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bcachefs: delete_dead_snapshot_keys_v2()

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Since extents, dirents and xattrs require an inode with the
corresponding snapshot ID to exists, we can avoid a lot of scanning by
only scanning those trees for keys to process if the correspending inode
exists.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet
2025-05-02 13:23:22 -04:00
parent e9756dd29f
commit 88f62ed60c
1 changed files with 136 additions and 28 deletions
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164
fs/bcachefs/snapshot.c
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@@ -1432,6 +1432,12 @@ static unsigned live_child(struct bch_fs *c, u32 id)
return ret;
}
static bool snapshot_id_dying(struct snapshot_delete *d, unsigned id)
{
return snapshot_list_has_id(&d->delete_leaves, id) ||
interior_delete_has_id(&d->delete_interior, id) != 0;
}
static int delete_dead_snapshots_process_key(struct btree_trans *trans,
struct btree_iter *iter,
struct bkey_s_c k)
@@ -1500,6 +1506,129 @@ static bool skip_unrelated_snapshot_tree(struct btree_trans *trans, struct btree
return ret;
}
static int delete_dead_snapshot_keys_v1(struct btree_trans *trans)
{
struct bch_fs *c = trans->c;
struct snapshot_delete *d = &c->snapshot_delete;
for (d->pos.btree = 0; d->pos.btree < BTREE_ID_NR; d->pos.btree++) {
struct disk_reservation res = { 0 };
u64 prev_inum = 0;
d->pos.pos = POS_MIN;
if (!btree_type_has_snapshots(d->pos.btree))
continue;
int ret = for_each_btree_key_commit(trans, iter,
d->pos.btree, POS_MIN,
BTREE_ITER_prefetch|BTREE_ITER_all_snapshots, k,
&res, NULL, BCH_TRANS_COMMIT_no_enospc, ({
d->pos.pos = iter.pos;
if (skip_unrelated_snapshot_tree(trans, &iter, &prev_inum))
continue;
delete_dead_snapshots_process_key(trans, &iter, k);
}));
bch2_disk_reservation_put(c, &res);
if (ret)
return ret;
}
return 0;
}
static int delete_dead_snapshot_keys_range(struct btree_trans *trans, enum btree_id btree,
struct bpos start, struct bpos end)
{
struct bch_fs *c = trans->c;
struct snapshot_delete *d = &c->snapshot_delete;
struct disk_reservation res = { 0 };
d->pos.btree = btree;
d->pos.pos = POS_MIN;
int ret = for_each_btree_key_max_commit(trans, iter,
btree, start, end,
BTREE_ITER_prefetch|BTREE_ITER_all_snapshots, k,
&res, NULL, BCH_TRANS_COMMIT_no_enospc, ({
d->pos.pos = iter.pos;
delete_dead_snapshots_process_key(trans, &iter, k);
}));
bch2_disk_reservation_put(c, &res);
return ret;
}
static int delete_dead_snapshot_keys_v2(struct btree_trans *trans)
{
struct bch_fs *c = trans->c;
struct snapshot_delete *d = &c->snapshot_delete;
struct disk_reservation res = { 0 };
u64 prev_inum = 0;
int ret = 0;
struct btree_iter iter;
bch2_trans_iter_init(trans, &iter, BTREE_ID_inodes, POS_MIN,
BTREE_ITER_prefetch|BTREE_ITER_all_snapshots);
while (1) {
struct bkey_s_c k;
ret = lockrestart_do(trans,
bkey_err(k = bch2_btree_iter_peek(trans, &iter)));
if (ret)
break;
if (!k.k)
break;
d->pos.btree = iter.btree_id;
d->pos.pos = iter.pos;
if (skip_unrelated_snapshot_tree(trans, &iter, &prev_inum))
continue;
if (snapshot_id_dying(d, k.k->p.snapshot)) {
struct bpos start = POS(k.k->p.offset, 0);
struct bpos end = POS(k.k->p.offset, U64_MAX);
ret = delete_dead_snapshot_keys_range(trans, BTREE_ID_extents, start, end) ?:
delete_dead_snapshot_keys_range(trans, BTREE_ID_dirents, start, end) ?:
delete_dead_snapshot_keys_range(trans, BTREE_ID_xattrs, start, end);
if (ret)
break;
bch2_btree_iter_set_pos(trans, &iter, POS(0, k.k->p.offset + 1));
} else {
bch2_btree_iter_advance(trans, &iter);
}
}
bch2_trans_iter_exit(trans, &iter);
if (ret)
goto err;
prev_inum = 0;
ret = for_each_btree_key_commit(trans, iter,
BTREE_ID_inodes, POS_MIN,
BTREE_ITER_prefetch|BTREE_ITER_all_snapshots, k,
&res, NULL, BCH_TRANS_COMMIT_no_enospc, ({
d->pos.btree = iter.btree_id;
d->pos.pos = iter.pos;
if (skip_unrelated_snapshot_tree(trans, &iter, &prev_inum))
continue;
delete_dead_snapshots_process_key(trans, &iter, k);
}));
err:
bch2_disk_reservation_put(c, &res);
return ret;
}
/*
* For a given snapshot, if it doesn't have a subvolume that points to it, and
* it doesn't have child snapshot nodes - it's now redundant and we can mark it
@@ -1683,34 +1812,13 @@ int bch2_delete_dead_snapshots(struct bch_fs *c)
goto err;
}
for (d->pos.btree = 0; d->pos.btree < BTREE_ID_NR; d->pos.btree++) {
struct disk_reservation res = { 0 };
u64 prev_inum = 0;
d->pos.pos = POS_MIN;
if (!btree_type_has_snapshots(d->pos.btree))
continue;
ret = for_each_btree_key_commit(trans, iter,
d->pos.btree, POS_MIN,
BTREE_ITER_prefetch|BTREE_ITER_all_snapshots, k,
&res, NULL, BCH_TRANS_COMMIT_no_enospc, ({
d->pos.pos = iter.pos;
if (skip_unrelated_snapshot_tree(trans, &iter, &prev_inum))
continue;
delete_dead_snapshots_process_key(trans, &iter, k);
}));
bch2_disk_reservation_put(c, &res);
if (!bch2_err_matches(ret, EROFS))
bch_err_msg(c, ret, "deleting keys from dying snapshots");
if (ret)
goto err;
}
ret = !bch2_request_incompat_feature(c, bcachefs_metadata_version_snapshot_deletion_v2)
? delete_dead_snapshot_keys_v2(trans)
: delete_dead_snapshot_keys_v1(trans);
if (!bch2_err_matches(ret, EROFS))
bch_err_msg(c, ret, "deleting keys from dying snapshots");
if (ret)
goto err;
darray_for_each(d->delete_leaves, i) {
ret = commit_do(trans, NULL, NULL, 0,