btrfs: use superblock state to print space_cache mount option

To make the contents of /proc/mounts better match the actual state of
the filesystem, base the display of the space cache mount options off
the contents of the super block rather than the last mount options
passed in. Since there are many scenarios where the mount will ignore a
space cache option, simply showing the passed in option is misleading.

For example, if we mount with -o remount,space_cache=v2 on a read-write
file system without an existing free space tree, we won't build a free
space tree, but /proc/mounts will read space_cache=v2 (until we mount
again and it goes away)

cache_generation is set iff space_cache=v1, FREE_SPACE_TREE is set iff
space_cache=v2, and if neither is the case, we print nospace_cache.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Boris Burkov <boris@bur.io>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index b2252184305cb6a46b66586991663b4ad1711e80..bd3ce2b4383873e1b36bd0aed5713b175cf4f027 100644 (file)
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1483,9 +1483,9 @@ static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
                seq_puts(seq, ",discard=async");
        if (!(info->sb->s_flags & SB_POSIXACL))
                seq_puts(seq, ",noacl");
-       if (btrfs_test_opt(info, SPACE_CACHE))
+       if (btrfs_free_space_cache_v1_active(info))
                seq_puts(seq, ",space_cache");
-       else if (btrfs_test_opt(info, FREE_SPACE_TREE))
+       else if (btrfs_fs_compat_ro(info, FREE_SPACE_TREE))
                seq_puts(seq, ",space_cache=v2");
        else
                seq_puts(seq, ",nospace_cache");