[Draft] Optimized read

src/blockstore.cpp

@@ -38,6 +38,11 @@ void blockstore_t::enqueue_op(blockstore_op_t *op)
     impl->enqueue_op(op);
 }
 
+int blockstore_t::read_bitmap(object_id oid, uint64_t target_version, void *bitmap, uint64_t *result_version)
+{
+    return impl->read_bitmap(oid, target_version, bitmap, result_version);
+}
+
 std::unordered_map<object_id, uint64_t> & blockstore_t::get_unstable_writes()
 {
     return impl->unstable_writes;

src/blockstore.h

@@ -179,6 +179,9 @@ public:
     // Submission
     void enqueue_op(blockstore_op_t *op);
 
+    // Simplified synchronous operation: get object bitmap & current version
+    int read_bitmap(object_id oid, uint64_t target_version, void *bitmap, uint64_t *result_version = NULL);
+
     // Unstable writes are added here (map of object_id -> version)
     std::unordered_map<object_id, uint64_t> & get_unstable_writes();
 

src/blockstore_impl.cpp

@@ -443,7 +443,7 @@ void blockstore_impl_t::process_list(blockstore_op_t *op)
         }
         for (; clean_it != clean_end; clean_it++)
         {
-            if (!pg_count || ((clean_it->first.inode + clean_it->first.stripe / pg_stripe_size) % pg_count) == list_pg)
+            if (!pg_count || ((clean_it->first.stripe / pg_stripe_size) % pg_count) == list_pg) // like map_to_pg()
             {
                 if (stable_count >= stable_alloc)
                 {
@@ -488,7 +488,7 @@ void blockstore_impl_t::process_list(blockstore_op_t *op)
         }
         for (; dirty_it != dirty_end; dirty_it++)
         {
-            if (!pg_count || ((dirty_it->first.oid.inode + dirty_it->first.oid.stripe / pg_stripe_size) % pg_count) == list_pg)
+            if (!pg_count || ((dirty_it->first.oid.stripe / pg_stripe_size) % pg_count) == list_pg) // like map_to_pg()
             {
                 if (IS_DELETE(dirty_it->second.state))
                 {

src/blockstore_impl.h

@@ -323,6 +323,9 @@ public:
     // Submission
     void enqueue_op(blockstore_op_t *op);
 
+    // Simplified synchronous operation: get object bitmap & current version
+    int read_bitmap(object_id oid, uint64_t target_version, void *bitmap, uint64_t *result_version = NULL);
+
     // Unstable writes are added here (map of object_id -> version)
     std::unordered_map<object_id, uint64_t> unstable_writes;
 

src/blockstore_read.cpp

@@ -268,3 +268,50 @@ void blockstore_impl_t::handle_read_event(ring_data_t *data, blockstore_op_t *op
         FINISH_OP(op);
     }
 }
+
+int blockstore_impl_t::read_bitmap(object_id oid, uint64_t target_version, void *bitmap, uint64_t *result_version)
+{
+    auto dirty_it = dirty_db.upper_bound((obj_ver_id){
+        .oid = oid,
+        .version = UINT64_MAX,
+    });
+    if (dirty_it != dirty_db.begin())
+        dirty_it--;
+    if (dirty_it != dirty_db.end())
+    {
+        while (dirty_it->first.oid == oid)
+        {
+            if (target_version >= dirty_it->first.version)
+            {
+                if (result_version)
+                    *result_version = dirty_it->first.version;
+                if (bitmap)
+                {
+                    void *bmp_ptr = (clean_entry_bitmap_size > sizeof(void*) ? dirty_it->second.bitmap : &dirty_it->second.bitmap);
+                    memcpy(bitmap, bmp_ptr, clean_entry_bitmap_size);
+                }
+                return 0;
+            }
+            if (dirty_it == dirty_db.begin())
+                break;
+            dirty_it--;
+        }
+    }
+    auto clean_it = clean_db.find(oid);
+    if (clean_it != clean_db.end())
+    {
+        if (result_version)
+            *result_version = clean_it->second.version;
+        if (bitmap)
+        {
+            void *bmp_ptr = get_clean_entry_bitmap(clean_it->second.location, clean_entry_bitmap_size);
+            memcpy(bitmap, bmp_ptr, clean_entry_bitmap_size);
+        }
+        return 0;
+    }
+    if (result_version)
+        *result_version = 0;
+    if (bitmap)
+        memset(bitmap, 0, clean_entry_bitmap_size);
+    return -ENOENT;
+}

