Re: [PATCH] Btrfs: return failure if btrfs_dev_replace_finishing() failed

[Eryu Guan <guaneryu@gmail.com>]

On Thu, Sep 25, 2014 at 06:28:14PM +0800, Eryu Guan wrote:
> device replace could fail due to another running scrub process, but this
> failure doesn't get returned to userspace.
> 
> The following steps could reproduce this issue
> 
> 	mkfs -t btrfs -f /dev/sdb1 /dev/sdb2
> 	mount /dev/sdb1 /mnt/btrfs
> 	while true; do
> 		btrfs scrub start -B /mnt/btrfs >/dev/null 2>&1
> 	done &
> 	btrfs replace start -Bf /dev/sdb2 /dev/sdb3 /mnt/btrfs
> 	# if this replace succeeded, do the following and repeat until
> 	# you see this log in dmesg
> 	# BTRFS: btrfs_scrub_dev(/dev/sdb2, 2, /dev/sdb3) failed -115
> 	#btrfs replace start -Bf /dev/sdb3 /dev/sdb2 /mnt/btrfs
> 
> 	# once you see the error log in dmesg, check return value of
> 	# replace
> 	echo $?
> 
> Also only WARN_ON if the return code is not -EINPROGRESS.
> 
> Signed-off-by: Eryu Guan <guaneryu@gmail.com>

Ping, any comments on this patch?

Thanks,
Eryu
> ---
>  fs/btrfs/dev-replace.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
> index eea26e1..44d32ab 100644
> --- a/fs/btrfs/dev-replace.c
> +++ b/fs/btrfs/dev-replace.c
> @@ -418,9 +418,11 @@ int btrfs_dev_replace_start(struct btrfs_root *root,
>  			      &dev_replace->scrub_progress, 0, 1);
>  
>  	ret = btrfs_dev_replace_finishing(root->fs_info, ret);
> -	WARN_ON(ret);
> +	/* don't warn if EINPROGRESS, someone else might be running scrub */
> +	if (ret != -EINPROGRESS)
> +		WARN_ON(ret);
>  
> -	return 0;
> +	return ret;
>  
>  leave:
>  	dev_replace->srcdev = NULL;
> @@ -538,7 +540,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
>  			btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
>  		mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
>  
> -		return 0;
> +		return scrub_ret;
>  	}
>  
>  	printk_in_rcu(KERN_INFO
> -- 
> 1.8.3.1
>