i thought it was a permission problem too. but it isn't, and i've found a way to make it work.

i have about 150 chinese songs (filenames and title/artist/album tags all in utf-8 edited by easytag and copied to the device from fedora) and the N900 can't read the tags of about a dozen of them (title/artist/album tags all empty). similar thing had happened to the earlier OS version of my N95 8GB (the tags weren't empty but they're messed up encodings) but a later update fixed that problem so that i didn't have to edit the tags on the N95.

anyway, after some trial and error, i've found that (in my case) only the title and artist tags can be updated successfully but not the album tag. i don't know if it has anything to do with the album art cuz when i edit the album tag, the album art will get chosen and mussorgsky will crash. i haven't tried not including album art for the affected albums so i don't know for sure. so for those dozen of songs, i edit the title tag to "1", "2", etc and the artist tag to "a", "b", etc, and keep the album tag unchanged (i.e. in their original utf-8 chinese). i copy those songs to the N900 and edit the title and artist tags with mussorgsky and it works.

i have a feeling this problem is the same as the one i encountered with my N95 8GB. i hope that a fix will be available soon.