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bcache: Fix for handling overlapping extents when reading in a btree node

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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@daterainc.com>
Cc: linux-stable <stable@vger.kernel.org> # >= v3.10
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kent Overstreet 2013-09-23 23:17:35 -07:00 committed by Linus Torvalds
parent a698e08c82
commit 84786438ed
1 changed files with 28 additions and 11 deletions
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39
drivers/md/bcache/bset.c
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@ -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);
}
}
}