pathbased:btrfs: initial subvol support

Added "Subvol" name in the extlinux.sys, and then btrfs fs code will
handle the subvol correctly. Also fixed the bug where CurrentDirName
and SubvolName should not exist in the first sector.

1 files changed, 89 insertions, 11 deletions

diff --git a/core/fs/btrfs/btrfs.c b/core/fs/btrfs/btrfs.c
index 31e24f77..ee042601 100644
--- a/core/fs/btrfs/btrfs.c
+++ b/core/fs/btrfs/btrfs.c
@@ -266,6 +266,21 @@ static int btrfs_comp_keys(struct btrfs_disk_key *k1, struct btrfs_disk_key *k2)
 	return 0;
 }
 
+/* compare keys but ignore offset, is useful to enumerate all same kind keys */
+static int btrfs_comp_keys_type(struct btrfs_disk_key *k1,
+					struct btrfs_disk_key *k2)
+{
+	if (k1->objectid > k2->objectid)
+		return 1;
+	if (k1->objectid < k2->objectid)
+		return -1;
+	if (k1->type > k2->type)
+		return 1;
+	if (k1->type < k2->type)
+		return -1;
+	return 0;
+}
+
 /* seach tree directly on disk ... */
 static int search_tree(u64 loffset, struct btrfs_disk_key *key,
 				struct btrfs_path *path)
@@ -394,8 +409,8 @@ static void btrfs_read_chunk_tree(void)
 		search_tree(sb.chunk_root, &search_key, &path);
 		do {
 			do {
-				if (path.item.key.objectid !=
-					BTRFS_FIRST_CHUNK_TREE_OBJECTID)
+				if (btrfs_comp_keys_type(&search_key,
+							&path.item.key))
 					break;
 				chunk = (struct btrfs_chunk *)(path.data);
 				/* insert to mapping table, ignore stripes */
@@ -405,8 +420,7 @@ static void btrfs_read_chunk_tree(void)
 				item.physical = chunk->stripe.offset;
 				insert_map(&item);
 			} while (!next_slot(&search_key, &path));
-			if (path.item.key.objectid !=
-				BTRFS_FIRST_CHUNK_TREE_OBJECTID)
+			if (btrfs_comp_keys_type(&search_key, &path.item.key))
 				break;
 		} while (!next_leaf(&search_key, &path));
 	}
@@ -417,13 +431,16 @@ static inline u64 btrfs_name_hash(const char *name, int len)
 	return btrfs_crc32c((u32)~1, name, len);
 }
 
-/* search a file with full path in fs_tree, do not support ../ ./ style path */
-static int btrfs_search_fs_tree(const char *fullpath, u64 *offset,
+/* search a file with full path or relative path */
+static int btrfs_search_fs_tree(const char *fpath, u64 *offset,
 						u64 *size, u8 *type)
 {
 	char name[256];
 	char *tmp = name;
-	u64 objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
+	/* this can be used as cwd during the file searching */
+	static u64 objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
+	static u8 level; /* dir level */
+	static u64 objs[16]; /* history for ../ operation */
 	int ret;
 	struct btrfs_disk_key search_key;
 	struct btrfs_path path;
@@ -431,16 +448,26 @@ static int btrfs_search_fs_tree(const char *fullpath, u64 *offset,
 	struct btrfs_inode_item inode_item;
 	struct btrfs_file_extent_item extent_item;
 
+	if (*fpath == '/' || *fpath == '\0') { /* full or null path */
+		objectid = BTRFS_FIRST_CHUNK_TREE_OBJECTID;
+		level = 0;
+		objs[level] = objectid;
+	}
 	*tmp = '\0';
 	while (1) {
-		char c = *(fullpath++);
+		char c = *(fpath++);
 
