RAID1: a new I/O barrier implementation to remove resync window

[linux-2.6-microblaze.git] / drivers / md / raid1.h

diff --git a/drivers/md/raid1.h b/drivers/md/raid1.h
index c52ef42..3442e8f 100644 (file)
--- a/drivers/md/raid1.h
+++ b/drivers/md/raid1.h
@@ -1,6 +1,29 @@
 #ifndef _RAID1_H
 #define _RAID1_H
 
+/*
+ * each barrier unit size is 64MB fow now
+ * note: it must be larger than RESYNC_DEPTH
+ */
+#define BARRIER_UNIT_SECTOR_BITS       17
+#define BARRIER_UNIT_SECTOR_SIZE       (1<<17)
+/*
+ * In struct r1conf, the following members are related to I/O barrier
+ * buckets,
+ *     int     *nr_pending;
+ *     int     *nr_waiting;
+ *     int     *nr_queued;
+ *     int     *barrier;
+ * Each of them points to array of integers, each array is designed to
+ * have BARRIER_BUCKETS_NR elements and occupy a single memory page. The
+ * data width of integer variables is 4, equal to 1<<(ilog2(sizeof(int))),
+ * BARRIER_BUCKETS_NR_BITS is defined as (PAGE_SHIFT - ilog2(sizeof(int)))
+ * to make sure an array of integers with BARRIER_BUCKETS_NR elements just
+ * exactly occupies a single memory page.
+ */
+#define BARRIER_BUCKETS_NR_BITS                (PAGE_SHIFT - ilog2(sizeof(int)))
+#define BARRIER_BUCKETS_NR             (1<<BARRIER_BUCKETS_NR_BITS)
+
 struct raid1_info {
        struct md_rdev  *rdev;
        sector_t        head_position;
@@ -35,25 +58,6 @@ struct r1conf {
                                                 */
        int                     raid_disks;
 
-       /* During resync, read_balancing is only allowed on the part
-        * of the array that has been resynced.  'next_resync' tells us
-        * where that is.
-        */
-       sector_t                next_resync;
-
-       /* When raid1 starts resync, we divide array into four partitions
-        * |---------|--------------|---------------------|-------------|
-        *        next_resync   start_next_window       end_window
-        * start_next_window = next_resync + NEXT_NORMALIO_DISTANCE
-        * end_window = start_next_window + NEXT_NORMALIO_DISTANCE
-        * current_window_requests means the count of normalIO between
-        *   start_next_window and end_window.
-        * next_window_requests means the count of normalIO after end_window.
-        * */
-       sector_t                start_next_window;
-       int                     current_window_requests;
-       int                     next_window_requests;
-
        spinlock_t              device_lock;
 
        /* list of 'struct r1bio' that need to be processed by raid1d,
@@ -79,10 +83,10 @@ struct r1conf {
         */
        wait_queue_head_t       wait_barrier;
        spinlock_t              resync_lock;
-       int                     nr_pending;
-       int                     nr_waiting;
-       int                     nr_queued;
-       int                     barrier;
+       int                     *nr_pending;
+       int                     *nr_waiting;
+       int                     *nr_queued;
+       int                     *barrier;
        int                     array_frozen;
 
        /* Set to 1 if a full sync is needed, (fresh device added).
@@ -135,7 +139,6 @@ struct r1bio {
                                                 * in this BehindIO request
                                                 */
        sector_t                sector;
-       sector_t                start_next_window;
        int                     sectors;
        unsigned long           state;
        struct mddev            *mddev;
@@ -185,4 +188,10 @@ enum r1bio_state {
        R1BIO_WriteError,
        R1BIO_FailFast,
 };
+
+static inline int sector_to_idx(sector_t sector)
+{
+       return hash_long(sector >> BARRIER_UNIT_SECTOR_BITS,
+                        BARRIER_BUCKETS_NR_BITS);
+}
 #endif