[fdmanana:misc-next 36/71] fs/btrfs/sysfs.c:811 btrfs_force_chunk_alloc_store() warn: passing zero to 'PTR_ERR'

[Dan Carpenter]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/fdmanana/linux.git misc-next
head:   e2a46f3f73fd5aac0241242d535905286a947113
commit: 46e1bce0ac340396474e5f604c2acb6644175854 [36/71] btrfs: sysfs: add force_chunk_alloc trigger to force allocation
config: m68k-randconfig-m031-20220608 (https://download.01.org/0day-ci/archive/20220610/202206101159.fXYW8bYv-lkp@xxxxxxxxx/config)
compiler: m68k-linux-gcc (GCC) 11.3.0

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

smatch warnings:
fs/btrfs/sysfs.c:811 btrfs_force_chunk_alloc_store() warn: passing zero to 'PTR_ERR'

vim +/PTR_ERR +811 fs/btrfs/sysfs.c

46e1bce0ac3403 Stefan Roesch 2022-02-08  782  static ssize_t btrfs_force_chunk_alloc_store(struct kobject *kobj,
46e1bce0ac3403 Stefan Roesch 2022-02-08  783  					     struct kobj_attribute *a,
46e1bce0ac3403 Stefan Roesch 2022-02-08  784  					     const char *buf, size_t len)
46e1bce0ac3403 Stefan Roesch 2022-02-08  785  {
46e1bce0ac3403 Stefan Roesch 2022-02-08  786  	struct btrfs_space_info *space_info = to_space_info(kobj);
46e1bce0ac3403 Stefan Roesch 2022-02-08  787  	struct btrfs_fs_info *fs_info = to_fs_info(get_btrfs_kobj(kobj));
46e1bce0ac3403 Stefan Roesch 2022-02-08  788  	struct btrfs_trans_handle *trans;
46e1bce0ac3403 Stefan Roesch 2022-02-08  789  	bool val;
46e1bce0ac3403 Stefan Roesch 2022-02-08  790  	int ret;
46e1bce0ac3403 Stefan Roesch 2022-02-08  791  
46e1bce0ac3403 Stefan Roesch 2022-02-08  792  	if (!capable(CAP_SYS_ADMIN))
46e1bce0ac3403 Stefan Roesch 2022-02-08  793  		return -EPERM;
46e1bce0ac3403 Stefan Roesch 2022-02-08  794  
46e1bce0ac3403 Stefan Roesch 2022-02-08  795  	if (sb_rdonly(fs_info->sb))
46e1bce0ac3403 Stefan Roesch 2022-02-08  796  		return -EROFS;
46e1bce0ac3403 Stefan Roesch 2022-02-08  797  
46e1bce0ac3403 Stefan Roesch 2022-02-08  798  	ret = kstrtobool(buf, &val);
46e1bce0ac3403 Stefan Roesch 2022-02-08  799  	if (ret)
46e1bce0ac3403 Stefan Roesch 2022-02-08  800  		return ret;
46e1bce0ac3403 Stefan Roesch 2022-02-08  801  
46e1bce0ac3403 Stefan Roesch 2022-02-08  802  	if (!val)
46e1bce0ac3403 Stefan Roesch 2022-02-08  803  		return -EINVAL;
46e1bce0ac3403 Stefan Roesch 2022-02-08  804  
46e1bce0ac3403 Stefan Roesch 2022-02-08  805  	/*
46e1bce0ac3403 Stefan Roesch 2022-02-08  806  	 * This is unsafe to be called from sysfs context and may cause
46e1bce0ac3403 Stefan Roesch 2022-02-08  807  	 * unexpected problems.
46e1bce0ac3403 Stefan Roesch 2022-02-08  808  	 */
46e1bce0ac3403 Stefan Roesch 2022-02-08  809  	trans = btrfs_start_transaction(fs_info->tree_root, 0);
46e1bce0ac3403 Stefan Roesch 2022-02-08  810  	if (!trans)
46e1bce0ac3403 Stefan Roesch 2022-02-08 @811  		return PTR_ERR(trans);

PTR_ERR(NULL) means success.

46e1bce0ac3403 Stefan Roesch 2022-02-08  812  	ret = btrfs_force_chunk_alloc(trans, space_info->flags);
46e1bce0ac3403 Stefan Roesch 2022-02-08  813  	btrfs_end_transaction(trans);
46e1bce0ac3403 Stefan Roesch 2022-02-08  814  
46e1bce0ac3403 Stefan Roesch 2022-02-08  815  	if (ret == 1)
46e1bce0ac3403 Stefan Roesch 2022-02-08  816  		return len;
46e1bce0ac3403 Stefan Roesch 2022-02-08  817  
46e1bce0ac3403 Stefan Roesch 2022-02-08  818  	return -ENOSPC;
46e1bce0ac3403 Stefan Roesch 2022-02-08  819  }

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