drbd: get rid of bio_split, allow bios of "arbitrary" size

Where "arbitrary" size is currently 1 MiB, which is the BIO_MAX_SIZE
for architectures with 4k PAGE_CACHE_SIZE (most).

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

1 files changed, 14 insertions, 6 deletions

diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 8f43a366b82c..2dbffb3b5485 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -1326,8 +1326,16 @@ struct bm_extent {
 #endif
 #endif
 
-#define HT_SHIFT 8
-#define DRBD_MAX_BIO_SIZE (1U<<(9+HT_SHIFT))
+/* BIO_MAX_SIZE is 256 * PAGE_CACHE_SIZE,
+ * so for typical PAGE_CACHE_SIZE of 4k, that is (1<<20) Byte.
+ * Since we may live in a mixed-platform cluster,
+ * we limit us to a platform agnostic constant here for now.
+ * A followup commit may allow even bigger BIO sizes,
+ * once we thought that through. */
+#define DRBD_MAX_BIO_SIZE (1 << 20)
+#if DRBD_MAX_BIO_SIZE > BIO_MAX_SIZE
+#error Architecture not supported: DRBD_MAX_BIO_SIZE > BIO_MAX_SIZE
+#endif
 #define DRBD_MAX_BIO_SIZE_SAFE (1 << 12)       /* Works always = 4k */
 
 #define DRBD_MAX_SIZE_H80_PACKET (1 << 15) /* The old header only allows packets up to 32Kib data */
@@ -2231,20 +2239,20 @@ static inline bool may_inc_ap_bio(struct drbd_conf *mdev)
         return true;
 }
 
-static inline bool inc_ap_bio_cond(struct drbd_conf *mdev, int count)
+static inline bool inc_ap_bio_cond(struct drbd_conf *mdev)
 {
         bool rv = false;
 
         spin_lock_irq(&mdev->tconn->req_lock);
         rv = may_inc_ap_bio(mdev);
         if (rv)
-                atomic_add(count, &mdev->ap_bio_cnt);
+                atomic_inc(&mdev->ap_bio_cnt);
         spin_unlock_irq(&mdev->tconn->req_lock);
 
         return rv;
 }
 
-static inline void inc_ap_bio(struct drbd_conf *mdev, int count)
+static inline void inc_ap_bio(struct drbd_conf *mdev)
 {
         /* we wait here
          *    as long as the device is suspended
@@ -2254,7 +2262,7 @@ static inline void inc_ap_bio(struct drbd_conf *mdev, int count)
          * to avoid races with the reconnect code,
          * we need to atomic_inc within the spinlock. */
 
-        wait_event(mdev->misc_wait, inc_ap_bio_cond(mdev, count));
+        wait_event(mdev->misc_wait, inc_ap_bio_cond(mdev));
 }
 
 static inline void dec_ap_bio(struct drbd_conf *mdev)