btrfs-progs: better space_cache=v2 support

index d47f0ae..d67b852 100644
@@ -467,6 +467,14 @@ struct btrfs_super_block {
  * ones specified below then we will fail to mount
  */
 #define BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE	(1ULL << 0)
+/*
+ * Older kernels on big-endian systems produced broken free space tree bitmaps,
+ * and btrfs-progs also used to corrupt the free space tree. If this bit is
+ * clear, then the free space tree cannot be trusted. btrfs-progs can also
+ * intentionally clear this bit to ask the kernel to rebuild the free space
+ * tree.
+ */
+#define BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE_VALID	(1ULL << 1)
 
 #define BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF	(1ULL << 0)
 #define BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL	(1ULL << 1)

@@ -493,6 +501,11 @@ struct btrfs_super_block {
 
 #define BTRFS_FEATURE_COMPAT_SUPP		0ULL
 
+/*
+ * The FREE_SPACE_TREE and FREE_SPACE_TREE_VALID compat_ro bits must not be
+ * added here until read-write support for the free space tree is implemented in
+ * btrfs-progs.
+ */
 #define BTRFS_FEATURE_COMPAT_RO_SUPP		0ULL
 
 #define BTRFS_FEATURE_INCOMPAT_SUPP			\

index d9f7bfb..ba0d708 100644
@@ -197,6 +197,16 @@ struct readable_flag_entry {
 	char *output;
 };
 
+#define DEF_COMPAT_RO_FLAG_ENTRY(bit_name)		\
+	{BTRFS_FEATURE_COMPAT_RO_##bit_name, #bit_name}
+
+static struct readable_flag_entry compat_ro_flags_array[] = {
+	DEF_COMPAT_RO_FLAG_ENTRY(FREE_SPACE_TREE),
+	DEF_COMPAT_RO_FLAG_ENTRY(FREE_SPACE_TREE_VALID),
+};
+static const int compat_ro_flags_num = sizeof(compat_ro_flags_array) /
+				       sizeof(struct readable_flag_entry);
+
 #define DEF_INCOMPAT_FLAG_ENTRY(bit_name)		\
 	{BTRFS_FEATURE_INCOMPAT_##bit_name, #bit_name}
 

@@ -268,6 +278,19 @@ static void __print_readable_flag(u64 flag, struct readable_flag_entry *array,
 	printf(")\n");
 }
 
+static void print_readable_compat_ro_flag(u64 flag)
+{
+	/*
+	 * We know about the FREE_SPACE_TREE{,_VALID} bits, but we don't
+	 * actually support them yet.
+	 */
+	return __print_readable_flag(flag, compat_ro_flags_array,
+				     compat_ro_flags_num,
+				     BTRFS_FEATURE_COMPAT_RO_SUPP |
+				     BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE |
+				     BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE_VALID);
+}
+
 static void print_readable_incompat_flag(u64 flag)
 {
 	return __print_readable_flag(flag, incompat_flags_array,

@@ -377,6 +400,7 @@ static void dump_superblock(struct btrfs_super_block *sb, int full)
 	       (unsigned long long)btrfs_super_compat_flags(sb));
 	printf("compat_ro_flags\t\t0x%llx\n",
 	       (unsigned long long)btrfs_super_compat_ro_flags(sb));
+	print_readable_compat_ro_flag(btrfs_super_compat_ro_flags(sb));
 	printf("incompat_flags\t\t0x%llx\n",
 	       (unsigned long long)btrfs_super_incompat_flags(sb));
 	print_readable_incompat_flag(btrfs_super_incompat_flags(sb));

index e33ee8b..e6b26ac 100644
@@ -1477,7 +1477,7 @@ open_ctree_with_broken_chunk(struct recover_control *rc)
 
 	memcpy(fs_info->fsid, &disk_super->fsid, BTRFS_FSID_SIZE);
 
-	ret = btrfs_check_fs_compatibility(disk_super, 1);
+	ret = btrfs_check_fs_compatibility(disk_super, OPEN_CTREE_WRITES);
 	if (ret)
 		goto out_devices;
 

index a576300..de25fcd 100644
@@ -904,7 +904,8 @@ free_all:
 	return NULL;
 }
 
-int btrfs_check_fs_compatibility(struct btrfs_super_block *sb, int writable)
+int btrfs_check_fs_compatibility(struct btrfs_super_block *sb,
+				 unsigned int flags)
 {
 	u64 features;
 

