34b4540e66
Since commit5679897eb1
("vfs: make sync_filesystem return errors from ->sync_fs"), the return value from sync_fs callback can be seen in sync_filesystem(). Thus the errseq_set opreation can be removed here. Depends-on: commit5679897eb1
("vfs: make sync_filesystem return errors from ->sync_fs") Signed-off-by: Haifeng Xu <haifeng.xu@shopee.com> Reviewed-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Amir Goldstein <amir73il@gmail.com>
1528 lines
38 KiB
C
1528 lines
38 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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*
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* Copyright (C) 2011 Novell Inc.
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*/
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#include <uapi/linux/magic.h>
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#include <linux/fs.h>
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#include <linux/namei.h>
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#include <linux/xattr.h>
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#include <linux/mount.h>
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#include <linux/parser.h>
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#include <linux/module.h>
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#include <linux/statfs.h>
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#include <linux/seq_file.h>
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#include <linux/posix_acl_xattr.h>
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#include <linux/exportfs.h>
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#include <linux/file.h>
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#include <linux/fs_context.h>
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#include <linux/fs_parser.h>
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#include "overlayfs.h"
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#include "params.h"
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MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
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MODULE_DESCRIPTION("Overlay filesystem");
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MODULE_LICENSE("GPL");
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struct ovl_dir_cache;
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static struct dentry *ovl_d_real(struct dentry *dentry, enum d_real_type type)
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{
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struct dentry *upper, *lower;
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int err;
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switch (type) {
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case D_REAL_DATA:
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case D_REAL_METADATA:
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break;
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default:
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goto bug;
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}
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if (!d_is_reg(dentry)) {
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/* d_real_inode() is only relevant for regular files */
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return dentry;
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}
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upper = ovl_dentry_upper(dentry);
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if (upper && (type == D_REAL_METADATA ||
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ovl_has_upperdata(d_inode(dentry))))
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return upper;
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if (type == D_REAL_METADATA) {
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lower = ovl_dentry_lower(dentry);
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goto real_lower;
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}
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/*
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* Best effort lazy lookup of lowerdata for D_REAL_DATA case to return
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* the real lowerdata dentry. The only current caller of d_real() with
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* D_REAL_DATA is d_real_inode() from trace_uprobe and this caller is
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* likely going to be followed reading from the file, before placing
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* uprobes on offset within the file, so lowerdata should be available
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* when setting the uprobe.
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*/
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err = ovl_verify_lowerdata(dentry);
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if (err)
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goto bug;
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lower = ovl_dentry_lowerdata(dentry);
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if (!lower)
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goto bug;
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real_lower:
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/* Handle recursion into stacked lower fs */
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return d_real(lower, type);
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bug:
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WARN(1, "%s(%pd4, %d): real dentry not found\n", __func__, dentry, type);
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return dentry;
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}
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static int ovl_revalidate_real(struct dentry *d, unsigned int flags, bool weak)
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{
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int ret = 1;
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if (!d)
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return 1;
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if (weak) {
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if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE)
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ret = d->d_op->d_weak_revalidate(d, flags);
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} else if (d->d_flags & DCACHE_OP_REVALIDATE) {
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ret = d->d_op->d_revalidate(d, flags);
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if (!ret) {
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if (!(flags & LOOKUP_RCU))
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d_invalidate(d);
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ret = -ESTALE;
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}
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}
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return ret;
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}
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static int ovl_dentry_revalidate_common(struct dentry *dentry,
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unsigned int flags, bool weak)
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{
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struct ovl_entry *oe;
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struct ovl_path *lowerstack;
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struct inode *inode = d_inode_rcu(dentry);
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struct dentry *upper;
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unsigned int i;
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int ret = 1;
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/* Careful in RCU mode */
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if (!inode)
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return -ECHILD;
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oe = OVL_I_E(inode);
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lowerstack = ovl_lowerstack(oe);
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upper = ovl_i_dentry_upper(inode);
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if (upper)
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ret = ovl_revalidate_real(upper, flags, weak);
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for (i = 0; ret > 0 && i < ovl_numlower(oe); i++)
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ret = ovl_revalidate_real(lowerstack[i].dentry, flags, weak);
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return ret;
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}
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static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags)
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{
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return ovl_dentry_revalidate_common(dentry, flags, false);
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}
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static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags)
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{
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return ovl_dentry_revalidate_common(dentry, flags, true);
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}
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static const struct dentry_operations ovl_dentry_operations = {
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.d_real = ovl_d_real,
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.d_revalidate = ovl_dentry_revalidate,
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.d_weak_revalidate = ovl_dentry_weak_revalidate,
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};
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static struct kmem_cache *ovl_inode_cachep;
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static struct inode *ovl_alloc_inode(struct super_block *sb)
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{
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struct ovl_inode *oi = alloc_inode_sb(sb, ovl_inode_cachep, GFP_KERNEL);
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if (!oi)
