linux-kernel - Re: [patch 6/8] fuse: clean up setting i

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Message-Id: <20080317220821.d0adb692.akpm@linux-foundation.org>
Date:	Mon, 17 Mar 2008 22:08:21 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-mm@...ck.org
Subject: Re: [patch 6/8] fuse: clean up setting i_size in write

On Mon, 17 Mar 2008 20:19:14 +0100 Miklos Szeredi <miklos@...redi.hu> wrote:

> From: Miklos Szeredi <mszeredi@...e.cz>
> 
> Extract common code for setting i_size in write functions into a
> common helper.
> 
> Signed-off-by: Miklos Szeredi <mszeredi@...e.cz>
> ---
>  fs/fuse/file.c |   28 +++++++++++++++-------------
>  1 file changed, 15 insertions(+), 13 deletions(-)
> 
> Index: linux/fs/fuse/file.c
> ===================================================================
> --- linux.orig/fs/fuse/file.c	2008-03-17 18:26:04.000000000 +0100
> +++ linux/fs/fuse/file.c	2008-03-17 18:26:28.000000000 +0100
> @@ -610,13 +610,24 @@ static int fuse_write_begin(struct file 
>  	return 0;
>  }
>  
> +static void fuse_write_update_size(struct inode *inode, loff_t pos)
> +{
> +	struct fuse_conn *fc = get_fuse_conn(inode);
> +	struct fuse_inode *fi = get_fuse_inode(inode);
> +
> +	spin_lock(&fc->lock);
> +	fi->attr_version = ++fc->attr_version;
> +	if (pos > inode->i_size)
> +		i_size_write(inode, pos);
> +	spin_unlock(&fc->lock);
> +}
>
> ...
>
> @@ -766,12 +772,8 @@ static ssize_t fuse_direct_io(struct fil
>  	}
>  	fuse_put_request(fc, req);
>  	if (res > 0) {
> -		if (write) {
> -			spin_lock(&fc->lock);
> -			if (pos > inode->i_size)
> -				i_size_write(inode, pos);
> -			spin_unlock(&fc->lock);
> -		}
> +		if (write)
> +			fuse_write_update_size(inode, pos);

We require that i_mutex be held here, to prevent i_size_write() deadlocks. 
Is it held?

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