btrfs: fix wrong calculation of stripe size

There are two tiny problem:
- One is When we check the chunk size is greater than the max chunk size or not,
  we should take mirrors into account, but the original code didn't.
- The other is btrfs shouldn't use the size of the residual free space as the
  length of of a dup chunk when doing chunk allocation. It is because the device
  space that a dup chunk needs is twice as large as the chunk size, if we use
  the size of the residual free space as the length of a dup chunk, we can not
  get enough free space. Fix it.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Reviewed-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 177b73179590..c50a85e0d08f 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2177,6 +2177,7 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
         int num_stripes = 1;
         int min_stripes = 1;
         int sub_stripes = 0;
+        int ncopies = 1;
         int looped = 0;
         int ret;
         int index;
@@ -2197,12 +2198,14 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
         if (type & (BTRFS_BLOCK_GROUP_DUP)) {
                 num_stripes = 2;
                 min_stripes = 2;
+                ncopies = 2;
         }
         if (type & (BTRFS_BLOCK_GROUP_RAID1)) {
                 if (fs_devices->rw_devices < 2)
                         return -ENOSPC;
                 num_stripes = 2;
                 min_stripes = 2;
+                ncopies = 2;
         }
         if (type & (BTRFS_BLOCK_GROUP_RAID10)) {
                 num_stripes = fs_devices->rw_devices;
@@ -2210,6 +2213,7 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
                         return -ENOSPC;
                 num_stripes &= ~(u32)1;
                 sub_stripes = 2;
+                ncopies = 2;
                 min_stripes = 4;
         }
 
@@ -2239,8 +2243,8 @@ again:
                 map->num_stripes = num_stripes;
         }
 
-        if (calc_size * num_stripes > max_chunk_size) {
-                calc_size = max_chunk_size;
+        if (calc_size * num_stripes > max_chunk_size * ncopies) {
+                calc_size = max_chunk_size * ncopies;
                 do_div(calc_size, num_stripes);
                 do_div(calc_size, stripe_len);
                 calc_size *= stripe_len;
@@ -2321,6 +2325,8 @@ again:
                 if (!looped && max_avail > 0) {
                         looped = 1;
                         calc_size = max_avail;
+                        if (type & BTRFS_BLOCK_GROUP_DUP)
+                                do_div(calc_size, 2);
                         goto again;
                 }
                 kfree(map);