linux-kernel - Re: ext3: bogus i_mode errors with 2.6.18.1

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Message-ID: <20061028142454.GA6182@schatzie.adilger.int>
Date:	Sat, 28 Oct 2006 22:24:54 +0800
From:	Andreas Dilger <adilger@...sterfs.com>
To:	Andre Noll <maan@...temlinux.org>
Cc:	Theodore Ts'o <tytso@....edu>, linux-kernel@...r.kernel.org,
	linux-ext4@...r.kernel.org, Eric Sandeen <esandeen@...hat.com>
Subject: Re: ext3: bogus i_mode errors with 2.6.18.1

On Oct 27, 2006  17:34 +0200, Andre Noll wrote:
> On 12:01, Andreas Dilger wrote:
> > Well, since we know at least one bit needs fixing and results in the block
> > being written to disk then setting the bits for all of the other metadata
> > blocks in this group has no extra IO cost (only a tiny amount of CPU).
> > Re-setting the bits if they are already set is not harmful.
> 
> I.e, something like
> 
>         int i;
>         ext3_fsblk_t bit;
>         unsigned long gdblocks = EXT3_SB(sb)->s_gdb_count;
> 
>         for (i = 0, bit = 1; i < gdblocks; i++, bit++)
>                 ext3_set_bit(bit, gdp_bh->b_data);
> 
> Is that correct?

Well, it needs to also handle backup superblock, bitmaps, inode table:

	if (ext3_bg_has_super())
		ext3_set_bit(0, gdp_bh->b_data);
	gdblocks = ext3_bg_num_gdb(sb, group);
	for (i = 0, bit = 1; i < gdblocks; i++, bit++)
		/* actually a bit more complex for INCOMPAT_META_BG fs */
		ext3_set_bit(i, gdp_bh->b_data);
	ext3_set_bit(gdp->bg_inode_bitmap % EXT3_BLOCKS_PER_GROUP(sb), ...);
	ext3_set_bit(gdp->bg_block_bitmap % EXT3_BLOCKS_PER_GROUP(sb), ...);
	for (i = 0, bit = gdp->bg_inode_table % EXT3_BLOCKS_PER_GROUP(sb);
	     i < EXT3_SB(sb)->s_itb_per_group; i++, bit++)
		ext3_set_bit(i, gdp_bh->b_data);
		
(or something close to this).

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

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