Re: [PATCH V2] block: null_blk: fix 'Invalid parameters' when loading module

[Jens Axboe]

On 3/5/18 9:07 PM, Ming Lei wrote:
> On ARM64, the default page size has been 64K on some distributions, and
> we should allow ARM64 people to play null_blk.
> 
> This patch fixes the issue by extend page bitmap size for supporting
> other non-4KB PAGE_SIZE.

Applied, thanks.

-- 
Jens Axboe

[PATCH V2] block: null_blk: fix 'Invalid parameters' when loading module

[Ming Lei]

On ARM64, the default page size has been 64K on some distributions, and
we should allow ARM64 people to play null_blk.

This patch fixes the issue by extend page bitmap size for supporting
other non-4KB PAGE_SIZE.

Cc: Bart Van Assche 
Cc: Shaohua Li 
Cc: Kyungchan Koh ,
Cc: weiping zhang 
Cc: Yi Zhang 
Reported-by: Yi Zhang 
Signed-off-by: Ming Lei 
---
 drivers/block/null_blk.c | 46 +-
 1 file changed, 25 insertions(+), 21 deletions(-)

diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index 51b16249028a..3c5a684de170 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -72,6 +72,7 @@ enum nullb_device_flags {
NULLB_DEV_FL_CACHE  = 3,
 };
 
+#define MAP_SZ ((PAGE_SIZE >> SECTOR_SHIFT) + 2)
 /*
  * nullb_page is a page in memory for nullb devices.
  *
@@ -86,10 +87,10 @@ enum nullb_device_flags {
  */
 struct nullb_page {
struct page *page;
-   unsigned long bitmap;
+   DECLARE_BITMAP(bitmap, MAP_SZ);
 };
-#define NULLB_PAGE_LOCK (sizeof(unsigned long) * 8 - 1)
-#define NULLB_PAGE_FREE (sizeof(unsigned long) * 8 - 2)
+#define NULLB_PAGE_LOCK (MAP_SZ - 1)
+#define NULLB_PAGE_FREE (MAP_SZ - 2)
 
 struct nullb_device {
struct nullb *nullb;
@@ -732,7 +733,7 @@ static struct nullb_page *null_alloc_page(gfp_t gfp_flags)
if (!t_page->page)
goto out_freepage;
 
-   t_page->bitmap = 0;
+   memset(t_page->bitmap, 0, sizeof(t_page->bitmap));
return t_page;
 out_freepage:
kfree(t_page);
@@ -742,13 +743,20 @@ static struct nullb_page *null_alloc_page(gfp_t gfp_flags)
 
 static void null_free_page(struct nullb_page *t_page)
 {
-   __set_bit(NULLB_PAGE_FREE, _page->bitmap);
-   if (test_bit(NULLB_PAGE_LOCK, _page->bitmap))
+   __set_bit(NULLB_PAGE_FREE, t_page->bitmap);
+   if (test_bit(NULLB_PAGE_LOCK, t_page->bitmap))
return;
__free_page(t_page->page);
kfree(t_page);
 }
 
+static bool null_page_empty(struct nullb_page *page)
+{
+   int size = MAP_SZ - 2;
+
+   return find_first_bit(page->bitmap, size) == size;
+}
+
 static void null_free_sector(struct nullb *nullb, sector_t sector,
bool is_cache)
 {
@@ -763,9 +771,9 @@ static void null_free_sector(struct nullb *nullb, sector_t 
sector,
 
t_page = radix_tree_lookup(root, idx);
if (t_page) {
-   __clear_bit(sector_bit, _page->bitmap);
+   __clear_bit(sector_bit, t_page->bitmap);
 
-   if (!t_page->bitmap) {
+   if (null_page_empty(t_page)) {
ret = radix_tree_delete_item(root, idx, t_page);
WARN_ON(ret != t_page);
null_free_page(ret);
@@ -836,7 +844,7 @@ static struct nullb_page *__null_lookup_page(struct nullb 
*nullb,
t_page = radix_tree_lookup(root, idx);
WARN_ON(t_page && t_page->page->index != idx);
 
-   if (t_page && (for_write || test_bit(sector_bit, _page->bitmap)))
+   if (t_page && (for_write || test_bit(sector_bit, t_page->bitmap)))
return t_page;
 
return NULL;
@@ -899,10 +907,10 @@ static int null_flush_cache_page(struct nullb *nullb, 
struct nullb_page *c_page)
 
t_page = null_insert_page(nullb, idx << PAGE_SECTORS_SHIFT, true);
 
-   __clear_bit(NULLB_PAGE_LOCK, _page->bitmap);
-   if (test_bit(NULLB_PAGE_FREE, _page->bitmap)) {
+   __clear_bit(NULLB_PAGE_LOCK, c_page->bitmap);
+   if (test_bit(NULLB_PAGE_FREE, c_page->bitmap)) {
null_free_page(c_page);
-   if (t_page && t_page->bitmap == 0) {
+   if (t_page && null_page_empty(t_page)) {
ret = radix_tree_delete_item(>dev->data,
idx, t_page);
null_free_page(t_page);
@@ -918,11 +926,11 @@ static int null_flush_cache_page(struct nullb *nullb, 
struct nullb_page *c_page)
 
for (i = 0; i < PAGE_SECTORS;
i += (nullb->dev->blocksize >> SECTOR_SHIFT)) {
-   if (test_bit(i, _page->bitmap)) {
+   if (test_bit(i, c_page->bitmap)) {
offset = (i << SECTOR_SHIFT);
memcpy(dst + offset, src + offset,
nullb->dev->blocksize);
-   __set_bit(i, _page->bitmap);
+   __set_bit(i, t_page->bitmap);
}
}
 
@@ -959,10 +967,10 @@ static int null_make_cache_space(struct nullb *nullb, 
unsigned long n)
 * We found the page which is being flushed to disk by other
 * threads
 */
-   if (test_bit(NULLB_PAGE_LOCK, _pages[i]->bitmap))
+   if (test_bit(NULLB_PAGE_LOCK,