XArray: Redesign xa_alloc API
It was too easy to forget to initialise the start index. Add an
xa_limit data structure which can be used to pass min & max, and
define a couple of special values for common cases. Also add some
more tests cribbed from the IDR test suite. Change the return value
from -ENOSPC to -EBUSY to match xa_insert().
Signed-off-by: Matthew Wilcox <willy@infradead.org>
diff --git a/lib/xarray.c b/lib/xarray.c
index 468fb7b..c707388 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -1615,23 +1615,23 @@
* __xa_alloc() - Find somewhere to store this entry in the XArray.
* @xa: XArray.
* @id: Pointer to ID.
- * @max: Maximum ID to allocate (inclusive).
+ * @limit: Range for allocated ID.
* @entry: New entry.
* @gfp: Memory allocation flags.
*
- * Allocates an unused ID in the range specified by @id and @max.
- * Updates the @id pointer with the index, then stores the entry at that
- * index. A concurrent lookup will not see an uninitialised @id.
+ * Finds an empty entry in @xa between @limit.min and @limit.max,
+ * stores the index into the @id pointer, then stores the entry at
+ * that index. A concurrent lookup will not see an uninitialised @id.
*
* Context: Any context. Expects xa_lock to be held on entry. May
* release and reacquire xa_lock if @gfp flags permit.
- * Return: 0 on success, -ENOMEM if memory allocation fails or -ENOSPC if
- * there is no more space in the XArray.
+ * Return: 0 on success, -ENOMEM if memory could not be allocated or
+ * -EBUSY if there are no free entries in @limit.
*/
-int __xa_alloc(struct xarray *xa, u32 *id, u32 max, void *entry, gfp_t gfp)
+int __xa_alloc(struct xarray *xa, u32 *id, void *entry,
+ struct xa_limit limit, gfp_t gfp)
{
XA_STATE(xas, xa, 0);
- int err;
if (WARN_ON_ONCE(xa_is_advanced(entry)))
return -EINVAL;
@@ -1642,18 +1642,17 @@
entry = XA_ZERO_ENTRY;
do {
- xas.xa_index = *id;
- xas_find_marked(&xas, max, XA_FREE_MARK);
+ xas.xa_index = limit.min;
+ xas_find_marked(&xas, limit.max, XA_FREE_MARK);
if (xas.xa_node == XAS_RESTART)
- xas_set_err(&xas, -ENOSPC);
+ xas_set_err(&xas, -EBUSY);
+ else
+ *id = xas.xa_index;
xas_store(&xas, entry);
xas_clear_mark(&xas, XA_FREE_MARK);
} while (__xas_nomem(&xas, gfp));
- err = xas_error(&xas);
- if (!err)
- *id = xas.xa_index;
- return err;
+ return xas_error(&xas);
}
EXPORT_SYMBOL(__xa_alloc);