btrfs-progs: Rename OPEN_CTREE_FS_PARTIAL to OPEN_CTREE_TEMPORARY_SUPER

The old flag OPEN_CTREE_FS_PARTIAL is in fact quite easy to be confused
with OPEN_CTREE_PARTIAL, which allow btrfs-progs to open damaged
filesystem (like corrupted extent/csum tree).

However OPEN_CTREE_FS_PARTIAL, unlike its name, is just allowing
btrfs-progs to open fs with temporary superblocks (which only has 6
basic trees on SINGLE meta/sys chunks).

The usage of FS_PARTIAL is really confusing here.

So rename OPEN_CTREE_FS_PARTIAL to OPEN_CTREE_TEMPORARY_SUPER, and add
extra comment for its behavior.
Also rename BTRFS_MAGIC_PARTIAL to BTRFS_MAGIC_TEMPORARY to keep the
naming consistent.

And with above comment, the usage of FS_PARTIAL in dump-tree is
obviously incorrect, fix it.

Fixes: 8698a2b9ba ("btrfs-progs: Allow inspect dump-tree to show specified tree block even some tree roots are corrupted")
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

cmds-inspect-dump-tree.c

@@ -221,7 +221,7 @@ int cmd_inspect_dump_tree(int argc, char **argv)
 	int uuid_tree_only = 0;
 	int roots_only = 0;
 	int root_backups = 0;
-	unsigned open_ctree_flags = OPEN_CTREE_FS_PARTIAL;
+	unsigned open_ctree_flags = OPEN_CTREE_PARTIAL;
 	u64 block_only = 0;
 	struct btrfs_root *tree_root_scan;
 	u64 tree_id = 0;

convert/common.c

@@ -116,7 +116,7 @@ static int setup_temp_super(int fd, struct btrfs_mkfs_config *cfg,
 
 	btrfs_set_super_bytenr(super, cfg->super_bytenr);
 	btrfs_set_super_num_devices(super, 1);
-	btrfs_set_super_magic(super, BTRFS_MAGIC_PARTIAL);
+	btrfs_set_super_magic(super, BTRFS_MAGIC_TEMPORARY);
 	btrfs_set_super_generation(super, 1);
 	btrfs_set_super_root(super, root_bytenr);
 	btrfs_set_super_chunk_root(super, chunk_bytenr);

convert/main.c

@@ -1140,7 +1140,7 @@ static int do_convert(const char *devname, u32 convert_flags, u32 nodesize,
 	}
 
 	root = open_ctree_fd(fd, devname, mkfs_cfg.super_bytenr,
-			     OPEN_CTREE_WRITES | OPEN_CTREE_FS_PARTIAL);
+			     OPEN_CTREE_WRITES | OPEN_CTREE_TEMPORARY_SUPER);
 	if (!root) {
 		error("unable to open ctree");
 		goto fail;
@@ -1230,7 +1230,7 @@ static int do_convert(const char *devname, u32 convert_flags, u32 nodesize,
 	}
 
 	root = open_ctree_fd(fd, devname, 0,
-			OPEN_CTREE_WRITES | OPEN_CTREE_FS_PARTIAL);
+			     OPEN_CTREE_WRITES | OPEN_CTREE_TEMPORARY_SUPER);
 	if (!root) {
 		error("unable to open ctree for finalization");
 		goto fail;

ctree.h

@@ -45,10 +45,12 @@ struct btrfs_free_space_ctl;
 #define BTRFS_MAGIC 0x4D5F53665248425FULL /* ascii _BHRfS_M, no null */
 
 /*
- * Fake signature for an unfinalized filesystem, structures might be partially
+ * Fake signature for an unfinalized filesystem, which only has barebone tree
- * created or missing.
+ * structures (normally 6 near empty trees, on SINGLE meta/sys temporary chunks)
+ *
+ * ascii !BHRfS_M, no null
  */
-#define BTRFS_MAGIC_PARTIAL 0x4D5F536652484221ULL /* ascii !BHRfS_M, no null */
+#define BTRFS_MAGIC_TEMPORARY 0x4D5F536652484221ULL
 
