btrfs: beef-up btrfs support with a limited understanding of quota

With this change we understand more than just leaf quota groups for
btrfs file systems. Specifically:

- When we create a subvolume we can now optionally add the new subvolume
  to all qgroups its parent subvolume was member of too. Alternatively
  it is also possible to insert an intermediary quota group between the
  parent's qgroups and the subvolume's leaf qgroup, which is useful for
  a concept of "subtree" qgroups, that contain a subvolume and all its
  children.

- The remove logic for subvolumes has been updated to optionally remove
  any leaf qgroups or "subtree" qgroups, following the logic above.

- The snapshot logic for subvolumes has been updated to replicate the
  original qgroup setup of the source, if it follows the "subtree"
  design described above. It will not cover qgroup setups that introduce
  arbitrary qgroups, especially those orthogonal to the subvolume
  hierarchy.

This also tries to be more graceful when setting up /var/lib/machines as
btrfs. For example, if mkfs.btrfs is missing we don't even try to set it
up as loopback device.

Fixes #1559
Fixes #1129

1 files changed, 55 insertions, 18 deletions

diff --git a/src/basic/btrfs-util.h b/src/basic/btrfs-util.h
index ad7c7009ab..fc9efd72d5 100644
--- a/src/basic/btrfs-util.h
+++ b/src/basic/btrfs-util.h
@@ -47,45 +47,82 @@ typedef enum BtrfsSnapshotFlags {
         BTRFS_SNAPSHOT_FALLBACK_COPY = 1,
         BTRFS_SNAPSHOT_READ_ONLY = 2,
         BTRFS_SNAPSHOT_RECURSIVE = 4,
+        BTRFS_SNAPSHOT_QUOTA = 8,
 } BtrfsSnapshotFlags;
 
+typedef enum BtrfsRemoveFlags {
+        BTRFS_REMOVE_RECURSIVE = 1,
+        BTRFS_REMOVE_QUOTA = 2,
+} BtrfsRemoveFlags;
+
 int btrfs_is_filesystem(int fd);
 int btrfs_is_subvol(int fd);
 
+int btrfs_reflink(int infd, int outfd);
+int btrfs_clone_range(int infd, uint64_t in_offset, int ofd, uint64_t out_offset, uint64_t sz);
+
+int btrfs_get_block_device_fd(int fd, dev_t *dev);
+int btrfs_get_block_device(const char *path, dev_t *dev);
+
+int btrfs_defrag_fd(int fd);
+int btrfs_defrag(const char *p);
+
+int btrfs_quota_enable_fd(int fd, bool b);
+int btrfs_quota_enable(const char *path, bool b);
+
+int btrfs_quota_scan_start(int fd);
+int btrfs_quota_scan_wait(int fd);
+int btrfs_quota_scan_ongoing(int fd);
+
+int btrfs_resize_loopback_fd(int fd, uint64_t size, bool grow_only);
+int btrfs_resize_loopback(const char *path, uint64_t size, bool grow_only);
+
 int btrfs_subvol_make(const char *path);
 int btrfs_subvol_make_label(const char *path);
 
 int btrfs_subvol_snapshot_fd(int old_fd, const char *new_path, BtrfsSnapshotFlags flags);
 int btrfs_subvol_snapshot(const char *old_path, const char *new_path, BtrfsSnapshotFlags flags);
 
+int btrfs_subvol_remove(const char *path, BtrfsRemoveFlags flags);
+int btrfs_subvol_remove_fd(int fd, const char *subvolume, BtrfsRemoveFlags flags);
+
 int btrfs_subvol_set_read_only_fd(int fd, bool b);
 int btrfs_subvol_set_read_only(const char *path, bool b);
 int btrfs_subvol_get_read_only_fd(int fd);
+
 int btrfs_subvol_get_id(int fd, const char *subvolume, uint64_t *ret);
 int btrfs_subvol_get_id_fd(int fd, uint64_t *ret);
-int btrfs_subvol_get_info_fd(int fd, BtrfsSubvolInfo *info);
-int btrfs_subvol_get_quota_fd(int fd, BtrfsQuotaInfo *quota);
+int btrfs_subvol_get_parent(int fd, uint64_t subvol_id, uint64_t *ret);
 
