[PATCH v3 6/8] btrfs-progs: simple quotas btrfstune

[Boris Burkov <boris@bur.io>]

Add the ability to enable simple quotas on an existing file system at
rest with btrfstune.

This is similar to the functionality in mkfs, except it must also find
all the roots for which it must create qgroups. Note that this *does
not* retroactively compute usage for existing extents as that is
impossible for data. This is consistent with the behavior of the live
enable ioctl.

Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
---
 Makefile     |   2 +-
 tune/main.c  |  18 +++++-
 tune/quota.c | 172 +++++++++++++++++++++++++++++++++++++++++++++++++++
 tune/tune.h  |   3 +
 4 files changed, 193 insertions(+), 2 deletions(-)
 create mode 100644 tune/quota.c

diff --git a/Makefile b/Makefile
index 5dfd3c01d..7419475dd 100644
--- a/Makefile
+++ b/Makefile
@@ -265,7 +265,7 @@ mkfs_objects = mkfs/main.o mkfs/common.o mkfs/rootdir.o
 image_objects = image/main.o image/sanitize.o image/image-create.o image/common.o \
 		image/image-restore.o
 tune_objects = tune/main.o tune/seeding.o tune/change-uuid.o tune/change-metadata-uuid.o \
-	       tune/convert-bgt.o tune/change-csum.o check/clear-cache.o
+	       tune/convert-bgt.o tune/change-csum.o tune/quota.o check/clear-cache.o
 all_objects = $(objects) $(cmds_objects) $(libbtrfs_objects) $(convert_objects) \
 	      $(mkfs_objects) $(image_objects) $(tune_objects) $(libbtrfsutil_objects)
 
diff --git a/tune/main.c b/tune/main.c
index 63539b991..895e4da03 100644
--- a/tune/main.c
+++ b/tune/main.c
@@ -103,6 +103,7 @@ static const char * const tune_usage[] = {
 	OPTLINE("-x", "enable skinny metadata extent refs (mkfs: skinny-metadata)"),
 	OPTLINE("-n", "enable no-holes feature (mkfs: no-holes, more efficient sparse file representation)"),
 	OPTLINE("-S <0|1>", "set/unset seeding status of a device"),
+	OPTLINE("-q", "enable simple quotas on the file system. (mkfs: squota)"),
 	OPTLINE("--convert-to-block-group-tree", "convert filesystem to track block groups in "
 			"the separate block-group-tree instead of extent tree (sets the incompat bit)"),
 	OPTLINE("--convert-from-block-group-tree",
@@ -153,6 +154,9 @@ enum btrfstune_group_enum {
 	 */
 	LEGACY,
 
+	/* Qgroup options */
+	QGROUP,
+
 	BTRFSTUNE_NR_GROUPS,
 };
 
@@ -189,6 +193,7 @@ int BOX_MAIN(btrfstune)(int argc, char *argv[])
 	char *new_fsid_str = NULL;
 	int ret;
 	u64 super_flags = 0;
+	int quota = 0;
 	int fd = -1;
 
 	btrfs_config_init();
@@ -211,7 +216,7 @@ int BOX_MAIN(btrfstune)(int argc, char *argv[])
 #endif
 			{ NULL, 0, NULL, 0 }
 		};
-		int c = getopt_long(argc, argv, "S:rxfuU:nmM:", long_options, NULL);
+		int c = getopt_long(argc, argv, "S:rxqfuU:nmM:", long_options, NULL);
 
