From: Omar Sandoval <osandov@xxxxxx> Hi, This patch series implements swap file support for Btrfs. If you don't remember versions 1-3, that's because they were almost 4 years ago [1] :) This attempt takes a very different approach from my original versions back then. As a refresher, the original idea was to go through ->read_iter() and ->write_iter() in O_DIRECT mode. It turns out that this is really hard to get right, because it effectively makes the GFP_NOFS flag meaningless, since now swapping out can go through the filesystem and grab locks and such. We could try to make the read/write path lockless for a swap file, but this would be too easy to get wrong. So, instead, this approach was inspired by the iomap swap file support [2], where we directly tell the swap code where it can find the swap extents while doing our own sanity checks. This has a bunch of restrictions, documented in patches 4 and 6. I have a bunch of xfstests for these cases at https://github.com/osandov/xfstests/tree/btrfs-swap. This series can also be found at https://github.com/osandov/linux/tree/btrfs-swap. All comments welcome. Thanks! 1: https://www.spinics.net/lists/linux-btrfs/msg40129.html 2: https://patchwork.kernel.org/patch/10390417/ Omar Sandoval (6): mm: split SWP_FILE into SWP_ACTIVATED and SWP_FS vfs: update swap_{,de}activate documentation Btrfs: push EXCL_OP set into btrfs_rm_device() Btrfs: prevent ioctls from interfering with a swap file Btrfs: rename get_chunk_map() and make it non-static Btrfs: support swap files Documentation/filesystems/Locking | 17 +-- Documentation/filesystems/vfs.txt | 12 +- fs/btrfs/ctree.h | 6 + fs/btrfs/disk-io.c | 3 + fs/btrfs/inode.c | 220 ++++++++++++++++++++++++++++++ fs/btrfs/ioctl.c | 64 ++++++--- fs/btrfs/volumes.c | 34 +++-- fs/btrfs/volumes.h | 2 + include/linux/swap.h | 13 +- mm/page_io.c | 6 +- mm/swapfile.c | 14 +- 11 files changed, 335 insertions(+), 56 deletions(-) -- 2.17.0
