On Tue, May 18, 2010 at 11:10:38AM +0530, Aneesh Kumar K. V wrote: > On Tue, 18 May 2010 11:33:50 +0900, "J. R. Okajima" <hooanon05@xxxxxxxxxxx> wrote: > > > > "Aneesh Kumar K.V": > > > This patch add a new superblock operations get_fsid that returns the > > > UUID mapping for the file system. The UUID returned is used to > > > identify the file system apart of file_handle > > > > I am afraid get_fsid in s_op may conflict with "fsid=" option in /etc/exports. > > Generally all FSs have UUID or device number and they can return "fsid" > > correctly. But some of them may not have such id, or users may assign > > different fsid for them. > > Is "fsid=" value passed to superblock and can FS return it? Otherwise > > they cannot implement ->get_fsid(). > > The file_handle I mentioned above is the file handle returned by > sys_name_to_handle_at syscall. NFS kernel server won't be using the > interface. > > If file system doesn't support a unique identifier then they can leave > ->get_fsid callback NULL. The UUID part of the file_handle will be zero > filled. If it is returning a UUID, then perhaps the call should be ->get_uuid to avoid any confusion with existing uses of "fsid". Alternatively, why do we even need a method for this? Why not just put a struct uuid into the struct super_block and have filesystems fill it out inside their fill_super callback to get_sb()? If it is not filled out, then it is zero, and the code that puts it into the file handle can just do an unconditional copy at that point... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
