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Merge branch 'overlayfs-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

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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
This commit is contained in:
Linus Torvalds
2017-05-10 09:03:48 -07:00
parent a2e5ad45a9 65f2673832
commit b948abf53a
10 changed files with 425 additions and 52 deletions
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9
Documentation/filesystems/overlayfs.txt
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@@ -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
---------------