[PATCH 4/4] xfs_restore: support fallocate when reserving space for a file

["Darrick J. Wong" <darrick.wong@oracle.com>]

From: Darrick J. Wong <darrick.wong@oracle.com>

Update the file creation helper to try fallocate when restoring a
filesystem before it tries RESVSP.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 configure.ac          |    2 ++
 include/builddefs.in  |    1 +
 m4/Makefile           |    1 +
 m4/package_libcdev.m4 |   15 +++++++++++++++
 restore/Makefile      |    4 ++++
 restore/dirattr.c     |   11 +++++++++++
 6 files changed, 34 insertions(+)
 create mode 100644 m4/package_libcdev.m4


diff --git a/configure.ac b/configure.ac
index a77054c..73dedd7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -84,6 +84,8 @@ AC_PACKAGE_NEED_ATTRIBUTES_H
 AC_PACKAGE_NEED_ATTRIBUTES_MACROS
 AC_PACKAGE_NEED_ATTRGET_LIBATTR
 
+AC_HAVE_FALLOCATE
+
 AC_MANUAL_FORMAT
 
 AC_CONFIG_FILES([include/builddefs])
diff --git a/include/builddefs.in b/include/builddefs.in
index 269c928..1c7e12f 100644
--- a/include/builddefs.in
+++ b/include/builddefs.in
@@ -69,6 +69,7 @@ ENABLE_SHARED	= @enable_shared@
 ENABLE_GETTEXT	= @enable_gettext@
 
 HAVE_ZIPPED_MANPAGES = @have_zipped_manpages@
+HAVE_FALLOCATE = @have_fallocate@
 
 GCCFLAGS = -funsigned-char -fno-strict-aliasing -Wall 
 #	   -Wbitwise -Wno-transparent-union -Wno-old-initializer -Wno-decl
diff --git a/m4/Makefile b/m4/Makefile
index 9a35056..ae452f7 100644
--- a/m4/Makefile
+++ b/m4/Makefile
@@ -16,6 +16,7 @@ LSRCFILES = \
 	manual_format.m4 \
 	package_attrdev.m4 \
 	package_globals.m4 \
+	package_libcdev.m4 \
 	package_ncurses.m4 \
 	package_pthread.m4 \
 	package_utilies.m4 \
diff --git a/m4/package_libcdev.m4 b/m4/package_libcdev.m4
new file mode 100644
index 0000000..050f82c
--- /dev/null
+++ b/m4/package_libcdev.m4
@@ -0,0 +1,15 @@
+#
+# Check if we have a fallocate libc call (Linux)
+#
+AC_DEFUN([AC_HAVE_FALLOCATE],
+  [ AC_MSG_CHECKING([for fallocate])
+    AC_TRY_LINK([
+#include <fcntl.h>
+#include <linux/falloc.h>
+    ], [
+         fallocate(0, 0, 0, 0);
+    ], have_fallocate=yes
+       AC_MSG_RESULT(yes),
+       AC_MSG_RESULT(no))
+    AC_SUBST(have_fallocate)
+  ])
diff --git a/restore/Makefile b/restore/Makefile
index 20c870a..ac3f8c8 100644
--- a/restore/Makefile
+++ b/restore/Makefile
@@ -102,6 +102,10 @@ LTDEPENDENCIES = $(LIBRMT)
 
 LCFLAGS = -DRESTORE
 
+ifeq ($(HAVE_FALLOCATE),yes)
+LCFLAGS += -DHAVE_FALLOCATE
+endif
+
 default: depend $(LTCOMMAND)
 
 include $(BUILDRULES)
diff --git a/restore/dirattr.c b/restore/dirattr.c
index 3fa8fb6..82eb1de 100644
--- a/restore/dirattr.c
+++ b/restore/dirattr.c
@@ -75,6 +75,17 @@ create_filled_file(
 	if (fd < 0)
 		return fd;
 
+#ifdef HAVE_FALLOCATE
+	ret = fallocate(fd, 0, 0, size);
+	if (ret && (errno != EOPNOTSUPP && errno != ENOTTY))
+		mlog(MLOG_VERBOSE | MLOG_NOTE,
+_("attempt to reserve %lld bytes for %s using %s failed: %s (%d)\n"),
+				size, pathname, "fallocate",
+				strerror(errno), errno);
+	if (ret == 0)
+		goto done;
+#endif
+
 	ret = ioctl(fd, XFS_IOC_RESVSP64, &fl);
 	if (ret && (errno != EOPNOTSUPP && errno != ENOTTY))
 		mlog(MLOG_VERBOSE | MLOG_NOTE,