src/cluster_client.cpp

@@ -582,7 +582,7 @@ void cluster_client_t::slice_rw(cluster_op_t *op)
     int i = 0;
     for (uint64_t stripe = first_stripe; stripe <= last_stripe; stripe += pg_block_size)
     {
-        pg_num_t pg_num = (op->cur_inode + stripe/pool_cfg.pg_stripe_size) % pool_cfg.real_pg_count + 1; // like map_to_pg()
+        pg_num_t pg_num = (stripe/pool_cfg.pg_stripe_size) % pool_cfg.real_pg_count + 1; // like map_to_pg()
         uint64_t begin = (op->offset < stripe ? stripe : op->offset);
         uint64_t end = (op->offset + op->len) > (stripe + pg_block_size)
             ? (stripe + pg_block_size) : (op->offset + op->len);

src/msgr_receive.cpp

@@ -232,6 +232,15 @@ void osd_messenger_t::handle_op_hdr(osd_client_t *cl)
         }
         cl->read_remaining = cur_op->req.sec_stab.len;
     }
+    else if (cur_op->req.hdr.opcode == OSD_OP_SEC_READ_BMP)
+    {
+        if (cur_op->req.sec_read_bmp.len > 0)
+        {
+            cur_op->buf = memalign_or_die(MEM_ALIGNMENT, cur_op->req.sec_read_bmp.len);
+            cl->recv_list.push_back(cur_op->buf, cur_op->req.sec_read_bmp.len);
+        }
+        cl->read_remaining = cur_op->req.sec_read_bmp.len;
+    }
     else if (cur_op->req.hdr.opcode == OSD_OP_READ)
     {
         cl->read_remaining = 0;

src/msgr_send.cpp

@@ -73,6 +73,7 @@ void osd_messenger_t::outbox_push(osd_op_t *cur_op)
         ? (cur_op->req.hdr.opcode == OSD_OP_READ ||
         cur_op->req.hdr.opcode == OSD_OP_SEC_READ ||
         cur_op->req.hdr.opcode == OSD_OP_SEC_LIST ||
+        cur_op->req.hdr.opcode == OSD_OP_SEC_READ_BMP ||
         cur_op->req.hdr.opcode == OSD_OP_SHOW_CONFIG)
         : (cur_op->req.hdr.opcode == OSD_OP_WRITE ||
         cur_op->req.hdr.opcode == OSD_OP_SEC_WRITE ||

src/osd.cpp

@@ -228,6 +228,7 @@ void osd_t::exec_op(osd_op_t *cur_op)
         cur_op->req.hdr.opcode != OSD_OP_SEC_READ &&
         cur_op->req.hdr.opcode != OSD_OP_SEC_LIST &&
         cur_op->req.hdr.opcode != OSD_OP_READ &&
+        cur_op->req.hdr.opcode != OSD_OP_SEC_READ_BMP &&
         cur_op->req.hdr.opcode != OSD_OP_SHOW_CONFIG)
     {
         // Readonly mode

src/osd.h

@@ -226,7 +226,7 @@ class osd_t
         uint64_t pg_count = pg_counts[INODE_POOL(oid.inode)];
         if (!pg_count)
             pg_count = 1;
-        return (oid.inode + oid.stripe / pg_stripe_size) % pg_count + 1;
+        return (oid.stripe / pg_stripe_size) % pg_count + 1;
     }
 
 public:

src/osd_ops.cpp

@@ -20,4 +20,5 @@ const char* osd_op_names[] = {
     "primary_sync",
     "primary_delete",
     "ping",
+    "sec_read_bmp",
 };

src/osd_ops.h

@@ -28,7 +28,8 @@
 #define OSD_OP_SYNC                 13
 #define OSD_OP_DELETE               14
 #define OSD_OP_PING                 15
-#define OSD_OP_MAX                  15
+#define OSD_OP_SEC_READ_BMP         16
+#define OSD_OP_MAX                  16
 // Alignment & limit for read/write operations
 #ifndef MEM_ALIGNMENT
 #define MEM_ALIGNMENT               512
@@ -59,7 +60,7 @@ struct __attribute__((__packed__)) osd_reply_header_t
 };
 
 // read or write to the secondary OSD
-struct __attribute__((__packed__)) osd_op_secondary_rw_t
+struct __attribute__((__packed__)) osd_op_sec_rw_t
 {
     osd_op_header_t header;
     // object
@@ -76,7 +77,7 @@ struct __attribute__((__packed__)) osd_op_secondary_rw_t
     uint32_t pad0;
 };
 
