Re: [PATCH 4.19 067/105] ext4: protect journal inodes blocks using block_validity

[Greg Kroah-Hartman]

On Wed, May 22, 2019 at 11:18:59AM +0200, Pavel Machek wrote:
> On Mon 2019-05-20 14:14:13, Greg Kroah-Hartman wrote:
> > From: Theodore Ts'o <tytso@xxxxxxx>
> > 
> > commit 345c0dbf3a30872d9b204db96b5857cd00808cae upstream.
> > 
> > Add the blocks which belong to the journal inode to block_validity's
> > system zone so attempts to deallocate or overwrite the journal due a
> > corrupted file system where the journal blocks are also claimed by
> > another inode.
> > 
> > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=202879
> > Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
> > Cc: stable@xxxxxxxxxx
> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> 
> > +static int ext4_protect_reserved_inode(struct super_block *sb, u32 ino)
> > +{
> > +	struct inode *inode;
> > +	struct ext4_sb_info *sbi = EXT4_SB(sb);
> > +	struct ext4_map_blocks map;
> > +	u32 i = 0, err = 0, num, n;
> > +
> > +	if ((ino < EXT4_ROOT_INO) ||
> > +	    (ino > le32_to_cpu(sbi->s_es->s_inodes_count)))
> > +		return -EINVAL;
> > +	inode = ext4_iget(sb, ino, EXT4_IGET_SPECIAL);
> > +	if (IS_ERR(inode))
> > +		return PTR_ERR(inode);
> > +	num = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
> > +	while (i < num) {
> > +		map.m_lblk = i;
> > +		map.m_len = num - i;
> > +		n = ext4_map_blocks(NULL, inode, &map, 0);
> > +		if (n < 0) {
> > +			err = n;
> > +			break;
> > +		}
> 
> n is unsigned, so this can not happen. Commit 102/ actually fixes this
> up. Should they be merged together?

No, we keep things identical to how they are upstream, otherwise it is
impossible to keep track of what happened here.

This patch, and 2 others were dropped anyway, so you don't have to worry
about it :)

greg k-h