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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: 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>
This commit is contained in:
Konstantin Khlebnikov 2012-06-05 21:36:33 +04:00 committed by Linus Torvalds
parent f9ba7179ce
commit fffaee365f
2 changed files with 7 additions and 1 deletions
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5
include/linux/radix-tree.h
View File

@ -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;
} }

3
lib/radix-tree.c
View File

@ -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)