linux-ext4 - Re: [PATCH 08/51] mke2fs: Allow metadata checksums to be turned on at mkfs time

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Date:	Mon, 19 Dec 2011 08:59:51 -0800
From:	"Darrick J. Wong" <djwong@...ibm.com>
To:	Andreas Dilger <adilger.kernel@...ger.ca>
Cc:	Theodore Tso <tytso@....edu>,
	Sunil Mushran <sunil.mushran@...cle.com>,
	Amir Goldstein <amir73il@...il.com>,
	Andi Kleen <andi@...stfloor.org>,
	Mingming Cao <cmm@...ibm.com>,
	Joel Becker <jlbec@...lplan.org>, linux-ext4@...r.kernel.org,
	Coly Li <colyli@...il.com>
Subject: Re: [PATCH 08/51] mke2fs: Allow metadata checksums to be turned on
	at mkfs time

On Mon, Dec 19, 2011 at 11:28:44AM +0100, Andreas Dilger wrote:
> On 2011-12-14, at 2:14 AM, Darrick J. Wong wrote:
> > Write out checksummed inodes even when writing out a zeroed table.
> 
> Looking at the code, this is only writing out checksummed inodes
> for the reserved inodes, not all of them, right?  Otherwise, going
> back to writing out the whole inode table would be really slowing
> down mke2fs compared to lazy_itable_init.

Assuming that the inodes numbered less than EXT2_FIRST_INO are reserved, then
yes it should be only writing reserved inodes (unless the user forces mkfs to
write all inodes).

--D
> 
> > diff --git a/misc/mke2fs.c b/misc/mke2fs.c
> > index 0ef2531..98af8b0 100644
> > --- a/misc/mke2fs.c
> > +++ b/misc/mke2fs.c
> > @@ -305,6 +305,27 @@ _("Warning: the backup superblock/group descriptors at block %u contain\n"
> > 	ext2fs_badblocks_list_iterate_end(bb_iter);
> > }
> > 
> > +static void write_reserved_inodes(ext2_filsys fs)
> > +{
> > +	errcode_t	retval;
> > +	ext2_ino_t	ino;
> > +	struct ext2_inode *inode;
> > +
> > +	retval = ext2fs_get_mem(EXT2_INODE_SIZE(fs->super), &inode);
> > +	if (retval) {
> > +		com_err("inode_init", retval,
> > +			"while allocating memory");
> > +		exit(1);
> > +	}
> > +	bzero(inode, EXT2_INODE_SIZE(fs->super));
> > +
> > +	for (ino = 1; ino < EXT2_FIRST_INO(fs->super); ino++)
> > +		ext2fs_write_inode_full(fs, ino, inode,
> > +					EXT2_INODE_SIZE(fs->super));
> > +
> > +	ext2fs_free_mem(&inode);
> > +}
> > +
> > static void write_inode_tables(ext2_filsys fs, int lazy_flag, int itable_zeroed)
> > {
> > 	errcode_t	retval;
> > @@ -350,6 +371,12 @@ static void write_inode_tables(ext2_filsys fs, int lazy_flag, int itable_zeroed)
> > 	ext2fs_zero_blocks2(0, 0, 0, 0, 0);
> > 	ext2fs_numeric_progress_close(fs, &progress,
> > 				      _("done                            \n"));
> > +
> > +	/* Reserved inodes must always have correct checksums */
> > +	if (fs->super->s_creator_os == EXT2_OS_LINUX &&
> > +	    fs->super->s_feature_ro_compat &
> > +	    EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)
> > +		write_reserved_inodes(fs);
> 
> > }
> 
> 
> Cheers, Andreas
> 
> 
> 
> 
> 

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