I apologize for sending this out so close to the start of the LSF-MM Summit. I've been trying to get some performance numbers worthy of sharing, but other work has been getting in the way. Those will follow, but I wanted everyone to get a chance to see the current state of the patchset. This patchset was begun by Zach Brown and was originally submitted for review in October, 2009. Feedback was positive, and I have picked up where he left off, porting his patches to 3.3 and adding support more file systems. http://www.spinics.net/lists/linux-fsdevel/msg27514.html This patch series adds a kernel interface to fs/aio.c so that kernel code can issue concurrent asynchronous IO to file systems. It adds an aio command and file system methods which specify io memory with pages instead of userspace addresses. This series was written to reduce the current overhead loop imposes by performing synchronus buffered file system IO from a kernel thread. These patches turn loop into a light weight layer that translates bios into iocbs. The downside of this is that in its current implementation, performance takes a big hit for non-synchonous I/O, since the underlying page cache is bypassed. The tradeoff is that all writes to the loop device make it to the underlying media, making loop-mounted file systems recoverable. Changes since version 1: The biggest change since my first posting is that I took Christoph Hellwig's advice and changed the direct_IO interface to use struct iov_iter, instead of duplicating code to handle both struct iovec and struct biovec separately. This really simplified the patchset, and made support for more filesystems trivial. I also reworked the nfs patch to coalesce the bvec pages into larger I/Os, and fixed a major oversight in btrfs. Dave Kleikamp (7): fuse: convert fuse to use iov_iter_copy_[to|from]_user dio: Convert direct_IO to use iov_iter dio: add bio_vec support to __blockdev_direct_IO() ext4: add support for read_iter and write_iter nfs: add support for read_iter, write_iter btrfs: add support for read_iter and write_iter fs: add read_iter and write_iter to more file systems Zach Brown (14): iov_iter: move into its own file iov_iter: add copy_to_user support iov_iter: hide iovec details behind ops function pointers iov_iter: add bvec support iov_iter: add a shorten call iov_iter: let callers extract iovecs and bio_vecs dio: create a dio_aligned() helper function fs: pull iov_iter use higher up the stack aio: add aio_kernel_() interface aio: add aio support for iov_iter arguments bio: add bvec_length(), like iov_length() loop: use aio to perform io on the underlying file ext3: add support for .read_iter and .write_iter ocfs2: add support for read_iter, write_iter, and direct_IO_bvec Documentation/filesystems/Locking | 4 +- Documentation/filesystems/vfs.txt | 4 +- drivers/block/loop.c | 55 ++++- fs/9p/vfs_addr.c | 8 +- fs/9p/vfs_file.c | 4 + fs/aio.c | 156 +++++++++++++ fs/block_dev.c | 8 +- fs/btrfs/file.c | 55 +++-- fs/btrfs/inode.c | 70 +++--- fs/ceph/addr.c | 3 +- fs/direct-io.c | 253 ++++++++++++++------- fs/ext2/file.c | 2 + fs/ext2/inode.c | 8 +- fs/ext3/file.c | 2 + fs/ext3/inode.c | 15 +- fs/ext4/ext4.h | 3 +- fs/ext4/file.c | 2 + fs/ext4/indirect.c | 16 +- fs/ext4/inode.c | 23 +- fs/fat/file.c | 2 + fs/fat/inode.c | 10 +- fs/fuse/file.c | 29 +-- fs/gfs2/aops.c | 7 +- fs/hfs/inode.c | 9 +- fs/hfsplus/inode.c | 8 +- fs/jfs/file.c | 2 + fs/jfs/inode.c | 7 +- fs/nfs/direct.c | 454 +++++++++++++++++++++++++++---------- fs/nfs/file.c | 51 +++-- fs/nilfs2/file.c | 2 + fs/nilfs2/inode.c | 8 +- fs/ocfs2/aops.c | 8 +- fs/ocfs2/file.c | 82 +++++-- fs/ocfs2/ocfs2_trace.h | 6 +- fs/reiserfs/file.c | 2 + fs/reiserfs/inode.c | 7 +- fs/xfs/xfs_aops.c | 11 +- include/linux/aio.h | 14 ++ include/linux/aio_abi.h | 2 + include/linux/bio.h | 8 + include/linux/fs.h | 131 +++++++++-- include/linux/loop.h | 1 + include/linux/nfs_fs.h | 9 +- mm/Makefile | 2 +- mm/filemap.c | 388 +++++++++++++------------------ mm/iov-iter.c | 377 ++++++++++++++++++++++++++++++ 46 files changed, 1677 insertions(+), 651 deletions(-) create mode 100644 mm/iov-iter.c -- 1.7.9.5 -- 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
