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bcachefs: bch2_snapshot_is_ancestor() now safe to call in early recovery

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this fixes an assertion pop in
  bch2_check_snapshot_trees() ->
  check_snapshot_tree() ->
  bch2_snapshot_tree_master_subvol() ->
  bch2_snapshot_is_ancestor()

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2024-03-17 20:39:42 -04:00
parent 1ba6f48f09
commit 1c31b83a4e
1 changed files with 18 additions and 14 deletions
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32
fs/bcachefs/snapshot.c
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@ -91,18 +91,20 @@ static int bch2_snapshot_tree_create(struct btree_trans *trans,
/* Snapshot nodes: */
static bool bch2_snapshot_is_ancestor_early(struct bch_fs *c, u32 id, u32 ancestor)
static bool __bch2_snapshot_is_ancestor_early(struct snapshot_table *t, u32 id, u32 ancestor)
{
struct snapshot_table *t;
rcu_read_lock();
t = rcu_dereference(c->snapshots);
while (id && id < ancestor)
id = __snapshot_t(t, id)->parent;
return id == ancestor;
}
static bool bch2_snapshot_is_ancestor_early(struct bch_fs *c, u32 id, u32 ancestor)
{
rcu_read_lock();
bool ret = __bch2_snapshot_is_ancestor_early(rcu_dereference(c->snapshots), id, ancestor);
rcu_read_unlock();
return id == ancestor;
return ret;
}
static inline u32 get_ancestor_below(struct snapshot_table *t, u32 id, u32 ancestor)
@ -120,13 +122,15 @@ static inline u32 get_ancestor_below(struct snapshot_table *t, u32 id, u32 ances
bool __bch2_snapshot_is_ancestor(struct bch_fs *c, u32 id, u32 ancestor)
{
struct snapshot_table *t;
bool ret;
EBUG_ON(c->recovery_pass_done <= BCH_RECOVERY_PASS_check_snapshots);
rcu_read_lock();
t = rcu_dereference(c->snapshots);
struct snapshot_table *t = rcu_dereference(c->snapshots);
if (unlikely(c->recovery_pass_done <= BCH_RECOVERY_PASS_check_snapshots)) {
ret = __bch2_snapshot_is_ancestor_early(t, id, ancestor);
goto out;
}
while (id && id < ancestor - IS_ANCESTOR_BITMAP)
id = get_ancestor_below(t, id, ancestor);
@ -134,11 +138,11 @@ bool __bch2_snapshot_is_ancestor(struct bch_fs *c, u32 id, u32 ancestor)
if (id && id < ancestor) {
ret = test_bit(ancestor - id - 1, __snapshot_t(t, id)->is_ancestor);
EBUG_ON(ret != bch2_snapshot_is_ancestor_early(c, id, ancestor));
EBUG_ON(ret != __bch2_snapshot_is_ancestor_early(t, id, ancestor));
} else {
ret = id == ancestor;
}
out:
rcu_read_unlock();
return ret;
@ -547,7 +551,7 @@ static int check_snapshot_tree(struct btree_trans *trans,
"snapshot tree points to missing subvolume:\n %s",
(printbuf_reset(&buf),
bch2_bkey_val_to_text(&buf, c, st.s_c), buf.buf)) ||
fsck_err_on(!bch2_snapshot_is_ancestor_early(c,
fsck_err_on(!bch2_snapshot_is_ancestor(c,
le32_to_cpu(subvol.snapshot),
root_id),
c, snapshot_tree_to_wrong_subvol,