On 3/4/19 5:45 PM, Dave Chinner wrote:
> On Mon, Mar 04, 2019 at 04:31:24PM -0500, tgill@xxxxxxxxxx wrote:
>> From: Todd Gill <tgill@xxxxxxxxxx>
>>
>> The xfs_only flag will allow the caller to request only XFS filesystems are
>> added to the fs table.
>>
>> For commands that are XFS specific (xfs_fsr, xfs_growfs, xfs_scrub) - pass
>> the flag as 1.
>>
>> The change avoids a hang when remote filesystem (like NFS) are non
>> responsive.
>
> I have the nagging feeling that this has been proposed, discussed
> and rejected previously. However, my search skills are sadly lacking
> today, because I can't find it in my local archive. Probably worth
> doing some more searching rather than repeating the discussion over
> again...
FWIW, this problem is relatively new. It crept in when we decided that
xfs_quota should work on ext4, and so we had to slurp in non-xfs
mountpoints. Yay.
Dave, I'm wondering if I didn't discuss this on IRC briefly and that's
what's triggering your memory...
May 03 17:32:07 <sandeen> dchinner, i'm not sure waht to do about our crazy is-it-mounted checks w.r.t. your subvols at this point.
May 03 17:32:18 <sandeen> I Kinda need to fix the "mkfs.xfs hangs on stuck nfs mounts, wut?!" problem
May 03 17:34:54 <djwong> check fsname[0] == '/' like e2fsprogs does :D
May 03 17:35:34 <sandeen> I pointed and laughed at that, but actually ...
May 03 17:35:46 <sandeen> dave's fs/volume paths will be full paths from /
May 03 17:36:12 <sandeen> you ... can't really get an actual device node in /proc/mounts w/ a relative path either, right?
May 03 17:36:15 <sandeen> maybe that's not so bad.
May 03 17:37:00 <sandeen> see if the "device" contains a : and then try to ping the stuff before it ;)
May 03 17:37:07 <sandeen> (I AM KIDDING)
May 03 17:37:44 <sandeen> anyway, skipping anything that doesn't start with '/' might actually be smart/ok
May 03 17:40:33 <sandeen> if youv'e somehow contrived an actual device that doesn't have a path in /proc/mounts and you go to try to mkfs it while mounted I think you get to keep all the explody bits.
May 03 17:53:00 <dchinner> sandeen: just ignore them - I'll do whatever I need to do to make them work again when your code hits the tree...
but ... I don't know if anything ever got sent.
I had also mused about something like:
May 02 14:36:27 <sandeen> I wonder if this is safe in the "is it mounted" loop:
May 02 14:36:27 <sandeen> while ((mnt = getmntent(f)) != NULL) {
May 02 14:36:27 <sandeen> /* If the "fsname" is't a stat-able device, skip it */
May 02 14:36:27 <sandeen> if (stat(mnt->mnt_fsname, &mst) < 0)
May 02 14:36:27 <sandeen> continue;
May 02 14:37:01 <sandeen> i.e. don't bother checking every procfs, nfs mount, tmpfs, cgroup, etc.
-Eric
