/* * Common operations required to be done after creation of file on upper. * If @hardlink is false, then @inode is a pre-allocated inode, we may or * may not use to instantiate the new dentry. */ static int ovl_instantiate(struct dentry *dentry, struct inode *inode, struct dentry *newdentry, bool hardlink) { struct ovl_inode_params oip = { .upperdentry = newdentry, .newinode = inode, }; ovl_dir_modified(dentry->d_parent, false); ovl_dentry_set_upper_alias(dentry); if (!hardlink) { /* * ovl_obtain_alias() can be called after ovl_create_real() * and before we get here, so we may get an inode from cache * with the same real upperdentry that is not the inode we * pre-allocated. In this case we will use the cached inode * to instantiate the new dentry. * * XXX: if we ever use ovl_obtain_alias() to decode directory * file handles, need to use ovl_get_inode_locked() and * d_instantiate_new() here to prevent from creating two * hashed directory inode aliases. */ inode = ovl_get_inode(dentry->d_sb, &oip); if (WARN_ON(IS_ERR(inode))) return PTR_ERR(inode); } else { WARN_ON(ovl_inode_real(inode) != d_inode(newdentry)); dput(newdentry); inc_nlink(inode); } d_instantiate(dentry, inode); if (inode != oip.newinode) { pr_warn_ratelimited("overlayfs: newly created inode found in cache (%pd2)\n", dentry); } /* Force lookup of new upper hardlink to find its lower */ if (hardlink) d_drop(dentry); return 0; }
static int ovl_fill_super(struct super_block *sb, void *data, int silent) { struct path upperpath = { }; struct dentry *root_dentry; struct ovl_entry *oe; struct ovl_fs *ofs; struct cred *cred; int err; err = -ENOMEM; ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL); if (!ofs) goto out; ofs->creator_cred = cred = prepare_creds(); if (!cred) goto out_err; ofs->config.index = ovl_index_def; ofs->config.nfs_export = ovl_nfs_export_def; ofs->config.xino = ovl_xino_def(); ofs->config.metacopy = ovl_metacopy_def; err = ovl_parse_opt((char *) data, &ofs->config); if (err) goto out_err; err = -EINVAL; if (!ofs->config.lowerdir) { if (!silent) pr_err("overlayfs: missing 'lowerdir'\n"); goto out_err; } sb->s_stack_depth = 0; sb->s_maxbytes = MAX_LFS_FILESIZE; /* Assume underlaying fs uses 32bit inodes unless proven otherwise */ if (ofs->config.xino != OVL_XINO_OFF) ofs->xino_bits = BITS_PER_LONG - 32; if (ofs->config.upperdir) { if (!ofs->config.workdir) { pr_err("overlayfs: missing 'workdir'\n"); goto out_err; } err = ovl_get_upper(ofs, &upperpath); if (err) goto out_err; err = ovl_get_workdir(ofs, &upperpath); if (err) goto out_err; if (!ofs->workdir) sb->s_flags |= SB_RDONLY; sb->s_stack_depth = ofs->upper_mnt->mnt_sb->s_stack_depth; sb->s_time_gran = ofs->upper_mnt->mnt_sb->s_time_gran; } oe = ovl_get_lowerstack(sb, ofs); err = PTR_ERR(oe); if (IS_ERR(oe)) goto out_err; /* If the upper fs is nonexistent, we mark overlayfs r/o too */ if (!ofs->upper_mnt) sb->s_flags |= SB_RDONLY; if (!(ovl_force_readonly(ofs)) && ofs->config.index) { err = ovl_get_indexdir(ofs, oe, &upperpath); if (err) goto out_free_oe; /* Force r/o mount with no index dir */ if (!ofs->indexdir) { dput(ofs->workdir); ofs->workdir = NULL; sb->s_flags |= SB_RDONLY; } } /* Show index=off in /proc/mounts for forced r/o mount */ if (!ofs->indexdir) { ofs->config.index = false; if (ofs->upper_mnt && ofs->config.nfs_export) { pr_warn("overlayfs: NFS export requires an index dir, falling back to nfs_export=off.\n"); ofs->config.nfs_export = false; } } if (ofs->config.metacopy && ofs->config.nfs_export) { pr_warn("overlayfs: NFS export is not supported with metadata only copy up, falling back to nfs_export=off.\n"); ofs->config.nfs_export = false; } if (ofs->config.nfs_export) sb->s_export_op = &ovl_export_operations; /* Never override disk quota limits or use reserved space */ cap_lower(cred->cap_effective, CAP_SYS_RESOURCE); sb->s_magic = OVERLAYFS_SUPER_MAGIC; sb->s_op = &ovl_super_operations; sb->s_xattr = ovl_xattr_handlers; sb->s_fs_info = ofs; sb->s_flags |= SB_POSIXACL; err = -ENOMEM; root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, 0)); if (!root_dentry) goto out_free_oe; root_dentry->d_fsdata = oe; mntput(upperpath.mnt); if (upperpath.dentry) { ovl_dentry_set_upper_alias(root_dentry); if (ovl_is_impuredir(upperpath.dentry)) ovl_set_flag(OVL_IMPURE, d_inode(root_dentry)); } /* Root is always merge -> can have whiteouts */ ovl_set_flag(OVL_WHITEOUTS, d_inode(root_dentry)); ovl_dentry_set_flag(OVL_E_CONNECTED, root_dentry); ovl_set_upperdata(d_inode(root_dentry)); ovl_inode_init(d_inode(root_dentry), upperpath.dentry, ovl_dentry_lower(root_dentry), NULL); sb->s_root = root_dentry; return 0; out_free_oe: ovl_entry_stack_free(oe); kfree(oe); out_err: path_put(&upperpath); ovl_free_fs(ofs); out: return err; }