MDEV-34450 os_file_write_func() is an overkill for ib_logfile0

log_file_t::read(), log_file_t::write(): Invoke pread() or pwrite()
directly, so that we can give more accurate diagnostics in case of
a failure, and so that we will avoid the overhead of setting up 5(!)
stack frames and related objects.

tpool::pwrite(): Add a missing const qualifier.

Author: dr-m

storage/innobase/log/log0log.cc

@@ -46,6 +46,7 @@ Created 12/9/1995 Heikki Tuuri
 #include "buf0dump.h"
 #include "log0sync.h"
 #include "log.h"
+#include "tpool.h"
 
 /*
 General philosophy of InnoDB redo-logs:
@@ -132,18 +133,57 @@ __attribute__((warn_unused_result))
 dberr_t log_file_t::read(os_offset_t offset, span<byte> buf) noexcept
 {
   ut_ad(is_opened());
-  return os_file_read(IORequestRead, m_file, buf.data(), offset, buf.size(),
-                      nullptr);
+  byte *data= buf.data();
+  size_t size= buf.size();
+  ut_ad(size);
+  ssize_t s;
+
+  for (;;)
+  {
+    s= IF_WIN(tpool::pread(m_file, data, size, offset),
+              pread(m_file, data, size, offset));
+    if (UNIV_UNLIKELY(s <= 0))
+      break;
+    size-= size_t(s);
+    if (!size)
+      return DB_SUCCESS;
+    offset+= s;
+    data+= s;
+    ut_a(size < buf.size());
+  }
+
+  sql_print_error("InnoDB: pread(\"ib_logfile0\") returned %zd,"
+                  " operating system error %u",
+                  s, unsigned(IF_WIN(GetLastError(), errno)));
+  return DB_IO_ERROR;
 }
 
 void log_file_t::write(os_offset_t offset, span<const byte> buf) noexcept
 {
   ut_ad(is_opened());
-  if (dberr_t err= os_file_write_func(IORequestWrite, "ib_logfile0", m_file,
-                                      buf.data(), offset, buf.size()))
-    ib::fatal() << "write(\"ib_logfile0\") returned " << err
-                << ". Operating system error number "
-                << IF_WIN(GetLastError(), errno) << ".";
+  const byte *data= buf.data();
+  size_t size= buf.size();
+  ut_ad(size);
+  ssize_t s;
+
+  for (;;)
+  {
+    s= IF_WIN(tpool::pwrite(m_file, data, size, offset),
+              pwrite(m_file, data, size, offset));
+    if (UNIV_UNLIKELY(s <= 0))
+      break;
+    size-= size_t(s);
+    if (!size)
+      return;
+    offset+= s;
+    data+= s;
+    ut_a(size < buf.size());
+  }
+
+  sql_print_error("[FATAL] InnoDB: pwrite(\"ib_logfile0\") returned %zd,"
+                  " operating system error %u",
+                  s, unsigned(IF_WIN(GetLastError(), errno)));
+  abort();
 }
 
 #ifdef HAVE_INNODB_MMAP

tpool/aio_simulated.cc

@@ -73,7 +73,7 @@ static WinIoInit win_io_init;
 
 
 SSIZE_T pread(const native_file_handle &h, void *buf, size_t count,
-                 unsigned long long offset)
+              unsigned long long offset)
 {
   OVERLAPPED ov{};
   ULARGE_INTEGER uli;
@@ -95,8 +95,8 @@ SSIZE_T pread(const native_file_handle &h, void *buf, size_t count,
   return -1;
 }
 
-SSIZE_T pwrite(const native_file_handle &h, void *buf, size_t count,
-                  unsigned long long offset)
+SSIZE_T pwrite(const native_file_handle &h, const void *buf, size_t count,
+               unsigned long long offset)
 {
   OVERLAPPED ov{};
   ULARGE_INTEGER uli;

tpool/tpool.h

@@ -293,10 +293,10 @@ create_thread_pool_win(int min_threads= DEFAULT_MIN_POOL_THREADS,
   opened with FILE_FLAG_OVERLAPPED, and bound to completion
   port.
 */
-SSIZE_T pwrite(const native_file_handle &h, void *buf, size_t count,
-           unsigned long long offset);
+SSIZE_T pwrite(const native_file_handle &h, const void *buf, size_t count,
+               unsigned long long offset);
 SSIZE_T pread(const native_file_handle &h, void *buf, size_t count,
-          unsigned long long offset);
+              unsigned long long offset);
 HANDLE win_get_syncio_event();
 #endif
 } // namespace tpool