Re: [PATCH 13/19] btrfs: qgroup: Drop fs_info parameter from btrfs_qgroup_trace_extent

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

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On 2018年07月18日 14:45, Lu Fengqi wrote:
> It can be fetched from the transaction handle.
> 
> Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
> ---
>  fs/btrfs/qgroup.c   | 13 ++++++-------
>  fs/btrfs/qgroup.h   |  5 ++---
>  fs/btrfs/tree-log.c |  2 +-
>  3 files changed, 9 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
> index c85c1a0e933a..01add73cb2aa 100644
> --- a/fs/btrfs/qgroup.c
> +++ b/fs/btrfs/qgroup.c
> @@ -1579,10 +1579,10 @@ int btrfs_qgroup_trace_extent_post(struct btrfs_fs_info *fs_info,
>  	return 0;
>  }
>  
> -int btrfs_qgroup_trace_extent(struct btrfs_trans_handle *trans,
> -		struct btrfs_fs_info *fs_info, u64 bytenr, u64 num_bytes,
> -		gfp_t gfp_flag)
> +int btrfs_qgroup_trace_extent(struct btrfs_trans_handle *trans, u64 bytenr,
> +			      u64 num_bytes, gfp_t gfp_flag)
>  {
> +	struct btrfs_fs_info *fs_info = trans->fs_info;

Just lines below, we do extra WARN_ON(trans == NULL).
So if we really hit some case with NULL trans, this would cause a NULL
pointer dereference.

Although I have to admit, I'm a little paranoid about possible NULL
trans passed in.
So maybe it's a good timing to remove that WARN_ON() too?

Thanks,
Qu

>  	struct btrfs_qgroup_extent_record *record;
>  	struct btrfs_delayed_ref_root *delayed_refs;
>  	int ret;
> @@ -1644,8 +1644,8 @@ int btrfs_qgroup_trace_leaf_items(struct btrfs_trans_handle *trans,
>  
>  		num_bytes = btrfs_file_extent_disk_num_bytes(eb, fi);
>  
> -		ret = btrfs_qgroup_trace_extent(trans, fs_info, bytenr,
> -						num_bytes, GFP_NOFS);
> +		ret = btrfs_qgroup_trace_extent(trans, bytenr, num_bytes,
> +						GFP_NOFS);
>  		if (ret)
>  			return ret;
>  	}
> @@ -1796,8 +1796,7 @@ int btrfs_qgroup_trace_subtree(struct btrfs_trans_handle *trans,
>  			btrfs_set_lock_blocking_rw(eb, BTRFS_READ_LOCK);
>  			path->locks[level] = BTRFS_READ_LOCK_BLOCKING;
>  
> -			ret = btrfs_qgroup_trace_extent(trans, fs_info,
> -							child_bytenr,
> +			ret = btrfs_qgroup_trace_extent(trans, child_bytenr,
>  							fs_info->nodesize,
>  							GFP_NOFS);
>  			if (ret)
> diff --git a/fs/btrfs/qgroup.h b/fs/btrfs/qgroup.h
> index 385367989ed6..0215dc0b1710 100644
> --- a/fs/btrfs/qgroup.h
> +++ b/fs/btrfs/qgroup.h
> @@ -212,9 +212,8 @@ int btrfs_qgroup_trace_extent_post(struct btrfs_fs_info *fs_info,
>   * Return <0 for error, like memory allocation failure or invalid parameter
>   * (NULL trans)
>   */
> -int btrfs_qgroup_trace_extent(struct btrfs_trans_handle *trans,
> -		struct btrfs_fs_info *fs_info, u64 bytenr, u64 num_bytes,
> -		gfp_t gfp_flag);
> +int btrfs_qgroup_trace_extent(struct btrfs_trans_handle *trans, u64 bytenr,
> +			      u64 num_bytes, gfp_t gfp_flag);
>  
>  /*
>   * Inform qgroup to trace all leaf items of data
> diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
> index 7b7498f1f641..10f6a4223897 100644
> --- a/fs/btrfs/tree-log.c
> +++ b/fs/btrfs/tree-log.c
> @@ -685,7 +685,7 @@ static noinline int replay_one_extent(struct btrfs_trans_handle *trans,
>  		 * as the owner of the file extent changed from log tree
>  		 * (doesn't affect qgroup) to fs/file tree(affects qgroup)
>  		 */
> -		ret = btrfs_qgroup_trace_extent(trans, fs_info,
> +		ret = btrfs_qgroup_trace_extent(trans,
>  				btrfs_file_extent_disk_bytenr(eb, item),
>  				btrfs_file_extent_disk_num_bytes(eb, item),
>  				GFP_NOFS);
> 


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