restore killability of old mutex_lock_killable(&inode->i_mutex) users

The ones that are taking it exclusive, that is...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/btrfs/ioctl.c

@@ -846,11 +846,9 @@ static noinline int btrfs_mksubvol(struct path *parent,
 	struct dentry *dentry;
 	int error;
 
-	inode_lock_nested(dir, I_MUTEX_PARENT);
-	// XXX: should've been
-	// mutex_lock_killable_nested(&dir->i_mutex, I_MUTEX_PARENT);
-	// if (error == -EINTR)
-	//	return error;
+	error = down_write_killable_nested(&dir->i_rwsem, I_MUTEX_PARENT);
+	if (error == -EINTR)
+		return error;
 
 	dentry = lookup_one_len(name, parent->dentry, namelen);
 	error = PTR_ERR(dentry);
@@ -2377,11 +2375,9 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
 		goto out;
 
 
-	inode_lock_nested(dir, I_MUTEX_PARENT);
-	// XXX: should've been
-	// err = mutex_lock_killable_nested(&dir->i_mutex, I_MUTEX_PARENT);
-	// if (err == -EINTR)
-	//	goto out_drop_write;
+	err = down_write_killable_nested(&dir->i_rwsem, I_MUTEX_PARENT);
+	if (err == -EINTR)
+		goto out_drop_write;
 	dentry = lookup_one_len(vol_args->name, parent, namelen);
 	if (IS_ERR(dentry)) {
 		err = PTR_ERR(dentry);
@@ -2571,7 +2567,7 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
 	dput(dentry);
 out_unlock_dir:
 	inode_unlock(dir);
-//out_drop_write:
+out_drop_write:
 	mnt_drop_write_file(file);
 out:
 	kfree(vol_args);

fs/overlayfs/readdir.c

@@ -218,9 +218,7 @@ static int ovl_check_whiteouts(struct dentry *dir, struct ovl_readdir_data *rdd)
 	cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
 	old_cred = override_creds(override_cred);
 
-	inode_lock(dir->d_inode);
-	err = 0;
-	// XXX: err = mutex_lock_killable(&dir->d_inode->i_mutex);
+	err = down_write_killable(&dir->d_inode->i_rwsem);
 	if (!err) {
 		while (rdd->first_maybe_whiteout) {
 			p = rdd->first_maybe_whiteout;

fs/readdir.c

@@ -35,13 +35,13 @@ int iterate_dir(struct file *file, struct dir_context *ctx)
 	if (res)
 		goto out;
 
-	if (shared)
+	if (shared) {
 		inode_lock_shared(inode);
-	else
-		inode_lock(inode);
-	// res = mutex_lock_killable(&inode->i_mutex);
-	// if (res)
-	//	goto out;
+	} else {
+		res = down_write_killable(&inode->i_rwsem);
+		if (res)
+			goto out;
+	}
 
 	res = -ENOENT;
 	if (!IS_DEADDIR(inode)) {