bcachefs: Atomic renames

3 files changed, 94 insertions, 40 deletions

diff --git a/drivers/md/bcache/dirent.c b/drivers/md/bcache/dirent.c
index e917bde7a6e7..e5ecc073825c 100644
--- a/drivers/md/bcache/dirent.c
+++ b/drivers/md/bcache/dirent.c
@@ -261,38 +261,94 @@ int bch_dirent_create(struct cache_set *c, u64 dir_inum, u8 type,
 	return ret;
 }
 
-int bch_dirent_update(struct cache_set *c, u64 dir_inum,
-		      const struct qstr *name, u64 dst_inum,
-		      u64 *journal_seq)
+int bch_dirent_rename(struct cache_set *c,
+		      u64 src_dir, const struct qstr *src_name,
+		      u64 dst_dir, const struct qstr *dst_name,
+		      u64 *journal_seq, bool overwriting)
 {
-	struct btree_iter iter;
+	struct btree_iter src_iter;
+	struct btree_iter dst_iter;
 	struct bkey_s_c k;
+	struct bkey_s_c_dirent src;
+	struct bkey_i_dirent *dst;
+	struct bkey_i delete;
 	struct keylist keys;
-	struct bkey_i_dirent *dirent;
-	int ret = -ENOENT;
+	int ret;
 
-	dirent = dirent_create_key(&keys, 0, name, dst_inum);
-	if (!dirent)
+	dst = dirent_create_key(&keys, 0, dst_name, 0);
+	if (!dst)
 		return -ENOMEM;
 
-	bch_btree_iter_init_intent(&iter, c, BTREE_ID_DIRENTS,
-				   POS(dir_inum, bch_dirent_hash(name)));
+	bch_btree_iter_init_intent(&src_iter, c, BTREE_ID_DIRENTS,
+				   POS(src_dir, bch_dirent_hash(src_name)));
+	bch_btree_iter_init_intent(&dst_iter, c, BTREE_ID_DIRENTS,
+				   POS(dst_dir, bch_dirent_hash(dst_name)));
+	bch_btree_iter_link(&src_iter, &dst_iter);
 
 	do {
-		k = __dirent_find(&iter, dir_inum, name);
-		if (IS_ERR(k.k))
-			return bch_btree_iter_unlock(&iter) ?: PTR_ERR(k.k);
+		/*
+		 * Have to traverse lower btree nodes before higher - due to
+		 * lock ordering.
+		 */
+		if (bkey_cmp(src_iter.pos, dst_iter.pos) < 0) {
+			k = __dirent_find(&src_iter, src_dir, src_name);
+			if (IS_ERR(k.k)) {
+				ret = PTR_ERR(k.k);
+				goto err;
+			}
+
+			src = bkey_s_c_to_dirent(k);
+
+			k = overwriting
+				? __dirent_find(&dst_iter, dst_dir, dst_name)
+				: __dirent_find_hole(&dst_iter, dst_dir, dst_name);
+			if (IS_ERR(k.k)) {
+				ret = PTR_ERR(k.k);
+				goto err;
+			}
+
+			dst->k.p = k.k->p;
+		} else {
+			k = overwriting
+				? __dirent_find(&dst_iter, dst_dir, dst_name)
+				: __dirent_find_hole(&dst_iter, dst_dir, dst_name);
+			if (IS_ERR(k.k)) {
+				ret = PTR_ERR(k.k);
+				goto err;
+			}
+
+			dst->k.p = k.k->p;
+
+			k = __dirent_find(&src_iter, src_dir, src_name);
+			if (IS_ERR(k.k)) {
+				ret = PTR_ERR(k.k);
+				goto err;
+			}
+
+			src = bkey_s_c_to_dirent(k);
+		}
 
-		dirent->k.p = k.k->p;
-		dirent->v.d_type = bkey_s_c_to_dirent(k).v->d_type;
+		bkey_init(&delete.k);
+		delete.k.p = src.k->p;
+		delete.k.type = BCH_DIRENT_WHITEOUT;
 
-		ret = bch_btree_insert_at(&iter, &keys, NULL,
-					  journal_seq,
-					  BTREE_INSERT_ATOMIC);
-	} while (ret == -EINTR);
+		dst->v.d_inum = src.v->d_inum;
+		dst->v.d_type = src.v->d_type;
 
-	bch_btree_iter_unlock(&iter);
+		ret = bch_btree_insert_at_multi((struct btree_insert_multi[]) {
+				{ &src_iter, &delete, },
+				{ &dst_iter, &dst->k_i, }}, 2,
+				journal_seq, 0);
+		bch_btree_iter_unlock(&src_iter);
+		bch_btree_iter_unlock(&dst_iter);
+	} while (ret == -EINTR);
 
