unmount prevented by open files within a subdirectory of .Spotlight-V100/ at the root of the file system (mds and/or related processes) about zfs HOT 4 CLOSED

Noted with thanks:

State of osx.zfs on July 1st
https://groups.google.com/d/msg/maczfs-devel/nbwJLBRgric/huZcY_-yjp4J

… Spotlight unmount issue …

from zfs.

If you export the POOL twice it will unmount and export.
Interestingly, if you umount /POOL it will fail, but "diskutil unmount /POOL" will succeed.
The primary call that diskutil uses appears to be DADiskUnmount.

I think the answer is to iokit the userland code as well, and do something similar to

main()
{
DADiskRef disk = NULL;
DASessionRef session = NULL;
session = DASessionCreate ( kCFAllocatorDefault );
if(session == NULL)
{
return false;
}
DASessionScheduleWithRunLoop(session, CFRunLoopGetCurrent(),
kCFRunLoopDefaultMode);
disk = DADiskCreateFromBSDName ( kCFAllocatorDefault, session, diskName);
if(disk == NULL)
return false;

 DADiskUnmount(disk, kDADiskUnmountOptionWhole,
CPCSServerSocket::SafeRemovalCallback, NULL);
 return true;
}


void CPCSServerSocket::SafeRemovalCallback( DADiskRef disk,
DADissenterRef dissenter, void * context )
{
 printf("CPCSServerSocket::SafeRemovalCallback disk-%p
dissenter-%p\n", disk, dissenter);
}               

Another option is to take the ZOL approach, and do system(diskutil unmount) - the code is already there, just not called. (for umount).

We can not use diskutil to mount the volume however, but we probably can use iokit. So currently I am favouring iokit in userland.

from zfs.

Thanks for the update and for the chat in IRC.

Indeed,

… Due to the complex and interwoven nature of Mac OS X, umount may fail often. …

As far as I recall, failures such as the one observed are not file system specific.

Noted: work in progress by lundman and the comments at lines 389 and 393 in today's https://github.com/zfs-osx/zfs/blob/d8a9613ab8fe707c61071d50eba53aea66f1214e/module/zfs/zfs_vnops_osx.c#L389

from zfs.

Following the advice in Apple's man-page, we now use diskutil to umount, and I must admit, it works rather well.

from zfs.