/*
* 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;
}
