xarray: Add xas_for_each_conflict

This iterator iterates over each entry that is stored in the index or
indices specified by the xa_state.  This is intended for use for a
conditional store of a multiindex entry, or to allow entries which are
about to be removed from the xarray to be disposed of properly.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
This commit is contained in:
Matthew Wilcox 2018-06-01 22:46:02 -04:00
parent 64d3e9a9e0
commit 4e99d4e957
3 changed files with 146 additions and 0 deletions

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@ -878,6 +878,7 @@ static inline bool xas_retry(struct xa_state *xas, const void *entry)
void *xas_load(struct xa_state *);
void *xas_store(struct xa_state *, void *entry);
void *xas_find(struct xa_state *, unsigned long max);
void *xas_find_conflict(struct xa_state *);
bool xas_get_mark(const struct xa_state *, xa_mark_t);
void xas_set_mark(const struct xa_state *, xa_mark_t);
@ -1088,6 +1089,22 @@ enum {
for (entry = xas_find_marked(xas, max, mark); entry; \
entry = xas_next_marked(xas, max, mark))
/**
* xas_for_each_conflict() - Iterate over a range of an XArray.
* @xas: XArray operation state.
* @entry: Entry retrieved from the array.
*
* The loop body will be executed for each entry in the XArray that lies
* within the range specified by @xas. If the loop completes successfully,
* any entries that lie in this range will be replaced by @entry. The caller
* may break out of the loop; if they do so, the contents of the XArray will
* be unchanged. The operation may fail due to an out of memory condition.
* The caller may also call xa_set_err() to exit the loop while setting an
* error to record the reason.
*/
#define xas_for_each_conflict(xas, entry) \
while ((entry = xas_find_conflict(xas)))
void *__xas_next(struct xa_state *);
void *__xas_prev(struct xa_state *);

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@ -365,6 +365,73 @@ static noinline void check_multi_store(struct xarray *xa)
#endif
}
static noinline void __check_store_iter(struct xarray *xa, unsigned long start,
unsigned int order, unsigned int present)
{
XA_STATE_ORDER(xas, xa, start, order);
void *entry;
unsigned int count = 0;
retry:
xas_lock(&xas);
xas_for_each_conflict(&xas, entry) {
XA_BUG_ON(xa, !xa_is_value(entry));
XA_BUG_ON(xa, entry < xa_mk_value(start));
XA_BUG_ON(xa, entry > xa_mk_value(start + (1UL << order) - 1));
count++;
}
xas_store(&xas, xa_mk_value(start));
xas_unlock(&xas);
if (xas_nomem(&xas, GFP_KERNEL)) {
count = 0;
goto retry;
}
XA_BUG_ON(xa, xas_error(&xas));
XA_BUG_ON(xa, count != present);
XA_BUG_ON(xa, xa_load(xa, start) != xa_mk_value(start));
XA_BUG_ON(xa, xa_load(xa, start + (1UL << order) - 1) !=
xa_mk_value(start));
xa_erase_index(xa, start);
}
static noinline void check_store_iter(struct xarray *xa)
{
unsigned int i, j;
unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 20 : 1;
for (i = 0; i < max_order; i++) {
unsigned int min = 1 << i;
unsigned int max = (2 << i) - 1;
__check_store_iter(xa, 0, i, 0);
XA_BUG_ON(xa, !xa_empty(xa));
__check_store_iter(xa, min, i, 0);
XA_BUG_ON(xa, !xa_empty(xa));
xa_store_index(xa, min, GFP_KERNEL);
__check_store_iter(xa, min, i, 1);
XA_BUG_ON(xa, !xa_empty(xa));
xa_store_index(xa, max, GFP_KERNEL);
__check_store_iter(xa, min, i, 1);
XA_BUG_ON(xa, !xa_empty(xa));
for (j = 0; j < min; j++)
xa_store_index(xa, j, GFP_KERNEL);
__check_store_iter(xa, 0, i, min);
XA_BUG_ON(xa, !xa_empty(xa));
for (j = 0; j < min; j++)
xa_store_index(xa, min + j, GFP_KERNEL);
__check_store_iter(xa, min, i, min);
XA_BUG_ON(xa, !xa_empty(xa));
}
#ifdef CONFIG_XARRAY_MULTI
xa_store_index(xa, 63, GFP_KERNEL);
xa_store_index(xa, 65, GFP_KERNEL);
__check_store_iter(xa, 64, 2, 1);
xa_erase_index(xa, 63);
#endif
XA_BUG_ON(xa, !xa_empty(xa));
}
static noinline void check_multi_find(struct xarray *xa)
{
#ifdef CONFIG_XARRAY_MULTI
@ -627,6 +694,7 @@ static int xarray_checks(void)
check_find(&array);
check_destroy(&array);
check_move(&array);
check_store_iter(&array);
printk("XArray: %u of %u tests passed\n", tests_passed, tests_run);
return (tests_run == tests_passed) ? 0 : -EINVAL;

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@ -1110,6 +1110,67 @@ max:
}
EXPORT_SYMBOL_GPL(xas_find_marked);
/**
* xas_find_conflict() - Find the next present entry in a range.
* @xas: XArray operation state.
*
* The @xas describes both a range and a position within that range.
*
* Context: Any context. Expects xa_lock to be held.
* Return: The next entry in the range covered by @xas or %NULL.
*/
void *xas_find_conflict(struct xa_state *xas)
{
void *curr;
if (xas_error(xas))
return NULL;
if (!xas->xa_node)
return NULL;
if (xas_top(xas->xa_node)) {
curr = xas_start(xas);
if (!curr)
return NULL;
while (xa_is_node(curr)) {
struct xa_node *node = xa_to_node(curr);
curr = xas_descend(xas, node);
}
if (curr)
return curr;
}
if (xas->xa_node->shift > xas->xa_shift)
return NULL;
for (;;) {
if (xas->xa_node->shift == xas->xa_shift) {
if ((xas->xa_offset & xas->xa_sibs) == xas->xa_sibs)
break;
} else if (xas->xa_offset == XA_CHUNK_MASK) {
xas->xa_offset = xas->xa_node->offset;
xas->xa_node = xa_parent_locked(xas->xa, xas->xa_node);
if (!xas->xa_node)
break;
continue;
}
curr = xa_entry_locked(xas->xa, xas->xa_node, ++xas->xa_offset);
if (xa_is_sibling(curr))
continue;
while (xa_is_node(curr)) {
xas->xa_node = xa_to_node(curr);
xas->xa_offset = 0;
curr = xa_entry_locked(xas->xa, xas->xa_node, 0);
}
if (curr)
return curr;
}
xas->xa_offset -= xas->xa_sibs;
return NULL;
}
EXPORT_SYMBOL_GPL(xas_find_conflict);
/**
* xa_init_flags() - Initialise an empty XArray with flags.
* @xa: XArray.