Re: [PATCH 4/9] 48bit support in extents

From: Andrew Morton
Date: Thu Aug 10 2006 - 02:38:47 EST

On Wed, 09 Aug 2006 18:21:13 -0700
Mingming Cao <cmm@xxxxxxxxxx> wrote:

> +/* this macro combines low and hi parts of phys. blocknr into ext4_fsblk_t */

This isn't a macro.

> +static inline ext4_fsblk_t ext_pblock(struct ext4_extent *ex)
> +{
> + ext4_fsblk_t block;
> +
> + block = le32_to_cpu(ex->ee_start);
> + if (sizeof(ext4_fsblk_t) > 4)
> + block |= ((ext4_fsblk_t) le16_to_cpu(ex->ee_start_hi) << 31) << 1;
> + return block;
> +}

Oh. I see the other patch did

typedef sector_t ext4_fs_block_t;

(except someone misspelled "block" as "blk" ;))

Do we really want to do this? I guess there's some value, for people with
32-bit machines who want extents and who are too mean to use a 64-bit
sector_t. But gee that's marginal. And it introduces interesting
compatibility questions and significantly adds to the testing burden.

I think that requiring 64-bit sector_t is reasonable?

Then again, I see from the other patches that considerable thought and
effort has gone into sustaining this turkey, so I guess I'm missing
something again.

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