And I cc'd [email protected] on all the patches instead of
[email protected] - guess I'm really out of the kernel
business now! Anyway, if you want your replies to go to lkml, you'll
have to hand edit the cc list.
-VAL
On Tue, Mar 22, 2011 at 6:58 PM, Valerie Aurora
<[email protected]> wrote:
> Hi union mounts fans(?),
>
> Here's my current union mounts patch set, against 2.6.36-rc5. ?I'm
> busy with other things[1] and unlikely to put in significant work on
> union mounts in the next year. ?I'm happy to answer questions from
> anyone else working on them.
>
> As always, git trees for the kernel, util-linux, and e2fsprogs, lots
> of documentation, and LWN articles describing the various problems
> unioning file systems will encounter are here:
>
> http://valerieaurora.org/union/
>
> The devkit linked to from that page includes my Usermode Linux testing
> environment, including root file system image. ?The README tells you
> how to run the test suite automatically (yes, an automated test suite
> - with Makefile and version control and comments and stuff!).
>
> I took a quick look at the current overlayfs patch set, and it's
> small, clean, and easy to understand. ?If it does what people need, I
> say ship it.
>
> Thanks to everyone who reviewed and submitted patches for union mounts!
>
> -VAL
>
> [1] http://adainitiative.org
>
> ---
>
> Felix Fietkau (2):
> ?whiteout: jffs2 whiteout support
> ?fallthru: jffs2 fallthru support
>
> Jan Blunck (9):
> ?VFS: Make lookup_hash() return a struct path
> ?autofs4: Save autofs trigger's vfsmount in super block info
> ?whiteout/NFSD: Don't return information about whiteouts to userspace
> ?whiteout: Add vfs_whiteout() and whiteout inode operation
> ?whiteout: Allow removal of a directory with whiteouts
> ?whiteout: tmpfs whiteout support
> ?union-mount: Introduce MNT_UNION and MS_UNION flags
> ?union-mount: Free union stack on removal of topmost dentry from
> ? ?dcache
> ?union-mount: Create IS_MNT_UNION()
>
> Valerie Aurora (63):
> ?VFS: Comment follow_mount() and friends
> ?Documentation: Fix trivial typo in filesystems/sharedsubtree.txt
> ?whiteout: Define opaque inode flags and operations
> ?ext2: Add ext2_dirent_in_use()
> ?ext2: Split ext2_add_entry() from ext2_add_link()
> ?whiteout: ext2 whiteout support
> ?fallthru: Basic fallthru definitions
> ?fallthru: ext2 fallthru support
> ?fallthru: tmpfs fallthru support
> ?VFS: Add hard read-only users count to superblock
> ?VFS: Make clone_mnt()/copy_tree()/collect_mounts() return errors
> ?VFS: Add CL_NO_SHARED flag to clone_mnt()/copy_tree()
> ?VFS: Add CL_NO_SLAVE flag to clone_mnt()/copy_tree()
> ?VFS: Add CL_MAKE_HARD_READONLY flag to clone_mnt()/copy_tree()
> ?union-mount: Union mounts documentation
> ?union-mount: Add CONFIG_UNION_MOUNT option
> ?union-mount: Create union_stack structure
> ?union-mount: Add two superblock fields for union mounts
> ?union-mount: Add union_alloc()
> ?union-mount: Add union_find_dir()
> ?union-mount: Create d_free_unions()
> ?union-mount: Create union_add_dir()
> ?union-mount: Add union_create_topmost_dir()
> ?union-mount: Create needs_lookup_union()
> ?union-mount: Create check_topmost_union_mnt()
> ?union-mount: Add clone_union_tree() and put_union_sb()
> ?union-mount: Create build_root_union()
> ?union-mount: Create prepare_mnt_union() and cleanup_mnt_union()
> ?union-mount: Prevent improper union-related remounts
> ?union-mount: Prevent topmost file system from being mounted elsewhere
> ?union-mount: Prevent bind mounts of union mounts
