drbd: allow to select specific bitmap pages for writeout
We are about to allow several changes to the active set in one activity
log transaction. We have to write out the corresponding bitmap pages as
well, if changed.
Introduce drbd_bm_mark_for_writeout(), then re-use the existing bitmap
writeout path to submit all marked pages in one go.
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
diff --git a/drivers/block/drbd/drbd_bitmap.c b/drivers/block/drbd/drbd_bitmap.c
index 4be7370..bc89c4a 100644
--- a/drivers/block/drbd/drbd_bitmap.c
+++ b/drivers/block/drbd/drbd_bitmap.c
@@ -188,6 +188,9 @@
/* to mark for lazy writeout once syncer cleared all clearable bits,
* we if bits have been cleared since last IO. */
#define BM_PAGE_LAZY_WRITEOUT 28
+/* pages marked with this "HINT" will be considered for writeout
+ * on activity log transactions */
+#define BM_PAGE_HINT_WRITEOUT 27
/* store_page_idx uses non-atomic assignment. It is only used directly after
* allocating the page. All other bm_set_page_* and bm_clear_page_* need to
@@ -237,6 +240,27 @@
set_bit(BM_PAGE_NEED_WRITEOUT, &page_private(page));
}
+/**
+ * drbd_bm_mark_for_writeout() - mark a page with a "hint" to be considered for writeout
+ * @mdev: DRBD device.
+ * @page_nr: the bitmap page to mark with the "hint" flag
+ *
+ * From within an activity log transaction, we mark a few pages with these
+ * hints, then call drbd_bm_write_hinted(), which will only write out changed
+ * pages which are flagged with this mark.
+ */
+void drbd_bm_mark_for_writeout(struct drbd_conf *mdev, int page_nr)
+{
+ struct page *page;
+ if (page_nr >= mdev->bitmap->bm_number_of_pages) {
+ dev_warn(DEV, "BAD: page_nr: %u, number_of_pages: %u\n",
+ page_nr, (int)mdev->bitmap->bm_number_of_pages);
+ return;
+ }
+ page = mdev->bitmap->bm_pages[page_nr];
+ set_bit(BM_PAGE_HINT_WRITEOUT, &page_private(page));
+}
+
static int bm_test_page_unchanged(struct page *page)
{
volatile const unsigned long *addr = &page_private(page);
@@ -897,6 +921,7 @@
struct completion done;
unsigned flags;
#define BM_AIO_COPY_PAGES 1
+#define BM_AIO_WRITE_HINTED 2
int error;
};
@@ -1007,13 +1032,13 @@
/*
* bm_rw: read/write the whole bitmap from/to its on disk location.
*/
-static int bm_rw(struct drbd_conf *mdev, int rw, unsigned lazy_writeout_upper_idx) __must_hold(local)
+static int bm_rw(struct drbd_conf *mdev, int rw, unsigned flags, unsigned lazy_writeout_upper_idx) __must_hold(local)
{
struct bm_aio_ctx ctx = {
.mdev = mdev,
.in_flight = ATOMIC_INIT(1),
.done = COMPLETION_INITIALIZER_ONSTACK(ctx.done),
- .flags = lazy_writeout_upper_idx ? BM_AIO_COPY_PAGES : 0,
+ .flags = flags,
};
struct drbd_bitmap *b = mdev->bitmap;
int num_pages, i, count = 0;
@@ -1042,6 +1067,10 @@
if (lazy_writeout_upper_idx && i == lazy_writeout_upper_idx)
break;
if (rw & WRITE) {
+ if ((flags & BM_AIO_WRITE_HINTED) &&
+ !test_and_clear_bit(BM_PAGE_HINT_WRITEOUT,
+ &page_private(b->bm_pages[i])))
+ continue;
if (bm_test_page_unchanged(b->bm_pages[i])) {
dynamic_dev_dbg(DEV, "skipped bm write for idx %u\n", i);
continue;
@@ -1099,7 +1128,7 @@
*/
int drbd_bm_read(struct drbd_conf *mdev) __must_hold(local)
{
- return bm_rw(mdev, READ, 0);
+ return bm_rw(mdev, READ, 0, 0);
}
/**
@@ -1110,7 +1139,7 @@
*/
int drbd_bm_write(struct drbd_conf *mdev) __must_hold(local)
{
- return bm_rw(mdev, WRITE, 0);
+ return bm_rw(mdev, WRITE, 0, 0);
}
/**
@@ -1120,12 +1149,20 @@
*/
int drbd_bm_write_lazy(struct drbd_conf *mdev, unsigned upper_idx) __must_hold(local)
{
- return bm_rw(mdev, WRITE, upper_idx);
+ return bm_rw(mdev, WRITE, BM_AIO_COPY_PAGES, upper_idx);
}
+/**
+ * drbd_bm_write_hinted() - Write bitmap pages with "hint" marks, if they have changed.
+ * @mdev: DRBD device.
+ */
+int drbd_bm_write_hinted(struct drbd_conf *mdev) __must_hold(local)
+{
+ return bm_rw(mdev, WRITE, BM_AIO_WRITE_HINTED | BM_AIO_COPY_PAGES, 0);
+}
/**
- * drbd_bm_write_page: Writes a PAGE_SIZE aligned piece of bitmap
+ * drbd_bm_write_page() - Writes a PAGE_SIZE aligned piece of bitmap
* @mdev: DRBD device.
* @idx: bitmap page index
*