On Fri, 7 Feb 2014 12:08:12 +0600 Roman Mamedov <r...@romanrm.net> wrote:
> > Earlier conventions would have stated Size ~900GB, and Avail ~900GB. But
> > that's not exactly true either, is it?
>
> Much better, and matching the user expectations of how RAID1 should behave,
> without a major "gotcha" blowing up into their face the first minute they are
> trying it out. In fact next step that I planned would be finding how to adjust
> also Size and Used on all my machines to show what you just mentioned.
OK done; again, this is just what I will personally use from now on (and for
anyone who finds this helpful).
----
--- fs/btrfs/super.c.orig 2014-02-06 01:28:36.636164982 +0600
+++ fs/btrfs/super.c 2014-02-08 17:16:50.361931959 +0600
@@ -1481,6 +1481,11 @@
}
kfree(devices_info);
+
+ if (type & BTRFS_BLOCK_GROUP_RAID1) {
+ do_div(avail_space, min_stripes);
+ }
+
*free_bytes = avail_space;
return 0;
}
@@ -1491,8 +1496,10 @@
struct btrfs_super_block *disk_super = fs_info->super_copy;
struct list_head *head = &fs_info->space_info;
struct btrfs_space_info *found;
+ u64 total_size;
u64 total_used = 0;
u64 total_free_data = 0;
+ u64 type;
int bits = dentry->d_sb->s_blocksize_bits;
__be32 *fsid = (__be32 *)fs_info->fsid;
int ret;
@@ -1512,7 +1519,13 @@
rcu_read_unlock();
buf->f_namelen = BTRFS_NAME_LEN;
- buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
+ total_size = btrfs_super_total_bytes(disk_super);
+ type = btrfs_get_alloc_profile(fs_info->tree_root, 1);
+ if (type & BTRFS_BLOCK_GROUP_RAID1) {
+ do_div(total_size, 2);
+ do_div(total_used, 2);
+ }
+ buf->f_blocks = total_size >> bits;
buf->f_bfree = buf->f_blocks - (total_used >> bits);
buf->f_bsize = dentry->d_sb->s_blocksize;
buf->f_type = BTRFS_SUPER_MAGIC;
----
2x1TB RAID1 with a 1GB file:
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 912G 1.1G 911G 1% /mnt/p2
--
With respect,
Roman
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