linux-kernel - Re: [patch] ext2: xip check fix

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Date:	Wed, 05 Dec 2007 16:43:16 +0100
From:	Carsten Otte <cotte@...ibm.com>
To:	Nick Piggin <npiggin@...e.de>
CC:	Christian Borntraeger <borntraeger@...ibm.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-fsdevel@...r.kernel.org,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Andrew Morton <akpm@...ux-foundation.org>, rob@...dley.net,
	Jens Axboe <axboe@...nel.dk>
Subject: Re: [patch] ext2: xip check fix

Nick Piggin wrote:
> Am I missing something here? I wonder how s390 works without this change?
> 
> --
> ext2 should not worry about checking sb->s_blocksize for XIP before the
> sb's blocksize actually gets set.
> 
> Signed-off-by: Nick Piggin <npiggin@...e.de>
> ---
> Index: linux-2.6/fs/ext2/super.c
> ===================================================================
> --- linux-2.6.orig/fs/ext2/super.c
> +++ linux-2.6/fs/ext2/super.c
> @@ -844,8 +844,7 @@ static int ext2_fill_super(struct super_
> 
>  	blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
> 
> -	if ((ext2_use_xip(sb)) && ((blocksize != PAGE_SIZE) ||
> -				  (sb->s_blocksize != blocksize))) {
> +	if (ext2_use_xip(sb) && blocksize != PAGE_SIZE) {
>  		if (!silent)
>  			printk("XIP: Unsupported blocksize\n");
>  		goto failed_mount;
"blocksize" contains the blocksize of the device here, and 
sb->s_blocksize does contain the filesystem block size as saved in the 
super block. Xip does only work, if both do match PAGE_SIZE because it 
does'nt support multiple calls to direct_access in the get_xip_page 
address space operation. Thus we check both here, actually this was 
changed from how it looks after your patch as a bugfix where our 
tester tried a 4k filesystem on a 2k blockdev.
Did I miss something?
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