Hi, In fs/namespace.c do_add_mount() we do this check: /* Refuse the same filesystem on the same mount point */ err = -EBUSY; if (path->mnt->mnt_sb == newmnt->mnt.mnt_sb && path->mnt->mnt_root == path->dentry) goto unlock; So that mount fails with EBUSY. But for networked filesystems (at least cifs and nfs) you can do this: mount //foo /mnt -o A mount //foo /mnt -o B # different options Since the SB are different it works, fine. But mounting a 3rd time with options A succeeds, where from a user POV I would have expected to fail. So to recap: mount //foo /mnt -o A mount //foo /mnt -o A # EBUSY => expected behaviour mount //foo /mnt -o A mount //foo /mnt -o B # ok => expected behaviour mount //foo /mnt -o A mount //foo /mnt -o B mount //foo /mnt -o A # ok => what? Shouldn't we check the stack of filesystems mounted at the path instead of just the last one? Cheers, -- Aurélien Aptel / SUSE Labs Samba Team GPG: 1839 CB5F 9F5B FB9B AA97 8C99 03C8 A49B 521B D5D3 SUSE Linux GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
