On Wed, Jul 12, 2017 at 03:20:50PM +0800, Anand Jain wrote:
> Unless the top level is mounted there is no way to know the
> details of all the subvolume. For example:
>
> mount -o subvol=sv1/newsv1 /dev/sdb /btrfs
>
> btrfs su list /btrfs
> ID 257 gen 12 top level 5 path sv1
> ID 258 gen 9 top level 257 path sv1/snap
> ID 259 gen 11 top level 257 path sv1/newsv1
>
> You can't subvol show for sv1 and sv1/snap as its paths aren't
> accessible to the user unless the its top level is mounted.
>
> This patch adds two new options to the existing btrfs subvol show
> cli. They are --rootid/-r or --uuid/-u, with this now the user will
> be able to look for a subvolume using the rootid OR the uuid.
Sounds good.
> ./btrfs su show -r 257 /btrfs
> sv1
> Name: sv1
> UUID: 30129358-c69d-3e4a-a662-29509cc69c95
> Parent UUID: -
> Received UUID: -
> Creation time: 2017-07-11 20:32:57 +0800
> Subvolume ID: 257
> Generation: 12
> Gen at creation: 7
> Parent ID: 5
> Top level ID: 5
> Flags: -
> Snapshot(s):
> sv1/snap
>
> Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
> ---
> btrfs-list.c | 4 +++-
> cmds-subvolume.c | 44 +++++++++++++++++++++++++++++++++++++++++---
> utils.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> utils.h | 5 ++++-
> 4 files changed, 100 insertions(+), 5 deletions(-)
>
> diff --git a/btrfs-list.c b/btrfs-list.c
> index 8eec05ea797f..92a537f425f3 100644
> --- a/btrfs-list.c
> +++ b/btrfs-list.c
> @@ -1582,7 +1582,9 @@ int btrfs_get_subvol(int fd, struct root_info *the_ri)
> rbn = rb_next(rbn);
> continue;
> }
> - if (!comp_entry_with_rootid(the_ri, ri, 0)) {
> +
> + if (!comp_entry_with_rootid(the_ri, ri, 0) ||
> + !uuid_compare(the_ri->uuid, ri->uuid)) {
> memcpy(the_ri, ri, offsetof(struct root_info, path));
> the_ri->path = strdup_or_null(ri->path);
> the_ri->name = strdup_or_null(ri->name);
> diff --git a/cmds-subvolume.c b/cmds-subvolume.c
> index de6204eabeaf..1fa54d1b24cf 100644
> --- a/cmds-subvolume.c
> +++ b/cmds-subvolume.c
> @@ -891,8 +891,11 @@ static int cmd_subvol_find_new(int argc, char **argv)
> }
>
> static const char * const cmd_subvol_show_usage[] = {
> - "btrfs subvolume show <subvol-path>",
> + "btrfs subvolume show [options] <subvol-path>|<mnt>",
> "Show more information of the subvolume",
> + "-r|--rootid rootid of the subvol to show",
> + "-u|--uuid uuid of the subvol to show",
> + "If no option is specified <subvol-path> will be shown.",
> NULL
> };
>
> @@ -907,8 +910,36 @@ static int cmd_subvol_show(int argc, char **argv)
> int fd = -1;
> int ret = 1;
> DIR *dirstream1 = NULL;
> + int by_rootid = 0;
> + int by_uuid = 0;
> + u64 rootid_arg;
> + u8 uuid_arg[BTRFS_UUID_SIZE];
>
> - clean_args_no_options(argc, argv, cmd_subvol_show_usage);
> + while (1) {
> + int c;
> + static const struct option long_options[] = {
> + { "rootid", required_argument, NULL, 'r'},
> + { "uuid", required_argument, NULL, 'u'},
> + { NULL, 0, NULL, 0 }
> + };
> +
> + c = getopt_long(argc, argv, "r:u:", long_options, NULL);
> + if (c < 0)
> + break;
> +
> + switch (c) {
> + case 'r':
> + rootid_arg = arg_strtou64(optarg);
> + by_rootid = 1;
> + break;
> + case 'u':
> + uuid_parse(optarg, uuid_arg);
> + by_uuid = 1;
> + break;
> + default:
> + usage(cmd_subvol_show_usage);
> + }
> + }
>
> if (check_argc_exact(argc - optind, 1))
> usage(cmd_subvol_show_usage);
> @@ -921,7 +952,14 @@ static int cmd_subvol_show(int argc, char **argv)
> goto out;
> }
>
> - ret = get_subvol_info(fullpath, &get_ri);
> + if (by_rootid) {
> + ret = get_subvol_info_by_rootid(fullpath, &get_ri, rootid_arg);
> + } else if (by_uuid) {
> + ret = get_subvol_info_by_uuid(fullpath, &get_ri, uuid_arg);
> + } else {
> + ret = get_subvol_info(fullpath, &get_ri);
> + }
Here rootid takes precedence if there are both options specified. I
think this should be handled as invalid syntax. If the rootid and uuid
do not match, it's not well defined and can cause silent breakage.
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