 		*(tmp++) = c;
 		if (!c)
 			break;
 		if (c == '/') {
 			*(tmp-1) = '\0';
-			if (strlen(name)) {/* a "real" dir */
+			if (!strcmp(name, "..")) {
+				if (level)
+					level--;
+				objectid = objs[level];
+			} else if (strlen(name) && strcmp(name, ".")) {
+				/* a "real" dir */
 				search_key.objectid = objectid;
 				search_key.type = BTRFS_DIR_ITEM_KEY;
 				search_key.offset =
@@ -456,6 +483,12 @@ static int btrfs_search_fs_tree(const char *fullpath, u64 *offset,
 					return -1;
 				}
 				objectid = dir_item.location.objectid;
+				level++;
+				if (level >= 16) {
+					printf("too many dir levels(>16)\n");
+					return -1;
+				}
+				objs[level] = objectid;
 			}
 			tmp = name;
 			*tmp = '\0';
@@ -531,6 +564,16 @@ static void btrfs_close_file(struct file *file)
     close_pvt(file->open_file);
 }
 
+/* set the cwd to the global Path in patcharea */
+static void btrfs_set_cwd(void)
+{
+	u64 tmp;
+	char path[FILENAME_MAX];
+
+	sprintf(path, "%s/", CurrentDirName);
+	btrfs_search_fs_tree(path, &tmp, &tmp, (u8 *)&tmp);
+}
+
 static void btrfs_searchdir(char *filename, struct file *file)
 {
 	struct open_file_t *open_file;
@@ -563,6 +606,8 @@ static void btrfs_searchdir(char *filename, struct file *file)
 		}
 		break;
 	} while (1);
+	/* restore the cwd, since the above search may change dir */
+	btrfs_set_cwd();
 }
 
 /* Load the config file, return 1 if failed, or 0 */
@@ -572,7 +617,6 @@ static int btrfs_load_config(void)
     com32sys_t regs;
 
     strcpy(ConfigName, config_name);
-    *(uint16_t *)CurrentDirName = ROOT_DIR_WORD;
 
     memset(&regs, 0, sizeof regs);
     regs.edi.w[0] = OFFS_WRT(ConfigName, 0);
@@ -615,9 +659,42 @@ static void btrfs_get_fs_tree(void)
 	struct btrfs_disk_key search_key;
 	struct btrfs_path path;
 	struct btrfs_root_item *tree;
+	bool subvol_ok = false;
+
+	/* check if subvol is filled by installer */
+	if (*SubvolName) {
+		search_key.objectid = BTRFS_FS_TREE_OBJECTID;
+		search_key.type = BTRFS_ROOT_REF_KEY;
+		search_key.offset = 0;
+		clear_path(&path);
+		if (search_tree(sb.root, &search_key, &path))
+			next_slot(&search_key, &path);
+		do {
+			do {
+				struct btrfs_root_ref *ref;
 
+				if (btrfs_comp_keys_type(&search_key,
+							&path.item.key))
+					break;
+				ref = (struct btrfs_root_ref *)path.data;
+				if (!strcmp((char*)(ref + 1), SubvolName)) {
+					subvol_ok = true;
+					break;
+				}
+			} while (!next_slot(&search_key, &path));
+			if (subvol_ok)
+				break;
+			if (btrfs_comp_keys_type(&search_key, &path.item.key))
+				break;
+		} while (!next_leaf(&search_key, &path));
+		if (!subvol_ok) /* should be impossible */
+			printf("no subvol found!\n");
+	}
 	/* find fs_tree from tree_root */
-	search_key.objectid = BTRFS_FS_TREE_OBJECTID;
+	if (subvol_ok)
+		search_key.objectid = path.item.key.offset;
+	else /* "default" volume */
+		search_key.objectid = BTRFS_FS_TREE_OBJECTID;
 	search_key.type = BTRFS_ROOT_ITEM_KEY;
 	search_key.offset = -1;
 	clear_path(&path);
@@ -638,6 +715,7 @@ static int btrfs_fs_init(struct fs_info *_fs)
 	btrfs_read_sys_chunk_array();
 	btrfs_read_chunk_tree();
 	btrfs_get_fs_tree();
+	btrfs_set_cwd();
 	cache_ready = 1;
 	return BTRFS_BLOCK_SHIFT;/* to determine cache size */
 }