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authorMatthew Wilcox <willy@infradead.org>2018-06-02 05:46:02 +0300
committerMatthew Wilcox <willy@infradead.org>2018-10-21 17:45:59 +0300
commit4e99d4e9579d3b950bf4b38d0d64eb1b9be78761 (patch)
treea3ecd9d06b4f0eb8bb05369887c9fbe133218e01 /lib/xarray.c
parent64d3e9a9e0cc51957d243dd2b0adc5d74ff5e128 (diff)
downloadlinux-4e99d4e9579d3b950bf4b38d0d64eb1b9be78761.tar.xz
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>
Diffstat (limited to 'lib/xarray.c')
-rw-r--r--lib/xarray.c61
1 files changed, 61 insertions, 0 deletions
diff --git a/lib/xarray.c b/lib/xarray.c
index 303c46579598..41f8ebc651f5 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -1111,6 +1111,67 @@ 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.
* @flags: XA_FLAG values.