> ?union-mount: Implement union mount
> ?union-mount: Temporarily disable some syscalls
> ?union-mount: Basic infrastructure of __lookup_union()
> ?union-mount: Process negative dentries in __lookup_union()
> ?union-mount: Return files found in lower layers in __lookup_union()
> ?union-mount: Build union stack in __lookup_union()
> ?union-mount: Follow mount in __lookup_union()
> ?union-mount: Add lookup_union()
> ?union-mount: Add do_lookup_union() wrapper for __lookup_union()
> ?union-mount: Call union lookup functions in lookup path
> ?union-mount: Create whiteout on unlink()
> ?union-mount: Create whiteout on rmdir()
> ?union-mount: Set opaque flag on new directories in unioned file
> ? ?systems
> ?union-mount: Copy up directory entries on first readdir()
> ?union-mount: Add generic_readdir_fallthru() helper
> ?fallthru: ext2 support for lookup of d_type/d_ino in fallthrus
> ?fallthru: tmpfs support for lookup of d_type/d_ino in fallthrus
> ?fallthru: jffs2 support for lookup of d_type/d_ino in fallthrus
> ?VFS: Split inode_permission() and create path_permission()
> ?VFS: Create user_path_nd() to lookup both parent and target
> ?union-mount: In-kernel file copyup routines
> ?union-mount: Implement union-aware access()/faccessat()
> ?union-mount: Implement union-aware link()
> ?union-mount: Implement union-aware rename()
> ?union-mount: Implement union-aware writable open()
> ?union-mount: Implement union-aware chown()
> ?union-mount: Implement union-aware truncate()
> ?union-mount: Implement union-aware chmod()/fchmodat()
> ?union-mount: Implement union-aware lchown()
> ?union-mount: Implement union-aware utimensat()
> ?union-mount: Implement union-aware setxattr()
> ?union-mount: Implement union-aware lsetxattr()
>
> ?Documentation/filesystems/sharedsubtree.txt | ? ?4 +-
> ?Documentation/filesystems/union-mounts.txt ?| ?751 +++++++++++++++++++++++++
> ?Documentation/filesystems/vfs.txt ? ? ? ? ? | ? 16 +-
> ?fs/Kconfig ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| ? 13 +
> ?fs/Makefile ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? | ? ?1 +
> ?fs/autofs4/autofs_i.h ? ? ? ? ? ? ? ? ? ? ? | ? ?1 +
> ?fs/autofs4/init.c ? ? ? ? ? ? ? ? ? ? ? ? ? | ? 11 +-
> ?fs/autofs4/root.c ? ? ? ? ? ? ? ? ? ? ? ? ? | ? ?6 +
> ?fs/compat.c ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? | ? ?9 +
> ?fs/dcache.c ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? | ? 32 +-
> ?fs/ext2/dir.c ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? | ?116 ++++-
> ?fs/ext2/ext2.h ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| ? ?3 +
> ?fs/ext2/inode.c ? ? ? ? ? ? ? ? ? ? ? ? ? ? | ? 11 +-
> ?fs/ext2/namei.c ? ? ? ? ? ? ? ? ? ? ? ? ? ? | ? 85 +++-
> ?fs/ext2/super.c ? ? ? ? ? ? ? ? ? ? ? ? ? ? | ? ?6 +
> ?fs/jffs2/dir.c ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| ?117 ++++-
> ?fs/jffs2/fs.c ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? | ? ?4 +
> ?fs/jffs2/super.c ? ? ? ? ? ? ? ? ? ? ? ? ? ?| ? ?2 +-
> ?fs/libfs.c ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| ? 20 +-
> ?fs/namei.c ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| ?807 ++++++++++++++++++++++++---
> ?fs/namespace.c ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| ?394 +++++++++++--
> ?fs/nfsd/nfs3xdr.c ? ? ? ? ? ? ? ? ? ? ? ? ? | ? ?5 +
> ?fs/nfsd/nfs4xdr.c ? ? ? ? ? ? ? ? ? ? ? ? ? | ? ?5 +
> ?fs/nfsd/nfsxdr.c ? ? ? ? ? ? ? ? ? ? ? ? ? ?| ? ?4 +
> ?fs/open.c ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? | ?116 ++++-
> ?fs/pnode.c ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| ? ?5 +-
