diff --git a/src/blockstore.h b/src/blockstore.h
index b99f6f0e..c0b24a7d 100644
--- a/src/blockstore.h
+++ b/src/blockstore.h
@@ -65,10 +65,9 @@ Input:
 - offset, len = offset and length within object. length may be zero, in that case
   read operation only returns the version / write operation only bumps the version
 - buf = pre-allocated buffer for data (read) / with data (write). may be NULL if len == 0.
-- bitmap = <entry_attr_size> bytes long arbitrary data stored for each object in the metadata area.
-  when <entry_attr_size> fits into pointer size, it should be passed as this field's value.
-  when it doesn't fit, this field should be a pointer to that piece of data.
-  named "bitmap" because it's used for the "external bitmap" in Vitastor.
+- bitmap = pointer to <entry_attr_size> bytes long (usually very short) arbitrary data
+  stored for each object in the metadata area.
+  Called "bitmap" because it's used for the "external bitmap" in Vitastor.
 
 Output:
 - retval = number of bytes actually read/written or negative error number (-EINVAL or -ENOSPC)
diff --git a/src/blockstore_read.cpp b/src/blockstore_read.cpp
index c0d79576..4747709a 100644
--- a/src/blockstore_read.cpp
+++ b/src/blockstore_read.cpp
@@ -149,10 +149,11 @@ int blockstore_impl_t::dequeue_read(blockstore_op_t *read_op)
                 if (!result_version)
                 {
                     result_version = dirty_it->first.version;
-                    if (entry_attr_size <= sizeof(void*))
-                        read_op->bitmap = dirty_it->second.bitmap;
-                    else if (read_op->bitmap)
-                        memcpy(read_op->bitmap, dirty_it->second.bitmap, entry_attr_size);
+                    if (read_op->bitmap)
+                    {
+                        void *bmp_ptr = (entry_attr_size > sizeof(void*) ? dirty_it->second.bitmap : &dirty_it->second.bitmap);
+                        memcpy(read_op->bitmap, bmp_ptr, entry_attr_size);
+                    }
                 }
                 if (!fulfill_read(read_op, fulfilled, dirty.offset, dirty.offset + dirty.len,
                     dirty.state, dirty_it->first.version, dirty.location + (IS_JOURNAL(dirty.state) ? 0 : dirty.offset)))
@@ -174,11 +175,11 @@ int blockstore_impl_t::dequeue_read(blockstore_op_t *read_op)
         if (!result_version)
         {
             result_version = clean_it->second.version;
-            void *clean_entry_bitmap = get_clean_entry_bitmap(clean_it->second.location, clean_entry_bitmap_size);
-            if (entry_attr_size <= sizeof(void*))
-                memcpy(&read_op->bitmap, clean_entry_bitmap, entry_attr_size);
-            else if (read_op->bitmap)
-                memcpy(read_op->bitmap, clean_entry_bitmap, entry_attr_size);
+            if (read_op->bitmap)
+            {
+                void *bmp_ptr = get_clean_entry_bitmap(clean_it->second.location, clean_entry_bitmap_size);
+                memcpy(read_op->bitmap, bmp_ptr, entry_attr_size);
+            }
         }
         if (fulfilled < read_op->len)
         {
diff --git a/src/blockstore_write.cpp b/src/blockstore_write.cpp
index 83a0e81e..3f840f2b 100644
--- a/src/blockstore_write.cpp
+++ b/src/blockstore_write.cpp
@@ -111,13 +111,9 @@ bool blockstore_impl_t::enqueue_write(blockstore_op_t *op)
         if (op->opcode == BS_OP_WRITE_STABLE)
             state |= BS_ST_INSTANT;
         if (entry_attr_size > sizeof(void*))
-        {
             bmp = calloc_or_die(1, entry_attr_size);
-            if (op->bitmap)
-                memcpy(bmp, op->bitmap, entry_attr_size);