-struct __attribute__((__packed__)) osd_reply_secondary_rw_t
+struct __attribute__((__packed__)) osd_reply_sec_rw_t
 {
     osd_reply_header_t header;
     // for reads and writes: assigned or read version number
@@ -87,7 +88,7 @@ struct __attribute__((__packed__)) osd_reply_secondary_rw_t
 };
 
 // delete object on the secondary OSD
-struct __attribute__((__packed__)) osd_op_secondary_del_t
+struct __attribute__((__packed__)) osd_op_sec_del_t
 {
     osd_op_header_t header;
     // object
@@ -96,37 +97,51 @@ struct __attribute__((__packed__)) osd_op_secondary_del_t
     uint64_t version;
 };
 
-struct __attribute__((__packed__)) osd_reply_secondary_del_t
+struct __attribute__((__packed__)) osd_reply_sec_del_t
 {
     osd_reply_header_t header;
     uint64_t version;
 };
 
 // sync to the secondary OSD
-struct __attribute__((__packed__)) osd_op_secondary_sync_t
+struct __attribute__((__packed__)) osd_op_sec_sync_t
 {
     osd_op_header_t header;
 };
 
-struct __attribute__((__packed__)) osd_reply_secondary_sync_t
+struct __attribute__((__packed__)) osd_reply_sec_sync_t
 {
     osd_reply_header_t header;
 };
 
 // stabilize or rollback objects on the secondary OSD
-struct __attribute__((__packed__)) osd_op_secondary_stabilize_t
+struct __attribute__((__packed__)) osd_op_sec_stab_t
 {
     osd_op_header_t header;
     // obj_ver_id array length in bytes
     uint64_t len;
 };
-typedef osd_op_secondary_stabilize_t osd_op_secondary_rollback_t;
+typedef osd_op_sec_stab_t osd_op_sec_rollback_t;
 
-struct __attribute__((__packed__)) osd_reply_secondary_stabilize_t
+struct __attribute__((__packed__)) osd_reply_sec_stab_t
 {
     osd_reply_header_t header;
 };
-typedef osd_reply_secondary_stabilize_t osd_reply_secondary_rollback_t;
+typedef osd_reply_sec_stab_t osd_reply_sec_rollback_t;
+
+// bulk read bitmaps from a secondary OSD
+struct __attribute__((__packed__)) osd_op_sec_read_bmp_t
+{
+    osd_op_header_t header;
+    // obj_ver_id array length in bytes
+    uint64_t len;
+};
+
+struct __attribute__((__packed__)) osd_reply_sec_read_bmp_t
+{
+    // retval is payload length in bytes. payload is {version,bitmap}[]
+    osd_reply_header_t header;
+};
 
 // show configuration
 struct __attribute__((__packed__)) osd_op_show_config_t
@@ -140,7 +155,7 @@ struct __attribute__((__packed__)) osd_reply_show_config_t
 };
 
 // list objects on replica
-struct __attribute__((__packed__)) osd_op_secondary_list_t
+struct __attribute__((__packed__)) osd_op_sec_list_t
 {
     osd_op_header_t header;
     // placement group total number and total count
@@ -151,7 +166,7 @@ struct __attribute__((__packed__)) osd_op_secondary_list_t
     uint64_t min_inode, max_inode;
 };
 
