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 the fat node structures to keep the current behaviour, and merged a patch from Jan Kara to remove the i_alloc_sem abuse from ext4. changes from v1: - update the fat patch description - replace my ext4 truncate_lock patch with Jan's rewrite of ext4_page_mkwrite - do not use wait_on_bit, but replace it with an opencoded hashed waitqueue - rename inode_dio_wake to inode_dio_done - add kerneldoc comments for inode_dio_wait and inode_dio_done - simplify the blockdev_direct_IO prototype - move the i_dio_count decrement into the ->end_io handler if present to make i_dio_count useful for filesystems delaying AIO completion - reorder the patch series - patches 1 to 5 are the meat, the rest is additonal tidyups in that area required for future improvements -- 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
