static int ovl_whiteout(struct dentry *upperdir, struct dentry *dentry)
{
int err;
struct dentry *newdentry;
const struct cred *old_cred;
struct cred *override_cred;
/* FIXME: recheck lower dentry to see if whiteout is really needed */
err = -ENOMEM;
override_cred = ovl_prepare_creds(dentry->d_sb);
if (!override_cred)
goto out;
override_cred->fsuid = make_kuid(override_cred->user_ns, 0);
if (!uid_valid(override_cred->fsuid))
override_cred->fsuid = GLOBAL_ROOT_UID;
override_cred->fsgid = make_kgid(override_cred->user_ns, 0);
if (!gid_valid(override_cred->fsgid))
override_cred->fsgid = GLOBAL_ROOT_GID;
old_cred = override_creds(override_cred);
newdentry = lookup_one_len(dentry->d_name.name, upperdir,
dentry->d_name.len);
err = PTR_ERR(newdentry);
if (IS_ERR(newdentry))
goto out_put_cred;
/* Just been removed within the same locked region */
WARN_ON(newdentry->d_inode);
err = vfs_symlink(upperdir->d_inode, newdentry, ovl_whiteout_symlink);
if (err)
goto out_dput;
ovl_dentry_version_inc(dentry->d_parent);
err = ovl_do_setxattr(newdentry, ovl_whiteout_xattr, "y", 1, 0);
if (err)
vfs_unlink(upperdir->d_inode, newdentry, NULL);
out_dput:
dput(newdentry);
out_put_cred:
revert_creds(old_cred);
put_cred(override_cred);
out:
if (err) {
/*
* There's no way to recover from failure to whiteout.
* What should we do? Log a big fat error and... ?
*/
pr_err("overlayfs: ERROR - failed to whiteout '%s'\n",
dentry->d_name.name);
}
return err;
}
static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry)
{
int err;
err = ovl_do_setxattr(upperdentry, OVL_XATTR_OPAQUE, "y", 1, 0);
if (!err)
ovl_dentry_set_opaque(dentry);
return err;
}
static int ovl_set_nlink_common(struct dentry *dentry,
struct dentry *realdentry, const char *format)
{
struct inode *inode = d_inode(dentry);
struct inode *realinode = d_inode(realdentry);
char buf[13];
int len;
len = snprintf(buf, sizeof(buf), format,
(int) (inode->i_nlink - realinode->i_nlink));
if (WARN_ON(len >= sizeof(buf)))
return -EIO;
return ovl_do_setxattr(ovl_dentry_upper(dentry),
OVL_XATTR_NLINK, buf, len, 0);
}
static int ovl_set_opaque(struct dentry *upperdentry)
{
return ovl_do_setxattr(upperdentry, OVL_XATTR_OPAQUE, "y", 1, 0);
}
static int ovl_set_opaque(struct dentry *upperdentry)
{
return ovl_do_setxattr(upperdentry, ovl_opaque_xattr, "y", 1, 0);
}
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;
}
