ovl: mark upper merge dir with type origin entries "impure"

An upper dir is marked "impure" to let ovl_iterate() know that this
directory may contain non pure upper entries whose d_ino may need to be
read from the origin inode.

We already mark a non-merge dir "impure" when moving a non-pure child
entry inside it, to let ovl_iterate() know not to iterate the non-merge
dir directly.

Mark also a merge dir "impure" when moving a non-pure child entry inside
it and when copying up a child entry inside it.

This can be used to optimize ovl_iterate() to perform a "pure merge" of
upper and lower directories, merging the content of the directories,
without having to read d_ino from origin inodes.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

1 files changed, 5 insertions, 26 deletions

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index f2a118ba00e4..a63a71656e9b 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -149,22 +149,6 @@ static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry)
 	return ovl_set_opaque_xerr(dentry, upperdentry, -EIO);
 }
 
-static int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry)
-{
-	int err;
-
-	/*
-	 * Do not fail when upper doesn't support xattrs.
-	 * Upper inodes won't have origin nor redirect xattr anyway.
-	 */
-	err = ovl_check_setxattr(dentry, upperdentry, OVL_XATTR_IMPURE,
-				 "y", 1, 0);
-	if (!err)
-		ovl_dentry_set_impure(dentry);
-
-	return err;
-}
-
 /* Common operations required to be done after creation of file on upper */
 static void ovl_instantiate(struct dentry *dentry, struct inode *inode,
 			    struct dentry *newdentry, bool hardlink)
@@ -976,21 +960,16 @@ static int ovl_rename(struct inode *olddir, struct dentry *old,
 	if (!samedir) {
 		/*
 		 * When moving a merge dir or non-dir with copy up origin into
-		 * a non-merge upper dir (a.k.a pure upper dir), we are making
-		 * the target parent dir "impure". ovl_iterate() iterates pure
-		 * upper dirs directly, because there is no need to filter out
-		 * whiteouts and merge dir content with lower dir. But for the
-		 * case of an "impure" upper dir, ovl_iterate() cannot iterate
-		 * the real directory directly, because it looks for the inode
-		 * numbers to fill d_ino in the entries origin inode.
+		 * a new parent, we are marking the new parent dir "impure".
+		 * When ovl_iterate() iterates an "impure" upper dir, it will
+		 * lookup the origin inodes of the entries to fill d_ino.
 		 */
-		if (ovl_type_origin(old) && !ovl_type_merge(new->d_parent)) {
+		if (ovl_type_origin(old)) {
 			err = ovl_set_impure(new->d_parent, new_upperdir);
 			if (err)
 				goto out_revert_creds;
 		}
-		if (!overwrite && ovl_type_origin(new) &&
-		    !ovl_type_merge(old->d_parent)) {
+		if (!overwrite && ovl_type_origin(new)) {
 			err = ovl_set_impure(old->d_parent, old_upperdir);
 			if (err)
 				goto out_revert_creds;