Re: [PATCH 2/2] btrfs: add balance args info during start and resume

[Nikolay Borisov <nborisov@suse.com>]

On 26.04.2018 11:01, Anand Jain wrote:
> Balance args info is an important information to be reviewed on the
> system under audit. So this patch adds that.

Would have been good to add example output to the change log.

> 
> Signed-off-by: Anand Jain <anand.jain@oracle.com>
> ---
>  fs/btrfs/volumes.c | 153 +++++++++++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 150 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index e688c993197f..3d47b36579b3 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -138,6 +138,32 @@ const char *get_raid_name(enum btrfs_raid_types type)
>  	return btrfs_raid_array[type].raid_name;
>  }
>  
> +static void get_all_raid_names(u64 bg_flags, char *raid_types)
> +{
> +	int i;
> +	bool found = false;
> +
> +	for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
> +		if (bg_flags & btrfs_raid_array[i].bg_flag) {
> +			if (found) {
> +				strcat(raid_types, "|");
> +				strcat(raid_types, btrfs_raid_array[i].raid_name);
> +			} else {
> +				found = true;
> +				sprintf(raid_types, "%s", btrfs_raid_array[i].raid_name);
> +			}
> +		}
> +	}
> +	if (bg_flags & BTRFS_AVAIL_ALLOC_BIT_SINGLE) {
> +		if (found) {
> +			strcat(raid_types, "|");
> +			strcat(raid_types, "single");
> +		} else {
> +			sprintf(raid_types, "%s", "single");
> +		}
> +	}
> +}
> +
>  static int init_first_rw_device(struct btrfs_trans_handle *trans,
>  				struct btrfs_fs_info *fs_info);
>  static int btrfs_relocate_sys_chunks(struct btrfs_fs_info *fs_info);
> @@ -3770,6 +3796,121 @@ static inline int validate_convert_profile(struct btrfs_balance_args *bctl_arg,
>  		 (bctl_arg->target & ~allowed)));
>  }
>  
> +static void get_balance_args(struct btrfs_balance_args *bargs, char *args)
> +{
> +	char value[64];
> +
> +	if (bargs->flags & BTRFS_BALANCE_ARGS_PROFILES) {
> +		strcat(args, "profiles=");
> +		get_all_raid_names(bargs->profiles, value);
> +		strcat(args, value);
> +		strcat(args, " ");
> +	}
> +
> +	if (bargs->flags & BTRFS_BALANCE_ARGS_USAGE) {
> +		snprintf(value, 64, "usage=%llu ", bargs->usage);
> +		strcat(args, value);
+	if (bg_flags & BTRFS_AVAIL_ALLOC_BIT_SINGLE) {
+		if (found) {
> +	}
> +
> +	if (bargs->flags & BTRFS_BALANCE_ARGS_USAGE_RANGE) {
> +		snprintf(value, 64, "usage_min=%u usage_max=%u ",
> +			bargs->usage_min, bargs->usage_max);
> +		strcat(args, value);
> +	}
> +
> +	if (bargs->flags & BTRFS_BALANCE_ARGS_DEVID) {
> +		snprintf(value, 64, "devid=%llu ", bargs->devid);
> +		strcat(args, value);
> +	}
> +
> +	if (bargs->flags & BTRFS_BALANCE_ARGS_DRANGE) {
> +		snprintf(value, 64, "pstart=%llu pend=%llu ",
> +			 bargs->pstart, bargs->pend);
> +		strcat(args, value);
> +	}
> +
> +	if (bargs->flags & BTRFS_BALANCE_ARGS_VRANGE) {
> +		snprintf(value, 64, "vstart=%llu vend %llu ",
> +			 bargs->vstart, bargs->vend);
> +		strcat(args, value);
> +	}
> +
> +	if (bargs->flags & BTRFS_BALANCE_ARGS_LIMIT) {
> +		snprintf(value, 64, "limit=%llu ", bargs->limit);
> +		strcat(args, value);
> +	}
> +
> +	if (bargs->flags & BTRFS_BALANCE_ARGS_LIMIT_RANGE) {
> +		snprintf(value, 64, "limit_min=%u limit_max=%u ",
> +			 bargs->limit_min, bargs->limit_max);
> +		strcat(args, value);
> +	}
> +
> +	if (bargs->flags & BTRFS_BALANCE_ARGS_STRIPES_RANGE) {
> +		snprintf(value, 64, "stripes_min=%u stripes_max=%u ",
> +			 bargs->stripes_min, bargs->stripes_max);
> +		strcat(args, value);
> +	}
> +
> +	if (bargs->flags & BTRFS_BALANCE_ARGS_CONVERT) {
> +		int index = btrfs_bg_flags_to_raid_index(bargs->target);
> +		snprintf(value, 64, "convert=%s ",
> +			 get_raid_name(index));
> +		strcat(args, value);
> +	}
> +

