Commit 08fe4db1 authored by Li Zefan's avatar Li Zefan Committed by Chris Mason
Browse files

Btrfs: Fix uninitialized root flags for subvolumes 



root_item->flags and root_item->byte_limit are not initialized when
a subvolume is created. This bug is not revealed until we added
readonly snapshot support - now you mount a btrfs filesystem and you
may find the subvolumes in it are readonly.

To work around this problem, we steal a bit from root_item->inode_item->flags,
and use it to indicate if those fields have been properly initialized.
When we read a tree root from disk, we check if the bit is set, and if
not we'll set the flag and initialize the two fields of the root item.

Reported-by: default avatarAndreas Philipp <philipp.andreas@gmail.com>
Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Tested-by: default avatarAndreas Philipp <philipp.andreas@gmail.com>
cc: stable@kernel.org
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent adae52b9

fs/btrfs/ctree.h

+4 −0
Original line number Diff line number Diff line
@@ -1284,6 +1284,8 @@ struct btrfs_root { 
#define BTRFS_INODE_DIRSYNC		(1 << 10)

#define BTRFS_INODE_COMPRESS		(1 << 11)



#define BTRFS_INODE_ROOT_ITEM_INIT	(1 << 31)



/* some macros to generate set/get funcs for the struct fields.  This

 * assumes there is a lefoo_to_cpu for every type, so lets make a simple

 * one for u8:
@@ -2359,6 +2361,8 @@ int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid); 
int btrfs_find_orphan_roots(struct btrfs_root *tree_root);

int btrfs_set_root_node(struct btrfs_root_item *item,

			struct extent_buffer *node);

void btrfs_check_and_init_root_item(struct btrfs_root_item *item);



/* dir-item.c */

int btrfs_insert_dir_item(struct btrfs_trans_handle *trans,

			  struct btrfs_root *root, const char *name,

fs/btrfs/disk-io.c

+3 −1
Original line number Diff line number Diff line
@@ -1276,8 +1276,10 @@ struct btrfs_root *btrfs_read_fs_root_no_radix(struct btrfs_root *tree_root, 
	root->commit_root = btrfs_root_node(root);

	BUG_ON(!root->node);

out:

	if (location->objectid != BTRFS_TREE_LOG_OBJECTID)

	if (location->objectid != BTRFS_TREE_LOG_OBJECTID) {

		root->ref_cows = 1;

		btrfs_check_and_init_root_item(&root->root_item);

	}



	return root;

}

fs/btrfs/ioctl.c

+4 −0
Original line number Diff line number Diff line
@@ -373,6 +373,10 @@ static noinline int create_subvol(struct btrfs_root *root, 
	inode_item->nbytes = cpu_to_le64(root->leafsize);

	inode_item->mode = cpu_to_le32(S_IFDIR | 0755);



	root_item.flags = 0;

	root_item.byte_limit = 0;

	inode_item->flags = cpu_to_le64(BTRFS_INODE_ROOT_ITEM_INIT);



	btrfs_set_root_bytenr(&root_item, leaf->start);

	btrfs_set_root_generation(&root_item, trans->transid);

	btrfs_set_root_level(&root_item, 0);

fs/btrfs/root-tree.c

+18 −0
Original line number Diff line number Diff line
@@ -473,3 +473,21 @@ again: 
	btrfs_free_path(path);

	return 0;

}



/*

 * Old btrfs forgets to init root_item->flags and root_item->byte_limit

 * for subvolumes. To work around this problem, we steal a bit from

 * root_item->inode_item->flags, and use it to indicate if those fields

 * have been properly initialized.

 */

void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)

{

	u64 inode_flags = le64_to_cpu(root_item->inode.flags);



	if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {

		inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;

		root_item->inode.flags = cpu_to_le64(inode_flags);

		root_item->flags = 0;

		root_item->byte_limit = 0;

	}

}

fs/btrfs/transaction.c

+1 −0
Original line number Diff line number Diff line
@@ -976,6 +976,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans, 
	record_root_in_trans(trans, root);

	btrfs_set_root_last_snapshot(&root->root_item, trans->transid);

	memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));

	btrfs_check_and_init_root_item(new_root_item);



	root_flags = btrfs_root_flags(new_root_item);

	if (pending->readonly)

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