MDEV-27812: Fix a race condition, and pacify MemorySanitizer

log_t::write_checkpoint(): Avoid a race condition with resize_abort()
by loading log_sys.resize_lsn only while holding the locks.
Also, remove an unnecessary write of all outstanding log before
switching log files.

log_t::write_buf(): Mark the entire block in the resize buffer
as initialized, to allow the test innodb.log_file_size_online to pass
when not using the mmap() based interface.

3 files changed, 14 insertions, 17 deletions

diff --git a/storage/innobase/buf/buf0flu.cc b/storage/innobase/buf/buf0flu.cc
index 04822c3cc00..090757ef7ce 100644
--- a/storage/innobase/buf/buf0flu.cc
+++ b/storage/innobase/buf/buf0flu.cc
@@ -1718,11 +1718,13 @@ inline void log_t::write_checkpoint(lsn_t end_lsn) noexcept
   mach_write_to_8(my_assume_aligned<8>(c + 8), end_lsn);
   mach_write_to_4(my_assume_aligned<4>(c + 60), my_crc32c(0, c, 60));
 
-  lsn_t resizing= resize_lsn.load(std::memory_order_relaxed);
+  lsn_t resizing;
 
 #ifdef HAVE_PMEM
   if (is_pmem())
   {
+    resizing= resize_lsn.load(std::memory_order_relaxed);
+
     if (resizing > 1 && resizing <= next_checkpoint_lsn)
     {
       memcpy_aligned<64>(resize_buf + CHECKPOINT_1, c, 64);
@@ -1737,6 +1739,7 @@ inline void log_t::write_checkpoint(lsn_t end_lsn) noexcept
     n_pending_checkpoint_writes++;
     latch.wr_unlock();
     log_write_and_flush_prepare();
+    resizing= resize_lsn.load(std::memory_order_relaxed);
     /* FIXME: issue an asynchronous write */
     log.write(offset, {c, get_block_size()});
     if (resizing > 1 && resizing <= next_checkpoint_lsn)
@@ -1747,16 +1750,11 @@ inline void log_t::write_checkpoint(lsn_t end_lsn) noexcept
       resize_log.write(0, {buf, 4096});
       aligned_free(buf);
       resize_log.write(CHECKPOINT_1, {c, get_block_size()});
-      latch.wr_lock(SRW_LOCK_CALL);
-      /* FIXME: write and flush outside exclusive latch */
-      ut_a(flush(write_buf<false>()));
-    }
-    else
-    {
-      if (srv_file_flush_method != SRV_O_DSYNC)
-        ut_a(log.flush());
-      latch.wr_lock(SRW_LOCK_CALL);
     }
+
+    if (srv_file_flush_method != SRV_O_DSYNC)
+      ut_a(log.flush());
+    latch.wr_lock(SRW_LOCK_CALL);
     n_pending_checkpoint_writes--;
     resizing= resize_lsn.load(std::memory_order_relaxed);
   }
diff --git a/storage/innobase/include/log0log.h b/storage/innobase/include/log0log.h
index 57ecc8ed3f5..7e20fc12cda 100644
--- a/storage/innobase/include/log0log.h
+++ b/storage/innobase/include/log0log.h
@@ -486,7 +486,7 @@ public:
   /** Write buf to ib_logfile0.
   @tparam release_latch whether to invoke latch.wr_unlock()
   @return the current log sequence number */
-  template<bool release_latch> lsn_t write_buf() noexcept;
+  template<bool release_latch> inline lsn_t write_buf() noexcept;
 
   /** Create the log. */
   void create(lsn_t lsn) noexcept;
diff --git a/storage/innobase/log/log0log.cc b/storage/innobase/log/log0log.cc
index dad5d695964..83b78ebf385 100644
--- a/storage/innobase/log/log0log.cc
+++ b/storage/innobase/log/log0log.cc
@@ -733,7 +733,7 @@ ATTRIBUTE_COLD void log_t::resize_write_buf(size_t length) noexcept
 /** Write buf to ib_logfile0.
 @tparam release_latch whether to invoke latch.wr_unlock()
 @return the current log sequence number */
-template<bool release_latch> lsn_t log_t::write_buf() noexcept
+template<bool release_latch> inline lsn_t log_t::write_buf() noexcept
 {
 #ifndef SUX_LOCK_GENERIC
   ut_ad(latch.is_write_locked());
@@ -777,16 +777,17 @@ template<bool release_latch> lsn_t log_t::write_buf() noexcept
       (We want to avoid memset() while holding mutex.)
       This block will be overwritten later, once records beyond
       the current LSN are generated. */
+# ifdef HAVE_valgrind
       MEM_MAKE_DEFINED(buf + length, get_block_size() - new_buf_free);
+      if (UNIV_LIKELY_NULL(resize_flush_buf))
+        MEM_MAKE_DEFINED(resize_buf + length, get_block_size() - new_buf_free);
+# endif
       buf[length]= 0; /* allow recovery to catch EOF faster */
       length&= ~block_size_1;
       memcpy_aligned<16>(flush_buf, buf + length, (new_buf_free + 15) & ~15);
       if (UNIV_LIKELY_NULL(resize_flush_buf))
-      {
-        MEM_MAKE_DEFINED(resize_buf + length, get_block_size() - new_buf_free);
         memcpy_aligned<16>(resize_flush_buf, resize_buf + length,
                            (new_buf_free + 15) & ~15);
-      }
       length+= get_block_size();
 #endif
     }
@@ -813,8 +814,6 @@ template<bool release_latch> lsn_t log_t::write_buf() noexcept
   return lsn;
 }
 
-template lsn_t log_t::write_buf<false>() noexcept;
-
 bool log_t::flush(lsn_t lsn) noexcept
 {
   ut_ad(lsn >= get_flushed_lsn());