md/raid5: simplify raid5_compute_sector interface

Rather than passing 'pd_idx' and 'qd_idx' to be filled in, pass
a 'struct stripe_head *' and fill in the relevant fields.  This is
more extensible.

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

1 files changed, 58 insertions, 60 deletions

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index cb3e157b52d3..2e2e64f6ef71 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -299,14 +299,13 @@ 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 previous,
-                           int *qd_idx);
+static void stripe_set_idx(sector_t stripe, raid5_conf_t *conf, int previous,
+                            struct stripe_head *sh);
 
 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
 {
         raid5_conf_t *conf = sh->raid_conf;
         int i;
-        int qd_idx;
 
         BUG_ON(atomic_read(&sh->count) != 0);
         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
@@ -320,8 +319,7 @@ 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, previous, &qd_idx);
-        sh->qd_idx = qd_idx;
+        stripe_set_idx(sector, conf, previous, sh);
         sh->state = 0;
 
 
@@ -1262,12 +1260,13 @@ static void error(mddev_t *mddev, mdk_rdev_t *rdev)
  * Output: index of the data and parity disk, and the sector # in them.
  */
 static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
-                                     int previous,
-                                     int *dd_idx, int *pd_idx, int *qd_idx)
+                                     int previous, int *dd_idx,
+                                     struct stripe_head *sh)
 {
         long stripe;
         unsigned long chunk_number;
         unsigned int chunk_offset;
+        int pd_idx, qd_idx;
         sector_t new_sector;
         int sectors_per_chunk = conf->chunk_size >> 9;
         int raid_disks = previous ? conf->previous_raid_disks
@@ -1296,30 +1295,30 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
         /*
          * Select the parity disk based on the user selected algorithm.
          */
-        *qd_idx = ~0;
+        pd_idx = qd_idx = ~0;
         switch(conf->level) {
         case 4:
-                *pd_idx = data_disks;
+                pd_idx = data_disks;
                 break;
         case 5:
                 switch (conf->algorithm) {
                 case ALGORITHM_LEFT_ASYMMETRIC:
-                        *pd_idx = data_disks - stripe % raid_disks;
-                        if (*dd_idx >= *pd_idx)
+                        pd_idx = data_disks - stripe % raid_disks;
+                        if (*dd_idx >= pd_idx)
                                 (*dd_idx)++;
                         break;
                 case ALGORITHM_RIGHT_ASYMMETRIC:
-                        *pd_idx = stripe % raid_disks;
-                        if (*dd_idx >= *pd_idx)
+                        pd_idx = stripe % raid_disks;
+                        if (*dd_idx >= pd_idx)
                                 (*dd_idx)++;
                         break;
                 case ALGORITHM_LEFT_SYMMETRIC:
-                        *pd_idx = data_disks - stripe % raid_disks;
-                        *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
+                        pd_idx = data_disks - stripe % raid_disks;
+                        *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
                         break;
                 case ALGORITHM_RIGHT_SYMMETRIC:
-                        *pd_idx = stripe % raid_disks;
-                        *dd_idx = (*pd_idx + 1 + *dd_idx) % raid_disks;
+                        pd_idx = stripe % raid_disks;
+                        *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
                         break;
                 default:
                         printk(KERN_ERR "raid5: unsupported algorithm %d\n",
@@ -1331,32 +1330,32 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
                 /**** FIX THIS ****/
                 switch (conf->algorithm) {
                 case ALGORITHM_LEFT_ASYMMETRIC:
-                        *pd_idx = raid_disks - 1 - (stripe % raid_disks);
-                        *qd_idx = *pd_idx + 1;
-                        if (*pd_idx == raid_disks-1) {
+                        pd_idx = raid_disks - 1 - (stripe % raid_disks);
+                        qd_idx = pd_idx + 1;
+                        if (pd_idx == raid_disks-1) {
                                 (*dd_idx)++;    /* Q D D D P */
-                                *qd_idx = 0;
-                        } else if (*dd_idx >= *pd_idx)
+                                qd_idx = 0;
+                        } else if (*dd_idx >= pd_idx)
                                 (*dd_idx) += 2; /* D D P Q D */
                         break;
                 case ALGORITHM_RIGHT_ASYMMETRIC:
-                        *pd_idx = stripe % raid_disks;
-                        *qd_idx = *pd_idx + 1;
-                        if (*pd_idx == raid_disks-1) {
+                        pd_idx = stripe % raid_disks;
+                        qd_idx = pd_idx + 1;
+                        if (pd_idx == raid_disks-1) {
                                 (*dd_idx)++;    /* Q D D D P */
-                                *qd_idx = 0;
-                        } else if (*dd_idx >= *pd_idx)
+                                qd_idx = 0;
+                        } else if (*dd_idx >= pd_idx)
                                 (*dd_idx) += 2; /* D D P Q D */
                         break;
                 case ALGORITHM_LEFT_SYMMETRIC:
-                        *pd_idx = raid_disks - 1 - (stripe % raid_disks);
-                        *qd_idx = (*pd_idx + 1) % raid_disks;
-                        *dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
+                        pd_idx = raid_disks - 1 - (stripe % raid_disks);
+                        qd_idx = (pd_idx + 1) % raid_disks;
+                        *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
                         break;
                 case ALGORITHM_RIGHT_SYMMETRIC:
-                        *pd_idx = stripe % raid_disks;
-                        *qd_idx = (*pd_idx + 1) % raid_disks;
-                        *dd_idx = (*pd_idx + 2 + *dd_idx) % raid_disks;
+                        pd_idx = stripe % raid_disks;
+                        qd_idx = (pd_idx + 1) % raid_disks;
+                        *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
                         break;
                 default:
                         printk(KERN_CRIT "raid6: unsupported algorithm %d\n",
@@ -1365,6 +1364,10 @@ static sector_t raid5_compute_sector(raid5_conf_t *conf, sector_t r_sector,
                 break;
         }
 
