Re: [PATCH 3/3] btrfs-progs: Add command to check if balance op is req

[Qu Wenruo <quwenruo@cn.fujitsu.com>]

At 10/18/2016 08:35 AM, Divya Indi wrote:
> Add new subcommand to btrfs inspect-internal
>
> btrfs inspect-internal balance_check <path>
> Checks whether 'btrfs balance' can help creating more space (Only
> considers data block groups).

I didn't think it's good to add a new subcommand just for that.

Why not output such relocation sugguestion for you previous bg-analyze 
subcommand?
(It's better to make it a parameter to trigger such output)

Thanks,
Qu
>
> Signed-off-by: Divya Indi <divya.indi@oracle.com>
> Reviewed-by: Ashish Samant <ashish.samant@oracle.com>
> Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
> ---
>  cmds-inspect.c |  147 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 147 insertions(+), 0 deletions(-)
>
> diff --git a/cmds-inspect.c b/cmds-inspect.c
> index 0e2f15a..5baaa49 100644
> --- a/cmds-inspect.c
> +++ b/cmds-inspect.c
> @@ -267,6 +267,151 @@ static const char * const cmd_inspect_inode_resolve_usage[] = {
>  	NULL
>  };
>
> +static const char * const cmd_inspect_balance_check_usage[] = {
> +	"btrfs inspect-internal balance_check <path>",
> +	"To check whether 'btrfs balance' can help creating more space",
> +	"",
> +	"",
> +	NULL
> +};
> +
> +static int cmd_inspect_balance_check(int argc, char **argv)
> +{
> +	struct btrfs_ioctl_search_args args;
> +	struct btrfs_ioctl_search_args bg_args;
> +	struct btrfs_ioctl_search_key *sk;
> +	struct btrfs_ioctl_search_key *bg_sk;
> +	struct btrfs_ioctl_search_header *header;
> +	struct btrfs_ioctl_search_header *bg_header;
> +	struct btrfs_block_group_item *bg;
> +	struct btrfs_chunk *chunk;
> +	unsigned long off = 0;
> +	unsigned long bg_off = 0;
> +	DIR *dirstream = NULL;
> +	int fd;
> +	int i;
> +	u64 total_free = 0;
> +	u64 min_used = (u64)-1;
> +	u64 free_of_min_used = 0;
> +	u64 bg_of_min_used = 0;
> +	u64 flags;
> +	u64 used;
> +	int ret = 0;
> +	int nr_data_bgs = 0;
> +
> +	if (check_argc_exact(argc, 2))
> +		usage(cmd_inspect_balance_check_usage);
> +
> +	fd = btrfs_open_dir(argv[optind], &dirstream, 1);
> +	if (fd < 0)
> +		return 1;
> +
> +	memset(&args, 0, sizeof(args));
> +	sk = &args.key;
> +	sk->min_offset = sk->min_transid = 0;
> +	sk->max_offset = sk->max_transid = (u64)-1;
> +
> +	printf("%20s%20s%20s\n", "Start", "Len", "Used");
> +	while (1) {
> +		ret = get_chunks(fd, &args);
> +		if (ret < 0)
> +			goto out;
> +
> +		/*
> +		 * it should not happen.
> +		 */
> +		if (sk->nr_items == 0)
> +			break;
> +
> +		off = 0;
> +		memset(&bg_args, 0, sizeof(bg_args));
> +		bg_sk = &bg_args.key;
> +
> +		/* For every chunk, look up 1 exact match for block group in
> +		 * the extent tree. */
> +		bg_sk->tree_id = BTRFS_EXTENT_TREE_OBJECTID;
> +		bg_sk->min_type = BTRFS_BLOCK_GROUP_ITEM_KEY;
> +		bg_sk->max_type = BTRFS_BLOCK_GROUP_ITEM_KEY;
> +		bg_sk->min_transid =  0;
> +		bg_sk->max_transid = (u64)-1;
> +
> +		for (i = 0; i < sk->nr_items; i++) {
> +			header = (struct btrfs_ioctl_search_header *)(args.buf
> +								      + off);
> +			off += sizeof(*header);
> +			if (header->type == BTRFS_CHUNK_ITEM_KEY) {
> +				chunk = (struct btrfs_chunk *)
> +					(args.buf + off);
> +				ret = get_bg_info(fd, &bg_args, header->offset,
> +						  chunk->length);
> +				if (ret < 0)
> +					goto out;
> +
> +				/*
> +				 * it should not happen.
> +				 */
> +				if (bg_sk->nr_items == 0)
> +					continue;
> +
> +				bg_off = 0;
> +				bg_header = (struct btrfs_ioctl_search_header *)
> +					    (bg_args.buf + bg_off);
> +				bg_off += sizeof(*bg_header);
> +				bg = (struct btrfs_block_group_item *)
> +				     (bg_args.buf + bg_off);
> +
> +				flags = btrfs_block_group_flags(bg);
> +				if (flags & BTRFS_BLOCK_GROUP_DATA) {
> +					used = btrfs_block_group_used(bg);
> +					nr_data_bgs++;
> +					printf("%20llu%20s%20s\n",
> +						bg_header->objectid,
> +						pretty_size(bg_header->offset),
> +						pretty_size(used));
> +					total_free += bg_header->offset - used;
> +					if (min_used >= used) {
> +						min_used = used;
> +						free_of_min_used =
> +							bg_header->offset - used;
> +						bg_of_min_used =
> +							bg_header->objectid;
> +					}
> +				}
> +			}
> +
> +			off += header->len;
> +			sk->min_offset = header->offset + header->len;
> +		}
> +		sk->nr_items = 4096;
> +
> +	}
> +
> +	if (nr_data_bgs <= 1) {
> +		printf("Data block groups in fs = %d, no need to do balance.\n",
> +				nr_data_bgs);
> +		ret = 1;
> +		goto out;
> +	}
> +
> +	printf("Total data bgs: %d\nTotal free space: %s\n"
> +	       "For min used bg %llu used = %s free = %s\n",
> +		nr_data_bgs, pretty_size(total_free), bg_of_min_used,
> +		pretty_size(min_used), pretty_size(free_of_min_used));
> +
> +	if (total_free - free_of_min_used > min_used) {
> +		printf("run 'btrfs balance start -dvrange=%llu..%llu <mountpoint>'\n",
> +				bg_of_min_used, bg_of_min_used + 1);
> +		ret = 0;
> +	} else {
> +		printf("Please don't balance data block groups, no free space\n");
> +		ret = 1;
> +	}
> +
> +out:
> +	close_file_or_dir(fd, dirstream);
> +	return ret;
> +}
> +
>  static int cmd_inspect_inode_resolve(int argc, char **argv)
>  {
>  	int fd;
> @@ -816,6 +961,8 @@ const struct cmd_group inspect_cmd_group = {
>  			cmd_inspect_min_dev_size_usage, NULL, 0 },
>  		{ "bg_analysis", cmd_inspect_bg_analysis,
>  			cmd_inspect_bg_analysis_usage, NULL, 0 },
> +		{ "balance_check", cmd_inspect_balance_check,
> +			cmd_inspect_balance_check_usage, NULL, 0 },
>  		{ "dump-tree", cmd_inspect_dump_tree,
>  				cmd_inspect_dump_tree_usage, NULL, 0 },
>  		{ "dump-super", cmd_inspect_dump_super,
>