[Ocfs2-tools-devel] [PATCH 5/6] fsck.ocfs2: Use the I/O cache.

[Tao Ma]

Hi Joel,
	The patch set looks good to me. Just one qs.
Joel Becker wrote:
> +static void o2fsck_init_cache(o2fsck_state *ost, enum o2fsck_cache_hint hint)
> +{
> +	errcode_t ret;
> +	uint64_t blocks_wanted;
> +	int leave_room;
> +	ocfs2_filesys *fs = ost->ost_fs;
> +	int max_slots = OCFS2_RAW_SB(fs->fs_super)->s_max_slots;
> +
> +	switch (hint) {
> +		case O2FSCK_CACHE_MODE_FULL:
> +			leave_room = 1;
> +			blocks_wanted = fs->fs_blocks;
> +			break;
> +		case O2FSCK_CACHE_MODE_JOURNAL:
> +			/*
> +			 * We need enough blocks for all the journal
> +			 * data.  Let's guess at 256M journals.
> +			 */
> +			leave_room = 0;
> +			blocks_wanted = ocfs2_blocks_in_bytes(fs,
> +					max_slots * 1024 * 1024 * 256);
> +			break;
> +		case O2FSCK_CACHE_MODE_NONE:
> +			return;
> +		default:
> +			assert(0);
> +	}
why we need max_slot * 256MB cache for the journal check?
I just went through the code and can't see we will use these journal 
files in the same time.

o2fsck_check_journals only check the journal header(it doesn't read the 
file content here, so the cache isn't filled) and make_journal if it is 
corrupted(well, here we may fill the cache in write_block, but they will 
never be used in replay since they are empty).

maybe_replay_journals will iterate the journal file one by one.

btw, I also think of wether we can add some flag in write_block saying 
that "don't fill in cache please. It will never be used again." For 
make_journal case, it is very useful.
Regards,
Tao