Merge pull request 'Garage v0.9' (#473) from next into main

Reviewed-on: https://git.deuxfleurs.fr/Deuxfleurs/garage/pulls/473

1 files changed, 257 insertions, 201 deletions

diff --git a/src/block/manager.rs b/src/block/manager.rs
index 3ece9a8a..2d1b5c67 100644
--- a/src/block/manager.rs
+++ b/src/block/manager.rs
@@ -3,7 +3,7 @@ use std::pin::Pin;
 use std::sync::Arc;
 use std::time::Duration;
 
-use arc_swap::ArcSwapOption;
+use arc_swap::{ArcSwap, ArcSwapOption};
 use async_trait::async_trait;
 use bytes::Bytes;
 use rand::prelude::*;
@@ -25,10 +25,11 @@ use garage_rpc::rpc_helper::netapp::stream::{stream_asyncread, ByteStream};
 use garage_db as db;
 
 use garage_util::background::{vars, BackgroundRunner};
+use garage_util::config::DataDirEnum;
 use garage_util::data::*;
 use garage_util::error::*;
 use garage_util::metrics::RecordDuration;
-use garage_util::persister::PersisterShared;
+use garage_util::persister::{Persister, PersisterShared};
 use garage_util::time::msec_to_rfc3339;
 
 use garage_rpc::rpc_helper::OrderTag;
@@ -38,6 +39,7 @@ use garage_rpc::*;
 use garage_table::replication::{TableReplication, TableShardedReplication};
 
 use crate::block::*;
+use crate::layout::*;
 use crate::metrics::*;
 use crate::rc::*;
 use crate::repair::*;
@@ -77,12 +79,16 @@ impl Rpc for BlockRpc {
 pub struct BlockManager {
 	/// Replication strategy, allowing to find on which node blocks should be located
 	pub replication: TableShardedReplication,
-	/// Directory in which block are stored
-	pub data_dir: PathBuf,
 
+	/// Data layout
+	pub(crate) data_layout: ArcSwap<DataLayout>,
+	/// Data layout persister
+	pub(crate) data_layout_persister: Persister<DataLayout>,
+
+	data_fsync: bool,
 	compression_level: Option<i32>,
 
-	mutation_lock: [Mutex<BlockManagerLocked>; 256],
+	mutation_lock: Vec<Mutex<BlockManagerLocked>>,
 
 	pub(crate) rc: BlockRc,
 	pub resync: BlockResyncManager,
@@ -105,6 +111,9 @@ pub struct BlockResyncErrorInfo {
 	pub next_try: u64,
 }
 
+// The number of different mutexes used to parallelize write access to data blocks
+const MUTEX_COUNT: usize = 256;
+
 // This custom struct contains functions that must only be ran
 // when the lock is held. We ensure that it is the case by storing
 // it INSIDE a Mutex.
@@ -113,11 +122,29 @@ struct BlockManagerLocked();
 impl BlockManager {
 	pub fn new(
 		db: &db::Db,
-		data_dir: PathBuf,
+		data_dir: DataDirEnum,
+		data_fsync: bool,
 		compression_level: Option<i32>,
 		replication: TableShardedReplication,
 		system: Arc<System>,
-	) -> Arc<Self> {
+	) -> Result<Arc<Self>, Error> {
+		// Load or compute layout, i.e. assignment of data blocks to the different data directories
+		let data_layout_persister: Persister<DataLayout> =
+			Persister::new(&system.metadata_dir, "data_layout");
+		let data_layout = match data_layout_persister.load() {
+			Ok(mut layout) => {
+				layout
+					.update(&data_dir)
+					.ok_or_message("invalid data_dir config")?;
+				layout
+			}
+			Err(_) => DataLayout::initialize(&data_dir).ok_or_message("invalid data_dir config")?,
+		};
+		data_layout_persister
+			.save(&data_layout)
+			.expect("cannot save data_layout");
+
+		// Open metadata tables
 		let rc = db
 			.open_tree("block_local_rc")
 			.expect("Unable to open block_local_rc tree");
@@ -140,9 +167,14 @@ impl BlockManager {
 
 		let block_manager = Arc::new(Self {
 			replication,
-			data_dir,
+			data_layout: ArcSwap::new(Arc::new(data_layout)),
+			data_layout_persister,
+			data_fsync,
 			compression_level,
-			mutation_lock: [(); 256].map(|_| Mutex::new(BlockManagerLocked())),
+			mutation_lock: vec![(); MUTEX_COUNT]
+				.iter()
+				.map(|_| Mutex::new(BlockManagerLocked()))
+				.collect::<Vec<_>>(),
 			rc,
 			resync,
 			system,
@@ -154,7 +186,7 @@ impl BlockManager {
 		block_manager.endpoint.set_handler(block_manager.clone());
 		block_manager.scrub_persister.set_with(|_| ()).unwrap();
 
