On Fri, Dec 06, 2019 at 04:55:43PM +0800, Liang Chen wrote: > __write_super assumes super block data starts at offset 0 of the page > read in with __bread from read_super, which is not true when page size > is not 4k. We encountered the issue on system with 64K page size - commonly > seen on aarch64 architecture. > > Instead of making any assumption on the offset of the data within the page, > this patch calls __bread again to locate the data. That should not introduce > an extra io since the page has been held when it's read in from read_super, > and __write_super is not on performance critical code path. No need to use buffer heads here, you can just use offset_in_page to calculate the offset. Similarly I think the read side shouldn't use buffer heads either (it is the only use of buffer heads in bcache!), a siple read_cache_page should be all that is needed.
