Revert "btrfs-progs: subvol delete: add options to delete the qgroup"

This reverts commit 9da773a.

There are several problems related to the --delete-qgroup option:

- Currently kernel doesn't allow to delete non-empty qgroups

- A qgroup can only be empty after fully dropped and a transaction is
  committed
  The tool doesn't take either factor into consideration

- Things like drop_subtree_threshold or other operations can mark qgroup
  inconsistent and skip accounting
  This can mean the target qgroup will never be empty until next rescan

On the other hand, even we do it the proper way, it would hugely delay
the command (wait until the subvolume to be cleaned).

Furthermore, even if the waiting is handled properly,
drop_subtree_threshold can still prevent us deleting the qgroup (qgroup
numbers are inconsistent, and accounting is skipped completely).

So the qgroup cleanup needs kernel to make it work properly.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: adam900710

Documentation/btrfs-subvolume.rst

@@ -112,13 +112,6 @@ delete [options] [<subvolume> [<subvolume>...]], delete -i|--subvolid <subvolid>
         -i|--subvolid <subvolid>
                 subvolume id to be removed instead of the <path> that should point to the
                 filesystem with the subvolume
-
-        --delete-qgroup
-                also delete the qgroup 0/subvolid if it exists
-
-        --no-delete-qgroup
-                do not delete the 0/subvolid qgroup (default)
-
         -v|--verbose
                 (deprecated) alias for global *-v* option
 

cmds/subvolume.c

@@ -348,8 +348,6 @@ static const char * const cmd_subvolume_delete_usage[] = {
 	OPTLINE("-c|--commit-after", "wait for transaction commit at the end of the operation"),
 	OPTLINE("-C|--commit-each", "wait for transaction commit after deleting each subvolume"),
 	OPTLINE("-i|--subvolid", "subvolume id of the to be removed subvolume"),
-	OPTLINE("--delete-qgroup", "also delete the qgroup 0/subvolid if it exists"),
-	OPTLINE("--no-delete-qgroup", "do not delete the qgroup 0/subvolid if it exists (default)"),
 	OPTLINE("-v|--verbose", "deprecated, alias for global -v option"),
 	HELPINFO_INSERT_GLOBALS,
 	HELPINFO_INSERT_VERBOSE,
@@ -378,20 +376,15 @@ static int cmd_subvolume_delete(const struct cmd_struct *cmd, int argc, char **a
 	enum { COMMIT_AFTER = 1, COMMIT_EACH = 2 };
 	enum btrfs_util_error err;
 	uint64_t default_subvol_id, target_subvol_id = 0;
-	bool opt_delete_qgroup = false;
 
 	optind = 0;
 	while (1) {
 		int c;
-		enum { GETOPT_VAL_DELETE_QGROUP = GETOPT_VAL_FIRST,
-		       GETOPT_VAL_NO_DELETE_QGROUP };
 		static const struct option long_options[] = {
 			{"commit-after", no_argument, NULL, 'c'},
 			{"commit-each", no_argument, NULL, 'C'},
 			{"subvolid", required_argument, NULL, 'i'},
 			{"verbose", no_argument, NULL, 'v'},
-			{"delete-qgroup", no_argument, NULL, GETOPT_VAL_DELETE_QGROUP },
-			{"no-delete-qgroup", no_argument, NULL, GETOPT_VAL_NO_DELETE_QGROUP },
 			{NULL, 0, NULL, 0}
 		};
 
@@ -412,12 +405,6 @@ static int cmd_subvolume_delete(const struct cmd_struct *cmd, int argc, char **a
 		case 'v':
 			bconf_be_verbose();
 			break;
-		case GETOPT_VAL_DELETE_QGROUP:
-			opt_delete_qgroup = true;
-			break;
-		case GETOPT_VAL_NO_DELETE_QGROUP:
-			opt_delete_qgroup = false;
-			break;
 		default:
 			usage_unknown_option(cmd, argv);
 		}
@@ -553,19 +540,6 @@ static int cmd_subvolume_delete(const struct cmd_struct *cmd, int argc, char **a
 			warning("deletion failed with EPERM, you don't have permissions or send may be in progress");
 		ret = 1;
 		goto out;
-	} else if (opt_delete_qgroup) {
-		struct btrfs_ioctl_qgroup_create_args args = { .qgroupid = target_subvol_id };
-
-		ret = ioctl(fd, BTRFS_IOC_QGROUP_CREATE, &args);
-		if (ret == 0) {
-			pr_verbose(LOG_DEFAULT, "Delete qgroup 0/%" PRIu64 "\n", target_subvol_id);
-		} else if (ret < 0 && (errno == ENOTCONN || errno == ENOENT)) {
-			/* Quotas not enabled, or there's no qgroup. */
-		} else {
-			warning("unable to delete qgroup 0/%llu: %m", subvolid);
-		}
-		/* Qgroup errors are not fatal. */
-		ret = 0;
 	}
 
 	if (commit_mode == COMMIT_EACH) {