-		block_manager
+		Ok(block_manager)
 	}
 
 	pub fn spawn_workers(self: &Arc<Self>, bg: &BackgroundRunner) {
@@ -201,44 +233,10 @@ impl BlockManager {
 		hash: &Hash,
 		order_tag: Option<OrderTag>,
 	) -> Result<(DataBlockHeader, ByteStream), Error> {
-		let who = self.replication.read_nodes(hash);
-		let who = self.system.rpc.request_order(&who);
-
-		for node in who.iter() {
-			let node_id = NodeID::from(*node);
-			let rpc = self.endpoint.call_streaming(
-				&node_id,
-				BlockRpc::GetBlock(*hash, order_tag),
-				PRIO_NORMAL | PRIO_SECONDARY,
-			);
-			tokio::select! {
-				res = rpc => {
-					let res = match res {
-						Ok(res) => res,
-						Err(e) => {
-							debug!("Node {:?} returned error: {}", node, e);
-							continue;
-						}
-					};
-					let (header, stream) = match res.into_parts() {
-						(Ok(BlockRpc::PutBlock { hash: _, header }), Some(stream)) => (header, stream),
-						_ => {
-							debug!("Node {:?} returned a malformed response", node);
-							continue;
-						}
-					};
-					return Ok((header, stream));
-				}
-				_ = tokio::time::sleep(self.system.rpc.rpc_timeout()) => {
-					debug!("Node {:?} didn't return block in time, trying next.", node);
-				}
-			};
-		}
-
-		Err(Error::Message(format!(
-			"Unable to read block {:?}: no node returned a valid block",
-			hash
-		)))
+		self.rpc_get_raw_block_internal(hash, order_tag, |header, stream| async move {
+			Ok((header, stream))
+		})
+		.await
 	}
 
 	/// Ask nodes that might have a (possibly compressed) block for it
@@ -248,6 +246,24 @@ impl BlockManager {
 		hash: &Hash,
 		order_tag: Option<OrderTag>,
 	) -> Result<DataBlock, Error> {
+		self.rpc_get_raw_block_internal(hash, order_tag, |header, stream| async move {
+			read_stream_to_end(stream)
+				.await
+				.map(|data| DataBlock::from_parts(header, data))
+		})
+		.await
+	}
+
+	async fn rpc_get_raw_block_internal<F, Fut, T>(
+		&self,
+		hash: &Hash,
+		order_tag: Option<OrderTag>,
+		f: F,
+	) -> Result<T, Error>
+	where
+		F: Fn(DataBlockHeader, ByteStream) -> Fut,
+		Fut: futures::Future<Output = Result<T, Error>>,
+	{
 		let who = self.replication.read_nodes(hash);
 		let who = self.system.rpc.request_order(&who);
 
@@ -263,34 +279,41 @@ impl BlockManager {
 					let res = match res {
 						Ok(res) => res,
 						Err(e) => {
-							debug!("Node {:?} returned error: {}", node, e);
+							debug!("Get block {:?}: node {:?} could not be contacted: {}", hash, node, e);
 							continue;
 						}
 					};
 					let (header, stream) = match res.into_parts() {
 						(Ok(BlockRpc::PutBlock { hash: _, header }), Some(stream)) => (header, stream),
-						_ => {
-							debug!("Node {:?} returned a malformed response", node);
+						(Ok(_), _) => {
+							debug!("Get block {:?}: node {:?} returned a malformed response", hash, node);
+							continue;
+						}
+						(Err(e), _) => {
+							debug!("Get block {:?}: node {:?} returned error: {}", hash, node, e);
 							continue;
 						}
 					};
-					match read_stream_to_end(stream).await {
-						Ok(bytes) => return Ok(DataBlock::from_parts(header, bytes)),
+					match f(header, stream).await {
+						Ok(ret) => return Ok(ret),
 						Err(e) => {
-							debug!("Error reading stream from node {:?}: {}", node, e);
+							debug!("Get block {:?}: error reading stream from node {:?}: {}", hash, node, e);
 						}
 					}
 				}
+				// TODO: sleep less long (fail early), initiate a second request earlier
+				// if the first one doesn't succeed rapidly
+				// TODO: keep first request running when initiating a new one and take the
+				// one that finishes earlier
 				_ = tokio::time::sleep(self.system.rpc.rpc_timeout()) => {
-					debug!("Node {:?} didn't return block in time, trying next.", node);
+					debug!("Get block {:?}: node {:?} didn't return block in time, trying next.", hash, node);
 				}
 			};
 		}
 
