Commit 19c30f4d authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

XArray: Fix xa_find_after with multi-index entries 



If the entry is of an order which is a multiple of XA_CHUNK_SIZE,
the current detection of sibling entries does not work.  Factor out
an xas_sibling() function to make xa_find_after() a little more
understandable, and write a new implementation that doesn't suffer from
the same bug.

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Cc: stable@vger.kernel.org
parent 430f24f9

lib/test_xarray.c

+19 −13
Original line number Diff line number Diff line
@@ -902,28 +902,30 @@ static noinline void check_store_iter(struct xarray *xa) 
	XA_BUG_ON(xa, !xa_empty(xa));

}



static noinline void check_multi_find(struct xarray *xa)

static noinline void check_multi_find_1(struct xarray *xa, unsigned order)

{

#ifdef CONFIG_XARRAY_MULTI

	unsigned long multi = 3 << order;

	unsigned long next = 4 << order;

	unsigned long index;



	xa_store_order(xa, 12, 2, xa_mk_value(12), GFP_KERNEL);

	XA_BUG_ON(xa, xa_store_index(xa, 16, GFP_KERNEL) != NULL);

	xa_store_order(xa, multi, order, xa_mk_value(multi), GFP_KERNEL);

	XA_BUG_ON(xa, xa_store_index(xa, next, GFP_KERNEL) != NULL);



	index = 0;

	XA_BUG_ON(xa, xa_find(xa, &index, ULONG_MAX, XA_PRESENT) !=

			xa_mk_value(12));

	XA_BUG_ON(xa, index != 12);

	index = 13;

			xa_mk_value(multi));

	XA_BUG_ON(xa, index != multi);

	index = multi + 1;

	XA_BUG_ON(xa, xa_find(xa, &index, ULONG_MAX, XA_PRESENT) !=

			xa_mk_value(12));

	XA_BUG_ON(xa, (index < 12) || (index >= 16));

			xa_mk_value(multi));

	XA_BUG_ON(xa, (index < multi) || (index >= next));

	XA_BUG_ON(xa, xa_find_after(xa, &index, ULONG_MAX, XA_PRESENT) !=

			xa_mk_value(16));

	XA_BUG_ON(xa, index != 16);

			xa_mk_value(next));

	XA_BUG_ON(xa, index != next);



	xa_erase_index(xa, 12);

	xa_erase_index(xa, 16);

	xa_erase_index(xa, multi);

	xa_erase_index(xa, next);

	XA_BUG_ON(xa, !xa_empty(xa));

#endif

}
@@ -1064,11 +1066,15 @@ static noinline void check_find_4(struct xarray *xa) 


static noinline void check_find(struct xarray *xa)

{

	unsigned i;



	check_find_1(xa);

	check_find_2(xa);

	check_find_3(xa);

	check_find_4(xa);

	check_multi_find(xa);



	for (i = 2; i < 10; i++)

		check_multi_find_1(xa, i);

	check_multi_find_2(xa);

}

lib/xarray.c

+13 −7
Original line number Diff line number Diff line
@@ -1826,6 +1826,17 @@ void *xa_find(struct xarray *xa, unsigned long *indexp, 
}

EXPORT_SYMBOL(xa_find);



static bool xas_sibling(struct xa_state *xas)

{

	struct xa_node *node = xas->xa_node;

	unsigned long mask;



	if (!node)

		return false;

	mask = (XA_CHUNK_SIZE << node->shift) - 1;

	return (xas->xa_index & mask) > (xas->xa_offset << node->shift);

}



/**

 * xa_find_after() - Search the XArray for a present entry.

 * @xa: XArray.
@@ -1860,13 +1871,8 @@ void *xa_find_after(struct xarray *xa, unsigned long *indexp, 
			entry = xas_find(&xas, max);

		if (xas.xa_node == XAS_BOUNDS)

			break;

		if (xas.xa_shift) {

			if (xas.xa_index & ((1UL << xas.xa_shift) - 1))

		if (xas_sibling(&xas))

			continue;

		} else {

			if (xas.xa_offset < (xas.xa_index & XA_CHUNK_MASK))

				continue;

		}

		if (!xas_retry(&xas, entry))

			break;

	}

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