Re: [PATCH] btrfs: make block group flags in balance printks human-readable

["Holger Hoffstätte" <holger@applied-asynchrony.com>]

On 11/04/16 08:26, Adam Borowski wrote:
> They're not even documented anywhere, letting users with no recourse but
> to RTFS.  It's no big burden to output the bitfield as words.
> 
> Also, display unknown flags as hex.
> 
> Signed-off-by: Adam Borowski <kilobyte@angband.pl>

Very helpful and works (for me) as advertised.

Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>

> ---
>  fs/btrfs/relocation.c | 34 ++++++++++++++++++++++++++++++++--
>  1 file changed, 32 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> index 0ec8ffa..388216f 100644
> --- a/fs/btrfs/relocation.c
> +++ b/fs/btrfs/relocation.c
> @@ -4326,6 +4326,34 @@ static struct reloc_control *alloc_reloc_control(struct btrfs_fs_info *fs_info)
>  }
>  
>  /*
> + * explain bit flags, prefixed by a '|' that'll be dropped
> + */
> +static void describe_block_group_flags(char *buf, u64 flags)
> +{
> +	if (!flags)
> +		*buf += sprintf(buf, "|NONE");
> +	else {
> +#define DESCRIBE_FLAG(f, d) \
> +			if (flags & BTRFS_BLOCK_GROUP_##f) { \
> +				buf += sprintf(buf, "|%s", d); \
> +				flags &= ~BTRFS_BLOCK_GROUP_##f; \
> +			}
> +		DESCRIBE_FLAG(DATA,     "data");
> +		DESCRIBE_FLAG(SYSTEM,   "system");
> +		DESCRIBE_FLAG(METADATA, "metadata");
> +		DESCRIBE_FLAG(RAID0,    "raid0");
> +		DESCRIBE_FLAG(RAID1,    "raid1");
> +		DESCRIBE_FLAG(DUP,      "dup");
> +		DESCRIBE_FLAG(RAID10,   "raid10");
> +		DESCRIBE_FLAG(RAID5,    "raid5");
> +		DESCRIBE_FLAG(RAID6,    "raid6");
> +		if (flags)
> +			buf += sprintf(buf, "|0x%llx", flags);
> +	}
> +	*buf = 0;
> +}
> +
> +/*
>   * function to relocate all extents in a block group.
>   */
>  int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
> @@ -4337,6 +4365,7 @@ int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
>  	int ret;
>  	int rw = 0;
>  	int err = 0;
> +	char flags_str[128];
>  
>  	rc = alloc_reloc_control(fs_info);
>  	if (!rc)
> @@ -4381,9 +4410,10 @@ int btrfs_relocate_block_group(struct btrfs_root *extent_root, u64 group_start)
>  		goto out;
>  	}
>  
> +	describe_block_group_flags(flags_str, rc->block_group->flags);
>  	btrfs_info(extent_root->fs_info,
> -		   "relocating block group %llu flags %llu",
> -		   rc->block_group->key.objectid, rc->block_group->flags);
> +		   "relocating block group %llu flags %s",
> +		   rc->block_group->key.objectid, flags_str+1);
>  
>  	btrfs_wait_block_group_reservations(rc->block_group);
>  	btrfs_wait_nocow_writers(rc->block_group);
>