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>

diff --git a/kernel/relay.c b/kernel/relay.c
index d6204a4..bc24dcd 100644 (file)
--- 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);