-struct __attribute__((__packed__)) osd_reply_secondary_list_t
+struct __attribute__((__packed__)) osd_reply_sec_list_t
 {
     osd_reply_header_t header;
     // stable object version count. header.retval = total object version count
@@ -194,11 +209,12 @@ struct __attribute__((__packed__)) osd_reply_sync_t
 union osd_any_op_t
 {
     osd_op_header_t hdr;
-    osd_op_secondary_rw_t sec_rw;
-    osd_op_secondary_del_t sec_del;
-    osd_op_secondary_sync_t sec_sync;
-    osd_op_secondary_stabilize_t sec_stab;
-    osd_op_secondary_list_t sec_list;
+    osd_op_sec_rw_t sec_rw;
+    osd_op_sec_del_t sec_del;
+    osd_op_sec_sync_t sec_sync;
+    osd_op_sec_stab_t sec_stab;
+    osd_op_sec_read_bmp_t sec_read_bmp;
+    osd_op_sec_list_t sec_list;
     osd_op_show_config_t show_conf;
     osd_op_rw_t rw;
     osd_op_sync_t sync;
@@ -208,11 +224,12 @@ union osd_any_op_t
 union osd_any_reply_t
 {
     osd_reply_header_t hdr;
-    osd_reply_secondary_rw_t sec_rw;
-    osd_reply_secondary_del_t sec_del;
-    osd_reply_secondary_sync_t sec_sync;
-    osd_reply_secondary_stabilize_t sec_stab;
-    osd_reply_secondary_list_t sec_list;
+    osd_reply_sec_rw_t sec_rw;
+    osd_reply_sec_del_t sec_del;
+    osd_reply_sec_sync_t sec_sync;
+    osd_reply_sec_stab_t sec_stab;
+    osd_reply_sec_read_bmp_t sec_read_bmp;
+    osd_reply_sec_list_t sec_list;
     osd_reply_show_config_t show_conf;
     osd_reply_rw_t rw;
     osd_reply_sync_t sync;

src/osd_primary.cpp

@@ -35,7 +35,7 @@ bool osd_t::prepare_primary_rw(osd_op_t *cur_op)
         // oid.stripe = starting offset of the parity stripe
         .stripe = (cur_op->req.rw.offset/pg_block_size)*pg_block_size,
     };
-    pg_num_t pg_num = (cur_op->req.rw.inode + oid.stripe/pool_cfg.pg_stripe_size) % pg_counts[pool_id] + 1;
+    pg_num_t pg_num = (oid.stripe/pool_cfg.pg_stripe_size) % pg_counts[pool_id] + 1; // like map_to_pg()
     auto pg_it = pgs.find({ .pool_id = pool_id, .pg_num = pg_num });
     if (pg_it == pgs.end() || !(pg_it->second.state & PG_ACTIVE))
     {
@@ -188,6 +188,187 @@ resume_2:
     finish_op(cur_op, cur_op->req.rw.len);
 }
 
