initramfs and /etc/mtab

[behlendorf]

Something odd. From my laptop booted into 2.6.37.1 and ZFS modules 
loaded, I can import the KQI created pool. But inside my initramfs, it 
fails to import the pool. 'zpool' command just comes out without 
finding anything. zpool list doesn't show any pools. /dev/sda, /dev/ 
sda1, /dev/sda2 are present. /dev/sda2 is where the rpool is. 
Where do we go from here? 
EDIT: got the clue. It looks like zpool in Brian's code is looking 
for /etc/mtab for some reason AND not cribbing about it though. Once I 
created a link from /proc/mounts to /etc/mtab, it imported the pool 
correctly. Something to fix. 

This port handles /etc/mtab slightly differently than the KQ port. The KQ port is designed to directly mount a filesystem with sys_mount() and then uses library calls to update mtab. This works but it's not 100% safe since the method for locking mtab has changed over time. To avoid this issue this port directly invokes the mount command which ensures that correct locking for your system is done. This might be a problem if your /etc/mtab file doesn't exist as in the case describe above. There is a --no-mtab option to mount which might be the right thing to do in this case.

[devsk]

But the issue happens during 'zpool import'. No pool is imported if /etc/mtab is not a link to /proc/mounts.

I did not test if mount needed /etc/mtab as well or not but judging from above comment, it looks like it would.

[behlendorf]

Oh, I missed that the 'zpool import' bit first time around. Yes, that is strange, off hand I'm not sure what could be causing that we'll have to dig in to it.

[behlendorf]

This issue has been addressed by the recent 'dracut' merge.