diff --git a/swh/storage/storage.py b/swh/storage/storage.py
index ffeb6484..ec99dc5c 100644
--- a/swh/storage/storage.py
+++ b/swh/storage/storage.py
@@ -1,72 +1,89 @@
 # Copyright (C) 2015  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 
 import psycopg2
 import tempfile
 
 from .db import Db
 from .objstorage import ObjStorage
 
 
+def db_transaction(meth):
+    """decorator to execute Storage methods within DB transactions
+
+    Decorated methods will have access to the following attributes:
+        self.cur: psycopg2 DB cursor
+
+    """
+    def _meth(self, *args, **kwargs):
+        with self.db.transaction() as cur:
+            try:
+                self.cur = cur
+                meth(self, *args, **kwargs)
+            finally:
+                self.cur = None
+    return _meth
+
+
 class Storage():
     """SWH storage proxy, encompassing DB and object storage
 
     """
 
     def __init__(self, db_conn, obj_root):
         """
         Args:
             db_conn: either a libpq connection string, or a psycopg2 connection
             obj_root: path to the root of the object storage
 
         """
         if isinstance(db_conn, psycopg2.extensions.connection):
             self.db = Db(db_conn)
         else:
             self.db = Db.connect(db_conn)
 
         self.objstorage = ObjStorage(obj_root)
 
+    @db_transaction
     def add_content(self, content):
         """Add content blobs to the storage
 
         Note: in case of DB errors, objects might have already been added to
         the object storage and will not be removed. Since addition to the
         object storage is idempotent, that should not be a problem.
 
         Args:
             content: iterable of dictionaries representing individual pieces of
                 content to add. Each dictionary has the following keys:
                 - data (bytes): the actual content
                 - one key for each checksum algorithm in
                   swh.core.hashutil(ALGORITHMS), mapped to the corresponding
                   checksum
 
         """
-        db = self.db
-        with db.transaction() as cur:
-            # create temporary table for metadata injection
-            db.content_mktemp(cur)
-
-            with tempfile.TemporaryFile('w+') as f:
-                # prepare tempfile for metadata COPY + add content data to
-                # object storage
-                for cont in content:
-                    cont['length'] = len(cont['data'])
-                    line = '\t'.join([cont['sha1'], cont['sha1_git'],
-                                      cont['sha256'], str(len(cont['data']))])\
-                        + '\n'
-                    f.write(line)
-                    self.objstorage.add_bytes(cont['data'],
-                                              obj_id=cont['sha1'])
-
-                # COPY metadata to temporary table
-                f.seek(0)
-                db.content_copy_to_temp(f, cur)
-
-            # move metadata in place
-            db.content_add_from_temp(cur)
-            db.conn.commit()
+        (db, cur) = (self.db, self.cur)
+        # create temporary table for metadata injection
+        db.content_mktemp(cur)
+
+        with tempfile.TemporaryFile('w+') as f:
+            # prepare tempfile for metadata COPY + add content data to
+            # object storage
+            for cont in content:
+                cont['length'] = len(cont['data'])
+                line = '\t'.join([cont['sha1'], cont['sha1_git'],
+                                  cont['sha256'], str(len(cont['data']))])\
+                    + '\n'
+                f.write(line)
+                self.objstorage.add_bytes(cont['data'],
+                                          obj_id=cont['sha1'])
+
+            # COPY metadata to temporary table
+            f.seek(0)
+            db.content_copy_to_temp(f, cur)
+
+        # move metadata in place
+        db.content_add_from_temp(cur)
+        db.conn.commit()