The patch titled
Subject: lib/xarray: introduce a new helper xas_get_order
has been added to the -mm mm-unstable branch. Its filename is
lib-xarray-introduce-a-new-helper-xas_get_order.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/lib-xarray-introduce-a-new-helper-xas_get_order.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Kairui Song <kasong@xxxxxxxxxxx>
Subject: lib/xarray: introduce a new helper xas_get_order
Date: Tue, 26 Mar 2024 01:14:04 +0800
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.
Also add new test for xas_get_order, to make the test work we have to
export xas_get_order with EXPORT_SYMBOL_GPL.
Link: https://lkml.kernel.org/r/20240325171405.99971-4-ryncsn@xxxxxxxxx
Signed-off-by: Kairui Song <kasong@xxxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/xarray.h | 6 ++++
lib/test_xarray.c | 32 +++++++++++++++++++++++++
lib/xarray.c | 49 ++++++++++++++++++++++++---------------
3 files changed, 69 insertions(+), 18 deletions(-)
--- a/include/linux/xarray.h~lib-xarray-introduce-a-new-helper-xas_get_order
+++ a/include/linux/xarray.h
@@ -1548,6 +1548,7 @@ void xas_create_range(struct xa_state *)
#ifdef CONFIG_XARRAY_MULTI
int xa_get_order(struct xarray *, unsigned long index);
+int xas_get_order(struct xa_state *xas);
void xas_split(struct xa_state *, void *entry, unsigned int order);
void xas_split_alloc(struct xa_state *, void *entry, unsigned int order, gfp_t);
#else
@@ -1555,6 +1556,11 @@ static inline int xa_get_order(struct xa
{
return 0;
}
+
+static inline int xas_get_order(struct xa_state *xas)
+{
+ return 0;
+}
static inline void xas_split(struct xa_state *xas, void *entry,
unsigned int order)
--- a/lib/test_xarray.c~lib-xarray-introduce-a-new-helper-xas_get_order
+++ a/lib/test_xarray.c
@@ -1984,6 +1984,37 @@ static noinline void check_get_order(str
}
}
+static noinline void check_xas_get_order(struct xarray *xa)
+{
+ XA_STATE(xas, xa, 0);
+
+ unsigned int max_order = IS_ENABLED(CONFIG_XARRAY_MULTI) ? 20 : 1;
+ unsigned int order;
+ unsigned long i, j;
+
+ for (order = 0; order < max_order; order++) {
+ for (i = 0; i < 10; i++) {
+ xas_set_order(&xas, i << order, order);
+ do {
+ xas_lock(&xas);
+ xas_store(&xas, xa_mk_value(i));
+ xas_unlock(&xas);
+ } while (xas_nomem(&xas, GFP_KERNEL));
+
+ xas_lock(&xas);
+ for (j = i << order; j < (i + 1) << order; j++) {
+ xas_set_order(&xas, j, 0);
+ xas_load(&xas);
+ XA_BUG_ON(xa, xas_get_order(&xas) != order);
+ }
+ xas_unlock(&xas);
+
+ xas_set_order(&xas, i << order, order);
+ xas_store(&xas, NULL);
+ }
+ }
+}
+
static noinline void check_destroy(struct xarray *xa)
{
unsigned long index;
@@ -2035,6 +2066,7 @@ static int xarray_checks(void)
check_multi_store(&array);
check_multi_store_advanced(&array);
check_get_order(&array);
+ check_xas_get_order(&array);
check_xa_alloc();
check_find(&array);
check_find_entry(&array);
--- a/lib/xarray.c~lib-xarray-introduce-a-new-helper-xas_get_order
+++ a/lib/xarray.c
@@ -1750,39 +1750,52 @@ unlock:
EXPORT_SYMBOL(xa_store_range);
/**
- * xa_get_order() - Get the order of an entry.
- * @xa: XArray.
- * @index: Index of the entry.
+ * xas_get_order() - Get the order of an loaded entry after xas_load.
+ * @xas: XArray operation state.
+ *
+ * Called after xas_load, the xas should not be in an error state.
*
* Return: A number between 0 and 63 indicating the order of the entry.
*/
-int xa_get_order(struct xarray *xa, unsigned long index)
+int xas_get_order(struct xa_state *xas)
{
- XA_STATE(xas, xa, index);
- void *entry;
int order = 0;
- rcu_read_lock();
- entry = xas_load(&xas);
-
- if (!entry)
- goto unlock;
-
- if (!xas.xa_node)
- goto unlock;
+ if (!xas->xa_node)
+ return 0;
for (;;) {
- unsigned int slot = xas.xa_offset + (1 << order);
+ unsigned int slot = xas->xa_offset + (1 << order);
if (slot >= XA_CHUNK_SIZE)
break;
- if (!xa_is_sibling(xas.xa_node->slots[slot]))
+ if (!xa_is_sibling(xas->xa_node->slots[slot]))
break;
order++;
}
- order += xas.xa_node->shift;
-unlock:
+ order += xas->xa_node->shift;
+ return order;
+}
+EXPORT_SYMBOL_GPL(xas_get_order);
+
+/**
+ * xa_get_order() - Get the order of an entry.
+ * @xa: XArray.
+ * @index: Index of the entry.
+ *
+ * Return: A number between 0 and 63 indicating the order of the entry.
+ */
+int xa_get_order(struct xarray *xa, unsigned long index)
+{
+ XA_STATE(xas, xa, index);
+ int order = 0;
+ void *entry;
+
+ rcu_read_lock();
+ entry = xas_load(&xas);
+ if (entry)
+ order = xas_get_order(&xas);
rcu_read_unlock();
return order;
_
Patches currently in -mm which might be from kasong@xxxxxxxxxxx are
mm-filemap-return-early-if-failed-to-allocate-memory-for-split.patch
mm-filemap-clean-up-hugetlb-exclusion-code.patch
lib-xarray-introduce-a-new-helper-xas_get_order.patch
mm-filemap-optimize-filemap-folio-adding.patch
