linux-ext4 - Re: [PATCH] jbd2: avoid the concurrent data writeback

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Date:	Mon, 15 Nov 2010 06:27:32 -0500
From:	Christoph Hellwig <hch@...radead.org>
To:	Feng Tang <feng.tang@...el.com>
Cc:	"Wu, Fengguang" <fengguang.wu@...el.com>,
	"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
	"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] jbd2: avoid the concurrent data writeback

On Mon, Nov 15, 2010 at 05:59:43PM +0800, Feng Tang wrote:
> + *
> + * Sometimes when this get called, the host inode may be under data
> + * syncing initiated by flush thread(especially for a large file), and 
> + * in such situation, we should skip this path of writeback
>   */
>  static int journal_submit_inode_data_buffers(struct address_space *mapping)
>  {
> @@ -181,6 +185,13 @@ static int journal_submit_inode_data_buffers(struct address_space *mapping)
>  		.range_end = i_size_read(mapping->host),
>  	};
>  
> +	spin_lock(&inode_lock);
> +	if (mapping->host->i_state & I_SYNC) {
> +		spin_unlock(&inode_lock);
> +		return 0;
> +	}
> +	spin_unlock(&inode_lock);
> +

inode_lock is not exported to modules, and that's for a pretty good
reason.  I think you want to change this code at a higher level to not
compete with the flusher threads at all.

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