> ?fs/pnode.h ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| ? ?3 +
> ?fs/readdir.c ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| ? 18 +
> ?fs/super.c ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| ? ?9 +
> ?fs/union.c ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| ?714 ++++++++++++++++++++++++
> ?fs/union.h ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| ?105 ++++
> ?fs/utimes.c ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? | ? 14 +-
> ?fs/xattr.c ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| ? 65 ++-
> ?include/linux/dcache.h ? ? ? ? ? ? ? ? ? ? ?| ? 37 ++-
> ?include/linux/ext2_fs.h ? ? ? ? ? ? ? ? ? ? | ? ?8 +
> ?include/linux/fs.h ? ? ? ? ? ? ? ? ? ? ? ? ?| ? 45 ++
> ?include/linux/jffs2.h ? ? ? ? ? ? ? ? ? ? ? | ? ?8 +
> ?include/linux/mount.h ? ? ? ? ? ? ? ? ? ? ? | ? ?4 +
> ?include/linux/namei.h ? ? ? ? ? ? ? ? ? ? ? | ? ?2 +
> ?kernel/audit_tree.c ? ? ? ? ? ? ? ? ? ? ? ? | ? 10 +-
> ?mm/shmem.c ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?| ?193 ++++++-
> ?41 files changed, 3551 insertions(+), 228 deletions(-)
> ?create mode 100644 Documentation/filesystems/union-mounts.txt
> ?create mode 100644 fs/union.c
> ?create mode 100644 fs/union.h
>
>
On 03/22/2011 10:12 PM, Valerie Aurora wrote:
> And I cc'd [email protected] on all the patches instead of
> [email protected] - guess I'm really out of the kernel
> business now! Anyway, if you want your replies to go to lkml, you'll
> have to hand edit the cc list.
>
> -VAL
>
Val, Miklos,
Can one or both of you summarize what we union mounts and overlay do better or
worse? Do we need both or just one?
Thanks!
Ric
On Thu, Mar 24, 2011 at 2:43 PM, Ric Wheeler <[email protected]> wrote:
> Can one or both of you summarize what we union mounts and overlay do better
> or worse? Do we need both or just one?
The semantics are very similar, the differences are in the implementation.
Union mounts:
- whiteout/opaque/fallthrough support in filesystems
- whiteout operation is atomic
- no dentry and inode duplication
- copy up on lookup and readdir
- does not support union of two read-only trees
- merged directory stored in upper tree
Overlayfs
- whiteout/opaque as xattrs
- whiteout operation is not atomic
- dentry and inode duplication(*)
- only copy up on modification
- supports union of two read-only trees
- merged directory not cached(**)
(*) it's possible to eliminate inode duplication of non-directories
with some VFS modifications
(**) caching should be possible to do
On 03/25/2011 07:38 AM, Szeredi Miklos wrote:
> On Thu, Mar 24, 2011 at 2:43 PM, Ric Wheeler<[email protected]> wrote:
>> Can one or both of you summarize what we union mounts and overlay do better
>> or worse? Do we need both or just one?
> The semantics are very similar, the differences are in the implementation.
>
> Union mounts:
>
> - whiteout/opaque/fallthrough support in filesystems
> - whiteout operation is atomic
> - no dentry and inode duplication
> - copy up on lookup and readdir
> - does not support union of two read-only trees
> - merged directory stored in upper tree
>
> Overlayfs
>
> - whiteout/opaque as xattrs
> - whiteout operation is not atomic
> - dentry and inode duplication(*)
> - only copy up on modification
> - supports union of two read-only trees
> - merged directory not cached(**)
>
> (*) it's possible to eliminate inode duplication of non-directories
> with some VFS modifications
> (**) caching should be possible to do
Thanks for the high level overview!
Ric