 #define BTRFS_MAX_MIRRORS 3
 

disk-io.c

@@ -1116,14 +1116,14 @@ static struct btrfs_fs_info *__open_ctree_fd(int fp, const char *path,
 		fs_info->ignore_chunk_tree_error = 1;
 
 	if ((flags & OPEN_CTREE_RECOVER_SUPER)
-	     && (flags & OPEN_CTREE_FS_PARTIAL)) {
+	     && (flags & OPEN_CTREE_TEMPORARY_SUPER)) {
 		fprintf(stderr,
-		    "cannot open a partially created filesystem for recovery");
+	"cannot open a filesystem with temporary super block for recovery");
 		goto out;
 	}
 
-	if (flags & OPEN_CTREE_FS_PARTIAL)
+	if (flags & OPEN_CTREE_TEMPORARY_SUPER)
-		sbflags = SBREAD_PARTIAL;
+		sbflags = SBREAD_TEMPORARY;
 
 	ret = btrfs_scan_fs_devices(fp, path, &fs_devices, sb_bytenr, sbflags,
 			(flags & OPEN_CTREE_NO_DEVICES));
@@ -1284,8 +1284,8 @@ static int check_super(struct btrfs_super_block *sb, unsigned sbflags)
 	int csum_size;
 
 	if (btrfs_super_magic(sb) != BTRFS_MAGIC) {
-		if (btrfs_super_magic(sb) == BTRFS_MAGIC_PARTIAL) {
+		if (btrfs_super_magic(sb) == BTRFS_MAGIC_TEMPORARY) {
-			if (!(sbflags & SBREAD_PARTIAL)) {
+			if (!(sbflags & SBREAD_TEMPORARY)) {
 				error("superblock magic doesn't match");
 				return -EIO;
 			}

disk-io.h

@@ -73,8 +73,12 @@ enum btrfs_open_ctree_flags {
 	 */
 	OPEN_CTREE_IGNORE_CHUNK_TREE_ERROR = (1U << 11),
 
-	/* Allow to open a partially created filesystem */
+	/*
-	OPEN_CTREE_FS_PARTIAL = (1U << 12),
+	 * Allow to open fs with temporary superblock (BTRFS_MAGIC_PARTIAL),
+	 * such fs contains very basic tree layout, just able to be opened.
+	 * Such temporary super is used for mkfs or convert.
+	 */
+	OPEN_CTREE_TEMPORARY_SUPER = (1U << 12),
 
 	/*
 	 * Invalidate the free space tree (i.e., clear the FREE_SPACE_TREE_VALID
@@ -95,7 +99,7 @@ enum btrfs_read_sb_flags {
 	 * Read superblock with the fake signature, cannot be used with
 	 * SBREAD_RECOVER
 	 */
-	SBREAD_PARTIAL		= (1 << 1),
+	SBREAD_TEMPORARY = (1 << 1),
 };
 
 /*

mkfs/common.c

@@ -189,7 +189,7 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
 
 	btrfs_set_super_bytenr(&super, cfg->blocks[MKFS_SUPER_BLOCK]);
 	btrfs_set_super_num_devices(&super, 1);
-	btrfs_set_super_magic(&super, BTRFS_MAGIC_PARTIAL);
+	btrfs_set_super_magic(&super, BTRFS_MAGIC_TEMPORARY);
 	btrfs_set_super_generation(&super, 1);
 	btrfs_set_super_root(&super, cfg->blocks[MKFS_ROOT_TREE]);
 	btrfs_set_super_chunk_root(&super, cfg->blocks[MKFS_CHUNK_TREE]);

mkfs/main.c

@@ -1099,7 +1099,7 @@ int main(int argc, char **argv)
 	}
 
 	fs_info = open_ctree_fs_info(file, 0, 0, 0,
-			OPEN_CTREE_WRITES | OPEN_CTREE_FS_PARTIAL);
+			OPEN_CTREE_WRITES | OPEN_CTREE_TEMPORARY_SUPER);
 	if (!fs_info) {
 		error("open ctree failed");
 		goto error;

utils.c

@@ -1050,7 +1050,7 @@ int btrfs_device_already_in_root(struct btrfs_root *root, int fd,
 	 * structures.
 	 */
 	if (btrfs_super_magic(disk_super) != BTRFS_MAGIC &&
-			btrfs_super_magic(disk_super) != BTRFS_MAGIC_PARTIAL)
+			btrfs_super_magic(disk_super) != BTRFS_MAGIC_TEMPORARY)
 		goto brelse;
 
 	if (!memcmp(disk_super->fsid, root->fs_info->super_copy->fsid,