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Date:   Mon, 24 Jul 2023 08:06:50 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Naohiro Aota <naohiro.aota@wdc.com>
Cc:     linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 4/8] btrfs: zoned: reserve zones for an active
 metadata/system block group
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> +static int reserved_zones(struct btrfs_fs_info *fs_info)
> +{
> +	const u64 flags[] = {BTRFS_BLOCK_GROUP_METADATA, BTRFS_BLOCK_GROUP_SYSTEM};
> +	int reserved = 0;
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(flags); i++) {
> +		u64 profile = btrfs_get_alloc_profile(fs_info, flags[i]);
> +
> +		switch (profile) {
> +		case 0: /* single */
> +			reserved += 1;
> +			break;
> +		case BTRFS_BLOCK_GROUP_DUP:
> +			reserved += 2;
> +			break;
> +		default:
> +			ASSERT(0);
> +			break;
> +		}
> +	}
> +
> +	return reserved;
> +}

Shouldn't we just store the number of reserved zones in fs_info instead
of recalculating this over and over?