diff --git a/src/backend/src/filesystem/ll_operations/ll_write.js b/src/backend/src/filesystem/ll_operations/ll_write.js
index 0b592274..b566dd4f 100644
--- a/src/backend/src/filesystem/ll_operations/ll_write.js
+++ b/src/backend/src/filesystem/ll_operations/ll_write.js
@@ -16,159 +16,17 @@
  * You should have received a copy of the GNU Affero General Public License
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
-const { Context } = require("../../util/context");
 const { LLFilesystemOperation } = require("./definitions");
-const { RESOURCE_STATUS_PENDING_CREATE } = require("../../modules/puterfs/ResourceService.js");
-const { NodeUIDSelector } = require("../node/selectors");
-const { UploadProgressTracker } = require("../storage/UploadProgressTracker");
-const FSNodeContext = require("../FSNodeContext");
 const APIError = require("../../api/APIError");
-const { stuck_detector_stream, hashing_stream } = require("../../util/streamutil");
-const { OperationFrame } = require("../../services/OperationTraceService");
-const { DB_WRITE } = require("../../services/database/consts");
-
-const crypto = require('crypto');
-
-const STUCK_STATUS_TIMEOUT = 10 * 1000;
-const STUCK_ALARM_TIMEOUT = 20 * 1000;
-
-/**
- * Base class for low-level write operations providing common storage upload functionality.
- * @extends LLFilesystemOperation
- */
-class LLWriteBase extends LLFilesystemOperation {
-    static MODULES = {
-        config: require('../../config.js'),
-        simple_retry: require('../../util/retryutil.js').simple_retry,
-    }
-
-    /**
-     * Uploads a file to storage with progress tracking and error handling.
-     * @param {Object} params - Upload parameters
-     * @param {string} params.uuid - Unique identifier for the file
-     * @param {string} [params.bucket] - Storage bucket name
-     * @param {string} [params.bucket_region] - Storage bucket region
-     * @param {Object} params.file - File object containing stream or buffer
-     * @param {Object} params.tmp - Temporary file information
-     * @returns {Promise<Object>} The upload state object
-     * @throws {APIError} When upload fails
-     */
-    async _storage_upload ({
-        uuid,
-        bucket, bucket_region, file,
-        tmp,
-    }) {
-        const { config } = this.modules;
-
-        const svc = Context.get('services');
-        const log = svc.get('log-service').create('fs._storage_upload');
-        const errors = svc.get('error-service').create(log);
-        const svc_event = svc.get('event');
-
-        const svc_mountpoint = svc.get('mountpoint');
-        // TODO (xiaochen): what if the provider is not PuterFSProvider?
-        const storage = svc_mountpoint.get_storage(PuterFSProvider.name);
-
-        bucket        ??= config.s3_bucket;
-        bucket_region ??= config.s3_region ?? config.region;
-
-        let upload_tracker = new UploadProgressTracker();
-
-        svc_event.emit('fs.storage.upload-progress', {
-            upload_tracker,
-            context: Context.get(),
-            meta: {
-                item_uid: uuid,
-                item_path: tmp.path,
-            }
-        })
-
-        if ( ! file.buffer ) {
-            let stream = file.stream;
-            let alarm_timeout = null;
-            stream = stuck_detector_stream(stream, {
-                timeout: STUCK_STATUS_TIMEOUT,
-                on_stuck: () => {
-                    this.frame.status = OperationFrame.FRAME_STATUS_STUCK;
-                    log.warn('Upload stream stuck might be stuck', {
-                        bucket_region,
-                        bucket,
-                        uuid,
-                    });
-                    alarm_timeout = setTimeout(() => {
-                        errors.report('fs.write.s3-upload', {
-                            message: 'Upload stream stuck for too long',
-                            alarm: true,
-                            extra: {
-                                bucket_region,
-                                bucket,
-                                uuid,
-                            },
-                        });
-                    }, STUCK_ALARM_TIMEOUT);
-                },
-                on_unstuck: () => {
-                    clearTimeout(alarm_timeout);
-                    this.frame.status = OperationFrame.FRAME_STATUS_WORKING;
-                }
-            });
-            file = { ...file, stream, };
-        }
-
-        let hashPromise;
-        if ( file.buffer ) {
-            const hash = crypto.createHash('sha256');
-            hash.update(file.buffer);
-            hashPromise = Promise.resolve(hash.digest('hex'));
-        } else {
-            const hs = hashing_stream(file.stream);
-            file.stream = hs.stream;
-            hashPromise = hs.hashPromise;
-        }
-
-        hashPromise.then(hash => {
-            const svc_event = Context.get('services').get('event');
-            this.log.debug('<fs.write>', { uuid, hash });
-            svc_event.emit('outer.fs.write-hash', {
-                hash, uuid,
-            });
-        });
-
-        const state_upload = storage.create_upload();
-
-        try {
-            await state_upload.run({
-                uid: uuid,
-                file,
-                storage_meta: { bucket, bucket_region },
-                storage_api: { progress_tracker: upload_tracker },
-            });
-        } catch (e) {
-            errors.report('fs.write.storage-upload', {
-                source: e || new Error('unknown'),
-                trace: true,
-                alarm: true,
-                extra: {
-                    bucket_region,
-                    bucket,
-                    uuid,
-                },
-            });
-            throw APIError.create('upload_failed');
-        }
-
-        return state_upload;
-    }
-}
 
 /**
  * The "overwrite" write operation.
  * 
  * This operation is used to write a file to an existing path.
  * 
- * @extends LLWriteBase
+ * @extends LLFilesystemOperation
  */
-class LLOWrite extends LLWriteBase {
+class LLOWrite extends LLFilesystemOperation {
     /**
      * Executes the overwrite operation by writing to an existing file node.
      * @returns {Promise<Object>} Result of the write operation
@@ -204,9 +62,9 @@ class LLOWrite extends LLWriteBase {
  * 
  * This operation is used to write a file to a non-existent path.
  * 
- * @extends LLWriteBase
+ * @extends LLFilesystemOperation
  */
-class LLCWrite extends LLWriteBase {
+class LLCWrite extends LLFilesystemOperation {
     static MODULES = {
         _path: require('path'),
         uuidv4: require('uuid').v4,