radix-tree: fix contiguous iterator (fffaee36) · Commits · 戴 / test

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:

Konstantin Khlebnikov <khlebnikov@openvz.org> Reported-and-bisected-by:

Hans de Bruin <jmdebruin@xmsnet.nl> Reported-and-bisected-by:

Ondrej Zary <linux@rainbow-software.org> Reported-bisected-and-tested-by:

Toralf 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:

Linus Torvalds <torvalds@linux-foundation.org>

include/linux/radix-tree.h

+4 −1

Original line number	Original line	Diff line number	Diff line
	@@ -368,10 +368,13 @@ radix_tree_next_slot(void *slot, struct radix_tree_iter iter, unsigned flags)
	iter->index++;		iter->index++;
	if (likely(*slot))		if (likely(*slot))
	return 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;		break;
	}		}
	}		}
			}
	return NULL;		return NULL;
	}		}

lib/radix-tree.c

+3 −0

Original line number	Original line	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.		* during iterating; it can be zero only at the beginning.
	* And we cannot overflow iter->next_index in a single step,		* And we cannot overflow iter->next_index in a single step,
	* because RADIX_TREE_MAP_SHIFT < BITS_PER_LONG.		* 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;		index = iter->next_index;
	if (!index && iter->index)		if (!index && iter->index)

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