+struct bitmap_request_t
+{
+    osd_num_t osd_num;
+    object_id oid;
+    uint64_t version;
+    void *bmp_buf;
+};
+
+inline bool operator < (const bitmap_request_t & a, const bitmap_request_t & b)
+{
+    return a.osd_num < b.osd_num || a.osd_num == b.osd_num && a.oid < b.oid;
+}
+
+bool osd_t::read_bitmaps()
+{
+    if (chain.size() > 1)
+    {
+        // First read all bitmaps
+        uint64_t stripe_count = (pool_cfg.scheme == POOL_SCHEME_REPLICATED ? 1 : pg_it->second.pg_size);
+        cur_op->snapshot_bitmaps = malloc_or_die(
+            // bitmaps
+            chain.size() * stripe_count * clean_entry_bitmap_size +
+            // chain itself
+            sizeof(inode_t) * chain.size() +
+            // 'missing' flags for each stripe
+            (pool_cfg.scheme == POOL_SCHEME_REPLICATED ? 0 : chain.size() * pg_size)
+        );
+        inode_t *chain_copy = (inode_t*)((void*)cur_op->snapshot_bitmaps
+            + chain.size() * stripe_count * clean_entry_bitmap_size);
+        uint8_t *missing_flags = (uint8_t*)((void*)chain_copy
+            + sizeof(inode_t) * chain.size());
+        memcpy(chain_copy, chain.data(), sizeof(inode_t) * chain.size()); // условно
+        if (pg.state == PG_ACTIVE)
+        {
+            std::vector<bitmap_request_t> bitmap_requests;
+            for (inode_t inode: chain)
+            {
+                object_id cur_oid = { .inode = inode, .stripe = op_data->oid.stripe };
+                auto vo_it = pg.ver_override.find(cur_oid);
+                bitmap_requests.push_back(vo_it != pg.ver_override.end() ? vo_it->second : UINT64_MAX);
+            }
+                submit_primary_subops(
+                    SUBMIT_READ_BITMAPS, target_ver,
+                    (op_data->scheme == POOL_SCHEME_REPLICATED ? pg.pg_size : op_data->pg_data_size),
+                    pg.cur_set.data(), cur_op
+                );
+        }
+        else
+        {
+            std::vector<bitmap_request_t> bitmap_requests;
+            for (inode_t inode: chain)
+            {
+                object_id cur_oid = { .inode = inode, .stripe = op_data->oid.stripe };
+                auto vo_it = pg.ver_override.find(cur_oid);
+                uint64_t target_version = vo_it != pg.ver_override.end() ? vo_it->second : UINT64_MAX;
+                uint64_t* cur_set = get_object_osd_set(pg, cur_oid, pg.cur_set.data(), NULL);
+                if (op_data->scheme == POOL_SCHEME_REPLICATED)
+                {
+                    osd_num_t read_target = 0;
+                    for (int i = 0; i < pg.pg_size; i++)
+                    {
+                        if (cur_set[i] == this->osd_num || cur_set[i] != 0 && read_target == 0)
+                        {
+                            // Select local or any other available OSD for reading
+                            read_target = cur_set[i];
+                        }
+                    }
+                    assert(read_target != 0);
+                    bitmap_requests.push_back((bitmap_request_t*){
+                        .osd_num = read_target,
+                        .oid = cur_oid,
+                        .version = target_version,
+                        .bmp_buf = cur_op->snapshot_bitmaps + chain_num*clean_entry_bitmap_size,
+                    });
+                }
+                else
+                {
+                    osd_rmw_stripe_t local_stripes[pg.pg_size];
+                    memcpy(local_stripes, op_data->stripes, sizeof(osd_rmw_stripe_t) * stripe_count);
+                    if (extend_missing_stripes(local_stripes, cur_set, op_data->pg_data_size, pg.pg_size) < 0)
+                    {
+                        free(snapshot_bitmaps);
+                        finish_op(cur_op, -EIO);
+                        return;
+                    }
+                    for (int i = 0; i < pg.pg_size; i++)
+                    {
+                        if (cur_set[i] != 0 && local_stripes[i].read_end != 0)
+                        {
+                            bitmap_requests.push_back((bitmap_request_t*){
+                                .osd_num = cur_set[i],
+                                .oid = cur_oid,
+                                .version = target_version,
+                                .bmp_buf = cur_op->snapshot_bitmaps + (chain_num*pg.pg_size + i)*clean_entry_bitmap_size,
+                            });
+                            missing_flags[chain_num*pg_size + i] = 0;
+                        }
+                        else
+                            missing_flags[chain_num*pg_size + i] = 1;
+                    }
+                }
+                chain_num++;
+            }
+            std::sort(bitmap_requests.begin(), bitmap_requests.end());
+            op_data->n_subops = 0;
+            for (int i = 0; i < bitmap_requests.size(); i++)
+            {
+                if ((i == bitmap_requests.size()-1 || bitmap_requests[i+1].osd_num != bitmap_requests[i].osd_num) &&
+                    bitmap_requests[i].osd_num != this->osd_num)
+                {
+                    op_data->n_subops++;
+                }
+            }
+            if (op_data->n_subops)
+            {
+                op_data->fact_ver = 0;
+                op_data->done = op_data->errors = 0;
+                op_data->subops = new osd_op_t[request_count];
+            }
+            for (int i = 0, subop_idx = 0; i < bitmap_requests.size(); i++)
+            {
+                if (i == bitmap_requests.size()-1 || bitmap_requests[i+1].osd_num != bitmap_requests[i].osd_num)
+                {
+                    osd_num_t subop_osd_num = bitmap_requests[i].osd_num;
+                    if (subop_osd_num == this->osd_num)
+                    {
+                        // Read synchronously
+                        for (int j = prev; j <= i; j++)
+                        {
+                            bs->read_bitmap(bitmap_requests[i].oid, bitmap_requests[i].version, bitmap_requests[i].bmp_buf, NULL);
+                        }
+                    }
+                    else
+                    {
+                        // Send to a remote OSD
+                        osd_op_t *subop = subops+subop_idx;
+                        subop->op_type = OSD_OP_OUT;
+                        subop->peer_fd = c_cli.osd_peer_fds.at(subop_osd_num);
+                        subop->buf = malloc_or_die(sizeof(obj_ver_id)*(i+1-prev));
+                        subop->req.sec_read_bmp = {
+                            .header = {
+                                .magic = SECONDARY_OSD_OP_MAGIC,
+                                .id = c_cli.next_subop_id++,
+                                .opcode = OSD_OP_SEC_READ_BMP,
+                            },
+                            .len = sizeof(obj_ver_id)*(i+1-prev),
+                        };
+                        obj_ver_id *ov = (obj_ver_id*)subop->buf;
+                        for (int j = prev; j <= i; j++, ov++)
+                        {
+                            ov->oid = bitmap_requests[i].oid;
+                            ov->version = bitmap_requests[i].version;
+                        }
+                        subop->callback = [cur_op, this](osd_op_t *subop)
+                        {
+                            int requested_count = subop->req.sec_read_bmp.len/sizeof(obj_ver_id);
+                            int fail_fd = subop->reply.hdr.retval != requested_count * (8 + clean_entry_bitmap_size) ? subop->peer_fd : -1;
+                            handle_primary_bitmap_subop(subop, cur_op);
+                            if (fail_fd >= 0)
+                            {
+                                // read_bitmaps operation failed, drop the connection
+                                c_cli.stop_client(fail_fd);
+                            }
+                        };
+                        c_cli.outbox_push(subop);
+                        subop_idx++;
+                    }
+                    prev = i+1;
+                }
+            }
+            if (op_data->n_subops)
+            {
+                // Wait for subops
+                return;
+            }
+            
+        }
+    }
+    
+}
+
 bool osd_t::check_write_queue(osd_op_t *cur_op, pg_t & pg)
 {
     osd_primary_op_data_t *op_data = cur_op->op_data;

