UPDATE: I have found the cause of the problem!
After dipping in and out of research into SMB, searching for the perfect configuration, I have had an illuminating test on a different system (Ubuntu).
In short, the errors were caused by the line in SMB conf:
fruit:metadata = stream
I was able to prevent the errors by using the default:
fruit:metadata = netatalk
I had seen other advice recommending using 'stream' setup (Samba Wiki!), but I guess the defaults are the defaults for a reason.
In long...
From vfs_fruit manual:
The module enables alternate data streams (ADS) support for a share, intercepts the OS X special streams "AFP_AfpInfo" and "AFP_Resource" and handles them in a special way. All other named streams are deferred to vfs_streams_xattr which must be loaded together with vfs_fruit.
So, there are two streams in addition to the main data stream:
AfpInfo (metadata) and
Resource (extra file resources I think).
Resource stream
fruit:resource = [ file | xattr | stream ]
Controls where the OS X resource fork is stored.
Settings:
file (default) - use a ._ AppleDouble file compatible with OS X and Netatalk
xattr - use a xattr, requires a filesystem with large xattr support and a file IO API compatible with xattrs, this boils down to Solaris and derived platforms and ZFS
stream (experimental) - pass the stream on to the next module in the VFS stack. Warning: this option should not be used with the streams_xattr module due to the extended attributes size limitations of most filesytems.
So, if "streams_xattr... must be loaded together with vfs_fruit", and
fruit:resource = stream "should not be used with the
streams_xattr module due to the extended attributes size limitations of most filesytems", then that means that we should not use
fruit:resource = stream unless we're on ZFS. Great! FreeNAS is ZFS. So the
Resource stream gets passed to the
streams_xattr module and everything is fine. One more reason to use FreeNAS
Metadata/AfpInfo stream
fruit:metadata = [ stream | netatalk ]
Controls where the OS X metadata stream is stored:
netatalk (default) - use Netatalk compatible xattr
stream - pass the stream on to the next module in the VFS stack
Using 'stream' we see the error in the logs when files are saved:
../../source3/modules/vfs_fruit.c:4218(fruit_pread_meta_stream)
fruit_pread_meta_stream: Removing [testiiiing.txt.sb-df65248a-abgu9M/testiiiing.txt:AFP_AfpInfo] failed
So, I tried switching it back to the default, and I stop getting this error in the logs. Instead, I see a file flash briefly in Mac's Finder when I save the file. The file has the same name I think - "
testiiiing.txt.sb-df65248a-abgu9M". This seems preferable to gigabytes of log files filled with errors.
If anyone with deeper knowledge of these things has any further explanation, or sees something wrong with the above, I would be keen to learn.
