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

1 files changed, 14 insertions, 5 deletions

diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 6e610a205e15..cfdea47313a1 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -40,6 +40,13 @@ const struct cred *ovl_override_creds(struct super_block *sb)
 	return override_creds(ofs->creator_cred);
 }
 
+struct super_block *ovl_same_sb(struct super_block *sb)
+{
+	struct ovl_fs *ofs = sb->s_fs_info;
+
+	return ofs->same_sb;
+}
+
 struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
 {
 	size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
@@ -75,11 +82,13 @@ enum ovl_path_type ovl_path_type(struct dentry *dentry)
 		type = __OVL_PATH_UPPER;
 
 		/*
-		 * Non-dir dentry can hold lower dentry from previous
-		 * location.
+		 * Non-dir dentry can hold lower dentry of its copy up origin.
 		 */
-		if (oe->numlower && d_is_dir(dentry))
-			type |= __OVL_PATH_MERGE;
+		if (oe->numlower) {
+			type |= __OVL_PATH_ORIGIN;
+			if (d_is_dir(dentry))
+				type |= __OVL_PATH_MERGE;
+		}
 	} else {
 		if (oe->numlower > 1)
 			type |= __OVL_PATH_MERGE;
@@ -100,7 +109,7 @@ void ovl_path_lower(struct dentry *dentry, struct path *path)
 {
 	struct ovl_entry *oe = dentry->d_fsdata;
 
-	*path = oe->numlower ? oe->lowerstack[0] : (struct path) { NULL, NULL };
+	*path = oe->numlower ? oe->lowerstack[0] : (struct path) { };
 }
 
 enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)