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authorMatthew Wilcox <willy@linux.intel.com>2016-12-15 02:09:04 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2016-12-15 03:04:10 +0300
commit2791653a6814d170fa893344618563a7b1da95c6 (patch)
tree635c8ca43b49ac15836e5d4b5786d64733661755 /lib
parente157b555945fb16ddc6cce605a1eb6b4135ea5f1 (diff)
downloadlinux-2791653a6814d170fa893344618563a7b1da95c6.tar.xz
radix-tree: add radix_tree_split_preload()
Calculate how many nodes we need to allocate to split an old_order entry into multiple entries, each of size new_order. The test suite checks that we allocated exactly the right number of nodes; neither too many (checked by rtp->nr == 0), nor too few (checked by comparing nr_allocated before and after the call to radix_tree_split()). Link: http://lkml.kernel.org/r/1480369871-5271-60-git-send-email-mawilcox@linuxonhyperv.com Signed-off-by: Matthew Wilcox <willy@linux.intel.com> Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Matthew Wilcox <mawilcox@microsoft.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/radix-tree.c24
1 files changed, 23 insertions, 1 deletions
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index ade2ed3f5190..be1183e62590 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -368,7 +368,7 @@ radix_tree_node_free(struct radix_tree_node *node)
* To make use of this facility, the radix tree must be initialised without
* __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
*/
-static int __radix_tree_preload(gfp_t gfp_mask, int nr)
+static int __radix_tree_preload(gfp_t gfp_mask, unsigned nr)
{
struct radix_tree_preload *rtp;
struct radix_tree_node *node;
@@ -434,6 +434,28 @@ int radix_tree_maybe_preload(gfp_t gfp_mask)
}
EXPORT_SYMBOL(radix_tree_maybe_preload);
+#ifdef CONFIG_RADIX_TREE_MULTIORDER
+/*
+ * Preload with enough objects to ensure that we can split a single entry
+ * of order @old_order into many entries of size @new_order
+ */
+int radix_tree_split_preload(unsigned int old_order, unsigned int new_order,
+ gfp_t gfp_mask)
+{
+ unsigned top = 1 << (old_order % RADIX_TREE_MAP_SHIFT);
+ unsigned layers = (old_order / RADIX_TREE_MAP_SHIFT) -
+ (new_order / RADIX_TREE_MAP_SHIFT);
+ unsigned nr = 0;
+
+ WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask));
+ BUG_ON(new_order >= old_order);
+
+ while (layers--)
+ nr = nr * RADIX_TREE_MAP_SIZE + 1;
+ return __radix_tree_preload(gfp_mask, top * nr);
+}
+#endif
+
/*
* The same as function above, but preload number of nodes required to insert
* (1 << order) continuous naturally-aligned elements.