relayfs: support larger relay buffer

Use vmalloc() and memset() instead of kcalloc() to allocate a page* array when
the array size is bigger than one page.  This enables relayfs to support
bigger relay buffers than 64MB on 4k-page system, 512MB on 16k-page system.

[akpm@linux-foundation.org: cleanup]
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: David Wilder <dwilder@us.ibm.com>
Reviewed-by: Tom Zanussi <zanussi@comcast.net>
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 32 insertions, 3 deletions

diff --git a/kernel/relay.c b/kernel/relay.c
index d6204a485818..bc24dcdc570f 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -65,6 +65,35 @@ static struct vm_operations_struct relay_file_mmap_ops = {
         .close = relay_file_mmap_close,
 };
 
+/*
+ * allocate an array of pointers of struct page
+ */
+static struct page **relay_alloc_page_array(unsigned int n_pages)
+{
+        struct page **array;
+        size_t pa_size = n_pages * sizeof(struct page *);
+
+        if (pa_size > PAGE_SIZE) {
+                array = vmalloc(pa_size);
+                if (array)
+                        memset(array, 0, pa_size);
+        } else {
+                array = kzalloc(pa_size, GFP_KERNEL);
+        }
+        return array;
+}
+
+/*
+ * free an array of pointers of struct page
+ */
+static void relay_free_page_array(struct page **array)
+{
+        if (is_vmalloc_addr(array))
+                vfree(array);
+        else
+                kfree(array);
+}
+
 /**
  *      relay_mmap_buf: - mmap channel buffer to process address space
  *      @buf: relay channel buffer
@@ -109,7 +138,7 @@ static void *relay_alloc_buf(struct rchan_buf *buf, size_t *size)
         *size = PAGE_ALIGN(*size);
         n_pages = *size >> PAGE_SHIFT;
 
-        buf->page_array = kcalloc(n_pages, sizeof(struct page *), GFP_KERNEL);
+        buf->page_array = relay_alloc_page_array(n_pages);
         if (!buf->page_array)
                 return NULL;
 
@@ -130,7 +159,7 @@ static void *relay_alloc_buf(struct rchan_buf *buf, size_t *size)
 depopulate:
         for (j = 0; j < i; j++)
                 __free_page(buf->page_array[j]);
-        kfree(buf->page_array);
+        relay_free_page_array(buf->page_array);
         return NULL;
 }
 
@@ -189,7 +218,7 @@ static void relay_destroy_buf(struct rchan_buf *buf)
                 vunmap(buf->start);
                 for (i = 0; i < buf->page_count; i++)
                         __free_page(buf->page_array[i]);
-                kfree(buf->page_array);
+                relay_free_page_array(buf->page_array);
         }
         chan->buf[buf->cpu] = NULL;
         kfree(buf->padding);