On 03/04/13 01:08, Eric Sandeen wrote:
On 4/1/13 5:26 PM, Steven Haigh wrote:
> On 04/02/2013 12:19 AM, Josef Bacik wrote:
>> On Sat, Mar 30, 2013 at 9:38 PM, Steven Haigh <netwiz(a)crc.id.au> wrote:
>>> Hi all,
>>>
>>> Firstly, Please CC me into replies as I'm not subscribed to this list.
>>>
>>> I'm trying to confirm that Fedora 18 has enabled trim for XFS
filesystems. I
>>> have added discard to the mount options in /etc/fstab - however I do not see
>>> it when looking at the output of 'mount':
...
>>> Can anyone share some insight into this?
>>>
>>
>> IIRC you have to rebuild your initrd so it picks up the new fstab
>> mount options for /, the other options is you should be able to do
>> mount -o remount,discard /. Thanks,
>
> Hi Josef,
>
> This was the basis of my query - even after a remount with the
> discard option, 'discard' still wasn't present in the options - as
> seen by the mount line quoted above.
Sorry I didn't see this earlier. Josef is right; discard is not a remountable
option on xfs, unfortunately (only inode64 and barrier options are remountable
today). So you could either put the option in the rootflags= kernel
commandline parameter, or rebuild the initrd after adding it to fstab
as Josef suggested so that it's initially mounted with the option.
Thanks for the reply Eric. I believe it would be helpful if this was
documented. I was expecting it to work the same way as ext4 - being a
simple remount would enable the discard option. Once that didn't work -
and especially as I didn't get an error in either the syslog or returned
from the command, I was starting to think it was a bug in the
implementation of TRIM in XFS.
I wonder if we should add something to the remount path to printk
when
a non-remountable option is encountered; I might look into that, otherwise
it's a little surprising (although semi-obvious when the problem doesn't
show up in /prcoc/mounts...).
I think this is probably the best way to handle things. The first thing
I did was to look at the return code from mount (which returned 0 - ie
success), then dmesg, then /var/log/messages. As I found nothing, I had
no hints on where to look.
The wiki page[1] for XFS does state that XFS supports TRIM - and it
mentions the changes to /etc/fstab to enable it. It doesn't however
mention that it needs to be on the initial mount - or that a remount
will not enable it.
The best of both worlds would be to have it output to the dmesg - or
even fail the mount command (if that is an option?) just like ext4 would
if you supply a bogus option set.
1:
http://xfs.org/index.php/FITRIM/discard
--
Steven Haigh
Email: netwiz(a)crc.id.au
Web:
https://www.crc.id.au
Phone: (03) 9001 6090 - 0412 935 897
Fax: (03) 8338 0299