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authorLi Zefan <lizf@cn.fujitsu.com>2011-12-01 14:06:42 +0800
committerLi Zefan <lizf@cn.fujitsu.com>2012-01-11 10:26:46 +0800
commitec9ef7a13be4dcce964c8503e8999087945e5b9e (patch)
treeafd97976c76c45fca7b659f8d81cbcd4995d2a7e /fs
parentde11cc12df17337979e0929d2831887432f236ca (diff)
downloadop-kernel-dev-ec9ef7a13be4dcce964c8503e8999087945e5b9e.zip
op-kernel-dev-ec9ef7a13be4dcce964c8503e8999087945e5b9e.tar.gz
Btrfs: simplfy calculation of stripe length for discard operation
For btrfs raid, while discarding a range of space, we'll need to know the start offset and length to discard for each device, and it's done in btrfs_map_block(). However the calculation is a bit complex for raid0 and raid10, so I reimplement it based on a fact that: dev1 dev2 dev3 (raid0) ----------------------------------- s0 s3 s6 s1 s4 s7 s2 s5 Each device has (total_stripes / nr_dev) stripes, or plus one. Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Diffstat (limited to 'fs')
-rw-r--r--fs/btrfs/volumes.c95
1 files changed, 31 insertions, 64 deletions
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 540fdd2..563ef65 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3024,80 +3024,47 @@ static int __btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
atomic_set(&bbio->error, 0);
if (rw & REQ_DISCARD) {
+ int factor = 0;
+ int sub_stripes = 0;
+ u64 stripes_per_dev = 0;
+ u32 remaining_stripes = 0;
+
+ if (map->type &
+ (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID10)) {
+ if (map->type & BTRFS_BLOCK_GROUP_RAID0)
+ sub_stripes = 1;
+ else
+ sub_stripes = map->sub_stripes;
+
+ factor = map->num_stripes / sub_stripes;
+ stripes_per_dev = div_u64_rem(stripe_nr_end -
+ stripe_nr_orig,
+ factor,
+ &remaining_stripes);
+ }
+
for (i = 0; i < num_stripes; i++) {
bbio->stripes[i].physical =
map->stripes[stripe_index].physical +
stripe_offset + stripe_nr * map->stripe_len;
bbio->stripes[i].dev = map->stripes[stripe_index].dev;
- if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
- u64 stripes;
- u32 last_stripe = 0;
- int j;
-
- div_u64_rem(stripe_nr_end - 1,
- map->num_stripes,
- &last_stripe);
-
- for (j = 0; j < map->num_stripes; j++) {
- u32 test;
-
- div_u64_rem(stripe_nr_end - 1 - j,
- map->num_stripes, &test);
- if (test == stripe_index)
- break;
- }
- stripes = stripe_nr_end - 1 - j;
- do_div(stripes, map->num_stripes);
- bbio->stripes[i].length = map->stripe_len *
- (stripes - stripe_nr + 1);
-
- if (i == 0) {
+ if (map->type & (BTRFS_BLOCK_GROUP_RAID0 |
+ BTRFS_BLOCK_GROUP_RAID10)) {
+ bbio->stripes[i].length = stripes_per_dev *
+ map->stripe_len;
+ if (i / sub_stripes < remaining_stripes)
+ bbio->stripes[i].length +=
+ map->stripe_len;
+ if (i < sub_stripes)
bbio->stripes[i].length -=
stripe_offset;
- stripe_offset = 0;
- }
- if (stripe_index == last_stripe)
- bbio->stripes[i].length -=
- stripe_end_offset;
- } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
- u64 stripes;
- int j;
- int factor = map->num_stripes /
- map->sub_stripes;
- u32 last_stripe = 0;
-
- div_u64_rem(stripe_nr_end - 1,
- factor, &last_stripe);
- last_stripe *= map->sub_stripes;
-
- for (j = 0; j < factor; j++) {
- u32 test;
-
- div_u64_rem(stripe_nr_end - 1 - j,
- factor, &test);
-
- if (test ==
- stripe_index / map->sub_stripes)
- break;
- }
- stripes = stripe_nr_end - 1 - j;
- do_div(stripes, factor);
- bbio->stripes[i].length = map->stripe_len *
- (stripes - stripe_nr + 1);
-
- if (i < map->sub_stripes) {
- bbio->stripes[i].length -=
- stripe_offset;
- if (i == map->sub_stripes - 1)
- stripe_offset = 0;
- }
- if (stripe_index >= last_stripe &&
- stripe_index <= (last_stripe +
- map->sub_stripes - 1)) {
+ if ((i / sub_stripes + 1) %
+ sub_stripes == remaining_stripes)
bbio->stripes[i].length -=
stripe_end_offset;
- }
+ if (i == sub_stripes - 1)
+ stripe_offset = 0;
} else
bbio->stripes[i].length = *length;
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