linux-kernel - Re: [patch -next] ext4: locking issue on error path

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Message-ID: <20120717081351.GA4513@gmail.com>
Date:	Tue, 17 Jul 2012 16:13:51 +0800
From:	Zheng Liu <gnehzuil.liu@...il.com>
To:	Dan Carpenter <dan.carpenter@...cle.com>
Cc:	Theodore Ts'o <tytso@....edu>, Zheng Liu <wenqing.lz@...bao.com>,
	Andreas Dilger <adilger.kernel@...ger.ca>,
	linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: [patch -next] ext4: locking issue on error path

On Tue, Jul 17, 2012 at 09:31:06AM +0300, Dan Carpenter wrote:
> We recently changed how the locking worked here, but this error path was
> missed.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>

Sorry, it is my fault.  Thanks for pointing out this bug.

Regards,
Zheng

> 
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 8c84070..2728fb7 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -3031,8 +3031,10 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
>  		if (!is_sync_kiocb(iocb)) {
>  			ext4_io_end_t *io_end =
>  				ext4_init_io_end(inode, GFP_NOFS);
> -			if (!io_end)
> -				return -ENOMEM;
> +			if (!io_end) {
> +				ret = -ENOMEM;
> +				goto retake_lock;
> +			}
>  			io_end->flag |= EXT4_IO_END_DIRECT;
>  			iocb->private = io_end;
>  			/*
> @@ -3094,6 +3096,7 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
>  			ext4_clear_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
>  		}
>  
> +retake_lock:
>  		/* take i_mutex locking again if we do a ovewrite dio */
>  		if (overwrite) {
>  			up_read(&EXT4_I(inode)->i_data_sem);
> --
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