feat(client): pre-create ufs files in writeback cache mode (#485) (#544)

Author: bigbigxu

curvine-client/src/unified/cache_sync_writer.rs

@@ -181,7 +181,7 @@ impl Writer for CacheSyncWriter {
     }
 
     async fn seek(&mut self, pos: i64) -> FsResult<()> {
-        if self.pos() != pos {
+        if self.pos() != pos && !self.has_rand_write {
             self.has_rand_write = true;
             if let Err(e) = self.job_client.cancel_job(&self.job_res.job_id).await {
                 warn!("cancel job {} failed: {}", self.job_res.job_id, e);

curvine-client/src/unified/unified_filesystem.rs

@@ -280,6 +280,9 @@ impl UnifiedFileSystem {
                 }
 
                 _ => {
+                    // ufs creates an empty file to prevent errors when accessing metadata.
+                    mount.ufs.create(&ufs_path, true).await?;
+
                     let writer = CacheSyncWriter::new(self, path, &mount, flags).await?;
                     Ok(UnifiedWriter::CacheSync(writer))
                 }

curvine-fuse/src/fs/curvine_file_system.rs

@@ -1327,9 +1327,7 @@ impl fs::FileSystem for CurvineFileSystem {
             };
             let res = self.create(op).await?;
             let handle = self.state.remove_handle(res.0.nodeid, res.1.fh);
-            if let Some(handle) = handle {
-                handle.complete(None).await?;
-            } else {
+            if handle.is_none() {
                 return err_fuse!(libc::EIO);
             }
             let out = fuse_entry_out {

curvine-server/src/master/fs/master_filesystem.rs

@@ -268,7 +268,7 @@ impl MasterFilesystem {
 
         let inode = match inp.get_last_inode() {
             None => {
-                return if flags.create() {
+                return if flags.create() || flags.append() {
                     drop(fs_dir);
                     let status = self.create_with_opts(path, opts, flags)?;
                     Ok(FileBlocks::new(status, vec![]))