-int btrfs_reflink(int infd, int outfd);
-int btrfs_clone_range(int infd, uint64_t in_offset, int ofd, uint64_t out_offset, uint64_t sz);
+int btrfs_subvol_get_info_fd(int fd, uint64_t subvol_id, BtrfsSubvolInfo *info);
 
-int btrfs_get_block_device_fd(int fd, dev_t *dev);
-int btrfs_get_block_device(const char *path, dev_t *dev);
+int btrfs_subvol_find_subtree_qgroup(int fd, uint64_t subvol_id, uint64_t *ret);
 
-int btrfs_defrag_fd(int fd);
-int btrfs_defrag(const char *p);
+int btrfs_subvol_get_subtree_quota(const char *path, uint64_t subvol_id, BtrfsQuotaInfo *quota);
+int btrfs_subvol_get_subtree_quota_fd(int fd, uint64_t subvol_id, BtrfsQuotaInfo *quota);
 
-int btrfs_quota_enable_fd(int fd, bool b);
-int btrfs_quota_enable(const char *path, bool b);
+int btrfs_subvol_set_subtree_quota_limit(const char *path, uint64_t subvol_id, uint64_t referenced_max);
+int btrfs_subvol_set_subtree_quota_limit_fd(int fd, uint64_t subvol_id, uint64_t referenced_max);
 
-int btrfs_quota_limit_fd(int fd, uint64_t referenced_max);
-int btrfs_quota_limit(const char *path, uint64_t referenced_max);
+int btrfs_subvol_auto_qgroup_fd(int fd, uint64_t subvol_id, bool new_qgroup);
+int btrfs_subvol_auto_qgroup(const char *path, uint64_t subvol_id, bool create_intermediary_qgroup);
 
-int btrfs_resize_loopback_fd(int fd, uint64_t size, bool grow_only);
-int btrfs_resize_loopback(const char *path, uint64_t size, bool grow_only);
+int btrfs_qgroupid_make(uint64_t level, uint64_t id, uint64_t *ret);
+int btrfs_qgroupid_split(uint64_t qgroupid, uint64_t *level, uint64_t *id);
+
+int btrfs_qgroup_create(int fd, uint64_t qgroupid);
+int btrfs_qgroup_destroy(int fd, uint64_t qgroupid);
+int btrfs_qgroup_destroy_recursive(int fd, uint64_t qgroupid);
+
+int btrfs_qgroup_set_limit_fd(int fd, uint64_t qgroupid, uint64_t referenced_max);
+int btrfs_qgroup_set_limit(const char *path, uint64_t qgroupid, uint64_t referenced_max);
+
+int btrfs_qgroup_copy_limits(int fd, uint64_t old_qgroupid, uint64_t new_qgroupid);
+
+int btrfs_qgroup_assign(int fd, uint64_t child, uint64_t parent);
+int btrfs_qgroup_unassign(int fd, uint64_t child, uint64_t parent);
 
-int btrfs_subvol_remove(const char *path, bool recursive);
-int btrfs_subvol_remove_fd(int fd, const char *subvolume, bool recursive);
+int btrfs_qgroup_find_parents(int fd, uint64_t qgroupid, uint64_t **ret);
 
-int btrfs_qgroup_create(int fd, uint64_t level, uint64_t id);
-int btrfs_qgroup_destroy(int fd, uint64_t level, uint64_t id);
+int btrfs_qgroup_get_quota_fd(int fd, uint64_t qgroupid, BtrfsQuotaInfo *quota);
+int btrfs_qgroup_get_quota(const char *path, uint64_t qgroupid, BtrfsQuotaInfo *quota);