@@ -923,13 +924,22 @@ int btrfs_check_fs_compatibility(struct btrfs_super_block *sb, int writable)
 		btrfs_set_super_incompat_flags(sb, features);
 	}
 
-	features = btrfs_super_compat_ro_flags(sb) &
-		~BTRFS_FEATURE_COMPAT_RO_SUPP;
-	if (writable && features) {
-		printk("couldn't open RDWR because of unsupported "
-		       "option features (%Lx).\n",
-		       (unsigned long long)features);
-		return -ENOTSUP;
+	features = btrfs_super_compat_ro_flags(sb);
+	if (flags & OPEN_CTREE_WRITES) {
+		if (flags & OPEN_CTREE_INVALIDATE_FST) {
+			/* Clear the FREE_SPACE_TREE_VALID bit on disk... */
+			features &= ~BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE_VALID;
+			btrfs_set_super_compat_ro_flags(sb, features);
+			/* ... and ignore the free space tree bit. */
+			features &= ~BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE;
+		}
+		if (features & ~BTRFS_FEATURE_COMPAT_RO_SUPP) {
+			printk("couldn't open RDWR because of unsupported "
+			       "option features (%Lx).\n",
+			       (unsigned long long)features);
+			return -ENOTSUP;
+		}
+
 	}
 	return 0;
 }

@@ -1320,8 +1330,7 @@ static struct btrfs_fs_info *__open_ctree_fd(int fp, const char *path,
 
 	memcpy(fs_info->fsid, &disk_super->fsid, BTRFS_FSID_SIZE);
 
-	ret = btrfs_check_fs_compatibility(fs_info->super_copy,
-					   flags & OPEN_CTREE_WRITES);
+	ret = btrfs_check_fs_compatibility(fs_info->super_copy, flags);
 	if (ret)
 		goto out_devices;
 

index 8ab36aa..d4a0e7f 100644
@@ -74,6 +74,12 @@ enum btrfs_open_ctree_flags {
 
 	/* Allow to open a partially created filesystem */
 	OPEN_CTREE_FS_PARTIAL = (1U << 12),
+
+	/*
+	 * Invalidate the free space tree (i.e., clear the FREE_SPACE_TREE_VALID
+	 * compat_ro bit).
+	 */
+	OPEN_CTREE_INVALIDATE_FST = (1U << 13),
 };
 
 /*

@@ -128,7 +134,8 @@ int clean_tree_block(struct btrfs_trans_handle *trans,
 
 void btrfs_free_fs_info(struct btrfs_fs_info *fs_info);
 struct btrfs_fs_info *btrfs_new_fs_info(int writable, u64 sb_bytenr);
-int btrfs_check_fs_compatibility(struct btrfs_super_block *sb, int writable);
+int btrfs_check_fs_compatibility(struct btrfs_super_block *sb,
+				 unsigned int flags);
 int btrfs_setup_all_roots(struct btrfs_fs_info *fs_info, u64 root_tree_bytenr,
 			  unsigned flags);
 void btrfs_release_all_roots(struct btrfs_fs_info *fs_info);

index d67b852..b433bca 100644
@@ -2504,6 +2504,10 @@ int btrfs_inc_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 		  struct extent_buffer *buf, int record_parent);
 int btrfs_dec_ref(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 		  struct extent_buffer *buf, int record_parent);
+int btrfs_free_tree_block(struct btrfs_trans_handle *trans,
+			  struct btrfs_root *root,
+			  struct extent_buffer *buf,
+			  u64 parent, int last_ref);
 int btrfs_free_extent(struct btrfs_trans_handle *trans,
 		      struct btrfs_root *root,
 		      u64 bytenr, u64 num_bytes, u64 parent,

@@ -2664,6 +2668,8 @@ int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root
 		      *root, struct btrfs_key *key, struct btrfs_root_item
 		      *item);
+int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
+		   struct btrfs_key *key);
 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
 		      *root, struct btrfs_key *key, struct btrfs_root_item
 		      *item);

index 3b1577e..b52c515 100644
@@ -2467,6 +2467,17 @@ static int del_pending_extents(struct btrfs_trans_handle *trans, struct
 	return err;
 }
 
