zfs snapshots sometimes give errors like "File name too long"

[Andrew Snow]

I have about 50 filesystems on July 8-current with pjd's patchset.

While snapshotting works on most of them, occasionally after I create a 
snapshot and try to use it, I get errors like this:

ls -la .zfs/snapshot
ls: 20081031_20653: File name too long

It does occur only on the longest ones, but they are nowhere near 
MAXNAMELEN (256) long, they are around 60 characters for the mount point 
plus another 14 for the snapshot name.