src/osd_primary_subops.cpp

@@ -165,8 +165,10 @@ void osd_t::submit_primary_subops(int submit_type, uint64_t op_version, int pg_s
                         .stripe = op_data->oid.stripe | stripe_num,
                     },
                     .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,
+                    .offset = submit_type == SUBMIT_READ_BITMAPS ? 0
+                        : (wr ? stripes[stripe_num].write_start : stripes[stripe_num].read_start),
+                    .len = submit_type == SUBMIT_READ_BITMAPS ? 0
+                        : (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,
                 });
@@ -196,8 +198,10 @@ void osd_t::submit_primary_subops(int submit_type, uint64_t op_version, int pg_s
                         .stripe = op_data->oid.stripe | stripe_num,
                     },
                     .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,
+                    .offset = submit_type == SUBMIT_READ_BITMAPS ? 0
+                        : (wr ? stripes[stripe_num].write_start : stripes[stripe_num].read_start),
+                    .len = submit_type == SUBMIT_READ_BITMAPS ? 0
+                        : (wr ? stripes[stripe_num].write_end - stripes[stripe_num].write_start : stripes[stripe_num].read_end - stripes[stripe_num].read_start),
                     .attr_len = wr ? clean_entry_bitmap_size : 0,
                 };
 #ifdef OSD_DEBUG
@@ -214,7 +218,7 @@ void osd_t::submit_primary_subops(int submit_type, uint64_t op_version, int pg_s
                         subops[i].iov.push_back(stripes[stripe_num].write_buf, stripes[stripe_num].write_end - stripes[stripe_num].write_start);
                     }
                 }
-                else
+                else if (submit_type != SUBMIT_READ_BITMAPS)
                 {
                     if (stripes[stripe_num].read_end > stripes[stripe_num].read_start)
                     {

src/osd_secondary.cpp

@@ -44,6 +44,25 @@ void osd_t::secondary_op_callback(osd_op_t *op)
 
 void osd_t::exec_secondary(osd_op_t *cur_op)
 {
+    if (cur_op->req.hdr.opcode == OSD_OP_SEC_READ_BMP)
+    {
+        int n = cur_op->req.sec_read_bmp.len / sizeof(obj_ver_id);
+        if (n > 0)
+        {
+            obj_ver_id *ov = (obj_ver_id*)cur_op->buf;
+            void *reply_buf = malloc_or_die(n * (8 + clean_entry_bitmap_size));
+            void *cur_buf = reply_buf;
+            for (int i = 0; i < n; i++)
+            {
+                bs->read_bitmap(ov[i].oid, ov[i].version, cur_buf + sizeof(uint64_t), (uint64_t*)cur_buf);
+                cur_buf += (8 + clean_entry_bitmap_size);
+            }
+            free(cur_op->buf);
+            cur_op->iov.push_back(cur_op->buf, cur_op->bs_op->retval * sizeof(obj_ver_id));
+        }
+        finish_op(cur_op, n * (8 + clean_entry_bitmap_size));
+        return;
+    }
     cur_op->bs_op = new blockstore_op_t();
     cur_op->bs_op->callback = [this, cur_op](blockstore_op_t* bs_op) { secondary_op_callback(cur_op); };
     cur_op->bs_op->opcode = (cur_op->req.hdr.opcode == OSD_OP_SEC_READ ? BS_OP_READ