i_alloc_sem has always been a bit of an odd "lock". It's the only remaining rw_semaphore that can be released by a different thread than the one that locked it, and it's use case in the core direct I/O code is more like a counter given that the writers already have external serialization.
This series removes it in favour of a simpler counter scheme, thus getting rid of the rw_semaphore non-owner APIs as requests by Thomas, while at the same time shrinking the size of struct inode by 160 bytes on 64-bit systems. The only nasty bit is that two filesystems (fat and ext4) have started abusing the lock for their own purposes. I've added a new rw_semaphore to their filesystem-specific inode structures to keep the current behaviour, but I suspect the maintainers might have smarted ideas to archive the same goal. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
