-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hubert Chan wrote: > On Mon, 27 Jun 2005 18:27:26 -0500, David Masover <[EMAIL PROTECTED]> said: > > >>Kyle Moffett wrote: >> >>>I think the '...' is just a bad idea in general, because it breaks >>>tar and such. An interface like this might be simpler to design and >>>use: >>> >>># mkdir /attr >>># mount -t attrfs attrfs /attr >>> >>>/attr/fd/$FD_NUM == '...' directory for a filedescriptor >>>/attr/fs/$DEV_NUM/$INODE_NUM == '...' directory for an inode > > > The most obvious (at least obvious for me) complaint about this is that > the attributes are separate from the file. (In other words, it's a bit > ugly. ;-) ) So if you want to backup a file, along with all its > (extended) attributes (or substreams, or ... etc. ...), you need to > backup the file, and find the appropriate /attr/fs/$DEV_NUM/$INODE_NUM > and back that up. If I want to edit an attribute, I need to find > $DEV_NUM and $INODE_NUM (which I have no idea how to do), rather than > just "edit foo/.../extended_attribute". (Or using your "getattrpath" > command, it would be a two-step process -- run getattrpath, then run > editor -- rather than a one-step process. Of course, this is only > mildly annoying.)
Especially considering you could add a tar/rsync flag to handle it for you. And most likely, each meta dir would have its own serialization method (read: file) so that you didn't find yourself trying to back up huge infinitely recursive structures, or accidentally triggering a huge tar operation, or something... > It also exposes a difference between attributes and regular files. > e.g. can I add attributes to an attribute? Under my scheme, yes, and it works the same way. > (say, I have a thumbnail > attribute for the file ~/foo, and I want to add a mime-type attribute to > that thumbnail attribute.) If you want to allow it, you have to be > careful not to run into a big loop generating an infinite number of > inodes in the attrfs. I'm not sure if inodes are a problem, but this kind of stuff would be up to the fs, not the attrfs or metafs. > That said, I prefer that interface over xattr or openat. Absolutely. But I think both should exist, so that programs currently using xattr will still work. Maybe you'd have: /meta/vfs/home/foo/attrs or something... Come to think of it, that changes the proposal a bit. You need a different way to access the meta-dir for files than for directories, if we're going to support /meta/vfs. No biggie: /meta/vfs/file/home/bob/sue.mpg/acl /meta/vfs/dir/home/bob/acl >>>It would be usable from a shell with a simple "getattrpath" command >>>which returns "fs/$DEV_NUM/$INODE_NUM" by stat-ing any given path. > > >>Still pretty annoying, but maybe a good idea, especially if the shell >>gets extended to support it. Not sure I like using inode numbers, >>though -- I like the idea of being able to symlink to stuff inside the >>meta-file dir. > > > The advantage of using inodes rather than pathnames is that it is robust > with respect to file renaming/moving. It also allows things like > adding attributes to symlinks (since the inode number for a symlink is > different from the inode number for the file that it points to). I think we need both interfaces, especially because the /meta/vfs interface makes looping easy. > You can still symlink. It just takes a little more effort to figure out > what $DEV_NUM/$INODE_NUM to use. Doesn't have the same effect. >>Actually, I like this. Give me some time to let it percolate. > > >>Hans, thoughts? Seems to be namespace fragmentation, but seems >>usable, less breakage, and so on. And should it be /attr or /meta? > > > For the mount point, it doesn't matter; it's up to the user. No, it's not. It's up to the user and the application developers. Sure, I could mount /proc somewhere else, but that would confuse some things. Mounting /meta somewhere else would confuse even more things. > It's the > attrfs or metafs or ???fs that matters (but which will greatly influence > whether people user /attr or /meta). True, but I think they should still hand down a decree of where it is to be mounted by default. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iQIVAwUBQsGxn3gHNmZLgCUhAQLWkg/+MIzXbygGoHubwLcw5SI1eeanVssukzF7 9kl+3qYcpbC6l/4fFkezBA8YCb8yy/VCfadAJ4Vgsr7T0rvGq1fvKIER6Q4LfU22 YCkHfU6dCnTmTjqHTFyYqZX95J6JXKUT/HCXn5AaYC5DIOYMp1gFHgj6P1wKOb/o KRvuOSIO0ta8fpPg6tBe6ve92sp99zqbacUplN+38+eBEIZUI7s7Dkg1lWX7ScyZ LVtHDEDJUuP0/Frq3xZHFKdgsVhoDtCm5Cl6EBX0OSubExPa/7ID2ANA+W01lqbm 9KMtXAcp/K8uOVkM8YDpFvvP2Ru/gp+iKy993lpGY9bEhIZ6BVz4zpVMvloHQe3a GCdsvub1yP7qQa/7LpkN6Shbw8W25iXcG0QUXa6XuiaJZIsVvRThrWOPXstx9GGQ KDZtMGIzH5vJcXQzIKzHMrfJBIKMmu3c/Et1EmdJy1t1PkH95+gGCrYc/nfBizfk NMYIp8S+RdGXwIcOWcwu4WspTJEZg1w7spXuydBZHd55YCq5JJE7lLNoK8Y3ZXks xC7b6Eo/0FgsxUmoQ9QYl9kzrxAejBGWmmTfsQGjFhu0Ep7jVCZHRRSq8r2RwRj/ AYY2JeFu7yRHsKy29BYipo0etR38Z5+Z0ZOn3iZZHHVz7D6u12U+69LXUEeyp46H mYzXXJOmIVA= =h/Gv -----END PGP SIGNATURE-----