+
+int btrfs_free_tree_block(struct btrfs_trans_handle *trans,
+			  struct btrfs_root *root,
+			  struct extent_buffer *buf,
+			  u64 parent, int last_ref)
+{
+	return btrfs_free_extent(trans, root, buf->start, buf->len, parent,
+				 root->root_key.objectid,
+				 btrfs_header_level(buf), 0);
+}
+
 /*
  * remove an extent from the root, returns 0 on success
  */

103 lines not on this page · raw message

index 7529a46..4845f13 100644
@@ -19,6 +19,7 @@
 #ifndef __BTRFS_FREE_SPACE_TREE_H__
 #define __BTRFS_FREE_SPACE_TREE_H__
 
+int btrfs_clear_free_space_tree(struct btrfs_fs_info *fs_info);
 int load_free_space_tree(struct btrfs_fs_info *fs_info,
 			 struct btrfs_block_group_cache *block_group);
 

index cca424e..ab01a14 100644
@@ -143,6 +143,31 @@ int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root
 	return ret;
 }
 
+/* drop the root item for 'key' from 'root' */
+int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
+		   struct btrfs_key *key)
+{
+	struct btrfs_path *path;
+	int ret;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+	ret = btrfs_search_slot(trans, root, key, path, -1, 1);
+	if (ret < 0)
+		goto out;
+
+	if (ret != 0) {
+		ret = -ENOENT;
+		goto out;
+	}
+
+	ret = btrfs_del_item(trans, root, path);
+out:
+	btrfs_free_path(path);
+	return ret;
+}
+
 /*
  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
  * or BTRFS_ROOT_BACKREF_KEY.

index 57c4300..0eca102 100644
@@ -11170,7 +11170,6 @@ const char * const cmd_check_usage[] = {
 	"--chunk-root <bytenr>       use the given bytenr for the chunk tree root",
 	"-p|--progress               indicate progress",
 	"--clear-space-cache v1|v2   clear space cache for v1 or v2",
-	"                            NOTE: v1 support implemented",
 	NULL
 };
 

@@ -11292,13 +11291,16 @@ int cmd_check(int argc, char **argv)
 				}
 				break;
 			case GETOPT_VAL_CLEAR_SPACE_CACHE:
-				if (strcmp(optarg, "v1") != 0) {
-					error(
-			"only v1 support implmented, unrecognized value %s",
-			optarg);
+				if (strcmp(optarg, "v1") == 0) {
+					clear_space_cache = 1;
+				} else if (strcmp(optarg, "v2") == 0) {
+					clear_space_cache = 2;
+					ctree_flags |= OPEN_CTREE_INVALIDATE_FST;
+				} else {
+					error("invalid argument to --clear-space-cache; "
+					      "must be v1 or v2");
 					exit(1);
 				}
-				clear_space_cache = 1;
 				ctree_flags |= OPEN_CTREE_WRITES;
 				break;
 		}

@@ -11352,11 +11354,10 @@ int cmd_check(int argc, char **argv)
 
 	global_info = info;
 	root = info->fs_root;
-	if (clear_space_cache) {
+	if (clear_space_cache == 1) {
 		if (btrfs_fs_compat_ro(info,
 				BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE)) {
-			error(
-			"free space cache v2 detected, clearing not implemented");
+			error("free space cache v2 detected; use --clear-space-cache v2");
 			ret = 1;
 			goto close_out;
 		}

@@ -11369,6 +11370,21 @@ int cmd_check(int argc, char **argv)
 			printf("Free space cache cleared\n");
 		}
 		goto close_out;
+	} else if (clear_space_cache == 2) {
+		if (!btrfs_fs_compat_ro(info, BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE)) {
+			printf("No free space cache v2 to clear\n");
+			ret = 0;
+			goto close_out;
+		}
+		printf("Clear free space cache v2\n");
+		ret = btrfs_clear_free_space_tree(info);
+		if (ret) {
+			error("Failed to clear free space cache v2");
+			ret = 1;
+		} else {
+			printf("Free space cache v2 cleared\n");
+		}
+		goto close_out;
 	}
 
 	/*