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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2017-05-10 09:03:48 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-05-10 09:03:48 -0700 |
| commit | b948abf53a381a0c681aadd612e2affba47f62bc (patch) | |
| tree | 006012adf8876af6fa1bdefa6361a673a9142c83 /Documentation/filesystems | |
| parent | a2e5ad45a9741068f357de4dbff50bb37c233e1b (diff) | |
| parent | 65f2673832d4647f6d46783d8d745d2b15d090c4 (diff) | |
Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs update from Miklos Szeredi:
"The biggest part of this is making st_dev/st_ino on the overlay behave
like a normal filesystem (i.e. st_ino doesn't change on copy up,
st_dev is the same for all files and directories). Currently this only
works if all layers are on the same filesystem, but future work will
move the general case towards more sane behavior.
There are also miscellaneous fixes, including fixes to handling
append-only files. There's a small change in the VFS, but that only
has an effect on overlayfs, since otherwise file->f_path.dentry->inode
and file_inode(file) are always the same"
* 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
ovl: update documentation w.r.t. constant inode numbers
ovl: persistent inode numbers for upper hardlinks
ovl: merge getattr for dir and nondir
ovl: constant st_ino/st_dev across copy up
ovl: persistent inode number for directories
ovl: set the ORIGIN type flag
ovl: lookup non-dir copy-up-origin by file handle
ovl: use an auxiliary var for overlay root entry
ovl: store file handle of lower inode on copy up
ovl: check if all layers are on the same fs
ovl: do not set overlay.opaque on non-dir create
ovl: check IS_APPEND() on real upper inode
vfs: ftruncate check IS_APPEND() on real upper inode
ovl: Use designated initializers
ovl: lockdep annotate of nested stacked overlayfs inode lock
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/overlayfs.txt | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/Documentation/filesystems/overlayfs.txt b/Documentation/filesystems/overlayfs.txt index 634d03e20c2d..c9e884b52698 100644 --- a/Documentation/filesystems/overlayfs.txt +++ b/Documentation/filesystems/overlayfs.txt @@ -21,12 +21,19 @@ from accessing the corresponding object from the original filesystem. This is most obvious from the 'st_dev' field returned by stat(2). While directories will report an st_dev from the overlay-filesystem, -all non-directory objects will report an st_dev from the lower or +non-directory objects may report an st_dev from the lower filesystem or upper filesystem that is providing the object. Similarly st_ino will only be unique when combined with st_dev, and both of these can change over the lifetime of a non-directory object. Many applications and tools ignore these values and will not be affected. +In the special case of all overlay layers on the same underlying +filesystem, all objects will report an st_dev from the overlay +filesystem and st_ino from the underlying filesystem. This will +make the overlay mount more compliant with filesystem scanners and +overlay objects will be distinguishable from the corresponding +objects in the original filesystem. + Upper and Lower --------------- |