static int ovl_get_indexdir(struct ovl_fs *ofs, struct ovl_entry *oe,
struct path *upperpath)
{
struct vfsmount *mnt = ofs->upper_mnt;
int err;
err = mnt_want_write(mnt);
if (err)
return err;
/* Verify lower root is upper root origin */
err = ovl_verify_origin(upperpath->dentry, oe->lowerstack[0].dentry,
true);
if (err) {
pr_err("overlayfs: failed to verify upper root origin\n");
goto out;
}
ofs->indexdir = ovl_workdir_create(ofs, OVL_INDEXDIR_NAME, true);
if (ofs->indexdir) {
/*
* Verify upper root is exclusively associated with index dir.
* Older kernels stored upper fh in "trusted.overlay.origin"
* xattr. If that xattr exists, verify that it is a match to
* upper dir file handle. In any case, verify or set xattr
* "trusted.overlay.upper" to indicate that index may have
* directory entries.
*/
if (ovl_check_origin_xattr(ofs->indexdir)) {
err = ovl_verify_set_fh(ofs->indexdir, OVL_XATTR_ORIGIN,
upperpath->dentry, true, false);
if (err)
pr_err("overlayfs: failed to verify index dir 'origin' xattr\n");
}
err = ovl_verify_upper(ofs->indexdir, upperpath->dentry, true);
if (err)
pr_err("overlayfs: failed to verify index dir 'upper' xattr\n");
/* Cleanup bad/stale/orphan index entries */
if (!err)
err = ovl_indexdir_cleanup(ofs);
}
if (err || !ofs->indexdir)
pr_warn("overlayfs: try deleting index dir or mounting with '-o index=off' to disable inodes index.\n");
out:
mnt_drop_write(mnt);
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;
}
static int ovl_make_workdir(struct ovl_fs *ofs, struct path *workpath)
{
struct vfsmount *mnt = ofs->upper_mnt;
struct dentry *temp;
int fh_type;
int err;
err = mnt_want_write(mnt);
if (err)
return err;
ofs->workdir = ovl_workdir_create(ofs, OVL_WORKDIR_NAME, false);
if (!ofs->workdir)
goto out;
/*
* Upper should support d_type, else whiteouts are visible. Given
* workdir and upper are on same fs, we can do iterate_dir() on
* workdir. This check requires successful creation of workdir in
* previous step.
*/
err = ovl_check_d_type_supported(workpath);
if (err < 0)
goto out;
/*
* We allowed this configuration and don't want to break users over
* kernel upgrade. So warn instead of erroring out.
*/
if (!err)
pr_warn("overlayfs: upper fs needs to support d_type.\n");
/* Check if upper/work fs supports O_TMPFILE */
temp = ovl_do_tmpfile(ofs->workdir, S_IFREG | 0);
ofs->tmpfile = !IS_ERR(temp);
if (ofs->tmpfile)
dput(temp);
else
pr_warn("overlayfs: upper fs does not support tmpfile.\n");
/*
* Check if upper/work fs supports trusted.overlay.* xattr
*/
err = ovl_do_setxattr(ofs->workdir, OVL_XATTR_OPAQUE, "0", 1, 0);
if (err) {
ofs->noxattr = true;
ofs->config.index = false;
ofs->config.metacopy = false;
pr_warn("overlayfs: upper fs does not support xattr, falling back to index=off and metacopy=off.\n");
err = 0;
} else {
vfs_removexattr(ofs->workdir, OVL_XATTR_OPAQUE);
}
/* Check if upper/work fs supports file handles */
fh_type = ovl_can_decode_fh(ofs->workdir->d_sb);
if (ofs->config.index && !fh_type) {
ofs->config.index = false;
pr_warn("overlayfs: upper fs does not support file handles, falling back to index=off.\n");
}
/* Check if upper fs has 32bit inode numbers */
if (fh_type != FILEID_INO32_GEN)
ofs->xino_bits = 0;
/* NFS export of r/w mount depends on index */
if (ofs->config.nfs_export && !ofs->config.index) {
pr_warn("overlayfs: NFS export requires \"index=on\", falling back to nfs_export=off.\n");
ofs->config.nfs_export = false;
}
out:
mnt_drop_write(mnt);
return err;
}
