Ming, I'm traveling today and probably won't be able to take a closer look until tomorrow. But from a quick glance this looks OK. > The integrity buffer can't be very big, for example, the max sectors > for one bio is 2560, one sector may take at most 8bytes for integrity > info, so the max size of integrity buffer is just 20k(<=5 pages). Just a comment on your rationale about 5 pages. buffer_head submissions have traditionally been small, and depending on your choice of allocator, new allocations would grow backwards in memory. So there were several common I/O patterns that produced a single, non-mergeable 8 byte integrity metadata allocation for every 512 bytes of data in the I/O. It's a pathological corner case. Just make sure it's something you handle when you muck with this. ext[23] and dd to the block device used to be able to reproduce this scenario easily. -- Martin K. Petersen Oracle Linux Engineering
