libmount: consolidate btrfs stuff, make it more portable

- add --with-btrfs (enabled by default)
- check for linux/btrfs.h
- add "btrfs" to libmount features list (see mount -V)
- #ifdef HAVE_BTRFS_SUPPORT for all btrfs stuff in libmount

Signed-off-by: Karel Zak <kzak@redhat.com>

5 files changed, 92 insertions, 133 deletions

diff --git a/libmount/src/Makemodule.am b/libmount/src/Makemodule.am
index 39d42d524..3a89d0de4 100644
--- a/libmount/src/Makemodule.am
+++ b/libmount/src/Makemodule.am
@@ -27,15 +27,18 @@ libmount_la_SOURCES = \
 
 if LINUX
 libmount_la_SOURCES += \
-	libmount/src/btrfs.c \
-	libmount/src/btrfs.h \
 	libmount/src/context.c \
 	libmount/src/context_loopdev.c \
 	libmount/src/context_mount.c \
 	libmount/src/context_umount.c \
 	libmount/src/monitor.c
+
+if HAVE_BTRFS
+libmount_la_SOURCES += libmount/src/btrfs.c
 endif
 
+endif # LINUX
+
 nodist_libmount_la_SOURCES = libmount/src/mountP.h
 
 libmount_la_LIBADD = \
diff --git a/libmount/src/btrfs.c b/libmount/src/btrfs.c
index 3c61a2a03..1db604a87 100644
--- a/libmount/src/btrfs.c
+++ b/libmount/src/btrfs.c
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 1999 Andrea Arcangeli <andrea@suse.de>
  * Copyright (C) 2016 David Sterba <dsterba@suse.cz>
  * Copyright (C) 2016 Stanislav Brabec <sbrabec@suse.cz>
  *
@@ -6,17 +7,89 @@
  * GNU Lesser General Public License.
  */
 
+#include <dirent.h>
+#include <sys/ioctl.h>
+#include <libio.h>
+#include <stdint.h>
+#include <linux/btrfs.h>
+
+#include "mountP.h"
+#include "bitops.h"
+
+
+/* linux/btrfs.h lacks large parts of stuff needed for getting default
+ * sub-volume. Suppose that if BTRFS_DIR_ITEM_KEY is not defined, all
+ * declarations are still missing.
+ */
+#ifndef BTRFS_DIR_ITEM_KEY
+
+/*
+ * dir items are the name -> inode pointers in a directory.  There is one
+ * for every name in a directory.
+ */
+#define BTRFS_DIR_ITEM_KEY	84
+
+/* holds pointers to all of the tree roots */
+#define BTRFS_ROOT_TREE_OBJECTID 1ULL
+
+/* directory objectid inside the root tree */
+#define BTRFS_ROOT_TREE_DIR_OBJECTID 6ULL
+
 /*
- * SECTION: btrfs
- * @title: btrfs
- * @short_description: special function for btrfs
+ * the key defines the order in the tree, and so it also defines (optimal)
+ * block layout.  objectid corresonds to the inode number.  The flags
+ * tells us things about the object, and is a kind of stream selector.
+ * so for a given inode, keys with flags of 1 might refer to the inode
+ * data, flags of 2 may point to file data in the btree and flags == 3
+ * may point to extents.
  *
- * btrfs contains function needed for manipulation with btrfs.
+ * offset is the starting byte offset for this key in the stream.
+ *
+ * btrfs_disk_key is in disk byte order.  struct btrfs_key is always
+ * in cpu native order.  Otherwise they are identical and their sizes
+ * should be the same (ie both packed)
  */
-#include <dirent.h>
-#include <sys/ioctl.h>
-#include <linux/magic.h>
-#include "btrfs.h"
+struct btrfs_disk_key {
+	uint64_t objectid; /* little endian */
+	uint8_t type;
+	uint64_t offset; /* little endian */
+} __attribute__ ((__packed__));
+
+struct btrfs_dir_item {
+	struct btrfs_disk_key location;
+	uint64_t transid; /* little endian */
+	uint16_t data_len; /* little endian */
+	uint16_t name_len; /* little endian */
+	uint8_t type;
+} __attribute__ ((__packed__));
+
+#define BTRFS_SETGET_STACK_FUNCS(name, type, member, bits)		\
+static inline uint##bits##_t btrfs_##name(const type *s)		\
+{									\
+	return le##bits##_to_cpu(s->member);				\
+}									\
+static inline void btrfs_set_##name(type *s, uint##bits##_t val)	\
+{									\
+	s->member = cpu_to_le##bits(val);				\
+}
+
+/* struct btrfs_disk_key */
+BTRFS_SETGET_STACK_FUNCS(disk_key_objectid, struct btrfs_disk_key,
+			 objectid, 64);
+
+BTRFS_SETGET_STACK_FUNCS(stack_dir_name_len, struct btrfs_dir_item, name_len, 16);
+
+/*
+  Red Black Trees
+*/
+struct rb_node {
+	unsigned long  __rb_parent_color;
+	struct rb_node *rb_right;
+	struct rb_node *rb_left;
+} __attribute__((aligned(sizeof(long))));
+    /* The alignment might seem pointless, but allegedly CRIS needs it */
+
+#endif /* BTRFS_DIR_ITEM_KEY */
 
