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authorDavid Rientjes <rientjes@google.com>2009-09-21 17:04:31 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-22 07:17:47 -0700
commit4af5a2f770cc8575840ccb1514ec76ecb592985c (patch)
tree7af18234d7d171a946925e65e987fd51648be3aa /lib/flex_array.c
parent19da3dd157f8db6fe727ff268dab4791d55a6371 (diff)
downloadvexpress-lsk-4af5a2f770cc8575840ccb1514ec76ecb592985c.tar.gz
flex_array: add flex_array_shrink function
Add a new function to the flex_array API: int flex_array_shrink(struct flex_array *fa) This function will free all unused second-level pages. Since elements are now poisoned if they are not allocated with __GFP_ZERO, it's possible to identify parts that consist solely of unused elements. flex_array_shrink() returns the number of pages freed. Signed-off-by: David Rientjes <rientjes@google.com> Cc: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/flex_array.c')
-rw-r--r--lib/flex_array.c40
1 files changed, 40 insertions, 0 deletions
diff --git a/lib/flex_array.c b/lib/flex_array.c
index e22d0e9776a..1b03bb55341 100644
--- a/lib/flex_array.c
+++ b/lib/flex_array.c
@@ -291,3 +291,43 @@ void *flex_array_get(struct flex_array *fa, unsigned int element_nr)
}
return &part->elements[index_inside_part(fa, element_nr)];
}
+
+static int part_is_free(struct flex_array_part *part)
+{
+ int i;
+
+ for (i = 0; i < sizeof(struct flex_array_part); i++)
+ if (part->elements[i] != FLEX_ARRAY_FREE)
+ return 0;
+ return 1;
+}
+
+/**
+ * flex_array_shrink - free unused second-level pages
+ *
+ * Frees all second-level pages that consist solely of unused
+ * elements. Returns the number of pages freed.
+ *
+ * Locking must be provided by the caller.
+ */
+int flex_array_shrink(struct flex_array *fa)
+{
+ struct flex_array_part *part;
+ int max_part = nr_base_part_ptrs();
+ int part_nr;
+ int ret = 0;
+
+ if (elements_fit_in_base(fa))
+ return ret;
+ for (part_nr = 0; part_nr < max_part; part_nr++) {
+ part = fa->parts[part_nr];
+ if (!part)
+ continue;
+ if (part_is_free(part)) {
+ fa->parts[part_nr] = NULL;
+ kfree(part);
+ ret++;
+ }
+ }
+ return ret;
+}