+        if (sh) {
+                sh->pd_idx = pd_idx;
+                sh->qd_idx = qd_idx;
+        }
         /*
          * Finally, compute the new sector number
          */
@@ -1382,8 +1385,9 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i)
         int sectors_per_chunk = conf->chunk_size >> 9;
         sector_t stripe;
         int chunk_offset;
-        int chunk_number, dummy1, dummy2, dummy3, dd_idx = i;
+        int chunk_number, dummy1, dd_idx = i;
         sector_t r_sector;
+        struct stripe_head sh2;
 
 
         chunk_offset = sector_div(new_sector, sectors_per_chunk);
@@ -1446,8 +1450,9 @@ static sector_t compute_blocknr(struct stripe_head *sh, int i)
 
         check = raid5_compute_sector(conf, r_sector,
                                      (raid_disks != conf->raid_disks),
-                                     &dummy1, &dummy2, &dummy3);
-        if (check != sh->sector || dummy1 != dd_idx || dummy2 != sh->pd_idx) {
+                                     &dummy1, &sh2);
+        if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
+                || sh2.qd_idx != sh->qd_idx) {
                 printk(KERN_ERR "compute_blocknr: map not correct\n");
                 return 0;
         }
@@ -1843,11 +1848,11 @@ 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 previous,
-                           int *qd_idxp)
+static void stripe_set_idx(sector_t stripe, raid5_conf_t *conf, int previous,
+                            struct stripe_head *sh)
 {
         int sectors_per_chunk = conf->chunk_size >> 9;
-        int pd_idx, dd_idx;
+        int dd_idx;
         int chunk_offset = sector_div(stripe, sectors_per_chunk);
         int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
 
@@ -1855,8 +1860,7 @@ static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int previous,
                              stripe * (disks - conf->max_degraded)
                              *sectors_per_chunk + chunk_offset,
                              previous,
-                             &dd_idx, &pd_idx, qd_idxp);
-        return pd_idx;
+                             &dd_idx, sh);
 }
 
 static void
@@ -2514,13 +2518,12 @@ static void handle_stripe_expansion(raid5_conf_t *conf, struct stripe_head *sh,
         clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
         for (i = 0; i < sh->disks; i++)
                 if (i != sh->pd_idx && (!r6s || i != r6s->qd_idx)) {
-                        int dd_idx, pd_idx, qd_idx, j;
+                        int dd_idx, j;
                         struct stripe_head *sh2;
 
                         sector_t bn = compute_blocknr(sh, i);
-                        sector_t s =
-                                raid5_compute_sector(conf, bn, 0,
-                                                     &dd_idx, &pd_idx, &qd_idx);
+                        sector_t s = raid5_compute_sector(conf, bn, 0,
+                                                          &dd_idx, NULL);
                         sh2 = get_active_stripe(conf, s, 0, 1);
                         if (sh2 == NULL)
                                 /* so far only the early blocks of this stripe
@@ -2804,11 +2807,9 @@ static bool handle_stripe5(struct stripe_head *sh)
 