-		Err(Error::Message(format!(
-			"Unable to read block {:?}: no node returned a valid block",
-			hash
-		)))
+		let msg = format!("Get block {:?}: no node returned a valid block", hash);
+		debug!("{}", msg);
+		Err(Error::Message(msg))
 	}
 
 	// ---- Public interface ----
@@ -468,8 +491,6 @@ impl BlockManager {
 	pub(crate) async fn write_block(&self, hash: &Hash, data: &DataBlock) -> Result<(), Error> {
 		let tracer = opentelemetry::global::tracer("garage");
 
-		let write_size = data.inner_buffer().len() as u64;
-
 		self.lock_mutate(hash)
 			.await
 			.write_block(hash, data, self)
@@ -479,8 +500,6 @@ impl BlockManager {
 			))
 			.await?;
 
-		self.metrics.bytes_written.add(write_size);
-
 		Ok(())
 	}
 
@@ -507,36 +526,42 @@ impl BlockManager {
 
 	/// Read block from disk, verifying it's integrity
 	pub(crate) async fn read_block(&self, hash: &Hash) -> Result<DataBlock, Error> {
-		let data = self
-			.read_block_internal(hash)
-			.bound_record_duration(&self.metrics.block_read_duration)
-			.await?;
-
-		self.metrics
-			.bytes_read
-			.add(data.inner_buffer().len() as u64);
-
-		Ok(data)
+		let tracer = opentelemetry::global::tracer("garage");
+		async {
+			match self.find_block(hash).await {
+				Some(p) => self.read_block_from(hash, &p).await,
+				None => {
+					// Not found but maybe we should have had it ??
+					self.resync
+						.put_to_resync(hash, 2 * self.system.rpc.rpc_timeout())?;
+					return Err(Error::Message(format!(
+						"block {:?} not found on node",
+						hash
+					)));
+				}
+			}
+		}
+		.bound_record_duration(&self.metrics.block_read_duration)
+		.with_context(Context::current_with_span(
+			tracer.start("BlockManager::read_block"),
+		))
+		.await
 	}
 
-	async fn read_block_internal(&self, hash: &Hash) -> Result<DataBlock, Error> {
-		let mut path = self.block_path(hash);
-		let compressed = match self.is_block_compressed(hash).await {
-			Ok(c) => c,
-			Err(e) => {
-				// Not found but maybe we should have had it ??
-				self.resync
-					.put_to_resync(hash, 2 * self.system.rpc.rpc_timeout())?;
-				return Err(Into::into(e));
-			}
+	pub(crate) async fn read_block_from(
+		&self,
+		hash: &Hash,
+		block_path: &DataBlockPath,
+	) -> Result<DataBlock, Error> {
+		let (path, compressed) = match block_path {
+			DataBlockPath::Plain(p) => (p, false),
+			DataBlockPath::Compressed(p) => (p, true),
 		};
-		if compressed {
-			path.set_extension("zst");
-		}
-		let mut f = fs::File::open(&path).await?;
 
+		let mut f = fs::File::open(&path).await?;
 		let mut data = vec![];
 		f.read_to_end(&mut data).await?;
+		self.metrics.bytes_read.add(data.len() as u64);
 		drop(f);
 
 		let data = if compressed {
@@ -548,29 +573,27 @@ impl BlockManager {
 		if data.verify(*hash).is_err() {
 			self.metrics.corruption_counter.add(1);
 
+			warn!(
+				"Block {:?} is corrupted. Renaming to .corrupted and resyncing.",
+				hash
+			);
 			self.lock_mutate(hash)
 				.await
-				.move_block_to_corrupted(hash, self)
+				.move_block_to_corrupted(block_path)
 				.await?;
 			self.resync.put_to_resync(hash, Duration::from_millis(0))?;
+
 			return Err(Error::CorruptData(*hash));
 		}
 