 /*
  * btrfs_get_default_subvol_id:
@@ -97,6 +170,5 @@ uint64_t btrfs_get_default_subvol_id(const char *path)
 
 out:
 	closedir(dirstream);
-
 	return found;
 }
diff --git a/libmount/src/btrfs.h b/libmount/src/btrfs.h
deleted file mode 100644
index ca49df511..000000000
--- a/libmount/src/btrfs.h
+++ /dev/null
@@ -1,122 +0,0 @@
-/* This is an excerpt from btrfs-progs-v4.3.1
- * All kernel types are converted to stdint.h types. */
-
-/*
- * Copyright (C) 2007 Oracle.  All rights reserved.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public
- * License v2 as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public
- * License along with this program; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 021110-1307, USA.
- */
-
-#include <libio.h>
-#include <stdint.h>
-#include <linux/btrfs.h>
-#include "mountP.h"
-#include "bitops.h"
-
-
-/* linux/btrfs.h lacks large parts of stuff needed for getting default
- * sub-volume. Suppose that if BTRFS_DIR_ITEM_KEY is not defined, all
- * declarations are still missing.
- */
-#ifndef BTRFS_DIR_ITEM_KEY
-
-
-/* from ctree.h */
-
-/*
- * dir items are the name -> inode pointers in a directory.  There is one
- * for every name in a directory.
- */
-#define BTRFS_DIR_ITEM_KEY	84
-
-/* holds pointers to all of the tree roots */
-#define BTRFS_ROOT_TREE_OBJECTID 1ULL
-
-/* directory objectid inside the root tree */
-#define BTRFS_ROOT_TREE_DIR_OBJECTID 6ULL
-
-/*
- * the key defines the order in the tree, and so it also defines (optimal)
- * block layout.  objectid corresonds to the inode number.  The flags
- * tells us things about the object, and is a kind of stream selector.
- * so for a given inode, keys with flags of 1 might refer to the inode
- * data, flags of 2 may point to file data in the btree and flags == 3
- * may point to extents.
- *
- * offset is the starting byte offset for this key in the stream.
- *
- * btrfs_disk_key is in disk byte order.  struct btrfs_key is always
- * in cpu native order.  Otherwise they are identical and their sizes
- * should be the same (ie both packed)
- */
-struct btrfs_disk_key {
-	uint64_t objectid; /* little endian */
-	uint8_t type;
-	uint64_t offset; /* little endian */
-} __attribute__ ((__packed__));
-
-struct btrfs_dir_item {
-	struct btrfs_disk_key location;
-	uint64_t transid; /* little endian */
-	uint16_t data_len; /* little endian */
-	uint16_t name_len; /* little endian */
-	uint8_t type;
-} __attribute__ ((__packed__));
-
-#define BTRFS_SETGET_STACK_FUNCS(name, type, member, bits)		\
-static inline uint##bits##_t btrfs_##name(const type *s)		\
-{									\
-	return le##bits##_to_cpu(s->member);				\
-}									\
-static inline void btrfs_set_##name(type *s, uint##bits##_t val)	\
-{									\
-	s->member = cpu_to_le##bits(val);				\
-}
-
-/* struct btrfs_disk_key */
-BTRFS_SETGET_STACK_FUNCS(disk_key_objectid, struct btrfs_disk_key,
-			 objectid, 64);
-
-BTRFS_SETGET_STACK_FUNCS(stack_dir_name_len, struct btrfs_dir_item, name_len, 16);
-
-
-/* from rbtree.h */
-
-/*
-  Red Black Trees
-  (C) 1999  Andrea Arcangeli <andrea@suse.de>
-
-  This program is free software; you can redistribute it and/or modify
-  it under the terms of the GNU General Public License as published by
-  the Free Software Foundation; either version 2 of the License, or
-  (at your option) any later version.
-
-  This program is distributed in the hope that it will be useful,
-  but WITHOUT ANY WARRANTY; without even the implied warranty of
-  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-  GNU General Public License for more details.
-
-  You should have received a copy of the GNU General Public License
-  along with this program; if not, write to the Free Software
-  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
-*/
-struct rb_node {
-	unsigned long  __rb_parent_color;
-	struct rb_node *rb_right;
-	struct rb_node *rb_left;
-} __attribute__((aligned(sizeof(long))));
-    /* The alignment might seem pointless, but allegedly CRIS needs it */
-
-#endif
diff --git a/libmount/src/tab.c b/libmount/src/tab.c
index 31b177fec..3099615aa 100644
--- a/libmount/src/tab.c
+++ b/libmount/src/tab.c
@@ -1315,6 +1315,7 @@ struct libmnt_fs *mnt_table_get_fs_root(struct libmnt_table *tb,
 		}
 	}
 
+#ifdef HAVE_BTRFS_SUPPORT
 	/*
 	 * btrfs-subvolume mount -- get subvolume name and use it as a root-fs path
 	 */
@@ -1381,6 +1382,8 @@ struct libmnt_fs *mnt_table_get_fs_root(struct libmnt_table *tb,
 		memcpy(p, vol, volsz);
 		*(root + sz) = '\0';
 	}
+#endif /* HAVE_BTRFS_SUPPORT */
+
 dflt:
 	if (!root) {
 		root = strdup("/");
diff --git a/libmount/src/version.c b/libmount/src/version.c
index d81d4323f..d0f61c928 100644
--- a/libmount/src/version.c
+++ b/libmount/src/version.c
@@ -25,6 +25,9 @@ static const char *lib_features[] = {
 #ifdef HAVE_SMACK
 	"smack",
 #endif
+#ifdef HAVE_BTRFS_SUPPORT
+	"btrfs",
+#endif
 #if !defined(NDEBUG)
 	"assert",	/* libc assert.h stuff */
 #endif