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bcachefs: Make snapshot_is_ancestor() safe

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Snapshot table accesses generally need to be checking for invalid
snapshot ID now, fix one that was missed.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2024-04-04 15:50:26 -04:00
parent e60aa47240
commit 01e5f4fc0f
1 changed files with 13 additions and 6 deletions
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19
fs/bcachefs/snapshot.c
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@ -125,6 +125,15 @@ static inline u32 get_ancestor_below(struct snapshot_table *t, u32 id, u32 ances
return s->parent;
}
static bool test_ancestor_bitmap(struct snapshot_table *t, u32 id, u32 ancestor)
{
const struct snapshot_t *s = __snapshot_t(t, id);
if (!s)
return false;
return test_bit(ancestor - id - 1, s->is_ancestor);
}
bool __bch2_snapshot_is_ancestor(struct bch_fs *c, u32 id, u32 ancestor)
{
bool ret;
@ -140,13 +149,11 @@ bool __bch2_snapshot_is_ancestor(struct bch_fs *c, u32 id, u32 ancestor)
while (id && id < ancestor - IS_ANCESTOR_BITMAP)
id = get_ancestor_below(t, id, ancestor);
if (id && id < ancestor) {
ret = test_bit(ancestor - id - 1, __snapshot_t(t, id)->is_ancestor);
ret = id && id < ancestor
? test_ancestor_bitmap(t, id, ancestor)
: id == ancestor;
EBUG_ON(ret != __bch2_snapshot_is_ancestor_early(t, id, ancestor));
} else {
ret = id == ancestor;
}
EBUG_ON(ret != __bch2_snapshot_is_ancestor_early(t, id, ancestor));
out:
rcu_read_unlock();