 		Ok(data)
 	}
 
-	/// Check if this node has a block and whether it needs it
-	pub(crate) async fn check_block_status(&self, hash: &Hash) -> Result<BlockStatus, Error> {
-		self.lock_mutate(hash)
-			.await
-			.check_block_status(hash, self)
-			.await
-	}
-
 	/// Check if this node should have a block, but don't actually have it
 	async fn need_block(&self, hash: &Hash) -> Result<bool, Error> {
-		let BlockStatus { exists, needed } = self.check_block_status(hash).await?;
-		Ok(needed.is_nonzero() && !exists)
+		let rc = self.rc.get_block_rc(hash)?;
+		let exists = self.find_block(hash).await.is_some();
+		Ok(rc.is_nonzero() && !exists)
 	}
 
 	/// Delete block if it is not needed anymore
@@ -581,59 +604,65 @@ impl BlockManager {
 			.await
 	}
 
-	/// Utility: gives the path of the directory in which a block should be found
-	fn block_dir(&self, hash: &Hash) -> PathBuf {
-		let mut path = self.data_dir.clone();
-		path.push(hex::encode(&hash.as_slice()[0..1]));
-		path.push(hex::encode(&hash.as_slice()[1..2]));
-		path
-	}
-
-	/// Utility: give the full path where a block should be found, minus extension if block is
-	/// compressed
-	fn block_path(&self, hash: &Hash) -> PathBuf {
-		let mut path = self.block_dir(hash);
-		path.push(hex::encode(hash.as_ref()));
-		path
-	}
+	/// Find the path where a block is currently stored
+	pub(crate) async fn find_block(&self, hash: &Hash) -> Option<DataBlockPath> {
+		let data_layout = self.data_layout.load_full();
+		let dirs = Some(data_layout.primary_block_dir(hash))
+			.into_iter()
+			.chain(data_layout.secondary_block_dirs(hash));
+		let filename = hex::encode(hash.as_ref());
 
-	/// Utility: check if block is stored compressed. Error if block is not stored
-	async fn is_block_compressed(&self, hash: &Hash) -> Result<bool, Error> {
-		let mut path = self.block_path(hash);
+		for dir in dirs {
+			let mut path = dir;
+			path.push(&filename);
 
-		// If compression is disabled on node - check for the raw block
-		// first and then a compressed one (as compression may have been
-		// previously enabled).
-		match self.compression_level {
-			None => {
+			if self.compression_level.is_none() {
+				// If compression is disabled on node - check for the raw block
+				// first and then a compressed one (as compression may have been
+				// previously enabled).
 				if fs::metadata(&path).await.is_ok() {
-					return Ok(false);
+					return Some(DataBlockPath::Plain(path));
 				}
-
 				path.set_extension("zst");
-
-				fs::metadata(&path).await.map(|_| true).map_err(Into::into)
-			}
-			_ => {
+				if fs::metadata(&path).await.is_ok() {
+					return Some(DataBlockPath::Compressed(path));
+				}
+			} else {
 				path.set_extension("zst");
-
 				if fs::metadata(&path).await.is_ok() {
-					return Ok(true);
+					return Some(DataBlockPath::Compressed(path));
 				}
-
 				path.set_extension("");
-
-				fs::metadata(&path).await.map(|_| false).map_err(Into::into)
+				if fs::metadata(&path).await.is_ok() {
+					return Some(DataBlockPath::Plain(path));
+				}
 			}
 		}
+
+		None
+	}
+
+	/// Rewrite a block at the primary location for its path and delete the old path.
+	/// Returns the number of bytes read/written
+	pub(crate) async fn fix_block_location(
+		&self,
+		hash: &Hash,
+		wrong_path: DataBlockPath,
+	) -> Result<usize, Error> {
+		self.lock_mutate(hash)
+			.await
+			.fix_block_location(hash, wrong_path, self)
+			.await
 	}
 
