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authorMatthew Wilcox <willy@infradead.org>2017-11-14 16:42:22 -0500
committerMatthew Wilcox <willy@infradead.org>2018-10-21 10:45:58 -0400
commit80a0a1a9a3cde9b23851e8eb7160e2786549306a (patch)
tree9f90a533bb16d5f91407e6d04d102ea4dbca225e /lib/xarray.c
parentb803b42823d0d9e8b6deccf01ffc2aba5d0738df (diff)
xarray: Extract entries from an XArray
The xa_extract function combines the functionality of radix_tree_gang_lookup() and radix_tree_gang_lookup_tagged(). It extracts entries matching the specified filter into a normal array. Signed-off-by: Matthew Wilcox <willy@infradead.org>
Diffstat (limited to 'lib/xarray.c')
-rw-r--r--lib/xarray.c80
1 files changed, 80 insertions, 0 deletions
diff --git a/lib/xarray.c b/lib/xarray.c
index 24494f42daa6..70e04810c8c2 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -1444,6 +1444,86 @@ void *xa_find_after(struct xarray *xa, unsigned long *indexp,
}
EXPORT_SYMBOL(xa_find_after);
+static unsigned int xas_extract_present(struct xa_state *xas, void **dst,
+ unsigned long max, unsigned int n)
+{
+ void *entry;
+ unsigned int i = 0;
+
+ rcu_read_lock();
+ xas_for_each(xas, entry, max) {
+ if (xas_retry(xas, entry))
+ continue;
+ dst[i++] = entry;
+ if (i == n)
+ break;
+ }
+ rcu_read_unlock();
+
+ return i;
+}
+
+static unsigned int xas_extract_marked(struct xa_state *xas, void **dst,
+ unsigned long max, unsigned int n, xa_mark_t mark)
+{
+ void *entry;
+ unsigned int i = 0;
+
+ rcu_read_lock();
+ xas_for_each_marked(xas, entry, max, mark) {
+ if (xas_retry(xas, entry))
+ continue;
+ dst[i++] = entry;
+ if (i == n)
+ break;
+ }
+ rcu_read_unlock();
+
+ return i;
+}
+
+/**
+ * xa_extract() - Copy selected entries from the XArray into a normal array.
+ * @xa: The source XArray to copy from.
+ * @dst: The buffer to copy entries into.
+ * @start: The first index in the XArray eligible to be selected.
+ * @max: The last index in the XArray eligible to be selected.
+ * @n: The maximum number of entries to copy.
+ * @filter: Selection criterion.
+ *
+ * Copies up to @n entries that match @filter from the XArray. The
+ * copied entries will have indices between @start and @max, inclusive.
+ *
+ * The @filter may be an XArray mark value, in which case entries which are
+ * marked with that mark will be copied. It may also be %XA_PRESENT, in
+ * which case all entries which are not NULL will be copied.
+ *
+ * The entries returned may not represent a snapshot of the XArray at a
+ * moment in time. For example, if another thread stores to index 5, then
+ * index 10, calling xa_extract() may return the old contents of index 5
+ * and the new contents of index 10. Indices not modified while this
+ * function is running will not be skipped.
+ *
+ * If you need stronger guarantees, holding the xa_lock across calls to this
+ * function will prevent concurrent modification.
+ *
+ * Context: Any context. Takes and releases the RCU lock.
+ * Return: The number of entries copied.
+ */
+unsigned int xa_extract(struct xarray *xa, void **dst, unsigned long start,
+ unsigned long max, unsigned int n, xa_mark_t filter)
+{
+ XA_STATE(xas, xa, start);
+
+ if (!n)
+ return 0;
+
+ if ((__force unsigned int)filter < XA_MAX_MARKS)
+ return xas_extract_marked(&xas, dst, max, n, filter);
+ return xas_extract_present(&xas, dst, max, n);
+}
+EXPORT_SYMBOL(xa_extract);
+
#ifdef XA_DEBUG
void xa_dump_node(const struct xa_node *node)
{