On 01/31/2014 11:02 AM, James Bottomley wrote: > 3. Increase pgoff_t and the radix tree indexes to u64 for > CONFIG_LBDAF. This will blow out the size of struct page on 32 > bits by 4 bytes and may have other knock on effects, but at > least it will be transparent. I'm not sure how many acrobatics we want to go through for 32-bit, but... Between page->mapping and page->index, we have 64 bits of space, which *should* be plenty to uniquely identify a block. We could easily add a second-level lookup somewhere so that we store some cookie for the address_space instead of a direct pointer. How many devices would need, practically? 8 bits worth? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>