 	async fn lock_mutate(&self, hash: &Hash) -> MutexGuard<'_, BlockManagerLocked> {
 		let tracer = opentelemetry::global::tracer("garage");
-		self.mutation_lock[hash.as_slice()[0] as usize]
+		let ilock = u16::from_be_bytes([hash.as_slice()[0], hash.as_slice()[1]]) as usize
+			% self.mutation_lock.len();
+		self.mutation_lock[ilock]
 			.lock()
 			.with_context(Context::current_with_span(
-				tracer.start("Acquire mutation_lock"),
+				tracer.start(format!("Acquire mutation_lock #{}", ilock)),
 			))
 			.await
 	}
@@ -646,7 +675,7 @@ impl StreamingEndpointHandler<BlockRpc> for BlockManager {
 			BlockRpc::PutBlock { hash, header } => Resp::new(
 				self.handle_put_block(*hash, *header, message.take_stream())
 					.await
-					.map(|_| BlockRpc::Ok),
+					.map(|()| BlockRpc::Ok),
 			),
 			BlockRpc::GetBlock(h, order_tag) => self.handle_get_block(h, *order_tag).await,
 			BlockRpc::NeedBlockQuery(h) => {
@@ -657,66 +686,78 @@ impl StreamingEndpointHandler<BlockRpc> for BlockManager {
 	}
 }
 
-pub(crate) struct BlockStatus {
-	pub(crate) exists: bool,
-	pub(crate) needed: RcEntry,
-}
-
 impl BlockManagerLocked {
-	async fn check_block_status(
+	async fn write_block(
 		&self,
 		hash: &Hash,
+		data: &DataBlock,
 		mgr: &BlockManager,
-	) -> Result<BlockStatus, Error> {
-		let exists = mgr.is_block_compressed(hash).await.is_ok();
-		let needed = mgr.rc.get_block_rc(hash)?;
-
-		Ok(BlockStatus { exists, needed })
+	) -> Result<(), Error> {
+		let existing_path = mgr.find_block(hash).await;
+		self.write_block_inner(hash, data, mgr, existing_path).await
 	}
 
-	async fn write_block(
+	async fn write_block_inner(
 		&self,
 		hash: &Hash,
 		data: &DataBlock,
 		mgr: &BlockManager,
+		existing_path: Option<DataBlockPath>,
 	) -> Result<(), Error> {
 		let compressed = data.is_compressed();
 		let data = data.inner_buffer();
 
-		let mut path = mgr.block_dir(hash);
-		let directory = path.clone();
-		path.push(hex::encode(hash));
+		let directory = mgr.data_layout.load().primary_block_dir(hash);
 
-		fs::create_dir_all(&directory).await?;
+		let mut tgt_path = directory.clone();
+		tgt_path.push(hex::encode(hash));
+		if compressed {
+			tgt_path.set_extension("zst");
+		}
 
-		let to_delete = match (mgr.is_block_compressed(hash).await, compressed) {
-			(Ok(true), _) => return Ok(()),
-			(Ok(false), false) => return Ok(()),
-			(Ok(false), true) => {
-				let path_to_delete = path.clone();
-				path.set_extension("zst");
-				Some(path_to_delete)
-			}
-			(Err(_), compressed) => {
-				if compressed {
-					path.set_extension("zst");
-				}
-				None
-			}
+		let to_delete = match (existing_path, compressed) {
+			// If the block is stored in the wrong directory,
+			// write it again at the correct path and delete the old path
+			(Some(DataBlockPath::Plain(p)), false) if p != tgt_path => Some(p),
+			(Some(DataBlockPath::Compressed(p)), true) if p != tgt_path => Some(p),
+
+			// If the block is already stored not compressed but we have a compressed
+			// copy, write the compressed copy and delete the uncompressed one
+			(Some(DataBlockPath::Plain(plain_path)), true) => Some(plain_path),
+
+			// If the block is already stored compressed,
+			// keep the stored copy, we have nothing to do
+			(Some(DataBlockPath::Compressed(_)), _) => return Ok(()),
+
+			// If the block is already stored not compressed,
+			// and we don't have a compressed copy either,
+			// keep the stored copy, we have nothing to do
+			(Some(DataBlockPath::Plain(_)), false) => return Ok(()),
+
+			// If the block isn't stored already, just store what is given to us
+			(None, _) => None,
 		};
+		assert!(to_delete.as_ref() != Some(&tgt_path));
 
-		let mut path_tmp = path.clone();
+		let mut path_tmp = tgt_path.clone();
 		let tmp_extension = format!("tmp{}", hex::encode(thread_rng().gen::<[u8; 4]>()));
 		path_tmp.set_extension(tmp_extension);
 
