3.11-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kent Overstreet <kmo@xxxxxxxxxxxxx>
commit 84786438ed17978d72eeced580ab757e4da8830b upstream.
btree_sort_fixup() was overly clever, because it was trying to avoid
pulling a key off the btree iterator in more than one place.
This led to a really obscure bug where we'd break early from the loop in
btree_sort_fixup() if the current key overlapped with keys in more than
one older set, and the next key it overlapped with was zero size.
Signed-off-by: Kent Overstreet <kmo@xxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/bcache/bset.c | 39 ++++++++++++++++++++++++++++-----------
1 file changed, 28 insertions(+), 11 deletions(-)
--- a/drivers/md/bcache/bset.c
+++ b/drivers/md/bcache/bset.c
@@ -926,28 +926,45 @@ struct bkey *bch_next_recurse_key(struct
/* Mergesort */
+static void sort_key_next(struct btree_iter *iter,
+ struct btree_iter_set *i)
+{
+ i->k = bkey_next(i->k);
+
+ if (i->k == i->end)
+ *i = iter->data[--iter->used];
+}
+
static void btree_sort_fixup(struct btree_iter *iter)
{
while (iter->used > 1) {
struct btree_iter_set *top = iter->data, *i = top + 1;
- struct bkey *k;
if (iter->used > 2 &&
btree_iter_cmp(i[0], i[1]))
i++;
- for (k = i->k;
- k != i->end && bkey_cmp(top->k, &START_KEY(k)) > 0;
- k = bkey_next(k))
- if (top->k > i->k)
- __bch_cut_front(top->k, k);
- else if (KEY_SIZE(k))
- bch_cut_back(&START_KEY(k), top->k);
-
- if (top->k < i->k || k == i->k)
+ if (bkey_cmp(top->k, &START_KEY(i->k)) <= 0)
break;
- heap_sift(iter, i - top, btree_iter_cmp);
+ if (!KEY_SIZE(i->k)) {
+ sort_key_next(iter, i);
+ heap_sift(iter, i - top, btree_iter_cmp);
+ continue;
+ }
+
+ if (top->k > i->k) {
+ if (bkey_cmp(top->k, i->k) >= 0)
+ sort_key_next(iter, i);
+ else
+ bch_cut_front(top->k, i->k);
+
+ heap_sift(iter, i - top, btree_iter_cmp);
+ } else {
+ /* can't happen because of comparison func */
+ BUG_ON(!bkey_cmp(&START_KEY(top->k), &START_KEY(i->k)));
+ bch_cut_back(&START_KEY(i->k), top->k);
+ }
}
}
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