md/raid5: change raid5_compute_sector and stripe_to_pdidx to take a 'previous' argument

This similar to the recent change to get_active_stripe.
There is no functional change, just come rearrangement to make
future patches cleaner.

Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 34 insertions, 44 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index c38310be0d9..c33073fe742 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -274,7 +274,7 @@ static int grow_buffers(struct stripe_head *sh, int num)
 }
 
 static void raid5_build_block(struct stripe_head *sh, int i);
-static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int disks);
+static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int previous);
 
 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
 {
@@ -293,7 +293,7 @@ static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
 
         sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
         sh->sector = sector;
-        sh->pd_idx = stripe_to_pdidx(sector, conf, sh->disks);
+        sh->pd_idx = stripe_to_pdidx(sector, conf, previous);
         sh->state = 0;
 
 
@@ -1233,15 +1233,18 @@ static void error(mddev_t *mddev, mdk_rdev_t *rdev)
  * Input: a 'big' sector number,
  * Output: index of the data and parity disk, and the sector # in them.
  */
-static sector_t raid5_compute_sector(sector_t r_sector, unsigned int raid_disks,
-                        unsigned int data_disks, unsigned int * dd_idx,
-                        unsigned int * pd_idx, raid5_conf_t *conf)
+static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
+                                     int previous,
+                                     int *dd_idx, int *pd_idx)
 {
         long stripe;
         unsigned long chunk_number;
         unsigned int chunk_offset;
         sector_t new_sector;
         int sectors_per_chunk = conf->chunk_size >> 9;
+        int raid_disks = previous ? conf->previous_raid_disks
+                                  : conf->raid_disks;
+        int data_disks = raid_disks - conf->max_degraded;
 
         /* First compute the information on this sector */
 
@@ -1406,7 +1409,9 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i)
         chunk_number = stripe * data_disks + i;
         r_sector = (sector_t)chunk_number * sectors_per_chunk + chunk_offset;
 
-        check = raid5_compute_sector(r_sector, raid_disks, data_disks, &dummy1, &dummy2, conf);
+        check = raid5_compute_sector(conf, r_sector,
+                                     (raid_disks != conf->raid_disks),
+                                     &dummy1, &dummy2);
         if (check != sh->sector || dummy1 != dd_idx || dummy2 != sh->pd_idx) {
                 printk(KERN_ERR "compute_blocknr: map not correct\n");
                 return 0;
@@ -1806,16 +1811,18 @@ static int page_is_zero(struct page *p)
                 memcmp(a, a+4, STRIPE_SIZE-4)==0);
 }
 
-static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int disks)
+static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int previous)
 {
         int sectors_per_chunk = conf->chunk_size >> 9;
         int pd_idx, dd_idx;
         int chunk_offset = sector_div(stripe, sectors_per_chunk);
+        int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
 
-        raid5_compute_sector(stripe * (disks - conf->max_degraded)
+        raid5_compute_sector(conf,
+                             stripe * (disks - conf->max_degraded)
                              *sectors_per_chunk + chunk_offset,
-                             disks, disks - conf->max_degraded,
-                             &dd_idx, &pd_idx, conf);
+                             previous,
+                             &dd_idx, &pd_idx);
         return pd_idx;
 }
 
@@ -2478,10 +2485,8 @@ static void handle_stripe_expansion(raid5_conf_t *conf, struct stripe_head *sh,
                         struct stripe_head *sh2;
 
