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lib/xarray: introduce a new helper xas_get_order
It can be used after xas_load to check the order of loaded entries. Compared to xa_get_order, it saves an XA_STATE and avoid a rewalk. Added new test for xas_get_order, to make the test work, we have to export xas_get_order with EXPORT_SYMBOL_GPL. Also fix a sparse warning by checking the slot value with xa_entry instead of accessing it directly, as suggested by Matthew Wilcox. [kasong@tencent.com: simplify comment, sparse warning fix, per Matthew Wilcox] Link: https://lkml.kernel.org/r/20240416071722.45997-4-ryncsn@gmail.com Link: https://lkml.kernel.org/r/20240415171857.19244-4-ryncsn@gmail.com Signed-off-by: Kairui Song <kasong@tencent.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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@ -1548,6 +1548,7 @@ void xas_create_range(struct xa_state *);
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#ifdef CONFIG_XARRAY_MULTI
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int xa_get_order(struct xarray *, unsigned long index);
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int xas_get_order(struct xa_state *xas);
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void xas_split(struct xa_state *, void *entry, unsigned int order);
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void xas_split_alloc(struct xa_state *, void *entry, unsigned int order, gfp_t);
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#else
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@ -1556,6 +1557,11 @@ static inline int xa_get_order(struct xarray *xa, unsigned long index)
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return 0;
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}
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static inline int xas_get_order(struct xa_state *xas)
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{
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return 0;
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}
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static inline void xas_split(struct xa_state *xas, void *entry,
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unsigned int order)
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{
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@ -1984,6 +1984,39 @@ static noinline void check_get_order(struct xarray *xa)
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}
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}
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static noinline void check_xas_get_order(struct xarray *xa)
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{
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XA_STATE(xas, xa, 0);
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unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 20 : 1;
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unsigned int order;
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unsigned long i, j;
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for (order = 0; order < max_order; order++) {
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for (i = 0; i < 10; i++) {
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xas_set_order(&xas, i << order, order);
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do {
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xas_lock(&xas);
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xas_store(&xas, xa_mk_value(i));
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xas_unlock(&xas);
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} while (xas_nomem(&xas, GFP_KERNEL));
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for (j = i << order; j < (i + 1) << order; j++) {
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xas_set_order(&xas, j, 0);
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rcu_read_lock();
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xas_load(&xas);
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XA_BUG_ON(xa, xas_get_order(&xas) != order);
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rcu_read_unlock();
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}
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xas_lock(&xas);
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xas_set_order(&xas, i << order, order);
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xas_store(&xas, NULL);
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xas_unlock(&xas);
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}
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}
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}
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static noinline void check_destroy(struct xarray *xa)
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{
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unsigned long index;
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@ -2035,6 +2068,7 @@ static int xarray_checks(void)
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check_multi_store(&array);
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check_multi_store_advanced(&array);
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check_get_order(&array);
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check_xas_get_order(&array);
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check_xa_alloc();
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check_find(&array);
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check_find_entry(&array);
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53
lib/xarray.c
53
lib/xarray.c
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@ -1749,6 +1749,36 @@ void *xa_store_range(struct xarray *xa, unsigned long first,
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}
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EXPORT_SYMBOL(xa_store_range);
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/**
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* xas_get_order() - Get the order of an entry.
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* @xas: XArray operation state.
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*
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* Called after xas_load, the xas should not be in an error state.
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*
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* Return: A number between 0 and 63 indicating the order of the entry.
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*/
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int xas_get_order(struct xa_state *xas)
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{
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int order = 0;
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if (!xas->xa_node)
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return 0;
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for (;;) {
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unsigned int slot = xas->xa_offset + (1 << order);
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if (slot >= XA_CHUNK_SIZE)
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break;
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if (!xa_is_sibling(xa_entry(xas->xa, xas->xa_node, slot)))
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break;
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order++;
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}
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order += xas->xa_node->shift;
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return order;
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}
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EXPORT_SYMBOL_GPL(xas_get_order);
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/**
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* xa_get_order() - Get the order of an entry.
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* @xa: XArray.
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@ -1759,30 +1789,13 @@ EXPORT_SYMBOL(xa_store_range);
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int xa_get_order(struct xarray *xa, unsigned long index)
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{
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XA_STATE(xas, xa, index);
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void *entry;
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int order = 0;
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void *entry;
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rcu_read_lock();
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entry = xas_load(&xas);
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if (!entry)
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goto unlock;
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if (!xas.xa_node)
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goto unlock;
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for (;;) {
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unsigned int slot = xas.xa_offset + (1 << order);
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if (slot >= XA_CHUNK_SIZE)
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break;
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if (!xa_is_sibling(xas.xa_node->slots[slot]))
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break;
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order++;
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}
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order += xas.xa_node->shift;
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unlock:
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if (entry)
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order = xas_get_order(&xas);
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rcu_read_unlock();
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return order;
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