ovl: pass ofs to setattr operations

Pass down struct ovl_fs to setattr operations so we can ultimately
retrieve the relevant upper mount and take the mount's idmapping into
account when creating new filesystem objects. This is needed to support
idmapped base layers with overlay.

Cc: <linux-unionfs@vger.kernel.org>
Tested-by: Giuseppe Scrivano <gscrivan@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/overlayfs/copy_up.c

@@ -292,7 +292,8 @@ out_fput:
 	return error;
 }
 
-static int ovl_set_size(struct dentry *upperdentry, struct kstat *stat)
+static int ovl_set_size(struct ovl_fs *ofs,
+			struct dentry *upperdentry, struct kstat *stat)
 {
 	struct iattr attr = {
 		.ia_valid = ATTR_SIZE,
@@ -302,7 +303,8 @@ static int ovl_set_size(struct dentry *upperdentry, struct kstat *stat)
 	return notify_change(&init_user_ns, upperdentry, &attr, NULL);
 }
 
-static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
+static int ovl_set_timestamps(struct ovl_fs *ofs, struct dentry *upperdentry,
+			      struct kstat *stat)
 {
 	struct iattr attr = {
 		.ia_valid =
@@ -314,7 +316,8 @@ static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
 	return notify_change(&init_user_ns, upperdentry, &attr, NULL);
 }
 
-int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
+int ovl_set_attr(struct ovl_fs *ofs, struct dentry *upperdentry,
+		 struct kstat *stat)
 {
 	int err = 0;
 
@@ -334,7 +337,7 @@ int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
 		err = notify_change(&init_user_ns, upperdentry, &attr, NULL);
 	}
 	if (!err)
-		ovl_set_timestamps(upperdentry, stat);
+		ovl_set_timestamps(ofs, upperdentry, stat);
 
 	return err;
 }
@@ -541,7 +544,7 @@ static int ovl_link_up(struct ovl_copy_up_ctx *c)
 
 		if (!err) {
 			/* Restore timestamps on parent (best effort) */
-			ovl_set_timestamps(upperdir, &c->pstat);
+			ovl_set_timestamps(ofs, upperdir, &c->pstat);
 			ovl_dentry_set_upper_alias(c->dentry);
 		}
 	}
@@ -615,9 +618,9 @@ static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
 
 	inode_lock(temp->d_inode);
 	if (S_ISREG(c->stat.mode))
-		err = ovl_set_size(temp, &c->stat);
+		err = ovl_set_size(ofs, temp, &c->stat);
 	if (!err)
-		err = ovl_set_attr(temp, &c->stat);
+		err = ovl_set_attr(ofs, temp, &c->stat);
 	inode_unlock(temp->d_inode);
 
 	return err;
@@ -839,7 +842,7 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
 
 		/* Restore timestamps on parent (best effort) */
 		inode_lock(udir);
-		ovl_set_timestamps(c->destdir, &c->pstat);
+		ovl_set_timestamps(ofs, c->destdir, &c->pstat);
 		inode_unlock(udir);
 
 		ovl_dentry_set_upper_alias(c->dentry);

fs/overlayfs/dir.c

@@ -408,7 +408,7 @@ static struct dentry *ovl_clear_empty(struct dentry *dentry,
 		goto out_cleanup;
 
 	inode_lock(opaquedir->d_inode);
-	err = ovl_set_attr(opaquedir, &stat);
+	err = ovl_set_attr(ofs, opaquedir, &stat);
 	inode_unlock(opaquedir->d_inode);
 	if (err)
 		goto out_cleanup;

fs/overlayfs/overlayfs.h

@@ -623,7 +623,7 @@ int ovl_copy_up_with_data(struct dentry *dentry);
 int ovl_maybe_copy_up(struct dentry *dentry, int flags);
 int ovl_copy_xattr(struct super_block *sb, struct dentry *old,
 		   struct dentry *new);
-int ovl_set_attr(struct dentry *upper, struct kstat *stat);
+int ovl_set_attr(struct ovl_fs *ofs, struct dentry *upper, struct kstat *stat);
 struct ovl_fh *ovl_encode_real_fh(struct ovl_fs *ofs, struct dentry *real,
 				  bool is_upper);
 int ovl_set_origin(struct ovl_fs *ofs, struct dentry *lower,