From ad520141b155786800261cc7e02ec02f0afe2643 Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Sat, 27 May 2023 23:19:13 -0400 Subject: bcachefs: Fix corruption with writeable snapshots When partially overwriting an extent in an older snapshot, the existing extent has to be split. If the existing extent was overwritten in a different (sibling) snapshot, we have to ensure that the split won't be visible in the sibling snapshot. data_update.c already has code for this, bch2_insert_snapshot_writeouts() - we just need to move it into btree_update_leaf.c and change bch2_trans_update_extent() to use it as well. Signed-off-by: Kent Overstreet --- fs/bcachefs/btree_update.h | 23 ++++++++++ fs/bcachefs/btree_update_leaf.c | 73 ++++++++++++++++++++++++++++++-- fs/bcachefs/data_update.c | 94 +++-------------------------------------- 3 files changed, 99 insertions(+), 91 deletions(-) diff --git a/fs/bcachefs/btree_update.h b/fs/bcachefs/btree_update.h index 1ac3a81e0af6..e90cf292f80b 100644 --- a/fs/bcachefs/btree_update.h +++ b/fs/bcachefs/btree_update.h @@ -4,6 +4,7 @@ #include "btree_iter.h" #include "journal.h" +#include "journal.h" struct bch_fs; struct btree; @@ -83,6 +84,28 @@ int bch2_btree_node_update_key(struct btree_trans *, struct btree_iter *, int bch2_btree_node_update_key_get_iter(struct btree_trans *, struct btree *, struct bkey_i *, bool); +int __bch2_insert_snapshot_whiteouts(struct btree_trans *, enum btree_id, + struct bpos, struct bpos); + +/* + * For use when splitting extents in existing snapshots: + * + * If @old_pos is an interior snapshot node, iterate over descendent snapshot + * nodes: for every descendent snapshot in whiche @old_pos is overwritten and + * not visible, emit a whiteout at @new_pos. + */ +static inline int bch2_insert_snapshot_whiteouts(struct btree_trans *trans, + enum btree_id btree, + struct bpos old_pos, + struct bpos new_pos) +{ + if (!btree_type_has_snapshots(btree) || + bkey_eq(old_pos, new_pos)) + return 0; + + return __bch2_insert_snapshot_whiteouts(trans, btree, old_pos, new_pos); +} + int bch2_trans_update_extent(struct btree_trans *, struct btree_iter *, struct bkey_i *, enum btree_update_flags); diff --git a/fs/bcachefs/btree_update_leaf.c b/fs/bcachefs/btree_update_leaf.c index 33693467810b..25d73db9adc6 100644 --- a/fs/bcachefs/btree_update_leaf.c +++ b/fs/bcachefs/btree_update_leaf.c @@ -1343,6 +1343,69 @@ static int need_whiteout_for_snapshot(struct btree_trans *trans, return ret; } + +int __bch2_insert_snapshot_whiteouts(struct btree_trans *trans, + enum btree_id id, + struct bpos old_pos, + struct bpos new_pos) +{ + struct bch_fs *c = trans->c; + struct btree_iter old_iter, new_iter; + struct bkey_s_c old_k, new_k; + snapshot_id_list s; + struct bkey_i *update; + int ret; + + if (!bch2_snapshot_has_children(c, old_pos.snapshot)) + return 0; + + darray_init(&s); + + bch2_trans_iter_init(trans, &old_iter, id, old_pos, + BTREE_ITER_NOT_EXTENTS| + BTREE_ITER_ALL_SNAPSHOTS); + while ((old_k = bch2_btree_iter_prev(&old_iter)).k && + !(ret = bkey_err(old_k)) && + bkey_eq(old_pos, old_k.k->p)) { + struct bpos whiteout_pos = + SPOS(new_pos.inode, new_pos.offset, old_k.k->p.snapshot);; + + if (!bch2_snapshot_is_ancestor(c, old_k.k->p.snapshot, old_pos.snapshot) || + snapshot_list_has_ancestor(c, &s, old_k.k->p.snapshot)) + continue; + + new_k = bch2_bkey_get_iter(trans, &new_iter, id, whiteout_pos, + BTREE_ITER_NOT_EXTENTS| + BTREE_ITER_INTENT); + ret = bkey_err(new_k); + if (ret) + break; + + if (new_k.k->type == KEY_TYPE_deleted) { + update = bch2_trans_kmalloc(trans, sizeof(struct bkey_i)); + ret = PTR_ERR_OR_ZERO(update); + if (ret) + break; + + bkey_init(&update->k); + update->k.p = whiteout_pos; + update->k.type = KEY_TYPE_whiteout; + + ret = bch2_trans_update(trans, &new_iter, update, + BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE); + } + bch2_trans_iter_exit(trans, &new_iter); + + ret = snapshot_list_add(c, &s, old_k.k->p.snapshot); + if (ret) + break; + } + bch2_trans_iter_exit(trans, &old_iter); + darray_exit(&s); + + return ret; +} + int bch2_trans_update_extent(struct btree_trans *trans, struct btree_iter *orig_iter, struct bkey_i *insert, @@ -1396,8 +1459,10 @@ int bch2_trans_update_extent(struct btree_trans *trans, bch2_cut_back(start, update); - ret = bch2_btree_insert_nonextent(trans, btree_id, update, - BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|flags); + ret = bch2_insert_snapshot_whiteouts(trans, btree_id, + k.k->p, update->k.p) ?: + bch2_btree_insert_nonextent(trans, btree_id, update, + BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|flags); if (ret) goto err; } @@ -1411,7 +1476,9 @@ int bch2_trans_update_extent(struct btree_trans *trans, bch2_cut_front(start, update); bch2_cut_back(insert->k.p, update); - ret = bch2_btree_insert_nonextent(trans, btree_id, update, + ret = bch2_insert_snapshot_whiteouts(trans, btree_id, + k.k->p, update->k.p) ?: + bch2_btree_insert_nonextent(trans, btree_id, update, BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE|flags); if (ret) goto err; diff --git a/fs/bcachefs/data_update.c b/fs/bcachefs/data_update.c index ae7e60d6e583..c89ee14f8b6b 100644 --- a/fs/bcachefs/data_update.c +++ b/fs/bcachefs/data_update.c @@ -16,81 +16,6 @@ #include "subvolume.h" #include "trace.h" -static int insert_snapshot_whiteouts(struct btree_trans *trans, - enum btree_id id, - struct bpos old_pos, - struct bpos new_pos) -{ - struct bch_fs *c = trans->c; - struct btree_iter iter, iter2; - struct bkey_s_c k, k2; - snapshot_id_list s; - struct bkey_i *update; - int ret; - - if (!btree_type_has_snapshots(id)) - return 0; - - darray_init(&s); - - if (!bch2_snapshot_has_children(c, old_pos.snapshot)) - return 0; - - bch2_trans_iter_init(trans, &iter, id, old_pos, - BTREE_ITER_NOT_EXTENTS| - BTREE_ITER_ALL_SNAPSHOTS); - while (1) { - k = bch2_btree_iter_prev(&iter); - ret = bkey_err(k); - if (ret) - break; - - if (!k.k) - break; - - if (!bkey_eq(old_pos, k.k->p)) - break; - - if (bch2_snapshot_is_ancestor(c, k.k->p.snapshot, old_pos.snapshot) && - !snapshot_list_has_ancestor(c, &s, k.k->p.snapshot)) { - struct bpos whiteout_pos = new_pos; - - whiteout_pos.snapshot = k.k->p.snapshot; - - k2 = bch2_bkey_get_iter(trans, &iter2, id, whiteout_pos, - BTREE_ITER_NOT_EXTENTS| - BTREE_ITER_INTENT); - ret = bkey_err(k2); - - if (!ret && k2.k->type == KEY_TYPE_deleted) { - update = bch2_trans_kmalloc(trans, sizeof(struct bkey_i)); - ret = PTR_ERR_OR_ZERO(update); - if (ret) - break; - - bkey_init(&update->k); - update->k.p = whiteout_pos; - update->k.type = KEY_TYPE_whiteout; - - ret = bch2_trans_update(trans, &iter2, update, - BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE); - } - bch2_trans_iter_exit(trans, &iter2); - - if (ret) - break; - - ret = snapshot_list_add(c, &s, k.k->p.snapshot); - if (ret) - break; - } - } - bch2_trans_iter_exit(trans, &iter); - darray_exit(&s); - - return ret; -} - static void trace_move_extent_finish2(struct bch_fs *c, struct bkey_s_c k) { if (trace_move_extent_finish_enabled()) { @@ -327,19 +252,12 @@ restart_drop_extra_replicas: next_pos = insert->k.p; - if (!bkey_eq(bkey_start_pos(&insert->k), bkey_start_pos(k.k))) { - ret = insert_snapshot_whiteouts(trans, m->btree_id, k.k->p, - bkey_start_pos(&insert->k)); - if (ret) - goto err; - } - - if (!bkey_eq(insert->k.p, k.k->p)) { - ret = insert_snapshot_whiteouts(trans, m->btree_id, - k.k->p, insert->k.p); - if (ret) - goto err; - } + ret = bch2_insert_snapshot_whiteouts(trans, m->btree_id, + k.k->p, bkey_start_pos(&insert->k)) ?: + bch2_insert_snapshot_whiteouts(trans, m->btree_id, + k.k->p, insert->k.p); + if (ret) + goto err; ret = bch2_trans_update(trans, &iter, insert, BTREE_UPDATE_INTERNAL_SNAPSHOT_NODE) ?: -- cgit v1.2.3