Re: [PATCH v2 04/18] btrfs: move space cache settings into open_ctree

[Anand Jain <anand.jain@oracle.com>]

> @@ -3287,6 +3287,12 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
>   	fs_info->csums_per_leaf = BTRFS_MAX_ITEM_SIZE(fs_info) / fs_info->csum_size;
>   	fs_info->stripesize = stripesize;
>   
> +	/*
> +	 * Handle the space caching options appropriately now that we have the
> +	 * super loaded and validated.
> +	 */
> +	btrfs_set_free_space_cache_settings(fs_info);
> +
>   	ret = btrfs_parse_options(fs_info, options, sb->s_flags);
>   	if (ret)
>   		goto fail_alloc;
> @@ -3298,17 +3304,6 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
>   	if (sectorsize < PAGE_SIZE) {
>   		struct btrfs_subpage_info *subpage_info;
>   
> -		/*
> -		 * V1 space cache has some hardcoded PAGE_SIZE usage, and is
> -		 * going to be deprecated.
> -		 *
> -		 * Force to use v2 cache for subpage case.
> -		 */
> -		btrfs_clear_opt(fs_info->mount_opt, SPACE_CACHE);
> -		btrfs_set_and_info(fs_info, FREE_SPACE_TREE,
> -			"forcing free space tree for sector size %u with page size %lu",
> -			sectorsize, PAGE_SIZE);
> -
>   		btrfs_warn(fs_info,
>   		"read-write for sector size %u with page size %lu is experimental",
>   			   sectorsize, PAGE_SIZE);
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index 639601d346d0..aef7e67538a3 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -266,6 +266,31 @@ static bool check_options(struct btrfs_fs_info *info, unsigned long flags)
>   	return true;
>   }
>   
> +void btrfs_set_free_space_cache_settings(struct btrfs_fs_info *fs_info)
> +{
> +	if (btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
> +		btrfs_set_opt(fs_info->mount_opt, FREE_SPACE_TREE);
> +	else if (btrfs_free_space_cache_v1_active(fs_info)) {
> +		if (btrfs_is_zoned(fs_info)) {
> +			btrfs_info(fs_info,
> +			"zoned: clearing existing space cache");
> +			btrfs_set_super_cache_generation(fs_info->super_copy, 0);
> +		} else {
> +			btrfs_set_opt(fs_info->mount_opt, SPACE_CACHE);
> +		}
> +	}
> +
> +	if (fs_info->sectorsize < PAGE_SIZE) {
> +		btrfs_clear_opt(fs_info->mount_opt, SPACE_CACHE);
> +		if (!btrfs_test_opt(fs_info, FREE_SPACE_TREE)) {
> +			btrfs_info(fs_info,
> +				   "forcing free space tree for sector size %u with page size %lu",
> +				   fs_info->sectorsize, PAGE_SIZE);
> +			btrfs_set_opt(fs_info->mount_opt, FREE_SPACE_TREE);
> +		}
> +	}
> +}
> +
>   static int parse_rescue_options(struct btrfs_fs_info *info, const char *options)
>   {
>   	char *opts;
> @@ -345,18 +370,6 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
>   	bool saved_compress_force;
>   	int no_compress = 0;
>   
> -	if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE))
> -		btrfs_set_opt(info->mount_opt, FREE_SPACE_TREE);
> -	else if (btrfs_free_space_cache_v1_active(info)) {
> -		if (btrfs_is_zoned(info)) {
> -			btrfs_info(info,
> -			"zoned: clearing existing space cache");
> -			btrfs_set_super_cache_generation(info->super_copy, 0);
> -		} else {
> -			btrfs_set_opt(info->mount_opt, SPACE_CACHE);
> -		}
> -	}
> -
>   	/*
>   	 * Even the options are empty, we still need to do extra check
>   	 * against new flags


btrfs_remount() calls btrfs_parse_options(), which previously handled
space cache/tree flags set/reset. However, with the move of this
functionality to a separate function, btrfs_set_free_space_cache_settings(),
the btrfs_remount() thread no longer has the space cache/tree flags
set/reset. The changelog provides no explanation for this change.
Could this be a bug?

Thanks, Anand