[PATCHv5 12/36] brd: make it handle huge pages

Kirill A. Shutemov
2016-11-29T11:22:40Z

Do not assume length of bio segment is never larger than PAGE_SIZE.
With huge pages it's HPAGE_PMD_SIZE (2M on x86-64).

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
drivers/block/brd.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index ad793f35632c..fd050445c5d7 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -202,12 +202,15 @@ static int copy_to_brd_setup(struct brd_device *brd, sector_t sector, size_t n)
size_t copy;

copy = min_t(size_t, n, PAGE_SIZE - offset);
+ n -= copy;
if (!brd_insert_page(brd, sector))
return -ENOSPC;
- if (copy < n) {
+ while (n) {
sector += copy >> SECTOR_SHIFT;
if (!brd_insert_page(brd, sector))
return -ENOSPC;
+ copy = min_t(size_t, n, PAGE_SIZE);
+ n -= copy;
}
return 0;
}
@@ -242,6 +245,7 @@ static void copy_to_brd(struct brd_device *brd, const void *src,
size_t copy;

copy = min_t(size_t, n, PAGE_SIZE - offset);
+ n -= copy;
page = brd_lookup_page(brd, sector);
BUG_ON(!page);

@@ -249,10 +253,11 @@ static void copy_to_brd(struct brd_device *brd, const void *src,
memcpy(dst + offset, src, copy);
kunmap_atomic(dst);

- if (copy < n) {
+ while (n) {
src += copy;
sector += copy >> SECTOR_SHIFT;
- copy = n - copy;
+ copy = min_t(size_t, n, PAGE_SIZE);
+ n -= copy;
page = brd_lookup_page(brd, sector);
BUG_ON(!page);

@@ -274,6 +279,7 @@ static void copy_from_brd(void *dst, struct brd_device *brd,
size_t copy;

copy = min_t(size_t, n, PAGE_SIZE - offset);
+ n -= copy;
page = brd_lookup_page(brd, sector);
if (page) {
src = kmap_atomic(page);
@@ -282,10 +288,11 @@ static void copy_from_brd(void *dst, struct brd_device *brd,
} else
memset(dst, 0, copy);

- if (copy < n) {
+ while (n) {
dst += copy;
sector += copy >> SECTOR_SHIFT;
- copy = n - copy;
+ copy = min_t(size_t, n, PAGE_SIZE);
+ n -= copy;
page = brd_lookup_page(brd, sector);
if (page) {
src = kmap_atomic(page);