linux-ext4 - Re: [PATCH 2/2] ext4: Remove code duplication in ext4_get_block_write

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Date:	Fri, 9 Nov 2012 12:29:57 -0500
From:	Theodore Ts'o <tytso@....edu>
To:	Anatol Pomozov <anatol.pomozov@...il.com>
Cc:	wenqing.lz@...bao.com, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 2/2] ext4: Remove code duplication in
 ext4_get_block_write_nolock()

There's a really serious bug in this patch which I didn't notice at
first:

> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -683,7 +683,7 @@ static int _ext4_get_block(struct inode *inode, sector_t iblock,
>  	map.m_lblk = iblock;
>  	map.m_len = bh->b_size >> inode->i_blkbits;
>  
> -	if (flags && !handle) {
> +	if (flags && !(flags | EXT4_GET_BLOCKS_NO_LOCK) && !handle) {
                            ^^^

This should obviously read:

	if (flags && !(flags & EXT4_GET_BLOCKS_NO_LOCK) && !handle) {

Otherwise xfstests #91 will blow out with a circular lockdep warning.

As a reminder, please do make sure you compile with lockdep enabled
when you run your tests; it's found more than one bug for me!

     	     	  	      	    	      - Ted
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