Re: [PATCH v2 2/3] ocfs2: detect released suballocator bg for fh_to_[dentry|parent]

[Joseph Qi <joseph.qi@linux.alibaba.com>]

On 7/29/24 4:04 PM, Heming Zhao wrote:
> After ocfs2 has the ability to reclaim suballoc free bg, the
> suballocator block group may be released. This change makes xfstest
> case 426 failed.
> 
> The existed code call stack:
> 
> ocfs2_fh_to_dentry //or ocfs2_fh_to_parent
>  ocfs2_get_dentry
>   ocfs2_test_inode_bit
>    ocfs2_test_suballoc_bit
>     ocfs2_read_group_descriptor
>      + read released bg, triggers validate fails, then cause -EROFS
> 
> how to fix:
> The read bg failure is expectation, we should ignore this error.
> 
> Signed-off-by: Heming Zhao <heming.zhao@suse.com>
> ---
>  fs/ocfs2/suballoc.c | 27 ++++++++++++++++++---------
>  1 file changed, 18 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
> index 1b64f4c87607..dc421f55ed8f 100644
> --- a/fs/ocfs2/suballoc.c
> +++ b/fs/ocfs2/suballoc.c
> @@ -3037,7 +3037,7 @@ static int ocfs2_test_suballoc_bit(struct ocfs2_super *osb,
>  	struct ocfs2_group_desc *group;
>  	struct buffer_head *group_bh = NULL;
>  	u64 bg_blkno;
> -	int status;
> +	int status, quiet = 0;
>  
>  	trace_ocfs2_test_suballoc_bit((unsigned long long)blkno,
>  				      (unsigned int)bit);
> @@ -3053,11 +3053,16 @@ static int ocfs2_test_suballoc_bit(struct ocfs2_super *osb,
>  
>  	bg_blkno = group_blkno ? group_blkno :
>  		   ocfs2_which_suballoc_group(blkno, bit);
> -	status = ocfs2_read_group_descriptor(suballoc, alloc_di, bg_blkno,
> +	status = ocfs2_read_hint_group_descriptor(suballoc, alloc_di, bg_blkno,
>  					     &group_bh);
>  	if (status < 0) {
> -		mlog(ML_ERROR, "read group %llu failed %d\n",
> -		     (unsigned long long)bg_blkno, status);
> +		if (status == -EIDRM) {

I don't think EIDRM is a proper error code in this case.
We can pass a output parameter or a flag to indicate a released one.
And please explicitly specify that this can be treated normally in
the related code logic of ocfs2_read_hint_group_descriptor().

Thanks,
Joseph

> +			quiet = 1;
> +			status = -EINVAL;
> +		} else {
> +			mlog(ML_ERROR, "read group %llu failed %d\n",
> +					(unsigned long long)bg_blkno, status);
> +		}
>  		goto bail;
>  	}
>  
> @@ -3067,7 +3072,7 @@ static int ocfs2_test_suballoc_bit(struct ocfs2_super *osb,
>  bail:
>  	brelse(group_bh);
>  
> -	if (status)
> +	if (status && (!quiet))
>  		mlog_errno(status);
>  	return status;
>  }
> @@ -3087,7 +3092,7 @@ static int ocfs2_test_suballoc_bit(struct ocfs2_super *osb,
>   */
>  int ocfs2_test_inode_bit(struct ocfs2_super *osb, u64 blkno, int *res)
>  {
> -	int status;
> +	int status, quiet = 0;
>  	u64 group_blkno = 0;
>  	u16 suballoc_bit = 0, suballoc_slot = 0;
>  	struct inode *inode_alloc_inode;
> @@ -3129,8 +3134,12 @@ int ocfs2_test_inode_bit(struct ocfs2_super *osb, u64 blkno, int *res)
>  
>  	status = ocfs2_test_suballoc_bit(osb, inode_alloc_inode, alloc_bh,
>  					 group_blkno, blkno, suballoc_bit, res);
> -	if (status < 0)
> -		mlog(ML_ERROR, "test suballoc bit failed %d\n", status);
> +	if (status < 0) {
> +		if (status == -EINVAL)
> +			quiet = 1;
> +		else
> +			mlog(ML_ERROR, "test suballoc bit failed %d\n", status);
> +	}
>  
>  	ocfs2_inode_unlock(inode_alloc_inode, 0);
>  	inode_unlock(inode_alloc_inode);
> @@ -3138,7 +3147,7 @@ int ocfs2_test_inode_bit(struct ocfs2_super *osb, u64 blkno, int *res)
>  	iput(inode_alloc_inode);
>  	brelse(alloc_bh);
>  bail:
> -	if (status)
> +	if (status && !quiet)
>  		mlog_errno(status);
>  	return status;
>  }