Messages in this thread Patch in this message | | | Date | Tue, 05 Jun 2012 19:59:10 +0400 | From | Konstantin Khlebnikov <> | Subject | Re: [bisected commit 0fc9d10] NFS-server corruption with 3.4 |
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Proper fix in attachment.
Konstantin Khlebnikov wrote: > OGAWA Hirofumi wrote: >> Konstantin Khlebnikov<khlebnikov@openvz.org> writes: >> >>> Hmm, very interesting! >>> Please try this patch, it must fix the problem and print some numbers to debug. >>> >> >> I think the bug is in radix_tree_for_each_contig(). >> >> radix_tree_next_slot() returns NULL if the slot was NULL (i.e. there is >> hole). But, slot == NULL is not meaning to stop iterate here. Actually, >> if slot is NULL, it gets next chunk. >> >> Bang. > > Yeah, you are right, I already found this too. > Currently I think how to fix this more accurately... > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
radix-tree: fix contiguous iterator
From: Konstantin Khlebnikov <khlebnikov@openvz.org>
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-and-bisected-by: Toralf Förster <toralf.foerster@gmx.de> --- include/linux/radix-tree.h | 5 ++++- lib/radix-tree.c | 3 +++ 2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/include/linux/radix-tree.h b/include/linux/radix-tree.h index 0d04cd6..ffc444c 100644 --- a/include/linux/radix-tree.h +++ b/include/linux/radix-tree.h @@ -368,8 +368,11 @@ 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; diff --git a/lib/radix-tree.c b/lib/radix-tree.c index 86516f5..3ac50dc 100644 --- a/lib/radix-tree.c +++ b/lib/radix-tree.c @@ -673,6 +673,9 @@ 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) | |