Having all those ifs as independent statements means we can potentially
have each and every value present, I haven't really counted how long the
string could potentially get. Is it not possible to convert some of them
into if/else if constructs or is it indeed possible to have all of them
present at once?

> +	/* If space was the last char remove it */
> +	if (strlen(args) && (args[strlen(args) - 1] == ' '))
> +		args[strlen(args) - 1] = '\0';
> +}
> +
> +static void print_balance_start_or_resume(struct btrfs_fs_info *fs_info)
> +{
> +	struct btrfs_balance_control *bctl = fs_info->balance_ctl;
> +	int log_size = 1024;
> +	char *args;
> +
> +	args = kzalloc(log_size, GFP_KERNEL);
> +	if (!args) {
> +		btrfs_warn(fs_info, "balance: failed to log: ENOMEM");
> +		return;
> +	}
> +
> +	if (bctl->flags & BTRFS_BALANCE_ARGS_SOFT) {
> +		strcat(args, "soft ");
> +	}
> +
> +	if (bctl->flags & BTRFS_BALANCE_FORCE) {
> +		strcat(args, "force ");
> +	}
> +
> +	if (bctl->flags & BTRFS_BALANCE_DATA) {
> +		strcat(args, "data ");
> +		get_balance_args(&bctl->data, args);
> +	}
> +
> +	if (bctl->flags & BTRFS_BALANCE_METADATA) {
> +		if (strlen(args) > 0)
> +			strcat(args, " ");
> +		strcat(args, "metadata ");
> +		get_balance_args(&bctl->meta, args);
> +	}
> +
> +	if (bctl->flags & BTRFS_BALANCE_SYSTEM) {
> +		if (strlen(args) > 0)
> +			strcat(args, " ");
> +		strcat(args, "system ");
> +		get_balance_args(&bctl->sys, args);
> +	}
> +
> +	BUG_ON(strlen(args) > log_size);
> +	btrfs_info(fs_info, "%s %s",
> +		   bctl->flags & BTRFS_BALANCE_RESUME ?\
> +		   "balance: resume":"balance: start", args);
> +
> +	kfree(args);
> +}
> +
>  /*
>   * Should be called with balance mutexe held
>   */
> @@ -3910,11 +4051,19 @@ int btrfs_balance(struct btrfs_balance_control *bctl,
>  
>  	ASSERT(!test_bit(BTRFS_FS_BALANCE_RUNNING, &fs_info->flags));
>  	set_bit(BTRFS_FS_BALANCE_RUNNING, &fs_info->flags);
> +	print_balance_start_or_resume(fs_info);
>  	mutex_unlock(&fs_info->balance_mutex);
>  
>  	ret = __btrfs_balance(fs_info);
>  
>  	mutex_lock(&fs_info->balance_mutex);
> +	if (ret == -ECANCELED && atomic_read(&fs_info->balance_pause_req))
> +		btrfs_info(fs_info, "balance: paused");
> +	else if (ret == -ECANCELED && atomic_read(&fs_info->balance_cancel_req))
> +		btrfs_info(fs_info, "balance: canceled");
> +	else
> +		btrfs_info(fs_info, "balance: ended with status: %d", ret);
> +

Unrelated change

>  	clear_bit(BTRFS_FS_BALANCE_RUNNING, &fs_info->flags);
>  
>  	if (bargs) {
> @@ -3947,10 +4096,8 @@ static int balance_kthread(void *data)
>  	int ret = 0;
>  
>  	mutex_lock(&fs_info->balance_mutex);
> -	if (fs_info->balance_ctl) {
> -		btrfs_info(fs_info, "balance: resuming");
> +	if (fs_info->balance_ctl)
>  		ret = btrfs_balance(fs_info->balance_ctl, NULL);
> -	}
Unrelated change.

>  	mutex_unlock(&fs_info->balance_mutex);
>  
>  	return ret;
>