Re: Are the btrfs mount options inconsistent?

[David Howells <dhowells@redhat.com>]

Qu Wenruo <quwenruo.btrfs@gmx.com> wrote:

> But to be more clear, NOSSD shouldn't be a special case.
> In fact currently NOSSD only affects whether we will output the message
> "enabling ssd optimization", no real effect if I didn't miss anything.

That's not quite true.  In:

	if (!btrfs_test_opt(fs_info, NOSSD) &&
	    !fs_info->fs_devices->rotating) {
		btrfs_set_and_info(fs_info, SSD, "enabling ssd optimizations");
	}

the call to btrfs_set_and_info() will turn on SSD.

What this seems to me is that, normally, SSD will be turned on automatically
unless at least one of the devices is a rotating medium - but this appears to
be explicitly suppressed by the NOSSD option.

David