XArray: Regularise xa_reserve

The xa_reserve() function was a little unusual in that it attempted to
be callable for all kinds of locking scenarios.  Make it look like the
other APIs with __xa_reserve, xa_reserve_bh and xa_reserve_irq variants.

Signed-off-by: Matthew Wilcox <willy@infradead.org>

2 files changed, 13 insertions, 11 deletions

diff --git a/lib/test_xarray.c b/lib/test_xarray.c
index 126127658b49..e5294b20b52f 100644
--- a/lib/test_xarray.c
+++ b/lib/test_xarray.c
@@ -373,6 +373,12 @@ static noinline void check_reserve(struct xarray *xa)
         xa_erase_index(xa, 12345678);
         XA_BUG_ON(xa, !xa_empty(xa));
 
+        /* And so does xa_insert */
+        xa_reserve(xa, 12345678, GFP_KERNEL);
+        XA_BUG_ON(xa, xa_insert(xa, 12345678, xa_mk_value(12345678), 0) != 0);
+        xa_erase_index(xa, 12345678);
+        XA_BUG_ON(xa, !xa_empty(xa));
+
         /* Can iterate through a reserved entry */
         xa_store_index(xa, 5, GFP_KERNEL);
         xa_reserve(xa, 6, GFP_KERNEL);
diff --git a/lib/xarray.c b/lib/xarray.c
index e7be4e47c6a9..9cab8cfef8a8 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -1488,7 +1488,7 @@ void *__xa_cmpxchg(struct xarray *xa, unsigned long index,
 EXPORT_SYMBOL(__xa_cmpxchg);
 
 /**
- * xa_reserve() - Reserve this index in the XArray.
+ * __xa_reserve() - Reserve this index in the XArray.
  * @xa: XArray.
  * @index: Index into array.
  * @gfp: Memory allocation flags.
@@ -1496,33 +1496,29 @@ EXPORT_SYMBOL(__xa_cmpxchg);
  * Ensures there is somewhere to store an entry at @index in the array.
  * If there is already something stored at @index, this function does
  * nothing.  If there was nothing there, the entry is marked as reserved.
- * Loads from @index will continue to see a %NULL pointer until a
- * subsequent store to @index.
+ * Loading from a reserved entry returns a %NULL pointer.
  *
  * If you do not use the entry that you have reserved, call xa_release()
  * or xa_erase() to free any unnecessary memory.
  *
- * Context: Process context.  Takes and releases the xa_lock, IRQ or BH safe
- * if specified in XArray flags.  May sleep if the @gfp flags permit.
+ * Context: Any context.  Expects the xa_lock to be held on entry.  May
+ * release the lock, sleep and reacquire the lock if the @gfp flags permit.
  * Return: 0 if the reservation succeeded or -ENOMEM if it failed.
  */
-int xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp)
+int __xa_reserve(struct xarray *xa, unsigned long index, gfp_t gfp)
 {
         XA_STATE(xas, xa, index);
-        unsigned int lock_type = xa_lock_type(xa);
         void *curr;
 
         do {
-                xas_lock_type(&xas, lock_type);
                 curr = xas_load(&xas);
                 if (!curr)
                         xas_store(&xas, XA_ZERO_ENTRY);
-                xas_unlock_type(&xas, lock_type);
-        } while (xas_nomem(&xas, gfp));
+        } while (__xas_nomem(&xas, gfp));
 
         return xas_error(&xas);
 }
-EXPORT_SYMBOL(xa_reserve);
+EXPORT_SYMBOL(__xa_reserve);
 
 #ifdef CONFIG_XARRAY_MULTI
 static void xas_set_range(struct xa_state *xas, unsigned long first,