                         sector_t bn = compute_blocknr(sh, i);
-                        sector_t s = raid5_compute_sector(bn, conf->raid_disks,
-                                                conf->raid_disks -
-                                                conf->max_degraded, &dd_idx,
-                                                &pd_idx, conf);
+                        sector_t s = raid5_compute_sector(conf, bn, 0,
+                                                          &dd_idx, &pd_idx);
                         sh2 = get_active_stripe(conf, s, 0, 1);
                         if (sh2 == NULL)
                                 /* so far only the early blocks of this stripe
@@ -2768,8 +2773,7 @@ static bool handle_stripe5(struct stripe_head *sh)
             !sh->reconstruct_state) {
                 /* Need to write out all blocks after computing parity */
                 sh->disks = conf->raid_disks;
-                sh->pd_idx = stripe_to_pdidx(sh->sector, conf,
-                        conf->raid_disks);
+                sh->pd_idx = stripe_to_pdidx(sh->sector, conf, 0);
                 schedule_reconstruction5(sh, &s, 1, 1);
         } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
@@ -2987,8 +2991,7 @@ static bool handle_stripe6(struct stripe_head *sh, struct page *tmp_page)
         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state)) {
                 /* Need to write out all blocks after computing P&Q */
                 sh->disks = conf->raid_disks;
-                sh->pd_idx = stripe_to_pdidx(sh->sector, conf,
-                                             conf->raid_disks);
+                sh->pd_idx = stripe_to_pdidx(sh->sector, conf, 0);
                 compute_parity6(sh, RECONSTRUCT_WRITE);
                 for (i = conf->raid_disks ; i-- ;  ) {
                         set_bit(R5_LOCKED, &sh->dev[i].flags);
@@ -3260,8 +3263,6 @@ static int chunk_aligned_read(struct request_queue *q, struct bio * raid_bio)
 {
         mddev_t *mddev = q->queuedata;
         raid5_conf_t *conf = mddev_to_conf(mddev);
-        const unsigned int raid_disks = conf->raid_disks;
-        const unsigned int data_disks = raid_disks - conf->max_degraded;
         unsigned int dd_idx, pd_idx;
         struct bio* align_bi;
         mdk_rdev_t *rdev;
@@ -3285,12 +3286,9 @@ static int chunk_aligned_read(struct request_queue *q, struct bio * raid_bio)
         /*
          *      compute position
          */
-        align_bi->bi_sector =  raid5_compute_sector(raid_bio->bi_sector,
-                                        raid_disks,
-                                        data_disks,
-                                        &dd_idx,
-                                        &pd_idx,
-                                        conf);
+        align_bi->bi_sector =  raid5_compute_sector(conf, raid_bio->bi_sector,
+                                                    0,
+                                                    &dd_idx, &pd_idx);
 
         rcu_read_lock();
         rdev = rcu_dereference(conf->disks[dd_idx].rdev);
@@ -3447,8 +3445,9 @@ static int make_request(struct request_queue *q, struct bio * bi)
                 }
                 data_disks = disks - conf->max_degraded;
 
-                new_sector = raid5_compute_sector(logical_sector, disks, data_disks,
-                                                  &dd_idx, &pd_idx, conf);
+                new_sector = raid5_compute_sector(conf, logical_sector,
+                                                  previous,
+                                                  &dd_idx, &pd_idx);
                 pr_debug("raid5: make_request, sector %llu logical %llu\n",
                         (unsigned long long)new_sector, 
                         (unsigned long long)logical_sector);
@@ -3625,14 +3624,12 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
          * block on the destination stripes.
          */
         first_sector =
-                raid5_compute_sector(sector_nr*(new_data_disks),
-                                     raid_disks, data_disks,
-                                     &dd_idx, &pd_idx, conf);
+                raid5_compute_sector(conf, sector_nr*(new_data_disks),
+                                     1, &dd_idx, &pd_idx);
         last_sector =
-                raid5_compute_sector((sector_nr+conf->chunk_size/512)
-                                     *(new_data_disks) -1,
-                                     raid_disks, data_disks,
-                                     &dd_idx, &pd_idx, conf);
+                raid5_compute_sector(conf, ((sector_nr+conf->chunk_size/512)
+                                            *(new_data_disks) - 1),
+                                     1, &dd_idx, &pd_idx);
         if (last_sector >= mddev->dev_sectors)
                 last_sector = mddev->dev_sectors - 1;
         while (first_sector <= last_sector) {
@@ -3669,8 +3666,6 @@ static inline sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *ski
 {
         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
         struct stripe_head *sh;
-        int pd_idx;
-        int raid_disks = conf->raid_disks;
         sector_t max_sector = mddev->dev_sectors;
         int sync_blocks;
         int still_degraded = 0;
@@ -3725,7 +3720,6 @@ static inline sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *ski
 
         bitmap_cond_end_sync(mddev->bitmap, sector_nr);
 
-        pd_idx = stripe_to_pdidx(sector_nr, conf, raid_disks);
         sh = get_active_stripe(conf, sector_nr, 0, 1);
         if (sh == NULL) {
                 sh = get_active_stripe(conf, sector_nr, 0, 0);
@@ -3777,12 +3771,8 @@ static int  retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
         int handled = 0;
 
         logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
-        sector = raid5_compute_sector(  logical_sector,
-                                        conf->raid_disks,
-                                        conf->raid_disks - conf->max_degraded,
-                                        &dd_idx,
-                                        &pd_idx,
-                                        conf);
+        sector = raid5_compute_sector(conf, logical_sector,
+                                      0, &dd_idx, &pd_idx);
         last_sector = raid_bio->bi_sector + (raid_bio->bi_size>>9);
 
         for (; logical_sector < last_sector;