Hi All, I am pleased to announce the overlayfs snapshots project. Overlayfs snapshots bring file level snapshots capability to any local file system. Project requirements: * Incremental read-only snapshots of directory sub-tree * Independent of underlying local file system * Snapshots use available file system disk space * Snapshot deletion automatically frees up disk space * Minimal performance overhead to file access in the writable mount * POSIX compliance for file system operation in the writable mount * File access to read-only snapshots may incur performance overhead * Reading from snapshots may exhibit overlayfs non-standard behavior * Take new snapshot in O(1) time and disk space * No upper limit on number or size of snapshots The project has a working POC[1] covering a partial list of the requirements, a tailored test suite[2] to verify snapshots consistency and a wiki[3] with more information about the project. The kernel Documentation page is also available in nice formatting at: https://github.com/amir73il/overlayfs/wiki/Snapshots-overview Contributions to overlayfs snapshots project are most welcome in the form of code review, testing, articles and public attention. Comments and questions are always welcome. Amir. [1] https://github.com/amir73il/linux/tree/ovl_snapshot [2] https://github.com/amir73il/unionmount-testsuite/tree/ovl_snapshot [3] https://github.com/amir73il/overlayfs/wiki/Overlayfs-snapshots Summary of overlayfs snapshots patches in [1]: ---------------------------------------------- Amir Goldstein (10): ovl: introduce snapshot mount ovl: explicit copy up/whiteout requests from snapshot mount ovl: implement snapshot mount lookup ovl: cow file to snapshot on open for write ovl: cow file/dir to snapshot on ovl_want_write() ovl: redirect dir on rename in snapshot mount ovl: fix set_acl crash with snapshot mount ovl: real dir operations for snapshot mount ovl: unhash removed dentries from snapshot ovl: overlayfs snapshots documentation Documentation/filesystems/overlayfs-snapshots.txt | 196 +++++++++++++++++ fs/overlayfs/Kconfig | 8 + fs/overlayfs/Makefile | 1 + fs/overlayfs/dir.c | 64 +++++- fs/overlayfs/inode.c | 2 +- fs/overlayfs/namei.c | 27 ++- fs/overlayfs/overlayfs.h | 14 ++ fs/overlayfs/ovl_entry.h | 7 +- fs/overlayfs/readdir.c | 4 +- fs/overlayfs/snapshot.c | 115 ++++++++++ fs/overlayfs/super.c | 253 +++++++++++++++++++--- fs/overlayfs/util.c | 17 ++ 12 files changed, 661 insertions(+), 47 deletions(-) create mode 100644 Documentation/filesystems/overlayfs-snapshots.txt create mode 100644 fs/overlayfs/snapshot.c -- 2.7.4 -- 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
