Adding upstream version 2.38.1.upstream/2.38.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 175 insertions, 0 deletions

diff --git a/libmount/src/btrfs.c b/libmount/src/btrfs.c
new file mode 100644
index 0000000..a831ce8
--- /dev/null
+++ b/libmount/src/btrfs.c
@@ -0,0 +1,175 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * This file is part of libmount from util-linux project.
+ *
+ * Copyright (C) 2016 David Sterba <dsterba@suse.cz>
+ * Copyright (C) 2016 Stanislav Brabec <sbrabec@suse.cz>
+ *
+ * libmount is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * Based on kernel ctree.h, rbtree.h and btrfs-progs.
+ */
+#include <dirent.h>
+#include <sys/ioctl.h>
+#include <stdlib.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
+
+/*
+ * the key defines the order in the tree, and so it also defines (optimal)
+ * block layout.  objectid corresponds with 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);				\
+}
+
+/* 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:
+ * @path: Path to mounted btrfs volume
+ *
+ * Searches for the btrfs default subvolume id.
+ *
+ * Returns: default subvolume id or UINT64_MAX (-1) in case of no
+ * default subvolume or error. In case of error, errno is set
+ * properly.
+ */
+uint64_t btrfs_get_default_subvol_id(const char *path)
+{
+	int iocret;
+	int fd;
+	DIR *dirstream;
+	struct btrfs_ioctl_search_args args;
+	struct btrfs_ioctl_search_key *sk = &args.key;
+	struct btrfs_ioctl_search_header *sh;
+	uint64_t found = UINT64_MAX;
+
+	dirstream = opendir(path);
+	if (!dirstream) {
+		DBG(BTRFS, ul_debug("opendir() failed for \"%s\" [errno=%d %m]", path, errno));
+		return UINT64_MAX;
+	}
+	fd = dirfd(dirstream);
+	if (fd < 0) {
+		DBG(BTRFS, ul_debug("dirfd(opendir()) failed for \"%s\" [errno=%d %m]", path, errno));
+		goto out;
+	}
+
+	memset(&args, 0, sizeof(args));
+	sk->tree_id = BTRFS_ROOT_TREE_OBJECTID;
+	sk->min_objectid = BTRFS_ROOT_TREE_DIR_OBJECTID;
+	sk->max_objectid = BTRFS_ROOT_TREE_DIR_OBJECTID;
+	sk->min_type = BTRFS_DIR_ITEM_KEY;
+	sk->max_type = BTRFS_DIR_ITEM_KEY;
+	sk->max_offset = UINT64_MAX;
+	sk->max_transid = UINT64_MAX;
+	sk->nr_items = 1;
+
+	iocret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &args);
+	if (iocret < 0) {
+		DBG(BTRFS, ul_debug("ioctl() failed for \"%s\" [errno=%d %m]", path, errno));
+		goto out;
+	}
+
+	/* the ioctl returns the number of items it found in nr_items */
+	if (sk->nr_items == 0) {
+		DBG(BTRFS, ul_debug("root tree dir object id not found"));
+		goto out;
+	}
+	DBG(BTRFS, ul_debug("found %d root tree dir object id items", sk->nr_items));
+
+	sh = (struct btrfs_ioctl_search_header *)args.buf;
+
+	if (sh->type == BTRFS_DIR_ITEM_KEY) {
+		struct btrfs_dir_item *di;
+		int name_len;
+		char *name;
+
+		di = (struct btrfs_dir_item *)(sh + 1);
+		name_len = btrfs_stack_dir_name_len(di);
+		name = (char *)(di + 1);
+
+		if (!strncmp("default", name, name_len)) {
+			found = btrfs_disk_key_objectid(&di->location);
+			DBG(BTRFS, ul_debug("\"default\" id is %llu", (unsigned long long)found));
+		} else {
+			DBG(BTRFS, ul_debug("\"default\" id not found in tree root"));
+			goto out;
+		}
+	} else {
+		DBG(BTRFS, ul_debug("unexpected type found: %d", (int)sh->type));
+		goto out;
+	}
+
+out:
+	closedir(dirstream);
+	return found;
+}