Al and Linus, Please consider overlayfs for inclusion into 3.7. It's used by Ubuntu and by various other projects. I regularly get emails asking when it will be included in mainline. Git tree is here: git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git overlayfs.v15 Thanks, Miklos --- Andy Whitcroft (3): overlayfs: add statfs support ovl: switch to __inode_permission() overlayfs: copy up i_uid/i_gid from the underlying inode Erez Zadok (1): overlayfs: implement show_options Miklos Szeredi (6): vfs: add i_op->dentry_open() vfs: export do_splice_direct() to modules vfs: introduce clone_private_mount() overlay filesystem fs: limit filesystem stacking depth vfs: export __inode_permission() to modules Neil Brown (1): overlay: overlay filesystem documentation Robin Dong (2): overlayfs: fix possible leak in ovl_new_inode overlayfs: create new inode in ovl_link --- Documentation/filesystems/Locking | 2 + Documentation/filesystems/overlayfs.txt | 199 +++++++++ Documentation/filesystems/vfs.txt | 7 + MAINTAINERS | 7 + fs/Kconfig | 1 + fs/Makefile | 1 + fs/ecryptfs/main.c | 7 + fs/internal.h | 5 - fs/namei.c | 10 +- fs/namespace.c | 18 + fs/open.c | 23 +- fs/overlayfs/Kconfig | 4 + fs/overlayfs/Makefile | 7 + fs/overlayfs/copy_up.c | 385 +++++++++++++++++ fs/overlayfs/dir.c | 604 +++++++++++++++++++++++++++ fs/overlayfs/inode.c | 372 +++++++++++++++++ fs/overlayfs/overlayfs.h | 70 ++++ fs/overlayfs/readdir.c | 566 +++++++++++++++++++++++++ fs/overlayfs/super.c | 685 +++++++++++++++++++++++++++++++ fs/splice.c | 1 + include/linux/fs.h | 14 + include/linux/mount.h | 3 + 22 files changed, 2981 insertions(+), 10 deletions(-) create mode 100644 Documentation/filesystems/overlayfs.txt create mode 100644 fs/overlayfs/Kconfig create mode 100644 fs/overlayfs/Makefile create mode 100644 fs/overlayfs/copy_up.c create mode 100644 fs/overlayfs/dir.c create mode 100644 fs/overlayfs/inode.c create mode 100644 fs/overlayfs/overlayfs.h create mode 100644 fs/overlayfs/readdir.c create mode 100644 fs/overlayfs/super.c ------------------------------------------------------------------------------ Changes from v14 to v15 - fix compile error with usernamespace - statfs: calculate correct f_namelen, fill f_type with own magic - documentation fixes ------------------------------------------------------------------------------ Changes from v13 to v14 - update to 3.6 - copy i_uid/i_gid from the underlying inode (patch by Andy Whitcroft) ------------------------------------------------------------------------------ Changes from v12 to v13 - create new inode in ovl_link (patch by Robin Dong) - switch to __inode_permission() (patch by Andy Whitcroft) ------------------------------------------------------------------------------ Changes from v11 to v12 - update to for-next of vfs tree - split __dentry_open argument cleanup patch from vfs-add-i_op-open.patch - change i_op->open and vfs_open so that they take "struct file *" ------------------------------------------------------------------------------ Changes from v10 to v11 - fix overlayfs over overlayfs - improve stack use of lookup and readdir - add limitations to documentation - make lower mount read-only - update permission and fsync to new API ------------------------------------------------------------------------------ Changes from v9 to v10 - prevent d_delete() from turning upperdentry negative (reported by Erez Zadok) - show mount options in /proc/mounts and friends (patch by Erez Zadok) - fix off-by-one error in readdir (reported by Jordi Pujol) ------------------------------------------------------------------------------ Changes from v8 to v9 - support xattr on tmpfs - fix build after split-up - fix remove after rename (reported by Jordi Pujol) - fix rename failure case ------------------------------------------------------------------------------ Changes from v7 to v8: - split overlayfs.c into smaller files - fix locking for copy up (reported by Al Viro) - locking analysis of copy up vs. directory rename added as a comment - tested with lockdep, fixed one lock annotation - other bug fixes ------------------------------------------------------------------------------ Changes from v6 to v7 - added patches from Felix Fietkau to fix deadlocks on jffs2 - optimized directory removal - properly clean up after copy-up and other failures ------------------------------------------------------------------------------ Changes from v5 to v6 - optimize directory merging o use rbtree for weeding out duplicates o use a cursor for current position within the stream - instead of f_op->open_other(), implement i_op->open() - don't share inodes for non-directory dentries - for now. I hope this can come back once RCU lookup code has settled. - misc bug fixes ------------------------------------------------------------------------------ Changes from v4 to v5 - fix copying up if fs doesn't support xattrs (Andy Whitcroft) - clone mounts to be used internally to access the underlying filesystems ------------------------------------------------------------------------------ Changes from v3 to v4 - export security_inode_permission to allow overlayfs to be modular (Andy Whitcroft) - add statfs support (Andy Whitcroft) - change BUG_ON to WARN_ON - Revert "vfs: add flag to allow rename to same inode", instead introduce s_op->is_same_inode() - overlayfs: fix rename to self - fix whiteout after rename ------------------------------------------------------------------------------ Changes from v2 to v3 - Minimal remount support. As overlayfs reflects the 'readonly' mount status in write-access to the upper filesystem, we must handle remount and either drop or take write access when the ro status changes. (NeilBrown) - Use correct seek function for directories. It is incorrect to call generic_llseek_file on a file from a different filesystem. For that we must use the seek function that the filesystem defines, which is called by vfs_llseek. Also, we only want to seek the realfile when is_real is true. Otherwise we just want to update our own f_pos pointer, so use generic_llseek_file for that. (NeilBrown) - Initialise is_real before use. The previous patch can use od->is_real before it is properly initialised is llseek is called before readdir. So factor out the initialisation of is_real and call it from both readdir and llseek when f_pos is 0. (NeilBrown) - Rename ovl_fill_cache to ovl_dir_read (NeilBrown) - Tiny optimisation in open_other handling (NeilBrown) - Assorted updates to Documentation/filesystems/overlayfs.txt (NeilBrown) - Make copy-up work for >=4G files, make it killable during copy-up. Need to fix recovery after a failed/interrupted copy-up. - Store and reference upper/lower dentries in overlay dentries. Store and reference upper/lower vfsmounts in overlay superblock. - Add necessary barriers for setting upper dentry in copyup and for retrieving upper dentry locklessly. - Make sure the right file is used for directory fsync() after copy-up. - Add locking to ovl_dir_llseek() to prevent concurrent call of ovl_dir_reset() with ovl_dir_read(). - Get rid of ovl_dentry_iput(). The VFS doesn't provide enough locking for this function that the contents of ->d_fsdata could be safely updated. - After copying up a non-directory unhash the dentry. This way the lower dentry ref, which is no longer necessary, can go away. This revealed a use-after-free bug in truncate handling in fs/namei.c:finish_open(). - Fix if a copy-up happens between the follow_linka the put_link calls. - Replace some WARN_ONs with BUG_ON. Some things just _really_ shouldn't happen. - Extract common code from ovl_unlink and ovl_rmdir to a helper function. - After unlink and rmdir unhash the dentry. This will get rid of the lower and upper dentry references after there are no more users of the deleted dentry. This is a safe replacement for the removed ->d_iput() functionality. - Added checks to unlink, rmdir and rename to verify that the parent-child relationship in the upper filesystem matches that of the overlay. This is necessary to prevent crash and/or corruption if the upper filesystem topology is being modified while part of the overlay. - Optimize checking whiteout and opaque attributes. - Optimize copy-up on truncate: don't copy up whole file before truncating - Misc bug fixes ------------------------------------------------------------------------------ Changes from v1 to v2 - rename "hybrid union filesystem" to "overlay filesystem" or overlayfs - added documentation written by Neil - correct st_dev for directories (reported by Neil) - use getattr() to get attributes from the underlying filesystems, this means that now an overlay filesystem itself can be the lower, read-only layer of another overlay - listxattr filters out private extended attributes - get write ref on the upper layer on mount unless the overlay itself is mounted read-only - raise capabilities for copy up, dealing with whiteouts and opaque directories. Now the overlay works for non-root users as well - "rm -rf" didn't work correctly in all cases if the directory was copied up between opendir and the first readdir, this is now fixed (and the directory operations consolidated) - simplified copy up, this broke optimization for truncate and open(O_TRUNC) (now file is copied up to be immediately truncated, will fix) - st_nlink for merged directories set to 1, this is an "illegal" value that normal filesystems never have but some use it to indicate that the number of subdirectories is unknown. Utilities (find, ...) seem to tolerate this well. - misc fixes I forgot about -- 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