-        }
-        else
-            bmp = op->bitmap;
+        if (op->bitmap)
+            memcpy((entry_attr_size > sizeof(void*) ? bmp : &bmp), op->bitmap, entry_attr_size);
     }
     dirty_db.emplace((obj_ver_id){
         .oid = op->oid,
diff --git a/src/msgr_op.h b/src/msgr_op.h
index 96612297..b2d268f1 100644
--- a/src/msgr_op.h
+++ b/src/msgr_op.h
@@ -162,6 +162,7 @@ struct osd_op_t
     blockstore_op_t *bs_op = NULL;
     void *buf = NULL;
     void *bitmap = NULL;
+    unsigned bmp_data = 0;
     void *rmw_buf = NULL;
     osd_primary_op_data_t* op_data = NULL;
     std::function<void(osd_op_t*)> callback;
diff --git a/src/msgr_receive.cpp b/src/msgr_receive.cpp
index 20fd085a..6f0d1188 100644
--- a/src/msgr_receive.cpp
+++ b/src/msgr_receive.cpp
@@ -209,13 +209,11 @@ void osd_messenger_t::handle_op_hdr(osd_client_t *cl)
     {
         if (cur_op->req.sec_rw.attr_len > 0)
         {
-            if (cur_op->req.sec_rw.attr_len > sizeof(void*))
-            {
+            if (cur_op->req.sec_rw.attr_len > sizeof(unsigned))
                 cur_op->bitmap = cur_op->rmw_buf = malloc_or_die(cur_op->req.sec_rw.attr_len);
-                cl->recv_list.push_back(cur_op->bitmap, cur_op->req.sec_rw.attr_len);
-            }
             else
-                cl->recv_list.push_back(&cur_op->bitmap, cur_op->req.sec_rw.attr_len);
+                cur_op->bitmap = &cur_op->bmp_data;
+            cl->recv_list.push_back(cur_op->bitmap, cur_op->req.sec_rw.attr_len);
         }
         if (cur_op->req.sec_rw.len > 0)
         {
diff --git a/src/msgr_send.cpp b/src/msgr_send.cpp
index c3cdefdf..d5c8090d 100644
--- a/src/msgr_send.cpp
+++ b/src/msgr_send.cpp
@@ -66,7 +66,7 @@ void osd_messenger_t::outbox_push(osd_op_t *cur_op)
             cur_op->req.sec_rw.attr_len > 0)
         {
             to_send_list.push_back((iovec){
-                .iov_base = (cur_op->reply.sec_rw.attr_len > sizeof(void*) ? cur_op->bitmap : &cur_op->bitmap),
+                .iov_base = cur_op->bitmap,
                 .iov_len = cur_op->reply.sec_rw.attr_len,
             });
             to_outbox.push_back(NULL);
diff --git a/src/osd_primary.cpp b/src/osd_primary.cpp
index 1bcf60df..c7da0fa9 100644
--- a/src/osd_primary.cpp
+++ b/src/osd_primary.cpp
@@ -2,6 +2,7 @@
 // License: VNPL-1.1 (see README.md for details)
 
 #include "osd_primary.h"
+#include "allocator.h"
 
 // read: read directly or read paired stripe(s), reconstruct, return
 // write: read paired stripe(s), reconstruct, modify, calculate parity, write
@@ -51,7 +52,8 @@ bool osd_t::prepare_primary_rw(osd_op_t *cur_op)
         return false;
     }
     osd_primary_op_data_t *op_data = (osd_primary_op_data_t*)calloc_or_die(
-        1, sizeof(osd_primary_op_data_t) + sizeof(osd_rmw_stripe_t) * (pool_cfg.scheme == POOL_SCHEME_REPLICATED ? 1 : pg_it->second.pg_size)
+        1, sizeof(osd_primary_op_data_t) + entry_attr_size +
+        sizeof(osd_rmw_stripe_t) * (pool_cfg.scheme == POOL_SCHEME_REPLICATED ? 1 : pg_it->second.pg_size)
     );
     op_data->pg_num = pg_num;
     op_data->oid = oid;
@@ -115,7 +117,7 @@ void osd_t::continue_primary_read(osd_op_t *cur_op)
         if (pg.state == PG_ACTIVE || op_data->scheme == POOL_SCHEME_REPLICATED)
         {
             // Fast happy-path
-            cur_op->buf = alloc_read_buffer(op_data->stripes, op_data->pg_data_size, 0, 0);
+            cur_op->buf = alloc_read_buffer(op_data->stripes, op_data->pg_data_size, 0, entry_attr_size);
             submit_primary_subops(SUBMIT_READ, op_data->target_ver,
