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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _BCACHEFS_SNAPSHOT_FORMAT_H
#define _BCACHEFS_SNAPSHOT_FORMAT_H
struct bch_snapshot {
struct bch_val v;
__le32 flags;
__le32 parent;
__le32 children[2];
__le32 subvol;
/* corresponds to a bch_snapshot_tree in BTREE_ID_snapshot_trees */
__le32 tree;
__le32 depth;
__le32 skip[3];
bch_le128 btime;
};
/*
* WILL_DELETE: leaf node that's no longer referenced by a subvolume, still has
* keys, will be deleted by delete_dead_snapshots
*
* SUBVOL: true if a subvol points to this snapshot (why do we have this?
* subvols are nonzero)
*
* DELETED: we never delete snapshot keys, we mark them as deleted so that we
* can distinguish between a key for a missing snapshot (and we have no idea
* what happened) and a key for a deleted snapshot (delete_dead_snapshots() missed
* something, key should be deleted)
*
* NO_KEYS: we don't remove interior snapshot nodes from snapshot trees at
* runtime, since we can't do the adjustements for the depth/skiplist field
* atomically - and that breaks e.g. is_ancestor(). Instead, we mark it to be
* deleted at the next remount; this tells us that we don't need to run the full
* delete_dead_snapshots().
*
*
* XXX - todo item:
*
* We should guard against a bitflip causing us to delete a snapshot incorrectly
* by cross checking with the subvolume btree: delete_dead_snapshots() can take
* out more data than any other codepath if it runs incorrectly
*/
LE32_BITMASK(BCH_SNAPSHOT_WILL_DELETE, struct bch_snapshot, flags, 0, 1)
LE32_BITMASK(BCH_SNAPSHOT_SUBVOL, struct bch_snapshot, flags, 1, 2)
LE32_BITMASK(BCH_SNAPSHOT_DELETED, struct bch_snapshot, flags, 2, 3)
LE32_BITMASK(BCH_SNAPSHOT_NO_KEYS, struct bch_snapshot, flags, 3, 4)
/*
* Snapshot trees:
*
* The snapshot_trees btree gives us persistent indentifier for each tree of
* bch_snapshot nodes, and allow us to record and easily find the root/master
* subvolume that other snapshots were created from:
*/
struct bch_snapshot_tree {
struct bch_val v;
__le32 master_subvol;
__le32 root_snapshot;
};
#endif /* _BCACHEFS_SNAPSHOT_FORMAT_H */
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