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Commit fffaee36 authored by Konstantin Khlebnikov's avatar Konstantin Khlebnikov Committed by Linus Torvalds
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radix-tree: fix contiguous iterator 



This patch fixes bug in macro radix_tree_for_each_contig().

If radix_tree_next_slot() sees NULL in next slot it returns NULL, but following
radix_tree_next_chunk() switches iterating into next chunk. As result iterating
becomes non-contiguous and breaks vfs "splice" and all its users.

Signed-off-by: default avatarKonstantin Khlebnikov <khlebnikov@openvz.org>
Reported-and-bisected-by: default avatarHans de Bruin <jmdebruin@xmsnet.nl>
Reported-and-bisected-by: default avatarOndrej Zary <linux@rainbow-software.org>
Reported-bisected-and-tested-by: default avatarToralf Förster <toralf.foerster@gmx.de>
Link: https://lkml.org/lkml/2012/6/5/64


Cc: stable <stable@vger.kernel.org> # 3.4.x
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f9ba7179

include/linux/radix-tree.h

+4 −1
Original line number Diff line number Diff line
@@ -368,10 +368,13 @@ radix_tree_next_slot(void **slot, struct radix_tree_iter *iter, unsigned flags) 
			iter->index++;

			if (likely(*slot))

				return slot;

			if (flags & RADIX_TREE_ITER_CONTIG)

			if (flags & RADIX_TREE_ITER_CONTIG) {

				/* forbid switching to the next chunk */

				iter->next_index = 0;

				break;

			}

		}

	}

	return NULL;

}

lib/radix-tree.c

+3 −0
Original line number Diff line number Diff line
@@ -686,6 +686,9 @@ void **radix_tree_next_chunk(struct radix_tree_root *root, 
	 * during iterating; it can be zero only at the beginning.

	 * And we cannot overflow iter->next_index in a single step,

	 * because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG.

	 *

	 * This condition also used by radix_tree_next_slot() to stop

	 * contiguous iterating, and forbid swithing to the next chunk.

	 */

	index = iter->next_index;

	if (!index && iter->index)