Btrfs: Calculate appropriate chunk sizes for both small and large filesystems

Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 93aa36e2436e0deebda1f6ec48ea2f2a4d982eeb..e3ddd7fb8edd341c94ac23ad9c8e37e3dc4a1987 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -627,6 +627,27 @@ int btrfs_add_system_chunk(struct btrfs_trans_handle *trans,
        return 0;
 }
 
+static u64 div_factor(u64 num, int factor)
+{
+       if (factor == 10)
+               return num;
+       num *= factor;
+       do_div(num, 10);
+       return num;
+}
+
+static u64 chunk_bytes_by_type(u64 type, u64 calc_size, int num_stripes,
+                              int sub_stripes)
+{
+       if (type & (BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_DUP))
+               return calc_size;
+       else if (type & BTRFS_BLOCK_GROUP_RAID10)
+               return calc_size * (num_stripes / sub_stripes);
+       else
+               return calc_size * num_stripes;
+}
+
+
 int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
                      struct btrfs_root *extent_root, u64 *start,
                      u64 *num_bytes, u64 type)
@@ -643,11 +664,14 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
        struct extent_map_tree *em_tree;
        struct map_lookup *map;
        struct extent_map *em;
+       int min_chunk_size = 8 * 1024 * 1024;
        u64 physical;
        u64 calc_size = 1024 * 1024 * 1024;
-       u64 min_free = calc_size;
+       u64 max_chunk_size = calc_size;
+       u64 min_free;
        u64 avail;
        u64 max_avail = 0;
+       u64 percent_max;
        int num_stripes = 1;
        int sub_stripes = 0;
        int looped = 0;
@@ -666,6 +690,8 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
        if (type & (BTRFS_BLOCK_GROUP_RAID1)) {
                num_stripes = min_t(u64, 2,
                                  btrfs_super_num_devices(&info->super_copy));
+               if (num_stripes < 2)
+                       return -ENOSPC;
        }
        if (type & (BTRFS_BLOCK_GROUP_RAID10)) {
                num_stripes = btrfs_super_num_devices(&info->super_copy);
@@ -674,13 +700,45 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
                num_stripes &= ~(u32)1;
                sub_stripes = 2;
        }
+
+       if (type & BTRFS_BLOCK_GROUP_DATA) {
+               max_chunk_size = 10 * calc_size;
+               min_chunk_size = 256 * 1024 * 1024;
+       } else if (type & BTRFS_BLOCK_GROUP_METADATA) {
+               max_chunk_size = 4 * calc_size;
+               min_chunk_size = 64 * 1024 * 1024;
+       } else {
+               min_chunk_size = 32 * 1024 * 1024;
+       }
+
+       /* we don't want a chunk larger than 10% of the FS */
+       percent_max = div_factor(btrfs_super_total_bytes(&info->super_copy), 1);
+       max_chunk_size = min(percent_max, max_chunk_size);
+
+       if (calc_size * num_stripes > max_chunk_size) {
+               calc_size = max_chunk_size;
+               do_div(calc_size, num_stripes);
+               do_div(calc_size, stripe_len);
+               calc_size *= stripe_len;
+       }
+       /* we don't want tiny stripes */
+       *num_bytes = chunk_bytes_by_type(type, calc_size,
+                                        num_stripes, sub_stripes);
+       calc_size = max_t(u64, chunk_bytes_by_type(type, min_chunk_size,
+                         num_stripes, sub_stripes), calc_size);
+
 again:
+       do_div(calc_size, stripe_len);
+       calc_size *= stripe_len;
+
        INIT_LIST_HEAD(&private_devs);
        cur = dev_list->next;
        index = 0;
 
        if (type & BTRFS_BLOCK_GROUP_DUP)
                min_free = calc_size * 2;
+       else
+               min_free = calc_size;
 
        /* build a private list of devices we will allocate from */
        while(index < num_stripes) {
@@ -727,13 +785,9 @@ again:
        }
 
        stripes = &chunk->stripe;
+       *num_bytes = chunk_bytes_by_type(type, calc_size,
+                                        num_stripes, sub_stripes);
 
-       if (type & (BTRFS_BLOCK_GROUP_RAID1 | BTRFS_BLOCK_GROUP_DUP))
-               *num_bytes = calc_size;
-       else if (type & BTRFS_BLOCK_GROUP_RAID10)
-               *num_bytes = calc_size * (num_stripes / sub_stripes);
-       else
-               *num_bytes = calc_size * num_stripes;
 
        index = 0;
 printk("new chunk type %Lu start %Lu size %Lu\n", type, key.offset, *num_bytes);