src/patches/suse-2.6.27.25/patches.fixes/0009-md-raid5-simplify-interface-for-init_stripe-and-get_.patch

   1 From b5663ba405fe3e51176ddb6c91a5e186590c26b5 Mon Sep 17 00:00:00 2001
   2 From: NeilBrown <neilb@suse.de>
   3 Date: Tue, 31 Mar 2009 14:39:38 +1100
   4 Subject: [PATCH] md/raid5: simplify interface for init_stripe and get_active_stripe
   5
   6 Rather than passing 'pd_idx' and 'disks' to these functions, just pass
   7 'previous' which tells whether to use the 'previous' or 'current'
   8 geometry during a reshape, and let init_stripe calculate
   9 disks and pd_idx and anything else it might need.
  10
  11 This is not a substantial simplification and even adds a division.
  12 However we will shortly be adding more complexity to init_stripe
  13 to handle more interesting 'reshape' activities, and without this
  14 change, the interface to these functions would get very complex.
  15
  16 Signed-off-by: NeilBrown <neilb@suse.de>
  17 ---
  18  drivers/md/raid5.c |   43 ++++++++++++++++++++++---------------------
  19  1 file changed, 22 insertions(+), 21 deletions(-)
  20
  21 --- linux-2.6.27-SLE11_BRANCH.orig/drivers/md/raid5.c
  22 +++ linux-2.6.27-SLE11_BRANCH/drivers/md/raid5.c
  23 @@ -276,8 +276,9 @@ static int grow_buffers(struct stripe_he
  24  }
  25
  26  static void raid5_build_block (struct stripe_head *sh, int i);
  27 +static int stripe_to_pdidx(sector_t stripe, raid5_conf_t *conf, int disks);
  28
  29 -static void init_stripe(struct stripe_head *sh, sector_t sector, int pd_idx, int disks)
  30 +static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
  31  {
  32         raid5_conf_t *conf = sh->raid_conf;
  33         int i;
  34 @@ -292,11 +293,11 @@ static void init_stripe(struct stripe_he
  35
  36         remove_hash(sh);
  37
  38 +       sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
  39         sh->sector = sector;
  40 -       sh->pd_idx = pd_idx;
  41 +       sh->pd_idx = stripe_to_pdidx(sector, conf, sh->disks);
  42         sh->state = 0;
  43
  44 -       sh->disks = disks;
  45
  46         for (i = sh->disks; i--; ) {
  47                 struct r5dev *dev = &sh->dev[i];
  48 @@ -332,10 +333,12 @@ static struct stripe_head *__find_stripe
  49  static void unplug_slaves(mddev_t *mddev);
  50  static void raid5_unplug_device(struct request_queue *q);
  51
  52 -static struct stripe_head *get_active_stripe(raid5_conf_t *conf, sector_t sector, int disks,
  53 -                                            int pd_idx, int noblock)
  54 +static struct stripe_head *
  55 +get_active_stripe(raid5_conf_t *conf, sector_t sector,
  56 +                 int previous, int noblock)
  57  {
  58         struct stripe_head *sh;
  59 +       int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
  60
  61         pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
  62
  63 @@ -363,7 +366,7 @@ static struct stripe_head *get_active_st
  64                                         );
  65                                 conf->inactive_blocked = 0;
  66                         } else
  67 -                               init_stripe(sh, sector, pd_idx, disks);
  68 +                               init_stripe(sh, sector, previous);
  69                 } else {
  70                         if (atomic_read(&sh->count)) {
  71                           BUG_ON(!list_empty(&sh->lru));
  72 @@ -2481,8 +2484,7 @@ static void handle_stripe_expansion(raid
  73                                                 conf->raid_disks -
  74                                                 conf->max_degraded, &dd_idx,
  75                                                 &pd_idx, conf);
  76 -                       sh2 = get_active_stripe(conf, s, conf->raid_disks,
  77 -                                               pd_idx, 1);
  78 +                       sh2 = get_active_stripe(conf, s, 0, 1);
  79                         if (sh2 == NULL)
  80                                 /* so far only the early blocks of this stripe
  81                                  * have been requested.  When later blocks
  82 @@ -3412,8 +3414,10 @@ static int make_request(struct request_q
  83         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
  84                 DEFINE_WAIT(w);
  85                 int disks, data_disks;
