomap_iop_set_range_uptodate(struct page *page, unsigned off, unsigned len)
>  	struct inode *inode = page->mapping->host;
>  	unsigned first = off >> inode->i_blkbits;
>  	unsigned last = (off + len - 1) >> inode->i_blkbits;
> -	bool uptodate = true;
>  	unsigned long flags;
> -	unsigned int i;
>  
>  	spin_lock_irqsave(&iop->uptodate_lock, flags);
> -	for (i = 0; i < i_blocks_per_page(inode, page); i++) {
> -		if (i >= first && i <= last)
> -			set_bit(i, iop->uptodate);
> -		else if (!test_bit(i, iop->uptodate))
> -			uptodate = false;
> -	}
> -
> -	if (uptodate)
> +	bitmap_set(iop->uptodate, first, last - first + 1);
> +	if (bitmap_full(iop->uptodate, i_blocks_per_page(inode, page)))
>  		SetPageUptodate(page);
>  	spin_unlock_irqrestore(&iop->uptodate_lock, flags);
>  }
> -- 
> 2.28.0
>