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Btrfs: Simplify device selection for mirrored reads

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Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason
2008-04-21 12:01:38 -04:00
parent f2d8d74d78
commit 3c12ac7205
2 changed files with 11 additions and 20 deletions
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23
fs/btrfs/volumes.c
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@@ -1029,19 +1029,8 @@ again:
else if (mirror_num) {
stripe_index = mirror_num - 1;
} else {
int i;
u64 least = (u64)-1;
struct btrfs_device *cur;
for (i = 0; i < map->num_stripes; i++) {
cur = map->stripes[i].dev;
spin_lock(&cur->io_lock);
if (cur->total_ios < least) {
least = cur->total_ios;
stripe_index = i;
}
spin_unlock(&cur->io_lock);
}
u64 orig_stripe_nr = stripe_nr;
stripe_index = do_div(orig_stripe_nr, num_stripes);
}
} else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
if (rw & (1 << BIO_RW))
@@ -1050,7 +1039,6 @@ again:
stripe_index = mirror_num - 1;
} else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
int factor = map->num_stripes / map->sub_stripes;
int orig_stripe_nr = stripe_nr;
stripe_index = do_div(stripe_nr, factor);
stripe_index *= map->sub_stripes;
@@ -1059,8 +1047,11 @@ again:
num_stripes = map->sub_stripes;
else if (mirror_num)
stripe_index += mirror_num - 1;
else
stripe_index += orig_stripe_nr % map->sub_stripes;
else {
u64 orig_stripe_nr = stripe_nr;
stripe_index += do_div(orig_stripe_nr,
map->sub_stripes);
}
} else {
/*
* after this do_div call, stripe_nr is the number of stripes