> > Looking at the FILE_ATTRIBUTE_* flags defined in SMB protocol > > (fs/smb/common/smb2pdu.h) I wonder how many of them will be > > needed for applications beyond the obvious ones that were listed. > > Well they only asked for seven of them. ;) > > I chatted with Ted about this yesterday, and ... some of the attributes > (like read only) imply that you'd want the linux server to enforce no > writing to the file; some like archive seem a little superfluous since > on linux you can compare cmtime from the backup against what's in the > file now; and still others (like hidden/system) might just be some dorky > thing that could be hidden in some xattr because a unix filesystem won't > care. > > And then there are other attrs like "integrity stream" where someone > with more experience with windows would have to tell me if fsverity > provides sufficient behaviors or not. > > But maybe we should start by plumbing one of those bits in? I guess the > gross part is that implies an ondisk inode format change or (gross) > xattr lookups in the open path. > I may be wrong, but I think there is a confusion in this thread. I don't think that Pali was looking for filesystems to implement storing those attributes. I read his email as a request to standardize a user API to get/set those attributes for the filesystems that already support them and possibly for vfs to enforce some of them (e.g. READONLY) in generic code. Nevertheless, I understand the confusion because I know there is also demand for storing those attributes by file servers in a standard way and for vfs to respect those attributes on the host. Full disclosure - I have an out of tree xfs patch that implements ioctls XFS_IOC_[GS]ETDOSATTRAT and stashes these attributes in the unused di_dmevmask space. Compared to the smb server alternative of storing those attributes as xattrs on the server, this saves a *lot* of IO in an SMB file browsing workload, where most of the inodes have large (ACL) xattrs that do not fit into the inode, because SMB protocol needs to return those attributes in a response to READDIR(PLUSPLUS), so it needs to read all the external xattr blocks. So yeh, I would love to have proper support in xfs... Thanks, Amir.