+	bch_keylist_free(&keys);
+	return ret;
+err:
+	ret = bch_btree_iter_unlock(&src_iter) ?: ret;
+	ret = bch_btree_iter_unlock(&dst_iter) ?: ret;
+	bch_keylist_free(&keys);
 	return ret;
 }
 
diff --git a/drivers/md/bcache/dirent.h b/drivers/md/bcache/dirent.h
index 4de22a53c875..9095bc844a4e 100644
--- a/drivers/md/bcache/dirent.h
+++ b/drivers/md/bcache/dirent.h
@@ -11,8 +11,9 @@ struct cache_set;
 
 int bch_dirent_create(struct cache_set *, u64, u8, const struct qstr *,
 		      u64, u64 *);
-int bch_dirent_update(struct cache_set *, u64, const struct qstr *, u64, u64 *);
 int bch_dirent_delete(struct cache_set *, u64, const struct qstr *);
+int bch_dirent_rename(struct cache_set *, u64, const struct qstr *,
+		      u64, const struct qstr *, u64 *, bool);
 u64 bch_dirent_lookup(struct cache_set *, u64, const struct qstr *);
 int bch_empty_dir(struct cache_set *, u64);
 int bch_readdir(struct file *, struct dir_context *);
diff --git a/drivers/md/bcache/fs.c b/drivers/md/bcache/fs.c
index cf3c1bef8667..1388d915014a 100644
--- a/drivers/md/bcache/fs.c
+++ b/drivers/md/bcache/fs.c
@@ -542,10 +542,10 @@ static int bch_rename(struct inode *old_dir, struct dentry *old_dentry,
 		if (bch_empty_dir(c, new_inode->i_ino))
 			return -ENOTEMPTY;
 
-		ret = bch_dirent_update(c, new_dir->i_ino,
-					&new_dentry->d_name,
-					old_inode->i_ino,
-					&ei->journal_seq);
+		ret = bch_dirent_rename(c,
+					old_dir->i_ino, &old_dentry->d_name,
+					new_dir->i_ino, &new_dentry->d_name,
+					&ei->journal_seq, true);
 		if (unlikely(ret))
 			return ret;
 
@@ -554,30 +554,30 @@ static int bch_rename(struct inode *old_dir, struct dentry *old_dentry,
 	} else if (new_inode) {
 		lockdep_assert_held(&new_inode->i_rwsem);
 
-		ret = bch_dirent_update(c, new_dir->i_ino,
-					&new_dentry->d_name,
-					old_inode->i_ino,
-					&ei->journal_seq);
+		ret = bch_dirent_rename(c,
+					old_dir->i_ino, &old_dentry->d_name,
+					new_dir->i_ino, &new_dentry->d_name,
+					&ei->journal_seq, true);
 		if (unlikely(ret))
 			return ret;
 
 		new_inode->i_ctime = now;
 		inode_dec_link_count(new_inode);
 	} else if (S_ISDIR(old_inode->i_mode)) {
-		ret = bch_vfs_dirent_create(c, new_dir,
-					    mode_to_type(old_inode->i_mode),
-					    &new_dentry->d_name,
-					    old_inode);
+		ret = bch_dirent_rename(c,
+					old_dir->i_ino, &old_dentry->d_name,
+					new_dir->i_ino, &new_dentry->d_name,
+					&ei->journal_seq, false);
 		if (unlikely(ret))
 			return ret;
 
 		inode_inc_link_count(new_dir);
 		inode_dec_link_count(old_dir);
 	} else {
-		ret = bch_vfs_dirent_create(c, new_dir,
-					    mode_to_type(old_inode->i_mode),
-					    &new_dentry->d_name,
-					    old_inode);
+		ret = bch_dirent_rename(c,
+					old_dir->i_ino, &old_dentry->d_name,
+					new_dir->i_ino, &new_dentry->d_name,
+					&ei->journal_seq, false);
 		if (unlikely(ret))
 			return ret;
 	}
@@ -587,9 +587,6 @@ static int bch_rename(struct inode *old_dir, struct dentry *old_dentry,
 	mark_inode_dirty_sync(old_dir);
 	mark_inode_dirty_sync(new_dir);
 
-	/* XXX: error handling */
-	bch_dirent_delete(c, old_dir->i_ino, &old_dentry->d_name);
-
 	mutex_lock(&ei->update_lock);
 	old_inode->i_ctime = now;
 	if (new_inode)