Commit 4a5c8d89 authored by Matthew Wilcox's avatar Matthew Wilcox
Browse files

XArray: Fix xa_reserve for 2-byte aligned entries 



If we reserve index 0, the next entry to be stored there might be 2-byte
aligned.  That means we have to create the root xa_node at the time of
reserving the initial entry.

Signed-off-by: default avatarMatthew Wilcox <willy@infradead.org>
parent 2fbe967b

lib/test_xarray.c

+10 −0
Original line number Diff line number Diff line
@@ -1355,6 +1355,10 @@ static void check_align_1(struct xarray *xa, char *name) 
	xa_destroy(xa);

}



/*

 * We should always be able to store without allocating memory after

 * reserving a slot.

 */

static void check_align_2(struct xarray *xa, char *name)

{

	int i;
@@ -1366,6 +1370,12 @@ static void check_align_2(struct xarray *xa, char *name) 
		xa_erase(xa, 0);

	}



	for (i = 0; i < 8; i++) {

		XA_BUG_ON(xa, xa_reserve(xa, 0, GFP_KERNEL) != 0);

		XA_BUG_ON(xa, xa_store(xa, 0, name + i, 0) != NULL);

		xa_erase(xa, 0);

	}



	XA_BUG_ON(xa, !xa_empty(xa));

}

lib/xarray.c

+5 −3
Original line number Diff line number Diff line
@@ -767,10 +767,12 @@ void *xas_store(struct xa_state *xas, void *entry) 
	void *first, *next;

	bool value = xa_is_value(entry);



	if (entry)

		first = xas_create(xas, !xa_is_node(entry));

	else

	if (entry) {

		bool allow_root = !xa_is_node(entry) && !xa_is_zero(entry);

		first = xas_create(xas, allow_root);

	} else {

		first = xas_load(xas);

	}



	if (xas_invalid(xas))

		return first;