Current syncfs(2) syscall on overlayfs just calls sync_filesystem() on upper_sb to synchronize whole dirty inodes in upper filesystem regardless of the overlay ownership of the inode. In the use case of container, when multiple containers using the same underlying upper filesystem, it has some shortcomings as below. (1) Performance Synchronization is probably heavy because it actually syncs unnecessary inodes for target overlayfs. (2) Interference Unplanned synchronization will probably impact IO performance of unrelated container processes on the other overlayfs. This series try to implement containerized syncfs for overlayfs so that only sync target dirty upper inodes which are belong to specific overlayfs instance. By doing this, it is able to reduce cost of synchronization and will not seriously impact IO performance of unrelated processes. Chengguang Xu (5): fs: introduce notifier list for vfs inode fs: export symbol of writeback_single_inode() ovl: setup overlayfs' private bdi ovl: monitor marking dirty activity of underlying upper inode ovl: impement containerized syncfs for overlayfs fs/fs-writeback.c | 7 ++++- fs/inode.c | 5 ++++ fs/overlayfs/inode.c | 28 +++++++++++++++++++- fs/overlayfs/overlayfs.h | 2 ++ fs/overlayfs/ovl_entry.h | 2 ++ fs/overlayfs/super.c | 65 ++++++++++++++++++++++++++++++++++++++++++++--- fs/overlayfs/util.c | 33 ++++++++++++++++++++++++ include/linux/fs.h | 6 +++++ include/linux/writeback.h | 1 + 9 files changed, 143 insertions(+), 6 deletions(-) -- 1.8.3.1
