btrfs-progs: build: detect fiemap shared flag but don't fail build

PATCH New David Sterba 1 participant 1 message Oct 14, 2016 Btrfs file system

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David Sterba

author maintainer

2016-10-14 17:04 UTC #0 lore raw

PATCH 1/1 btrfs-progs: build: detect fiemap shared flag but don't fail build

The FIEMAP_EXTENT_SHARED fiemap flag was introduced in 2.6.33. If the headers do not provide the definition, the build will fail. The support of the fiemap sharing depends on the running kernel. There are still systems with 2.6.32 kernel headers but running newer versions.

To support such environment, don't fail build, provide own defintion of the structure and detect if there's an old kernel in use in the relevant command (btrfs fi du).

Reported-by Abhay Sachan <[email protected]>

Signed-off-by David Sterba <[email protected]>

---
 cmds-fi-du.c | 14 ++++++++++++++
 configure.ac | 10 +++++++++-
 2 files changed, 23 insertions(+), 1 deletion(-)

cmds-fi-du.c +14 -0

index a5b66e6fdf1a..895c242e821c 100644
@@ -27,8 +27,13 @@
 
 #include <sys/ioctl.h>
 #include <linux/fs.h>
+#include <linux/version.h>
 #include <linux/fiemap.h>
 
+#if !defined(FIEMAP_EXTENT_SHARED) && (HAVE_OWN_FIEMAP_EXTENT_SHARED_DEFINE == 1)
+#define FIEMAP_EXTENT_SHARED           0x00002000
+#endif
+
 #include "utils.h"
 #include "commands.h"
 #include "kerncompat.h"

@@ -546,6 +551,7 @@ int cmd_filesystem_du(int argc, char **argv)
 {
 	int ret = 0, err = 0;
 	int i;
+	u32 kernel_version;
 
 	unit_mode = get_unit_mode_from_arg(&argc, argv, 1);

@@ -570,6 +576,14 @@ int cmd_filesystem_du(int argc, char **argv)
 	if (check_argc_min(argc - optind, 1))
 		usage(cmd_filesystem_du_usage);
 
+	kernel_version = get_running_kernel_version();
+
+	if (kernel_version < KERNEL_VERSION(2,6,33)) {
+		warning(
+"old kernel version detected, shared space will be reported as exclusive\n"
+"due to missing support for FIEMAP_EXTENT_SHARED flag");
+	}
+
 	printf("%10s  %10s  %10s  %s\n", "Total", "Exclusive", "Set shared",
 			"Filename");

configure.ac +9 -1

index 8fd8f425a076..9c6df3b9d4ed 100644
@@ -144,8 +144,16 @@ if test "$DISABLE_BTRFSCONVERT" = 0 && test "x$convertfs" = "x"; then
 	AC_MSG_ERROR([no filesystems for convert, use --disable-convert instead])
 fi
 
+HAVE_OWN_FIEMAP_EXTENT_SHARED_DEFINE=0
 AX_CHECK_DEFINE([linux/fiemap.h], [FIEMAP_EXTENT_SHARED], [],
-		[AC_MSG_ERROR([no definition of FIEMAP_EXTENT_SHARED found])])
+		[HAVE_OWN_FIEMAP_EXTENT_SHARED_DEFINE=1
+		 AC_MSG_WARN([no definition of FIEMAP_EXTENT_SHARED found, probably old kernel, will use own defintion, 'btrfs fi du' might report wrong numbers])])
+
+if test "x$HAVE_OWN_FIEMAP_EXTENT_SHARED_DEFINE" == "x1"; then
+AC_DEFINE([HAVE_OWN_FIEMAP_EXTENT_SHARED_DEFINE], [1], [We defined FIEMAP_EXTENT_SHARED])
+else
+AC_DEFINE([HAVE_OWN_FIEMAP_EXTENT_SHARED_DEFINE], [0], [We did not define FIEMAP_EXTENT_SHARED])
+fi
 
 dnl Define <NAME>_LIBS= and <NAME>_CFLAGS= by pkg-config
 dnl

Signature · 1 line

2.10.0