On Thu, Nov 29, 2012 at 2:16 PM, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > But you're right. The direct-IO code really *is* violating that, and > knows that get_block() ends up being defined in i_blkbits regardless > of b_size. It turns out fs/ioctl.c does the same - it fills in the buffer head with some random bh->b_size too. I think it's not even a power of two in that case. And I guess it's understandable - they don't actually *use* the buffer, they just want the offset. So the b_size field really is just random crap to the users of the get_block interfaces, since they've never cared before. Ugh, this was definitely a dark and disgusting underbelly of the VFS layer. We've not had to really touch it for a *looong* time.. Linus -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html