linux-ext4 - Re: [PATCH 6/7] ext4: endless truncate due to nonlocked dio readers V2

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Date:	Thu, 13 Sep 2012 18:41:36 +0800
From:	Zheng Liu <gnehzuil.liu@...il.com>
To:	Dmitry Monakhov <dmonakhov@...nvz.org>
Cc:	linux-ext4@...r.kernel.org, tytso@....edu, jack@...e.cz,
	wenqing.lz@...bao.com
Subject: Re: [PATCH 6/7] ext4: endless truncate due to nonlocked dio readers
 V2

Hi Dmitry,

Could you please provide more detailed workload to convince me?  I
am thinking about whether we really need to disable dioread_nolock
feature in here.  In our benchmarks, we don't see this problem.

Regards,
Zheng

On Sun, Sep 09, 2012 at 09:27:13PM +0400, Dmitry Monakhov wrote:
> If we have enough aggressive DIO readers, truncate and other dio
> waiters will wait forever inside inode_dio_wait(). It is reasonable
> to disable nonlock DIO read optimization during truncate.
> 
> Signed-off-by: Dmitry Monakhov <dmonakhov@...nvz.org>
> ---
>  fs/ext4/extents.c |    2 +-
>  fs/ext4/fsync.c   |    2 +-
>  fs/ext4/inode.c   |    2 +-
>  3 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 8252651..b5b801f 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -4853,7 +4853,7 @@ int ext4_ext_punch_hole(struct file *file, loff_t offset, loff_t length)
>  	}
>  
>  	/* finish any pending end_io work */
> -	inode_dio_wait(inode);
> +	ext4_inode_dio_wait(inode, 1);
>  	ext4_flush_completed_IO(inode);
>  
>  	credits = ext4_writepage_trans_blocks(inode);
> diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
> index 290c5cf..bdf6bfd 100644
> --- a/fs/ext4/fsync.c
> +++ b/fs/ext4/fsync.c
> @@ -204,7 +204,7 @@ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
>  	if (inode->i_sb->s_flags & MS_RDONLY)
>  		goto out;
>  
> -	inode_dio_wait(inode);
> +	ext4_inode_dio_wait(inode, 1);
>  	ret = ext4_flush_completed_IO(inode);
>  	if (ret < 0)
>  		goto out;
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 93e6b09..a850026 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -4335,7 +4335,7 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
>  			truncate_setsize(inode, attr->ia_size);
>  			/* Inode size will be reduced, wait for dio in flight */
>  			if (orphan)
> -				inode_dio_wait(inode);
> +				ext4_inode_dio_wait(inode, 1);
>  		}
>  		ext4_truncate(inode);
>  	}
> -- 
> 1.7.7.6
> 
> --
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