static int ovl_get_upper(struct ovl_fs *ofs, struct path *upperpath) { struct vfsmount *upper_mnt; int err; err = ovl_mount_dir(ofs->config.upperdir, upperpath); if (err) goto out; /* Upper fs should not be r/o */ if (sb_rdonly(upperpath->mnt->mnt_sb)) { pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n"); err = -EINVAL; goto out; } err = ovl_check_namelen(upperpath, ofs, ofs->config.upperdir); if (err) goto out; upper_mnt = clone_private_mount(upperpath); err = PTR_ERR(upper_mnt); if (IS_ERR(upper_mnt)) { pr_err("overlayfs: failed to clone upperpath\n"); goto out; } /* Don't inherit atime flags */ upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME); ofs->upper_mnt = upper_mnt; err = -EBUSY; if (ovl_inuse_trylock(ofs->upper_mnt->mnt_root)) { ofs->upperdir_locked = true; } else if (ofs->config.index) { pr_err("overlayfs: upperdir is in-use by another mount, mount with '-o index=off' to override exclusive upperdir protection.\n"); goto out; } else { pr_warn("overlayfs: upperdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n"); } err = 0; out: return err; }
static int ovl_get_workdir(struct ovl_fs *ofs, struct path *upperpath) { int err; struct path workpath = { }; err = ovl_mount_dir(ofs->config.workdir, &workpath); if (err) goto out; err = -EINVAL; if (upperpath->mnt != workpath.mnt) { pr_err("overlayfs: workdir and upperdir must reside under the same mount\n"); goto out; } if (!ovl_workdir_ok(workpath.dentry, upperpath->dentry)) { pr_err("overlayfs: workdir and upperdir must be separate subtrees\n"); goto out; } ofs->workbasedir = dget(workpath.dentry); err = -EBUSY; if (ovl_inuse_trylock(ofs->workbasedir)) { ofs->workdir_locked = true; } else if (ofs->config.index) { pr_err("overlayfs: workdir is in-use by another mount, mount with '-o index=off' to override exclusive workdir protection.\n"); goto out; } else { pr_warn("overlayfs: workdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n"); } err = ovl_make_workdir(ofs, &workpath); if (err) goto out; err = 0; out: path_put(&workpath); return err; }
static int ovl_fill_super(struct super_block *sb, void *data, int silent) { struct path lowerpath; struct path upperpath; struct path workpath; struct inode *root_inode; struct dentry *root_dentry; struct ovl_entry *oe; struct ovl_fs *ufs; struct kstatfs statfs; int err; err = -ENOMEM; ufs = kmalloc(sizeof(struct ovl_fs), GFP_KERNEL); if (!ufs) goto out; err = ovl_parse_opt((char *) data, &ufs->config); if (err) goto out_free_ufs; /* FIXME: workdir is not needed for a R/O mount */ err = -EINVAL; if (!ufs->config.upperdir || !ufs->config.lowerdir || !ufs->config.workdir) { pr_err("overlayfs: missing upperdir or lowerdir or workdir\n"); goto out_free_config; } oe = ovl_alloc_entry(); if (oe == NULL) goto out_free_config; err = ovl_mount_dir(ufs->config.upperdir, &upperpath); if (err) goto out_free_oe; err = ovl_mount_dir(ufs->config.lowerdir, &lowerpath); if (err) goto out_put_upperpath; err = ovl_mount_dir(ufs->config.workdir, &workpath); if (err) goto out_put_lowerpath; err = -EINVAL; if (!S_ISDIR(upperpath.dentry->d_inode->i_mode) || !S_ISDIR(lowerpath.dentry->d_inode->i_mode) || !S_ISDIR(workpath.dentry->d_inode->i_mode)) { pr_err("overlayfs: upperdir or lowerdir or workdir not a directory\n"); goto out_put_workpath; } if (upperpath.mnt != workpath.mnt) { pr_err("overlayfs: workdir and upperdir must reside under the same mount\n"); goto out_put_workpath; } if (upperpath.dentry == workpath.dentry || d_ancestor(upperpath.dentry, workpath.dentry) || d_ancestor(workpath.dentry, upperpath.dentry)) { pr_err("overlayfs: workdir and upperdir must be separate subtrees\n"); goto out_put_workpath; } err = vfs_statfs(&lowerpath, &statfs); if (err) { pr_err("overlayfs: statfs failed on lowerpath\n"); goto out_put_workpath; } ufs->lower_namelen = statfs.f_namelen; sb->s_stack_depth = max(upperpath.mnt->mnt_sb->s_stack_depth, lowerpath.mnt->mnt_sb->s_stack_depth) + 1; err = -EINVAL; if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { pr_err("overlayfs: maximum fs stacking depth exceeded\n"); goto out_put_lowerpath; } ufs->upper_mnt = clone_private_mount(&upperpath); err = PTR_ERR(ufs->upper_mnt); if (IS_ERR(ufs->upper_mnt)) { pr_err("overlayfs: failed to clone upperpath\n"); goto out_put_workpath; } ufs->lower_mnt = clone_private_mount(&lowerpath); err = PTR_ERR(ufs->lower_mnt); if (IS_ERR(ufs->lower_mnt)) { pr_err("overlayfs: failed to clone lowerpath\n"); goto out_put_upper_mnt; } ufs->workdir = ovl_workdir_create(ufs->upper_mnt, workpath.dentry); err = PTR_ERR(ufs->workdir); if (IS_ERR(ufs->workdir)) { pr_err("overlayfs: failed to create directory %s/%s\n", ufs->config.workdir, OVL_WORKDIR_NAME); goto out_put_lower_mnt; } /* * Make lower_mnt R/O. That way fchmod/fchown on lower file * will fail instead of modifying lower fs. */ ufs->lower_mnt->mnt_flags |= MNT_READONLY; /* If the upper fs is r/o, we mark overlayfs r/o too */ if (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY) sb->s_flags |= MS_RDONLY; err = -ENOMEM; root_inode = ovl_new_inode(sb, S_IFDIR, oe); if (!root_inode) goto out_put_workdir; root_dentry = d_make_root(root_inode); if (!root_dentry) goto out_put_workdir; mntput(upperpath.mnt); mntput(lowerpath.mnt); path_put(&workpath); oe->__upperdentry = dget(upperpath.dentry); oe->lowerdentry = lowerpath.dentry; root_dentry->d_fsdata = oe; root_dentry->d_op = &ovl_dentry_operations; sb->s_magic = OVERLAYFS_SUPER_MAGIC; sb->s_op = &ovl_super_operations; sb->s_root = root_dentry; sb->s_fs_info = ufs; return 0; out_put_workdir: dput(ufs->workdir); out_put_lower_mnt: mntput(ufs->lower_mnt); out_put_upper_mnt: mntput(ufs->upper_mnt); out_put_workpath: path_put(&workpath); out_put_lowerpath: path_put(&lowerpath); out_put_upperpath: path_put(&upperpath); out_free_oe: kfree(oe); out_free_config: kfree(ufs->config.lowerdir); kfree(ufs->config.upperdir); kfree(ufs->config.workdir); out_free_ufs: kfree(ufs); out: return err; }