On 4/2/13 9:30 AM, Ric Wheeler wrote: > On 04/02/2013 10:26 AM, Steven Haigh wrote: >> 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 <net...@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 >> > > Is there any reason that discard cannot be enabled on remount like it is for > other file systems? And disabled on remount for completeness?
Discard should be one of the easier ones to change on remount; things like quota are tougher. I was talking w/ Dave about this just yesterday, and he pointed out that we might need to serialize access to some of the things that would get changed on a remount. BTW Steven - we often recommend against runtime trim, and suggest fstrim instead, for performance reasons. Just something to maybe keep in mind and experiment with. -Eric > Seems like something that we would definitely want to be consistent across > file systems on, > > Ric > -- devel mailing list devel@lists.fedoraproject.org https://admin.fedoraproject.org/mailman/listinfo/devel