                 (op_data->scheme == POOL_SCHEME_REPLICATED ? pg.pg_size : op_data->pg_data_size), pg.cur_set.data(), cur_op);
             op_data->st = 1;
@@ -133,7 +135,7 @@ void osd_t::continue_primary_read(osd_op_t *cur_op)
             op_data->pg_size = pg.pg_size;
             op_data->scheme = pg.scheme;
             op_data->degraded = 1;
-            cur_op->buf = alloc_read_buffer(op_data->stripes, pg.pg_size, 0, 0);
+            cur_op->buf = alloc_read_buffer(op_data->stripes, pg.pg_size, 0, entry_attr_size);
             submit_primary_subops(SUBMIT_READ, op_data->target_ver, pg.pg_size, cur_set, cur_op);
             op_data->st = 1;
         }
@@ -152,11 +154,11 @@ resume_2:
         osd_rmw_stripe_t *stripes = op_data->stripes;
         if (op_data->scheme == POOL_SCHEME_XOR)
         {
-            reconstruct_stripes_xor(stripes, op_data->pg_size, 0);
+            reconstruct_stripes_xor(stripes, op_data->pg_size, entry_attr_size);
         }
         else if (op_data->scheme == POOL_SCHEME_JERASURE)
         {
-            reconstruct_stripes_jerasure(stripes, op_data->pg_size, op_data->pg_data_size, 0);
+            reconstruct_stripes_jerasure(stripes, op_data->pg_size, op_data->pg_data_size, entry_attr_size);
         }
         for (int role = 0; role < op_data->pg_size; role++)
         {
diff --git a/src/osd_primary_subops.cpp b/src/osd_primary_subops.cpp
index 47aa0a0c..0a81ebf4 100644
--- a/src/osd_primary_subops.cpp
+++ b/src/osd_primary_subops.cpp
@@ -145,6 +145,7 @@ void osd_t::submit_primary_subops(int submit_type, uint64_t op_version, int pg_s
                     .offset = wr ? stripes[stripe_num].write_start : stripes[stripe_num].read_start,
                     .len = wr ? stripes[stripe_num].write_end - stripes[stripe_num].write_start : stripes[stripe_num].read_end - stripes[stripe_num].read_start,
                     .buf = wr ? stripes[stripe_num].write_buf : stripes[stripe_num].read_buf,
+                    .bitmap = stripes[stripe_num].bmp_buf,
                 });
 #ifdef OSD_DEBUG
                 printf(
@@ -159,6 +160,7 @@ void osd_t::submit_primary_subops(int submit_type, uint64_t op_version, int pg_s
             {
                 subops[i].op_type = OSD_OP_OUT;
                 subops[i].peer_fd = c_cli.osd_peer_fds.at(role_osd_num);
+                subops[i].bitmap = stripes[stripe_num].bmp_buf;
                 subops[i].req.sec_rw = {
                     .header = {
                         .magic = SECONDARY_OSD_OP_MAGIC,
@@ -172,6 +174,7 @@ void osd_t::submit_primary_subops(int submit_type, uint64_t op_version, int pg_s
                     .version = op_version,
                     .offset = wr ? stripes[stripe_num].write_start : stripes[stripe_num].read_start,
                     .len = wr ? stripes[stripe_num].write_end - stripes[stripe_num].write_start : stripes[stripe_num].read_end - stripes[stripe_num].read_start,
+                    .attr_len = entry_attr_size,
                 };
 #ifdef OSD_DEBUG
                 printf(
diff --git a/src/osd_primary_write.cpp b/src/osd_primary_write.cpp
index e984b219..0b242182 100644
--- a/src/osd_primary_write.cpp
+++ b/src/osd_primary_write.cpp
@@ -65,6 +65,7 @@ resume_1:
         op_data->stripes[0].write_start = op_data->stripes[0].req_start;
         op_data->stripes[0].write_end = op_data->stripes[0].req_end;
         op_data->stripes[0].write_buf = cur_op->buf;
+        op_data->stripes[0].bmp_buf = (void*)(op_data->stripes+1);
         if (pg.cur_set.data() != op_data->prev_set && (op_data->stripes[0].write_start != 0 ||
             op_data->stripes[0].write_end != bs_block_size))