+		fs::create_dir_all(&directory).await?;
+
 		let mut delete_on_drop = DeleteOnDrop(Some(path_tmp.clone()));
 
 		let mut f = fs::File::create(&path_tmp).await?;
 		f.write_all(data).await?;
-		f.sync_all().await?;
+		mgr.metrics.bytes_written.add(data.len() as u64);
+
+		if mgr.data_fsync {
+			f.sync_all().await?;
+		}
+
 		drop(f);
 
-		fs::rename(path_tmp, path).await?;
+		fs::rename(path_tmp, tgt_path).await?;
 
 		delete_on_drop.cancel();
 
@@ -724,52 +765,67 @@ impl BlockManagerLocked {
 			fs::remove_file(to_delete).await?;
 		}
 
-		// We want to ensure that when this function returns, data is properly persisted
-		// to disk. The first step is the sync_all above that does an fsync on the data file.
-		// Now, we do an fsync on the containing directory, to ensure that the rename
-		// is persisted properly. See:
-		// http://thedjbway.b0llix.net/qmail/syncdir.html
-		let dir = fs::OpenOptions::new()
-			.read(true)
-			.mode(0)
-			.open(directory)
-			.await?;
-		dir.sync_all().await?;
-		drop(dir);
+		if mgr.data_fsync {
+			// We want to ensure that when this function returns, data is properly persisted
+			// to disk. The first step is the sync_all above that does an fsync on the data file.
+			// Now, we do an fsync on the containing directory, to ensure that the rename
+			// is persisted properly. See:
+			// http://thedjbway.b0llix.net/qmail/syncdir.html
+			let dir = fs::OpenOptions::new()
+				.read(true)
+				.mode(0)
+				.open(directory)
+				.await?;
+			dir.sync_all().await?;
+			drop(dir);
+		}
 
 		Ok(())
 	}
 
-	async fn move_block_to_corrupted(&self, hash: &Hash, mgr: &BlockManager) -> Result<(), Error> {
-		warn!(
-			"Block {:?} is corrupted. Renaming to .corrupted and resyncing.",
-			hash
-		);
-		let mut path = mgr.block_path(hash);
-		let mut path2 = path.clone();
-		if mgr.is_block_compressed(hash).await? {
-			path.set_extension("zst");
-			path2.set_extension("zst.corrupted");
-		} else {
-			path2.set_extension("corrupted");
-		}
+	async fn move_block_to_corrupted(&self, block_path: &DataBlockPath) -> Result<(), Error> {
+		let (path, path2) = match block_path {
+			DataBlockPath::Plain(p) => {
+				let mut p2 = p.clone();
+				p2.set_extension("corrupted");
+				(p, p2)
+			}
+			DataBlockPath::Compressed(p) => {
+				let mut p2 = p.clone();
+				p2.set_extension("zst.corrupted");
+				(p, p2)
+			}
+		};
+
 		fs::rename(path, path2).await?;
 		Ok(())
 	}
 
 	async fn delete_if_unneeded(&self, hash: &Hash, mgr: &BlockManager) -> Result<(), Error> {
-		let BlockStatus { exists, needed } = self.check_block_status(hash, mgr).await?;
-
-		if exists && needed.is_deletable() {
-			let mut path = mgr.block_path(hash);
-			if mgr.is_block_compressed(hash).await? {
-				path.set_extension("zst");
+		let rc = mgr.rc.get_block_rc(hash)?;
+		if rc.is_deletable() {
+			while let Some(path) = mgr.find_block(hash).await {
+				let path = match path {
+					DataBlockPath::Plain(p) | DataBlockPath::Compressed(p) => p,
+				};
+				fs::remove_file(path).await?;
+				mgr.metrics.delete_counter.add(1);
 			}
-			fs::remove_file(path).await?;
-			mgr.metrics.delete_counter.add(1);
 		}
 		Ok(())
 	}
+
+	async fn fix_block_location(
+		&self,
+		hash: &Hash,
+		wrong_path: DataBlockPath,
+		mgr: &BlockManager,
+	) -> Result<usize, Error> {
+		let data = mgr.read_block_from(hash, &wrong_path).await?;
+		self.write_block_inner(hash, &data, mgr, Some(wrong_path))
+			.await?;
+		Ok(data.inner_buffer().len())
+	}
 }
 
 async fn read_stream_to_end(mut stream: ByteStream) -> Result<Bytes, Error> {