[Ocfs2-tools-devel] Add compress dirs option in fsck.ocfs2

[Joel Becker]

On Mon, Aug 31, 2009 at 06:47:00PM -0500, Goldwyn Rodrigues wrote:
> @@ -804,8 +807,29 @@ static unsigned pass2_dir_block_iterate(o2fsck_dirblock_entry *dbe,
>  				dirent->name, (uint64_t)dirent->inode);
>  		o2fsck_icount_delta(dd->ost->ost_icount_refs, dirent->inode, 1);
>  next:
> -		offset += dirent->rec_len;
> +		saved_reclen = dirent->rec_len;
> +		if (dd->ost->ost_compress_dirs) {
> +			if (prev && prev->inode) {
> +				/*Bring previous rec_len to required space */
> +				prev->rec_len = OCFS2_DIR_REC_LEN(prev->name_len);
> +				write_off += prev->rec_len;
> +			}
> +			if (write_off < offset) {
> +				verbosef("ino: %llu woff: %u off: %u\n",
> +					dirent->inode, write_off, offset);
> +				memmove(dd->dirblock_buf + write_off,
> +					dd->dirblock_buf + offset,
> +					OCFS2_DIR_REC_LEN(dirent->name_len));
> +				dirent = (struct ocfs2_dir_entry *)(dd->dirblock_buf + write_off);
> +				/* Cover space from our new location to
> +				* the next dirent */
> +				dirent->rec_len = saved_reclen + offset - write_off;
> +
> +				ret_flags |= OCFS2_DIRENT_CHANGED;
> +			}
> +		}
>  		prev = dirent;
> +		offset += saved_reclen;
>  	}

	Two things.  First, what about empty records?  Imagine you've
just seen a dirent, set its rec_len to saved_reclen+offset-write_off.
You set prev=dirent.  Then next pass is a deleted dirent, dirent->inode
= 0.  You skip this block and set prev=dirent.  Then you come to another
valid dirent.  However, prev->inode is zero, and so you won't update the
first dirent's rec_len, nor will you update write_off correctly.
	Second thing, when you reach the end of the block there is no
guarantee the last dirent->rec_len covers the entire block.  It will if
it was the last dirent, but not if there were empty ones after it.

Joel

-- 

Life's Little Instruction Book #337

	"Reread your favorite book."

Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker at oracle.com
Phone: (650) 506-8127