Re: [PATCH v3] btrfs-progs: add --subvol option to mkfs.btrfs

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

在 2024/7/30 23:51, Mark Harmstone 写道:
> This patch adds a --subvol option, which tells mkfs.btrfs to create the
> specified directories as subvolumes.
>
> Given a populated directory img, the command
>
> $ mkfs.btrfs --rootdir img --subvol img/usr --subvol img/home --subvol img/home/username /dev/loop0
>
> will create subvolumes usr and home within the FS root, and subvolume
> username within the home subvolume. It will fail if any of the
> directories do not yet exist.
>
> Signed-off-by: Mark Harmstone <maharmstone@fb.com>
[...]
> @@ -570,6 +626,76 @@ static int traverse_directory(struct btrfs_trans_handle *trans,
>   				pr_verbose(LOG_INFO, "ADD: %s\n", tmp);
>   			}
>
> +			if (S_ISDIR(st.st_mode)) {
> +				if (!strcmp(parent_dir_entry->dest_dir, "")) {
> +					strcpy(cur_dest, cur_file->d_name);
> +				} else {
> +					strcpy(cur_dest, parent_dir_entry->dest_dir);
> +					strcat(cur_dest, "/");
> +					strcat(cur_dest, cur_file->d_name);
> +				}
> +			}
> +
> +			if (!list_empty(subvols) && S_ISDIR(st.st_mode)) {
> +				struct rootdir_subvol *s;
> +				bool found = false;
> +
> +				list_for_each_entry(s, subvols, list) {
> +					if (!strcmp(cur_dest, s->destpath)) {
> +						found = true;
> +						break;
> +					}
> +				}
> +
> +				if (found) {

Although I'm still not a fan of merging subvolume creation now, before
we refactor the existing way of adding/linking new inodes, at least the
code style can be improved.

Under most case we prefer to reduce the indent by exiting early for
non-hit cases.

In this case, we prefer something like :

				if (!found)
					continue;
				/* do the subvolume add/link here */

Thanks,
Qu