Commit 848cce0d authored by Li Zefan's avatar Li Zefan Committed by David Sterba
Browse files

Btrfs: avoid setting ->d_op twice 



Follow those instructions, and you'll trigger a warning in the
beginning of d_set_d_op():

  # mkfs.btrfs /dev/loop3
  # mount /dev/loop3 /mnt
  # btrfs sub create /mnt/sub
  # btrfs sub snap /mnt /mnt/snap
  # touch /mnt/snap/sub
  touch: cannot touch `tmp': Permission denied

__d_alloc() set d_op to sb->s_d_op (btrfs_dentry_operations), and
then simple_lookup() reset it to simple_dentry_operations, which
triggered the warning.

Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
parent d53ba474

fs/btrfs/inode.c

+9 −5
Original line number Diff line number Diff line
@@ -4069,7 +4069,7 @@ static struct inode *new_simple_dir(struct super_block *s, 
	BTRFS_I(inode)->dummy_inode = 1;



	inode->i_ino = BTRFS_EMPTY_SUBVOL_DIR_OBJECTID;

	inode->i_op = &simple_dir_inode_operations;

	inode->i_op = &btrfs_dir_ro_inode_operations;

	inode->i_fop = &simple_dir_operations;

	inode->i_mode = S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO;

	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
@@ -4140,14 +4140,18 @@ struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry) 
static int btrfs_dentry_delete(const struct dentry *dentry)

{

	struct btrfs_root *root;

	struct inode *inode = dentry->d_inode;



	if (!dentry->d_inode && !IS_ROOT(dentry))

		dentry = dentry->d_parent;

	if (!inode && !IS_ROOT(dentry))

		inode = dentry->d_parent->d_inode;



	if (dentry->d_inode) {

		root = BTRFS_I(dentry->d_inode)->root;

	if (inode) {

		root = BTRFS_I(inode)->root;

		if (btrfs_root_refs(&root->root_item) == 0)

			return 1;



		if (btrfs_ino(inode) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)

			return 1;

	}

	return 0;

}

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