Handle posix_fallocate() errors.

On some platforms, posix_fallocate() is available but may still return
EINVAL if the underlying filesystem does not support it.  So, in case
of an error, fall through to the alternate implementation that just
writes zeros.

Per buildfarm failure and analysis by Tom Lane.

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index f97ab1ae3a221bf0b75f205314b43a4dbbf9a36d..77e5c3b5d85ad7907e9b5403bbe93141a297c468 100644 (file)
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -2259,6 +2259,7 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock)
        XLogSegNo       installed_segno;
        int                     max_advance;
        int                     fd;
+       bool            zero_fill = true;
 
        XLogFilePath(path, ThisTimeLineID, logsegno);
 
@@ -2301,24 +2302,18 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock)
                                 errmsg("could not create file \"%s\": %m", tmppath)));
 
 #ifdef HAVE_POSIX_FALLOCATE
-       {
-               errno = posix_fallocate(fd, 0, XLogSegSize);
-
-               if (errno)
-               {
-                       int errno_saved = errno;
-
-                       close(fd);
-                       unlink(tmppath);
-                       errno = errno_saved;
+       /*
+        * If posix_fallocate() is available and succeeds, then the file is
+        * properly allocated and we don't need to zero-fill it (which is less
+        * efficient).  In case of an error, fall back to writing zeros, because on
+        * some platforms posix_fallocate() is available but will not always
+        * succeed in cases where zero-filling will.
+        */
+       if (posix_fallocate(fd, 0, XLogSegSize) == 0)
+               zero_fill = false;
+#endif /* HAVE_POSIX_FALLOCATE */
 
-                       ereport(ERROR,
-                                       (errcode_for_file_access(),
-                                        errmsg("could not allocate space for file \"%s\" using posix_fallocate: %m",
-                                                       tmppath)));
-               }
-       }
-#else /* !HAVE_POSIX_FALLOCATE */
+       if (zero_fill)
        {
                /*
                 * Allocate a buffer full of zeros. This is done before opening the
@@ -2366,7 +2361,6 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock)
                }
                pfree(zbuffer);
        }
-#endif /* HAVE_POSIX_FALLOCATE */
 
        if (pg_fsync(fd) != 0)
        {