drbd: Allow drbd_epoch_entries to use multiple bios.

This should allow for better performance if the lower level IO stack
of the peers differs in limits exposed either via the queue,
or via some merge_bvec_fn.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

1 files changed, 11 insertions, 7 deletions

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 93d150661f4b..28ef76bd5230 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -2215,9 +2215,9 @@ void drbd_bcast_ee(struct drbd_conf *mdev,
 {
         struct cn_msg *cn_reply;
         struct drbd_nl_cfg_reply *reply;
-        struct bio_vec *bvec;
         unsigned short *tl;
-        int i;
+        struct page *page;
+        unsigned len;
 
         if (!e)
                 return;
@@ -2255,11 +2255,15 @@ void drbd_bcast_ee(struct drbd_conf *mdev,
         put_unaligned(T_ee_data, tl++);
         put_unaligned(e->size, tl++);
 
-        __bio_for_each_segment(bvec, e->private_bio, i, 0) {
-                void *d = kmap(bvec->bv_page);
-                memcpy(tl, d + bvec->bv_offset, bvec->bv_len);
-                kunmap(bvec->bv_page);
-                tl=(unsigned short*)((char*)tl + bvec->bv_len);
+        len = e->size;
+        page = e->pages;
+        page_chain_for_each(page) {
+                void *d = kmap_atomic(page, KM_USER0);
+                unsigned l = min_t(unsigned, len, PAGE_SIZE);
+                memcpy(tl, d, l);
+                kunmap_atomic(d, KM_USER0);
+                tl = (unsigned short*)((char*)tl + l);
+                len -= l;
         }
         put_unaligned(TT_END, tl++); /* Close the tag list */