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lib/xarray: introduce a new helper xas_get_order 

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.

Added new test for xas_get_order, to make the test work, we have to export
xas_get_order with EXPORT_SYMBOL_GPL.

Also fix a sparse warning by checking the slot value with xa_entry instead
of accessing it directly, as suggested by Matthew Wilcox.

[kasong@tencent.com: simplify comment, sparse warning fix, per Matthew Wilcox]
  Link: https://lkml.kernel.org/r/20240416071722.45997-4-ryncsn@gmail.com
Link: https://lkml.kernel.org/r/20240415171857.19244-4-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Kairui Song 2024-04-16 01:18:55 +08:00 committed by Andrew Morton
parent b2ebcf9d3d
commit a4864671ca
3 changed files with 73 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/linux/xarray.h
View File

@ -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
@ -1556,6 +1557,11 @@ static inline int xa_get_order(struct xarray *xa, unsigned long index)
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)
{

34
lib/test_xarray.c
View File

@ -1984,6 +1984,39 @@ static noinline void check_get_order(struct xarray *xa)
}
}
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));
for (j = i << order; j < (i + 1) << order; j++) {
xas_set_order(&xas, j, 0);
rcu_read_lock();
xas_load(&xas);
XA_BUG_ON(xa, xas_get_order(&xas) != order);
rcu_read_unlock();
}
xas_lock(&xas);
xas_set_order(&xas, i << order, order);
xas_store(&xas, NULL);
xas_unlock(&xas);
}
}
}
static noinline void check_destroy(struct xarray *xa)
{
unsigned long index;
@ -2035,6 +2068,7 @@ 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);

53
lib/xarray.c
View File

@ -1749,6 +1749,36 @@ unlock:
}
EXPORT_SYMBOL(xa_store_range);
/**
* xas_get_order() - Get the order of an entry.
* @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 xas_get_order(struct xa_state *xas)
{
int order = 0;
if (!xas->xa_node)
return 0;
for (;;) {
unsigned int slot = xas->xa_offset + (1 << order);
if (slot >= XA_CHUNK_SIZE)
break;
if (!xa_is_sibling(xa_entry(xas->xa, xas->xa_node, slot)))
break;
order++;
}
order += xas->xa_node->shift;
return order;
}
EXPORT_SYMBOL_GPL(xas_get_order);
/**
* xa_get_order() - Get the order of an entry.
* @xa: XArray.
@ -1759,30 +1789,13 @@ EXPORT_SYMBOL(xa_store_range);
int xa_get_order(struct xarray *xa, unsigned long index)
{
XA_STATE(xas, xa, index);
void *entry;
int order = 0;
void *entry;
rcu_read_lock();
entry = xas_load(&xas);
if (!entry)
goto unlock;
if (!xas.xa_node)
goto unlock;
for (;;) {
unsigned int slot = xas.xa_offset + (1 << order);
if (slot >= XA_CHUNK_SIZE)
break;
if (!xa_is_sibling(xas.xa_node->slots[slot]))
break;
order++;
}
order += xas.xa_node->shift;
unlock:
if (entry)
order = xas_get_order(&xas);
rcu_read_unlock();
return order;