David P. Quigley wrote:
Looking through the code I see two references to xattrs, one is the index of the xattr table in the superblock and there seems to be struct member in one of the inode structures that is an index into this table. Looking through the code I don't see either of these used at all. Do you intend to add xattr support at some point? I saw reference to the desire to add xattr support in an email from 2004 but you said that the code has been rewritten since then. If you are going to add xattr support you probably want to add it to more than just regular files. In SELinux and other LSMs symlinks and directories are also labeled so they will need xattr entries.
Yes and yes. I am intending to add xattr support, something that's been on my to-do list for a long time (since 2004 as you said), but it's been something which I've never got the time to do. Once (if) Squashfs is mainlined, it will be the next thing.
The xattr references in the layout is my attempt at forward planning to avoid making an incompatible layout change when I finally get around to implementing it. My plan is to put xattrs in a table (referenced by the superblock), and then put indexes in "extended" inodes which index into the table (as you noticed). The general idea in Squashfs is that inodes get optimised for normally occurring cases, and less common cases (that would need a bigger inode) get to use an extended inode. Squashfs currently has an extended regular file inode, which is where the xattr index will sit, and so this has had an xattr index added. The other inodes don't currently have extended inodes, these will be defined when I implement xattrs (which is why they're missing).
Having said that, I've fscked up and forgotten to add an xattr field to the extended directory inode which is currently defined :)
Thanks for spotting this. Phillip
Dave
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