Maria - various fixes around durability of files:

1) on Mac OS X >=10.3, fcntl() is recommended over fsync (from the
man page: "[With fsync()] the disk drive may also re-order the data
so that later writes may be present while earlier writes are not.
Applications such as databases that require a strict ordering of writes
should use F_FULLFSYNC to ensure their data is written in the order
they expect"). I have seen two other pieces of software changing from
fsync to F_FULLFSYNC on Mac OS X.
2) to make a file creation/deletion/renaming durable on Linux (at least
ext2 as I have tested) (see "man fsync"), a fsync() on the directory
is needed: new functions to do that, and a flag MY_SYNC_DIR to do
it in my_create/my_delete/my_rename.
3) now using this directory syncing when creating he frm if
opt_sync_frm, and for Maria's control file when it is created.


include/my_sys.h:
  new flag to my_create/my_delete/my_rename, which asks to sync the
  directory after the operation is done (currently does nothing except
  on Linux)
libmysql/CMakeLists.txt:
  my_create() now depends on my_sync() so my_sync is needed for libmysql
libmysql/Makefile.shared:
  my_create() now depends on my_sync() so my_sync is needed for libmysql
mysys/my_create.c:
  my_create() can now sync the directory if asked for
mysys/my_delete.c:
  my_delete() can now sync the directory if asked for
mysys/my_open.c:
  it was a bug that my_close() is done on fd but a positive fd would
  still be returned, by my_register_filename().
mysys/my_rename.c:
  my_rename() can now sync the two directories (the one of "from" and
  the one of "to") if asked for.
mysys/my_sync.c:
  On recent Mac OS X, fcntl(F_FULLFSYNC) is recommended over fsync()
  (see "man fsync" on Mac OS X 10.3).
  my_sync_dir(): to sync a directory after a file creation/deletion/
  renaming; can be called directly or via MY_SYNC_DIR in my_create/
  my_delete/my_rename(). No-op except on Linux (see "man fsync" on Linux).
  my_sync_dir_from_file(): same as above, just more practical when the
  caller has a file name but no directory name ready.
  Should the #warning even be a #error? I mean do we want to release
  binaries which don't guarantee any durability?
sql/log.cc:
  a TODO for the future.
sql/unireg.cc:
  If we sync the frm it makes sense to also sync its creation in the
  directory.
storage/maria/ma_control_file.c:
  control file is vital, try to make it to disk

1 files changed, 74 insertions, 0 deletions

diff --git a/mysys/my_sync.c b/mysys/my_sync.c
index c557324b52c..eaa26ef07a7 100644
--- a/mysys/my_sync.c
+++ b/mysys/my_sync.c
@@ -49,6 +49,12 @@ int my_sync(File fd, myf my_flags)
 
   do
   {
+#if defined(F_FULLFSYNC)
+    /* Recent Mac OS X versions insist this call is safer than fsync() */
+    if (!(res= fcntl(fd, F_FULLFSYNC, 0)))
+      break; /* ok */
+    /* Some fs don't support F_FULLFSYNC and fail above, fallback: */
+#endif
 #if defined(HAVE_FDATASYNC)
     res= fdatasync(fd);
 #elif defined(HAVE_FSYNC)
@@ -56,6 +62,7 @@ int my_sync(File fd, myf my_flags)
 #elif defined(__WIN__)
     res= _commit(fd);
 #else
+#warning Cannot find a way to sync a file, durability in danger
     res= 0;					/* No sync (strange OS) */
 #endif
   } while (res == -1 && errno == EINTR);
@@ -74,3 +81,70 @@ int my_sync(File fd, myf my_flags)
   DBUG_RETURN(res);
 } /* my_sync */
 
+
+/*
+  Force directory information to disk. Only Linux is known to need this to
+  make sure a file creation/deletion/renaming in(from,to) this directory
+  durable.
+
+  SYNOPSIS
+    my_sync_dir()
+    dir_name             the name of the directory
+    my_flags             unused
+
+  RETURN
+    nothing (the sync may fail sometimes).
+*/
+void my_sync_dir(const char *dir_name, myf my_flags __attribute__((unused)))
+{
+#ifdef TARGET_OS_LINUX
+  DBUG_ENTER("my_sync_dir");
+  DBUG_PRINT("my",("Dir: '%s'  my_flags: %d", dir_name, my_flags));
+  File dir_fd;
+  int error= 0;
+  /*
+    Syncing a dir does not work on all filesystems (e.g. tmpfs->EINVAL) :
+    ignore errors. But print them to the debug log.
+  */
+  if (((dir_fd= my_open(dir_name, O_RDONLY, MYF(0))) >= 0))
+  {
+    if (my_sync(dir_fd, MYF(0)))
+    {
+      error= errno;
+      DBUG_PRINT("info",("my_sync failed errno: %d", error));
+    }
+    my_close(dir_fd, MYF(0));
+  }
+  else
+  {
+    error= errno;
+    DBUG_PRINT("info",("my_open failed errno: %d", error));
+  }
+  DBUG_VOID_RETURN;
+#endif
+}
+
+
+/*
+  Force directory information to disk. Only Linux is known to need this to
+  make sure a file creation/deletion/renaming in(from,to) this directory
+  durable.
+
+  SYNOPSIS
+    my_sync_dir_by_file()
+    file_name            the name of a file in the directory
+    my_flags             unused
+
+  RETURN
+    nothing (the sync may fail sometimes).
+*/
+void my_sync_dir_by_file(const char *file_name,
+                         myf my_flags __attribute__((unused)))
+{
+#ifdef TARGET_OS_LINUX
+  char dir_name[FN_REFLEN];
+  dirname_part(dir_name, file_name);
+  return my_sync_dir(dir_name, my_flags);
+#endif
+}
+