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XArray: Fix xa_reserve for 2-byte aligned entries 

If we reserve index 0, the next entry to be stored there might be 2-byte
aligned.  That means we have to create the root xa_node at the time of
reserving the initial entry.

Signed-off-by: Matthew Wilcox <willy@infradead.org>
This commit is contained in:
Matthew Wilcox 2019-02-21 17:54:44 -05:00
parent 2fbe967b3e
commit 4a5c8d8989
2 changed files with 15 additions and 3 deletions
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10
lib/test_xarray.c
View File

@ -1355,6 +1355,10 @@ static void check_align_1(struct xarray *xa, char *name)
xa_destroy(xa);
}
/*
* We should always be able to store without allocating memory after
* reserving a slot.
*/
static void check_align_2(struct xarray *xa, char *name)
{
int i;
@ -1366,6 +1370,12 @@ static void check_align_2(struct xarray *xa, char *name)
xa_erase(xa, 0);
}
for (i = 0; i < 8; i++) {
XA_BUG_ON(xa, xa_reserve(xa, 0, GFP_KERNEL) != 0);
XA_BUG_ON(xa, xa_store(xa, 0, name + i, 0) != NULL);
xa_erase(xa, 0);
}
XA_BUG_ON(xa, !xa_empty(xa));
}

8
lib/xarray.c
View File

@ -767,10 +767,12 @@ void *xas_store(struct xa_state *xas, void *entry)
void *first, *next;
bool value = xa_is_value(entry);
if (entry)
first = xas_create(xas, !xa_is_node(entry));
else
if (entry) {
bool allow_root = !xa_is_node(entry) && !xa_is_zero(entry);
first = xas_create(xas, allow_root);
} else {
first = xas_load(xas);
}
if (xas_invalid(xas))
return first;