         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
             !sh->reconstruct_state) {
-                int qd_idx;
                 /* Need to write out all blocks after computing parity */
                 sh->disks = conf->raid_disks;
-                sh->pd_idx = stripe_to_pdidx(sh->sector, conf, 0, &qd_idx);
-                sh->qd_idx = qd_idx;
+                stripe_set_idx(sh->sector, conf, 0, sh);
                 schedule_reconstruction5(sh, &s, 1, 1);
         } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
@@ -3025,10 +3026,8 @@ 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 */
-                int qd_idx;
                 sh->disks = conf->raid_disks;
-                sh->pd_idx = stripe_to_pdidx(sh->sector, conf, 0, &qd_idx);
-                sh->qd_idx = qd_idx;
+                stripe_set_idx(sh->sector, conf, 0, sh);
                 compute_parity6(sh, RECONSTRUCT_WRITE);
                 for (i = conf->raid_disks ; i-- ;  ) {
                         set_bit(R5_LOCKED, &sh->dev[i].flags);
@@ -3300,7 +3299,7 @@ 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);
-        unsigned int dd_idx, pd_idx, qd_idx;
+        unsigned int dd_idx;
         struct bio* align_bi;
         mdk_rdev_t *rdev;
 
@@ -3325,7 +3324,7 @@ static int chunk_aligned_read(struct request_queue *q, struct bio * raid_bio)
          */
         align_bi->bi_sector =  raid5_compute_sector(conf, raid_bio->bi_sector,
                                                     0,
-                                                    &dd_idx, &pd_idx, &qd_idx);
+                                                    &dd_idx, NULL);
 
         rcu_read_lock();
         rdev = rcu_dereference(conf->disks[dd_idx].rdev);
@@ -3417,7 +3416,7 @@ static int make_request(struct request_queue *q, struct bio * bi)
 {
         mddev_t *mddev = q->queuedata;
         raid5_conf_t *conf = mddev_to_conf(mddev);
-        int dd_idx, pd_idx, qd_idx;
+        int dd_idx;
         sector_t new_sector;
         sector_t logical_sector, last_sector;
         struct stripe_head *sh;
@@ -3484,7 +3483,7 @@ static int make_request(struct request_queue *q, struct bio * bi)
 
                 new_sector = raid5_compute_sector(conf, logical_sector,
                                                   previous,
-                                                  &dd_idx, &pd_idx, &qd_idx);
+                                                  &dd_idx, NULL);
                 pr_debug("raid5: make_request, sector %llu logical %llu\n",
                         (unsigned long long)new_sector, 
                         (unsigned long long)logical_sector);
@@ -3572,7 +3571,6 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
          */
         raid5_conf_t *conf = (raid5_conf_t *) mddev->private;
         struct stripe_head *sh;
-        int pd_idx, qd_idx;
         sector_t first_sector, last_sector;
         int raid_disks = conf->previous_raid_disks;
         int data_disks = raid_disks - conf->max_degraded;
@@ -3662,11 +3660,11 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
          */
         first_sector =
                 raid5_compute_sector(conf, sector_nr*(new_data_disks),
-                                     1, &dd_idx, &pd_idx, &qd_idx);
+                                     1, &dd_idx, NULL);
         last_sector =
                 raid5_compute_sector(conf, ((sector_nr+conf->chunk_size/512)
                                             *(new_data_disks) - 1),
-                                     1, &dd_idx, &pd_idx, &qd_idx);
+                                     1, &dd_idx, NULL);
         if (last_sector >= mddev->dev_sectors)
                 last_sector = mddev->dev_sectors - 1;
         while (first_sector <= last_sector) {
@@ -3801,7 +3799,7 @@ static int  retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
          * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
          */
         struct stripe_head *sh;
-        int dd_idx, pd_idx, qd_idx;
+        int dd_idx;
         sector_t sector, logical_sector, last_sector;
         int scnt = 0;
         int remaining;
@@ -3809,7 +3807,7 @@ static int  retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
 
         logical_sector = raid_bio->bi_sector & ~((sector_t)STRIPE_SECTORS-1);
         sector = raid5_compute_sector(conf, logical_sector,
-                                      0, &dd_idx, &pd_idx, &qd_idx);
+                                      0, &dd_idx, NULL);
         last_sector = raid_bio->bi_sector + (raid_bio->bi_size>>9);
 
         for (; logical_sector < last_sector;