From 0053546f8b7d05875d0f78b85114a0acf4757a8b Mon Sep 17 00:00:00 2001
From: Vitaliy Filippov <vitalif@yourcmc.ru>
Date: Sun, 9 Nov 2025 14:47:47 +0300
Subject: [PATCH] Remove zerofill in blockstore (an old and unused artifact)

---
 src/blockstore/blockstore_impl.cpp  |  7 ++-----
 src/blockstore/blockstore_impl.h    |  4 +---
 src/blockstore/blockstore_write.cpp | 20 ++------------------
 3 files changed, 5 insertions(+), 26 deletions(-)

diff --git a/src/blockstore/blockstore_impl.cpp b/src/blockstore/blockstore_impl.cpp
index f4d17246..4d8cbe06 100644
--- a/src/blockstore/blockstore_impl.cpp
+++ b/src/blockstore/blockstore_impl.cpp
@@ -23,14 +23,12 @@ blockstore_impl_t::blockstore_impl_t(blockstore_config_t & config, ring_loop_i *
         dsk.open_meta();
         dsk.open_journal();
         dsk.calc_lengths();
-        zero_object = (uint8_t*)memalign_or_die(MEM_ALIGNMENT, dsk.data_block_size);
     }
     catch (std::exception & e)
     {
         dsk.close_all();
         throw;
     }
-    memset(zero_object, 0, dsk.data_block_size);
     meta_superblock = (uint8_t*)memalign_or_die(MEM_ALIGNMENT, dsk.meta_block_size);
     memset(meta_superblock, 0, dsk.meta_block_size);
 }
@@ -55,8 +53,6 @@ blockstore_impl_t::~blockstore_impl_t()
         free(buffer_area);
     if (meta_superblock)
         free(meta_superblock);
-    if (zero_object)
-        free(zero_object);
     ringloop->unregister_consumer(&ring_consumer);
     dsk.close_all();
 }
@@ -281,7 +277,8 @@ void blockstore_impl_t::enqueue_op(blockstore_op_t *op)
         ((op->opcode == BS_OP_READ || op->opcode == BS_OP_WRITE || op->opcode == BS_OP_WRITE_STABLE) && (
             op->offset >= dsk.data_block_size ||
             op->len > dsk.data_block_size-op->offset ||
-            (op->len % dsk.disk_alignment)
+            (op->offset % dsk.bitmap_granularity) ||
+            (op->len % dsk.bitmap_granularity)
         )) ||
         readonly && op->opcode != BS_OP_READ && op->opcode != BS_OP_LIST)
     {
diff --git a/src/blockstore/blockstore_impl.h b/src/blockstore/blockstore_impl.h
index a8dd3be1..c667e4dd 100644
--- a/src/blockstore/blockstore_impl.h
+++ b/src/blockstore/blockstore_impl.h
@@ -58,7 +58,6 @@ struct blockstore_op_private_t
     int stab_pos;
 
     // Write
-    struct iovec iov_zerofill[3];
     timespec tv_begin;
 };
 
@@ -111,7 +110,6 @@ public:
     std::vector<blockstore_op_t*> submit_queue;
     int unsynced_data_write_count = 0, unsynced_buffer_write_count = 0, unsynced_meta_write_count = 0;
     int unsynced_queued_ops = 0;
-    uint8_t *zero_object = NULL;
 
     std::vector<uint32_t> pending_modified_blocks;
     robin_hood::unordered_flat_map<uint32_t, bs_modified_block_t> modified_blocks;
@@ -226,6 +224,6 @@ public:
     inline uint32_t get_block_size() { return dsk.data_block_size; }
     inline uint64_t get_block_count() { return dsk.block_count; }
     uint64_t get_free_block_count();
-    inline uint32_t get_bitmap_granularity() { return dsk.disk_alignment; }
+    inline uint32_t get_bitmap_granularity() { return dsk.bitmap_granularity; }
     inline uint64_t get_journal_size() { return dsk.journal_len; }
 };
diff --git a/src/blockstore/blockstore_write.cpp b/src/blockstore/blockstore_write.cpp
index 0df432cf..5cd6a119 100644
--- a/src/blockstore/blockstore_write.cpp
+++ b/src/blockstore/blockstore_write.cpp
@@ -174,25 +174,9 @@ enospc:
         heap->use_data(op->oid.inode, PRIV(op)->location);
         io_uring_sqe *sqe = get_sqe();
         ring_data_t *data = ((ring_data_t*)sqe->user_data);
-        uint64_t stripe_offset = (op->offset % dsk.bitmap_granularity);
-        uint64_t stripe_end = (op->offset + op->len) % dsk.bitmap_granularity;
-        // Zero fill up to dsk.bitmap_granularity
-        int vcnt = 0;
-        if (stripe_offset)
-        {
-            PRIV(op)->iov_zerofill[vcnt++] = (struct iovec){ zero_object, (size_t)stripe_offset };
-        }
-        PRIV(op)->iov_zerofill[vcnt++] = (struct iovec){ op->buf, op->len };
-        if (stripe_end)
-        {
-            stripe_end = dsk.bitmap_granularity - stripe_end;
-            PRIV(op)->iov_zerofill[vcnt++] = (struct iovec){ zero_object, (size_t)stripe_end };
-        }
-        data->iov.iov_len = op->len + stripe_offset + stripe_end; // to check it in the callback
+        data->iov = (struct iovec){ op->buf, op->len };
         data->callback = [this, op](ring_data_t *data) { handle_write_event(data, op); };
-        io_uring_prep_writev(
-            sqe, dsk.data_fd, PRIV(op)->iov_zerofill, vcnt, dsk.data_offset + loc + op->offset - stripe_offset
-        );
+        io_uring_prep_writev(sqe, dsk.data_fd, &data->iov, 1, dsk.data_offset + loc + op->offset);
         PRIV(op)->pending_ops++;
         PRIV(op)->op_state = 1;
         write_iodepth++;