 		if (c < 0)
 			break;
@@ -229,6 +234,10 @@ int BOX_MAIN(btrfstune)(int argc, char *argv[])
 			super_flags |= BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA;
 			btrfstune_cmd_groups[LEGACY] = true;
 			break;
+		case 'q':
+			quota = 1;
+			btrfstune_cmd_groups[QGROUP] = true;
+			break;
 		case 'n':
 			super_flags |= BTRFS_FEATURE_INCOMPAT_NO_HOLES;
 			btrfstune_cmd_groups[LEGACY] = true;
@@ -499,6 +508,13 @@ int BOX_MAIN(btrfstune)(int argc, char *argv[])
 		ret = change_uuid(fs_info, new_fsid_str);
 		goto out;
 	}
+
+	if (quota) {
+		ret = enable_quota(root->fs_info, true);
+		if (ret)
+			goto out;
+	}
+
 out:
 	if (ret < 0) {
 		fs_info->readonly = 1;
diff --git a/tune/quota.c b/tune/quota.c
new file mode 100644
index 000000000..949cfc409
--- /dev/null
+++ b/tune/quota.c
@@ -0,0 +1,172 @@
+#include <errno.h>
+
+#include "common/messages.h"
+#include "kernel-shared/ctree.h"
+#include "kernel-shared/disk-io.h"
+#include "kernel-shared/transaction.h"
+#include "kernel-shared/uapi/btrfs_tree.h"
+#include "tune/tune.h"
+
+static int create_qgroup(struct btrfs_fs_info *fs_info,
+			 struct btrfs_trans_handle *trans,
+			 u64 qgroupid)
+{
+	struct btrfs_path path;
+	struct btrfs_root *quota_root = fs_info->quota_root;
+	struct btrfs_key key;
+	int ret;
+
+	if (qgroupid >> BTRFS_QGROUP_LEVEL_SHIFT) {
+		error("qgroup level other than 0 is not supported yet");
+		return -ENOTTY;
+	}
+
+	key.objectid = 0;
+	key.type = BTRFS_QGROUP_INFO_KEY;
+	key.offset = qgroupid;
+
+	btrfs_init_path(&path);
+	ret = btrfs_insert_empty_item(trans, quota_root, &path, &key,
+				      sizeof(struct btrfs_qgroup_info_item));
+	btrfs_release_path(&path);
+	if (ret < 0)
+		return ret;
+
+	key.objectid = 0;
+	key.type = BTRFS_QGROUP_LIMIT_KEY;
+	key.offset = qgroupid;
+	ret = btrfs_insert_empty_item(trans, quota_root, &path, &key,
+				      sizeof(struct btrfs_qgroup_limit_item));
+	btrfs_release_path(&path);
+
+	printf("created qgroup for %llu\n", qgroupid);
+	return ret;
+}
+
+static int create_qgroups(struct btrfs_fs_info *fs_info,
+			  struct btrfs_trans_handle *trans)
+{
+	struct btrfs_key key = {
+		.objectid = 0,
+		.type = BTRFS_ROOT_REF_KEY,
+		.offset = 0,
+	};
+	struct btrfs_path path;
+	struct extent_buffer *leaf;
+	int slot;
+	struct btrfs_root *tree_root = fs_info->tree_root;
+	int ret;
+
+
+	ret = create_qgroup(fs_info, trans, BTRFS_FS_TREE_OBJECTID);
+	if (ret)
+		goto out;
+
+	btrfs_init_path(&path);
+	ret = btrfs_search_slot_for_read(tree_root, &key, &path, 1, 0);
+	if (ret)
+		goto out;
+
+	while (1) {
+		slot = path.slots[0];
+		leaf = path.nodes[0];
+		btrfs_item_key_to_cpu(leaf, &key, slot);
+		if (key.type == BTRFS_ROOT_REF_KEY) {
+			ret = create_qgroup(fs_info, trans, key.offset);
+			if (ret)
+				goto out;
+		}
+		ret = btrfs_next_item(tree_root, &path);
+		if (ret < 0) {
+			error("failed to advance to next item");
+			goto out;
+		}
+		if (ret)
+			break;
+	}
+
+out:
+	btrfs_release_path(&path);
+	return ret;
+}
+
+int enable_quota(struct btrfs_fs_info *fs_info, bool simple)
+{
+	struct btrfs_super_block *sb = fs_info->super_copy;
+	struct btrfs_trans_handle *trans;
+	int super_flags = btrfs_super_incompat_flags(sb);
+	struct btrfs_qgroup_status_item *qsi;
+	struct btrfs_root *quota_root;
+	struct btrfs_path path;
+	struct btrfs_key key;
+	int flags;
+	int ret;
+
+	trans = btrfs_start_transaction(fs_info->tree_root, 2);
+	if (IS_ERR(trans)) {
+		ret = PTR_ERR(trans);
+		errno = -ret;
+		error_msg(ERROR_MSG_START_TRANS, "%m");
+		return ret;
+	}
+
+	ret = btrfs_create_root(trans, fs_info, BTRFS_QUOTA_TREE_OBJECTID);
+	if (ret < 0) {
+		error("failed to create quota root: %d (%m)", ret);
+		goto fail;
+	}
+	quota_root = fs_info->quota_root;
+
+	/* Create the qgroup status item */
+	key.objectid = 0;
+	key.type = BTRFS_QGROUP_STATUS_KEY;
+	key.offset = 0;
+
+	btrfs_init_path(&path);
+	ret = btrfs_insert_empty_item(trans, quota_root, &path, &key,
+				      sizeof(*qsi));
+	if (ret < 0) {
+		error("failed to insert qgroup status item: %d (%m)", ret);
+		goto fail;
+	}
+
+	qsi = btrfs_item_ptr(path.nodes[0], path.slots[0],
+			     struct btrfs_qgroup_status_item);
+	btrfs_set_qgroup_status_generation(path.nodes[0], qsi, trans->transid);
+	btrfs_set_qgroup_status_rescan(path.nodes[0], qsi, 0);
+	flags = BTRFS_QGROUP_STATUS_FLAG_ON;
+	if (simple) {
+		btrfs_set_qgroup_status_enable_gen(path.nodes[0], qsi, trans->transid);
+		flags |= BTRFS_QGROUP_STATUS_FLAG_SIMPLE_MODE;
+	} else {
+		flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
+	}
+
+	btrfs_set_qgroup_status_version(path.nodes[0], qsi, 1);
+	btrfs_set_qgroup_status_flags(path.nodes[0], qsi, flags);
+	btrfs_release_path(&path);
+
+	/* Create the qgroup items */
+	ret = create_qgroups(fs_info, trans);
+	if (ret < 0) {
+		error("failed to create qgroup items for subvols %d (%m)", ret);
+		goto fail;
+	}
+
+	/* Set squota incompat flag */
+	if (simple) {
+		super_flags |= BTRFS_FEATURE_INCOMPAT_SIMPLE_QUOTA;
+		btrfs_set_super_incompat_flags(sb, super_flags);
+	}
+
+	ret = btrfs_commit_transaction(trans, fs_info->tree_root);
+	if (ret < 0) {
+		errno = -ret;
+		error_msg(ERROR_MSG_COMMIT_TRANS, "%m");
+		return ret;
+	}
+	return ret;
+fail:
+	btrfs_abort_transaction(trans, ret);
+	return ret;
+}
diff --git a/tune/tune.h b/tune/tune.h
index 0ef249d89..cbf33b2e7 100644
--- a/tune/tune.h
+++ b/tune/tune.h
@@ -33,4 +33,7 @@ int convert_to_bg_tree(struct btrfs_fs_info *fs_info);
 int convert_to_extent_tree(struct btrfs_fs_info *fs_info);
 
 int btrfs_change_csum_type(struct btrfs_fs_info *fs_info, u16 new_csum_type);
+
+int enable_quota(struct btrfs_fs_info *fs_info, bool simple);
+
 #endif
-- 
2.42.0