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>

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index cb3e157..2e2e64f 100644 (file)
--- 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;