  86 +               int previous;
  87
  88         retry:
  89 +               previous = 0;
  90                 prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
  91                 if (likely(conf->expand_progress == MaxSector))
  92                         disks = conf->raid_disks;
  93 @@ -3428,9 +3432,10 @@ static int make_request(struct request_q
  94                          */
  95                         spin_lock_irq(&conf->device_lock);
  96                         disks = conf->raid_disks;
  97 -                       if (logical_sector >= conf->expand_progress)
  98 +                       if (logical_sector >= conf->expand_progress) {
  99                                 disks = conf->previous_raid_disks;
 100 -                       else {
 101 +                               previous = 1;
 102 +                       } else {
 103                                 if (logical_sector >= conf->expand_lo) {
 104                                         spin_unlock_irq(&conf->device_lock);
 105                                         schedule();
 106 @@ -3447,7 +3452,8 @@ static int make_request(struct request_q
 107                         (unsigned long long)new_sector,
 108                         (unsigned long long)logical_sector);
 109
 110 -               sh = get_active_stripe(conf, new_sector, disks, pd_idx, (bi->bi_rw&RWA_MASK));
 111 +               sh = get_active_stripe(conf, new_sector, previous,
 112 +                                      (bi->bi_rw&RWA_MASK));
 113                 if (sh) {
 114                         if (unlikely(conf->expand_progress != MaxSector)) {
 115                                 /* expansion might have moved on while waiting for a
 116 @@ -3581,9 +3587,7 @@ static sector_t reshape_request(mddev_t
 117         for (i=0; i < conf->chunk_size/512; i+= STRIPE_SECTORS) {
 118                 int j;
 119                 int skipped = 0;
 120 -               pd_idx = stripe_to_pdidx(sector_nr+i, conf, conf->raid_disks);
 121 -               sh = get_active_stripe(conf, sector_nr+i,
 122 -                                      conf->raid_disks, pd_idx, 0);
 123 +               sh = get_active_stripe(conf, sector_nr+i, 0, 0);
 124                 set_bit(STRIPE_EXPANDING, &sh->state);
 125                 atomic_inc(&conf->reshape_stripes);
 126                 /* If any of this stripe is beyond the end of the old
 127 @@ -3631,10 +3635,7 @@ static sector_t reshape_request(mddev_t
 128         if (last_sector >= (mddev->size<<1))
 129                 last_sector = (mddev->size<<1)-1;
 130         while (first_sector <= last_sector) {
 131 -               pd_idx = stripe_to_pdidx(first_sector, conf,
 132 -                                        conf->previous_raid_disks);
 133 -               sh = get_active_stripe(conf, first_sector,
 134 -                                      conf->previous_raid_disks, pd_idx, 0);
 135 +               sh = get_active_stripe(conf, first_sector, 1, 0);
 136                 set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
 137                 set_bit(STRIPE_HANDLE, &sh->state);
 138                 release_stripe(sh);
 139 @@ -3724,9 +3725,9 @@ static inline sector_t sync_request(mdde
 140         bitmap_cond_end_sync(mddev->bitmap, sector_nr);
 141
 142         pd_idx = stripe_to_pdidx(sector_nr, conf, raid_disks);
 143 -       sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 1);
 144 +       sh = get_active_stripe(conf, sector_nr, 0, 1);
 145         if (sh == NULL) {
 146 -               sh = get_active_stripe(conf, sector_nr, raid_disks, pd_idx, 0);
 147 +               sh = get_active_stripe(conf, sector_nr, 0, 0);
 148                 /* make sure we don't swamp the stripe cache if someone else
 149                  * is trying to get access
 150                  */
 151 @@ -3792,7 +3793,7 @@ static int  retry_aligned_read(raid5_con
 152                         /* already done this stripe */
 153                         continue;
 154
 155 -               sh = get_active_stripe(conf, sector, conf->raid_disks, pd_idx, 1);
 156 +               sh = get_active_stripe(conf, sector, 0, 1);
 157
 158                 if (!sh) {
 159                         /* failed to get a stripe - must wait */