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xarray: Track free entries in an XArray

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Add the optional ability to track which entries in an XArray are free
and provide xa_alloc() to replace most of the functionality of the IDR.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
This commit is contained in:
Matthew Wilcox
2018-07-04 10:50:12 -04:00
parent 3d5bd6e1a0
commit 371c752dc6
4 changed files with 266 additions and 7 deletions
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61
lib/test_xarray.c
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@@ -33,6 +33,15 @@ static void *xa_store_index(struct xarray *xa, unsigned long index, gfp_t gfp)
return xa_store(xa, index, xa_mk_value(index & LONG_MAX), gfp);
}
static void xa_alloc_index(struct xarray *xa, unsigned long index, gfp_t gfp)
{
u32 id = 0;
XA_BUG_ON(xa, xa_alloc(xa, &id, UINT_MAX, xa_mk_value(index & LONG_MAX),
gfp) != 0);
XA_BUG_ON(xa, id != index);
}
static void xa_erase_index(struct xarray *xa, unsigned long index)
{
XA_BUG_ON(xa, xa_erase(xa, index) != xa_mk_value(index & LONG_MAX));
@@ -404,6 +413,57 @@ static noinline void check_multi_store(struct xarray *xa)
#endif
}
static DEFINE_XARRAY_ALLOC(xa0);
static noinline void check_xa_alloc(void)
{
int i;
u32 id;
/* An empty array should assign 0 to the first alloc */
xa_alloc_index(&xa0, 0, GFP_KERNEL);
/* Erasing it should make the array empty again */
xa_erase_index(&xa0, 0);
XA_BUG_ON(&xa0, !xa_empty(&xa0));
/* And it should assign 0 again */
xa_alloc_index(&xa0, 0, GFP_KERNEL);
/* The next assigned ID should be 1 */
xa_alloc_index(&xa0, 1, GFP_KERNEL);
xa_erase_index(&xa0, 1);
/* Storing a value should mark it used */
xa_store_index(&xa0, 1, GFP_KERNEL);
xa_alloc_index(&xa0, 2, GFP_KERNEL);
/* If we then erase 0, it should be free */
xa_erase_index(&xa0, 0);
xa_alloc_index(&xa0, 0, GFP_KERNEL);
xa_erase_index(&xa0, 1);
xa_erase_index(&xa0, 2);
for (i = 1; i < 5000; i++) {
xa_alloc_index(&xa0, i, GFP_KERNEL);
}
xa_destroy(&xa0);
id = 0xfffffffeU;
XA_BUG_ON(&xa0, xa_alloc(&xa0, &id, UINT_MAX, xa_mk_value(0),
GFP_KERNEL) != 0);
XA_BUG_ON(&xa0, id != 0xfffffffeU);
XA_BUG_ON(&xa0, xa_alloc(&xa0, &id, UINT_MAX, xa_mk_value(0),
GFP_KERNEL) != 0);
XA_BUG_ON(&xa0, id != 0xffffffffU);
XA_BUG_ON(&xa0, xa_alloc(&xa0, &id, UINT_MAX, xa_mk_value(0),
GFP_KERNEL) != -ENOSPC);
XA_BUG_ON(&xa0, id != 0xffffffffU);
xa_destroy(&xa0);
}
static noinline void __check_store_iter(struct xarray *xa, unsigned long start,
unsigned int order, unsigned int present)
{
@@ -849,6 +909,7 @@ static int xarray_checks(void)
check_cmpxchg(&array);
check_reserve(&array);
check_multi_store(&array);
check_xa_alloc();
check_find(&array);
check_destroy(&array);
check_move(&array);