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Commit 84786438 authored by Kent Overstreet's avatar Kent Overstreet Committed by Linus Torvalds
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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: default avatarKent Overstreet <kmo@daterainc.com>
Cc: linux-stable <stable@vger.kernel.org> # >= v3.10
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a698e08c

drivers/md/bcache/bset.c

+28 −11
Original line number Diff line number Diff line
@@ -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;



		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);

		}

	}

}