From 84786438ed17978d72eeced580ab757e4da8830b Mon Sep 17 00:00:00 2001 From: Kent Overstreet Date: Mon, 23 Sep 2013 23:17:35 -0700 Subject: [PATCH] bcache: Fix for handling overlapping extents when reading in a btree node 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 Cc: linux-stable # >= v3.10 Signed-off-by: Linus Torvalds --- drivers/md/bcache/bset.c | 39 ++++++++++++++++++++++++++++----------- 1 file changed, 28 insertions(+), 11 deletions(-) diff --git a/drivers/md/bcache/bset.c b/drivers/md/bcache/bset.c index 8010eed06a51..22d1ae72c282 100644 --- a/drivers/md/bcache/bset.c +++ b/drivers/md/bcache/bset.c @@ -926,28 +926,45 @@ struct bkey *bch_next_recurse_key(struct btree *b, struct bkey *search) /* 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); + } } }