On Mon, Oct 02, 2017 at 03:25:40PM +0900, Misono, Tomohiro wrote:
> This patch changes "subvol set-default" to also accept the subvolume path
> for convenience.
>
> This is the one of the issue on github:
> https://github.com/kdave/btrfs-progs/issues/35
>
> If there are two args, they are assumed as subvol id and path to the fs
> (the same as current behavior), and if there is only one arg, it is assumed
> as the path to the subvolume. Therefore there is no ambiguity between subvol
> id and subvol name, which is mentioned in the above issue page.
>
> subvol id is resolved by get_subvol_info() which is used by "subvol show".
>
> Signed-off-by: Tomohiro Misono <[email protected]>
> ---
> Documentation/btrfs-subvolume.asciidoc | 10 +++----
> cmds-subvolume.c | 48
> ++++++++++++++++++++++++++--------
> 2 files changed, 42 insertions(+), 16 deletions(-)
>
> diff --git a/Documentation/btrfs-subvolume.asciidoc
> b/Documentation/btrfs-subvolume.asciidoc
> index 5cfe885..df27460 100644
> --- a/Documentation/btrfs-subvolume.asciidoc
> +++ b/Documentation/btrfs-subvolume.asciidoc
> @@ -142,12 +142,12 @@ you can add \'\+' or \'-' in front of each items, \'+'
> means ascending,
> for --sort you can combine some items together by \',', just like
> --sort=+ogen,-gen,path,rootid.
>
> -*set-default* <id> <path>::
> -Set the subvolume of the filesystem <path> which is mounted as
> -default.
> +*set-default* [<subvolume>|<id> <path>]::
> +Set the subvolume of the filesystem which is mounted as default.
> +
> -The subvolume is identified by <id>, which is returned by the *subvolume
> list*
> -command.
> +If <id> and <path> is given, the subvolume is identified by <id>,
> +which is returned by the *subvolume list* command. The filesystem
> +is specified by <path>.
>
> *show* <path>::
> Show information of a given subvolume in the <path>.
> diff --git a/cmds-subvolume.c b/cmds-subvolume.c
> index 666f6e0..5bf8295 100644
> --- a/cmds-subvolume.c
> +++ b/cmds-subvolume.c
> @@ -803,28 +803,54 @@ out:
> }
>
> static const char * const cmd_subvol_set_default_usage[] = {
> - "btrfs subvolume set-default <subvolid> <path>",
> - "Set the default subvolume of a filesystem",
> + "btrfs subvolume set-default [<subvolume>|<subvolid> <path>]",
> + "Set the default subvolume of the filesystem mounted as default.",
> + "The subvolume can be specified by its path,",
> + "or the pair of subvolume id and path to the filesystem.",
> NULL
> };
>
> static int cmd_subvol_set_default(int argc, char **argv)
> {
> - int ret=0, fd, e;
> - u64 objectid;
> - char *path;
> - char *subvolid;
> - DIR *dirstream = NULL;
> + int ret = 0;
> + int fd, e;
> + u64 objectid;
> + char *path;
> + char *subvolid;
> + DIR *dirstream = NULL;
Please don't change unrelated code, I'll drop it from the patch.
>
> clean_args_no_options(argc, argv, cmd_subvol_set_default_usage);
>
> - if (check_argc_exact(argc - optind, 2))
> + if (check_argc_min(argc - optind, 1) ||
> + check_argc_max(argc - optind, 2))
> usage(cmd_subvol_set_default_usage);
>
> - subvolid = argv[optind];
> - path = argv[optind + 1];
> + if (argc - optind == 1) {
> + /* path to the subvolume is specified */
> + struct root_info ri;
> + char *fullpath;
>
> - objectid = arg_strtou64(subvolid);
> + path = argv[optind];
> + fullpath = realpath(path, NULL);
> + if (!fullpath) {
> + error("cannot find real path for '%s': %s",
> + path, strerror(errno));
> + return 1;
> + }
> +
> + ret = get_subvol_info(fullpath, &ri);
That's an overkill, we just need to read the subvolume id of the given
path, but get_subvol_info reads the entire subvolume list and more.
Instead, please use lookup_path_rootid + test_issubvolume and we need to
avoid the empty subvol (inode number 2).
> + free(fullpath);
> +
> + if (ret)
> + return 1;
> +
> + objectid = ri.root_id;
> + } else {
> + /* subvol id and path to the filesystem are specified */
> + subvolid = argv[optind];
> + path = argv[optind + 1];
> + objectid = arg_strtou64(subvolid);
> + }
>
> fd = btrfs_open_dir(path, &dirstream, 1);
> if (fd < 0)
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