Re: [patch] ext2: xip check fix

On Wed, Dec 05, 2007 at 04:43:16PM +0100, Carsten Otte wrote:
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@xxxxxxx>
---
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.

You mean blocksize is the size of the ext2 block, and s_blocksize is the
default size of the block device.


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?

However, the bdev block size may be changed with sb_set_blocksize. It
doesn't actually have to match the hardware sector size -- if this
does matter for XIP, then I think you need some other check here.
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