         {
@@ -77,7 +78,7 @@ resume_1:
     else
     {
         cur_op->rmw_buf = calc_rmw(cur_op->buf, op_data->stripes, op_data->prev_set,
-            pg.pg_size, op_data->pg_data_size, pg.pg_cursize, pg.cur_set.data(), bs_block_size, 0);
+            pg.pg_size, op_data->pg_data_size, pg.pg_cursize, pg.cur_set.data(), bs_block_size, entry_attr_size);
         if (!cur_op->rmw_buf)
         {
             // Refuse partial overwrite of an incomplete object
@@ -98,7 +99,9 @@ resume_3:
     }
     if (op_data->scheme == POOL_SCHEME_REPLICATED)
     {
-        // Only (possibly) copy new data from the request into the recovery buffer
+        // Set bitmap bits
+        bitmap_set(op_data->stripes[0].bmp_buf, op_data->stripes[0].write_start, op_data->stripes[0].write_end, bs_bitmap_granularity);
+        // Possibly copy new data from the request into the recovery buffer
         if (pg.cur_set.data() != op_data->prev_set && (op_data->stripes[0].write_start != 0 ||
             op_data->stripes[0].write_end != bs_block_size))
         {
@@ -120,11 +123,11 @@ resume_3:
         // Recover missing stripes, calculate parity
         if (pg.scheme == POOL_SCHEME_XOR)
         {
-            calc_rmw_parity_xor(op_data->stripes, pg.pg_size, op_data->prev_set, pg.cur_set.data(), bs_block_size, 0);
+            calc_rmw_parity_xor(op_data->stripes, pg.pg_size, op_data->prev_set, pg.cur_set.data(), bs_block_size, entry_attr_size);
         }
         else if (pg.scheme == POOL_SCHEME_JERASURE)
         {
-            calc_rmw_parity_jerasure(op_data->stripes, pg.pg_size, op_data->pg_data_size, op_data->prev_set, pg.cur_set.data(), bs_block_size, 0);
+            calc_rmw_parity_jerasure(op_data->stripes, pg.pg_size, op_data->pg_data_size, op_data->prev_set, pg.cur_set.data(), bs_block_size, entry_attr_size);
         }
     }
     // Send writes
diff --git a/src/osd_rmw.cpp b/src/osd_rmw.cpp
index 1796b9ca..0000d83f 100644
--- a/src/osd_rmw.cpp
+++ b/src/osd_rmw.cpp
@@ -332,6 +332,7 @@ void* alloc_read_buffer(osd_rmw_stripe_t *stripes, int read_pg_size, uint64_t ad
         }
     }
     // Bitmaps are allocated in the end so data buffers remain aligned
+    // FIXME: Don't allocate bitmaps here because it probably increases memory fragmentation
     if (bitmap_size > 0)
     {
         for (int role = 0; role < read_pg_size; role++)
diff --git a/src/osd_secondary.cpp b/src/osd_secondary.cpp
index e25850db..bb596612 100644
--- a/src/osd_secondary.cpp
+++ b/src/osd_secondary.cpp
@@ -19,11 +19,6 @@ void osd_t::secondary_op_callback(osd_op_t *op)
     }
     if (op->req.hdr.opcode == OSD_OP_SEC_READ)
     {
-        if (entry_attr_size > 0)
-        {
-            op->reply.sec_rw.attr_len = entry_attr_size;
-            op->iov.push_back((entry_attr_size > sizeof(void*) ? op->bitmap : &op->bs_op->bitmap), entry_attr_size);
-        }
         if (op->bs_op->retval > 0)
         {
             op->iov.push_back(op->buf, op->bs_op->retval);
@@ -65,8 +60,10 @@ void osd_t::exec_secondary(osd_op_t *cur_op)
         if (cur_op->req.hdr.opcode == OSD_OP_SEC_READ)
         {
             // Allocate memory for the read operation
-            if (entry_attr_size > sizeof(void*))
+            if (entry_attr_size > sizeof(unsigned))
                 cur_op->bitmap = cur_op->rmw_buf = malloc_or_die(entry_attr_size);
+            else
+                cur_op->bitmap = &cur_op->bmp_data;
             if (cur_op->req.sec_rw.len > 0)
                 cur_op->buf = memalign_or_die(MEM_ALIGNMENT, cur_op->req.sec_rw.len);
         }