From eb55b2fe20835e8951bbec3ab91b7b1ee1c08516 Mon Sep 17 00:00:00 2001
From: Vitaliy Filippov <vitalif@yourcmc.ru>
Date: Tue, 19 Nov 2019 20:03:19 +0300
Subject: [PATCH] Initialize sector 0 of the journal

---
 blockstore_init.cpp | 71 ++++++++++++++++++++++++++++++---------------
 blockstore_init.h   |  3 +-
 2 files changed, 50 insertions(+), 24 deletions(-)

diff --git a/blockstore_init.cpp b/blockstore_init.cpp
index 7cdc4bbe..96856ce5 100644
--- a/blockstore_init.cpp
+++ b/blockstore_init.cpp
@@ -101,6 +101,14 @@ void blockstore_init_meta::handle_entries(struct clean_disk_entry* entries, int
 blockstore_init_journal::blockstore_init_journal(blockstore *bs)
 {
     this->bs = bs;
+    simple_callback = [this](ring_data_t *data1)
+    {
+        if (data1->res != data1->iov.iov_len)
+        {
+            throw std::runtime_error(std::string("I/O operation failed while reading journal: ") + strerror(-data1->res));
+        }
+        wait_count--;
+    };
 }
 
 bool iszero(uint64_t *buf, int len)
@@ -134,6 +142,12 @@ void blockstore_init_journal::handle_event(ring_data_t *data1)
     submitted = 0;
 }
 
+#define GET_SQE() \
+    sqe = bs->get_sqe();\
+    if (!sqe)\
+        throw std::runtime_error("io_uring is full while trying to read journal");\
+    data = ((ring_data_t*)sqe->user_data)
+
 int blockstore_init_journal::loop()
 {
     if (wait_state == 1)
@@ -142,42 +156,58 @@ int blockstore_init_journal::loop()
         goto resume_2;
     else if (wait_state == 3)
         goto resume_3;
+    else if (wait_state == 4)
+        goto resume_4;
     journal_buffer = (uint8_t*)memalign(DISK_ALIGNMENT, 2*JOURNAL_BUFFER_SIZE);
     // Read first block of the journal
     sqe = bs->get_sqe();
     if (!sqe)
-    {
         throw std::runtime_error("io_uring is full while trying to read journal");
-    }
     data = ((ring_data_t*)sqe->user_data);
     data->iov = { journal_buffer, 512 };
-    data->callback = [this](ring_data_t *data1)
-    {
-        if (data1->res != 512)
-        {
-            throw std::runtime_error(
-                std::string("read journal failed at offset ") + std::to_string(0) +
-                std::string(": ") + strerror(-data1->res)
-            );
-        }
-        done_buf = 1;
-    };
+    data->callback = simple_callback;
     my_uring_prep_readv(sqe, bs->journal.fd, &data->iov, 1, bs->journal.offset);
     bs->ringloop->submit();
-    done_buf = 0;
+    wait_count = 1;
 resume_1:
-    if (done_buf == 0)
+    if (wait_count > 0)
     {
         wait_state = 1;
         return 1;
     }
-    done_buf = 0;
     if (iszero((uint64_t*)journal_buffer, 3))
     {
         // Journal is empty
-        // FIXME handle this wrapping to 512 better
+        // FIXME handle this wrapping to 512 better ... and align it to 4096
         bs->journal.used_start = 512;
         bs->journal.next_free = 512;
+        // Initialize journal "superblock"
+        GET_SQE();
+        memset(journal_buffer, 0, 512);
+        *((journal_entry_start*)journal_buffer) = {
+            .crc32 = 0,
+            .magic = JOURNAL_MAGIC,
+            .type = JE_START,
+            .size = sizeof(journal_entry_start),
+            .reserved = 0,
+            .journal_start = bs->journal.used_start,
+        };
+        ((journal_entry_start*)journal_buffer)->crc32 = je_crc32((journal_entry*)journal_buffer);
+        data->iov = (struct iovec){ journal_buffer, 512 };
+        data->callback = simple_callback;
+        my_uring_prep_writev(sqe, bs->journal.fd, &data->iov, 1, bs->journal.offset);
+        wait_count++;
+        GET_SQE();
+        my_uring_prep_fsync(sqe, bs->journal.fd, 0);
+        data->callback = simple_callback;
+        wait_count++;
+        bs->ringloop->submit();
+    resume_4:
+        if (wait_count > 0)
+        {
+            wait_state = 4;
+            return 1;
+        }
     }
     else
     {
@@ -208,12 +238,7 @@ resume_1:
             }
             else
             {
-                sqe = bs->get_sqe();
-                if (!sqe)
-                {
-                    throw std::runtime_error("io_uring is full while trying to read journal");
-                }
-                data = ((ring_data_t*)sqe->user_data);
+                GET_SQE();
                 uint64_t end = bs->journal.len;
                 if (journal_pos < bs->journal.used_start)
                 {
diff --git a/blockstore_init.h b/blockstore_init.h
index 683a0d2c..90f2a0ca 100644
--- a/blockstore_init.h
+++ b/blockstore_init.h
@@ -16,7 +16,7 @@ public:
 class blockstore_init_journal
 {
     blockstore *bs;
-    int wait_state = 0;
+    int wait_state = 0, wait_count = 0;
     uint8_t *journal_buffer = NULL;
     uint32_t crc32_last = 0;
     bool started = false;
@@ -27,6 +27,7 @@ class blockstore_init_journal
     struct io_uring_sqe *sqe;
     struct ring_data_t *data;
     journal_entry_start *je_start;
+    std::function<void(ring_data_t*)> simple_callback;
     int handle_journal_part(void *buf, uint64_t len);
     void handle_event(ring_data_t *data);
 public: