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Subject: Re: [PATCH v2 26/27] btrfs-progs: use libbtrfsutil for subvolume list
To: Omar Sandoval <osandov@osandov.com>, <linux-btrfs@vger.kernel.org>
CC: <kernel-team@fb.com>
References: <cover.1518720598.git.osandov@fb.com>
 <6492726d6e89bf792627e4431f7ba7691f09c3d2.1518720598.git.osandov@fb.com>
From: "Misono, Tomohiro" <misono.tomohiro@jp.fujitsu.com>
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Date: Fri, 23 Feb 2018 11:26:35 +0900
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On 2018/02/16 4:05, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>

> +static struct subvol_list *btrfs_list_deleted_subvols(int fd,
> +						      struct btrfs_list_filter_set *filter_set)
> +{
> +	struct subvol_list *subvols = NULL;
> +	uint64_t *ids = NULL;
> +	size_t i, n;
> +	enum btrfs_util_error err;
> +	int ret = -1;
> +
> +	err = btrfs_util_deleted_subvolumes_fd(fd, &ids, &n);
> +	if (err) {
> +		error_btrfs_util(err);
> +		return NULL;
> +	}
> +
> +	subvols = malloc(sizeof(*subvols) + n * sizeof(subvols->subvols[0]));
> +	if (!subvols) {
> +		error("out of memory");
> +		goto out;
> +	}
> +
> +	subvols->num = 0;
> +	for (i = 0; i < n; i++) {
> +		struct listed_subvol *subvol = &subvols->subvols[subvols->num];
> +
> +		err = btrfs_util_subvolume_info_fd(fd, ids[i], &subvol->info);
> +		if (err) {

I think there is a small chance that subvolume would be removed from tree between 
btrfs_util_deleted_subvolumes_fd() and btrfs_util_subvolume_info_fd().
So, error of BTRFS_UTIL_ERROR_SUBVOLUME_NOT_FOUND should be ignored.

> +			error_btrfs_util(err);
> +			goto out;
> +		}
> +
> +		subvol->path = strdup("DELETED");
> +		if (!subvol->path)
> +			goto out;
> +
> +		if (!filters_match(subvol, filter_set)) {
> +			free(subvol->path);
> +			continue;
> +		}
> +
> +		subvols->num++;
> +	}
> +
> +	ret = 0;
> +out:
> +	if (ret) {
> +		free_subvol_list(subvols);
> +		subvols = NULL;
> +		free(ids);
> +	}
> +	return subvols;
> +}