md/raid5: simplify interface for init_stripe and get_active_stripe

Rather than passing 'pd_idx' and 'disks' to these functions, just pass
'previous' which tells whether to use the 'previous' or 'current'
geometry during a reshape, and let init_stripe calculate
disks and pd_idx and anything else it might need.

This is not a substantial simplification and even adds a division.
However we will shortly be adding more complexity to init_stripe
to handle more interesting 'reshape' activities, and without this
change, the interface to these functions would get very complex.

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

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 4d71423..c38310b 100644 (file)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -274,8 +274,9 @@ 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 void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx, int disks)
+static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
 {
        raid5_conf_t *conf = sh->raid_conf;
        int i;
@@ -290,11 +291,11 @@ static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx, int
 
        remove_hash(sh);
 
+       sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
        sh->sector = sector;
-       sh->pd_idx = pd_idx;
+       sh->pd_idx = stripe_to_pdidx(sector, conf, sh->disks);
        sh->state = 0;
 
-       sh->disks = disks;
 
        for (i = sh->disks; i--; ) {
                struct r5dev *dev = &sh->dev[i];
@@ -330,10 +331,12 @@ static struct stripe_head *__find_stripe(raid5_conf_t *conf, sector_t sector, in
 static void unplug_slaves(mddev_t *mddev);
 static void raid5_unplug_device(struct request_queue *q);
 
-static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector, int disks,
-                                            int pd_idx, int noblock)
+static struct stripe_head *
+get_active_stripe(raid5_conf_t *conf, sector_t sector,
+                 int previous, int noblock)
 {
        struct stripe_head *sh;
+       int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
 
        pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
 
@@ -361,7 +364,7 @@ static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector
                                        );
                                conf->inactive_blocked = 0;
                        } else
-                               init_stripe(sh, sector, pd_idx, disks);
+                               init_stripe(sh, sector, previous);
                } else {
                        if (atomic_read(&sh->count)) {
                          BUG_ON(!list_empty(&sh->lru));
@@ -2479,8 +2482,7 @@ static void handle_stripe_expansion(raid5_conf_t *conf, struct stripe_head *sh,
                                                conf->raid_disks -
                                                conf->max_degraded, &dd_idx,
                                                &pd_idx, conf);
-                       sh2 = get_active_stripe(conf, s, conf->raid_disks,
-                                               pd_idx, 1);
+                       sh2 = get_active_stripe(conf, s, 0, 1);
                        if (sh2 == NULL)
                                /* so far only the early blocks of this stripe
                                 * have been requested.  When later blocks
@@ -3413,8 +3415,10 @@ static int make_request(struct request_queue *q, struct bio * bi)
        for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
                DEFINE_WAIT(w);
                int disks, data_disks;
+               int previous;
 
        retry:
+               previous = 0;
                prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
                if (likely(conf->expand_progress == MaxSector))
                        disks = conf->raid_disks;
@@ -3429,9 +3433,10 @@ static int make_request(struct request_queue *q, struct bio * bi)
                         */
                        spin_lock_irq(&conf->device_lock);
                        disks = conf->raid_disks;
-                       if (logical_sector >= conf->expand_progress)
+                       if (logical_sector >= conf->expand_progress) {
                                disks = conf->previous_raid_disks;
-                       else {
+                               previous = 1;
+                       } else {
                                if (logical_sector >= conf->expand_lo) {
                                        spin_unlock_irq(&conf->device_lock);
                                        schedule();
@@ -3448,7 +3453,8 @@ static int make_request(struct request_queue *q, struct bio * bi)
                        (unsigned long long)new_sector, 
                        (unsigned long long)logical_sector);
 
-               sh = get_active_stripe(conf, new_sector, disks, pd_idx, (bi->bi_rw&RWA_MASK));
+               sh = get_active_stripe(conf, new_sector, previous,
+                                      (bi->bi_rw&RWA_MASK));
                if (sh) {
                        if (unlikely(conf->expand_progress != MaxSector)) {
                                /* expansion might have moved on while waiting for a
@@ -3582,9 +3588,7 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
        for (i=0; i < conf->chunk_size/512; i+= STRIPE_SECTORS) {
                int j;
                int skipped = 0;
-               pd_idx = stripe_to_pdidx(sector_nr+i, conf, conf->raid_disks);
-               sh = get_active_stripe(conf, sector_nr+i,
-                                      conf->raid_disks, pd_idx, 0);
+               sh = get_active_stripe(conf, sector_nr+i, 0, 0);
                set_bit(STRIPE_EXPANDING, &sh->state);
                atomic_inc(&conf->reshape_stripes);
                /* If any of this stripe is beyond the end of the old
@@ -3632,10 +3636,7 @@ static sector_t reshape_request(mddev_t *mddev, sector_t sector_nr, int *skipped
        if (last_sector >= mddev->dev_sectors)
                last_sector = mddev->dev_sectors - 1;
        while (first_sector <= last_sector) {
-               pd_idx = stripe_to_pdidx(first_sector, conf,
-                                        conf->previous_raid_disks);
-               sh = get_active_stripe(conf, first_sector,
-                                      conf->previous_raid_disks, pd_idx, 0);
+               sh = get_active_stripe(conf, first_sector, 1, 0);
                set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
                set_bit(STRIPE_HANDLE, &sh->state);
                release_stripe(sh);
@@ -3725,9 +3726,9 @@ 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, raid_disks, pd_idx, 1);
+       sh = get_active_stripe(conf, sector_nr, 0, 1);
        if (sh == NULL) {
-               sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 0);
+               sh = get_active_stripe(conf, sector_nr, 0, 0);
                /* make sure we don't swamp the stripe cache if someone else
                 * is trying to get access
                 */
@@ -3793,7 +3794,7 @@ static int  retry_aligned_read(raid5_conf_t *conf, struct bio *raid_bio)
                        /* already done this stripe */
                        continue;
 
-               sh = get_active_stripe(conf, sector, conf->raid_disks, pd_idx, 1);
+               sh = get_active_stripe(conf, sector, 0, 1);
 
                if (!sh) {
                        /* failed to get a stripe - must wait */