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return NULL;
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oi->cache = NULL;
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oi->redirect = NULL;
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oi->version = 0;
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oi->flags = 0;
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oi->__upperdentry = NULL;
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oi->lowerdata_redirect = NULL;
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oi->oe = NULL;
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mutex_init(&oi->lock);
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return &oi->vfs_inode;
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}
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static void ovl_free_inode(struct inode *inode)
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{
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struct ovl_inode *oi = OVL_I(inode);
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kfree(oi->redirect);
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kfree(oi->oe);
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mutex_destroy(&oi->lock);
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kmem_cache_free(ovl_inode_cachep, oi);
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}
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static void ovl_destroy_inode(struct inode *inode)
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{
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struct ovl_inode *oi = OVL_I(inode);
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dput(oi->__upperdentry);
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ovl_stack_put(ovl_lowerstack(oi->oe), ovl_numlower(oi->oe));
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if (S_ISDIR(inode->i_mode))
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ovl_dir_cache_free(inode);
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else
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kfree(oi->lowerdata_redirect);
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}
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static void ovl_put_super(struct super_block *sb)
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{
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struct ovl_fs *ofs = OVL_FS(sb);
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if (ofs)
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ovl_free_fs(ofs);
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}
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/* Sync real dirty inodes in upper filesystem (if it exists) */
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static int ovl_sync_fs(struct super_block *sb, int wait)
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{
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struct ovl_fs *ofs = OVL_FS(sb);
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struct super_block *upper_sb;
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int ret;
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ret = ovl_sync_status(ofs);
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if (ret < 0)
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return -EIO;
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if (!ret)
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return ret;
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/*
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* Not called for sync(2) call or an emergency sync (SB_I_SKIP_SYNC).
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* All the super blocks will be iterated, including upper_sb.
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*
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* If this is a syncfs(2) call, then we do need to call
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* sync_filesystem() on upper_sb, but enough if we do it when being
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* called with wait == 1.
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*/
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if (!wait)
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return 0;
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upper_sb = ovl_upper_mnt(ofs)->mnt_sb;
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down_read(&upper_sb->s_umount);
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ret = sync_filesystem(upper_sb);
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up_read(&upper_sb->s_umount);
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return ret;
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}
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/**
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* ovl_statfs
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* @dentry: The dentry to query
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* @buf: The struct kstatfs to fill in with stats
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*
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* Get the filesystem statistics. As writes always target the upper layer
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* filesystem pass the statfs to the upper filesystem (if it exists)
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*/
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static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
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{
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struct super_block *sb = dentry->d_sb;
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struct ovl_fs *ofs = OVL_FS(sb);
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struct dentry *root_dentry = sb->s_root;
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struct path path;
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int err;
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ovl_path_real(root_dentry, &path);
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err = vfs_statfs(&path, buf);
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if (!err) {
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buf->f_namelen = ofs->namelen;
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buf->f_type = OVERLAYFS_SUPER_MAGIC;
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if (ovl_has_fsid(ofs))
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buf->f_fsid = uuid_to_fsid(sb->s_uuid.b);
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}
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return err;
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}
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static const struct super_operations ovl_super_operations = {
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.alloc_inode = ovl_alloc_inode,
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.free_inode = ovl_free_inode,
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.destroy_inode = ovl_destroy_inode,
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.drop_inode = generic_delete_inode,
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.put_super = ovl_put_super,
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.sync_fs = ovl_sync_fs,
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.statfs = ovl_statfs,
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.show_options = ovl_show_options,
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};
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#define OVL_WORKDIR_NAME "work"
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#define OVL_INDEXDIR_NAME "index"
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static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
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const char *name, bool persist)
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{
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struct inode *dir = ofs->workbasedir->d_inode;
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struct vfsmount *mnt = ovl_upper_mnt(ofs);
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struct dentry *work;
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int err;
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bool retried = false;
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inode_lock_nested(dir, I_MUTEX_PARENT);
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retry:
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work = ovl_lookup_upper(ofs, name, ofs->workbasedir, strlen(name));
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if (!IS_ERR(work)) {
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struct iattr attr = {
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.ia_valid = ATTR_MODE,
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.ia_mode = S_IFDIR | 0,
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};
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if (work->d_inode) {
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err = -EEXIST;
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if (retried)
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goto out_dput;
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if (persist)
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goto out_unlock;
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retried = true;
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err = ovl_workdir_cleanup(ofs, dir, mnt, work, 0);
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dput(work);
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if (err == -EINVAL) {
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work = ERR_PTR(err);
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goto out_unlock;
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}
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goto retry;
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}
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err = ovl_mkdir_real(ofs, dir, &work, attr.ia_mode);
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if (err)
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goto out_dput;
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/* Weird filesystem returning with hashed negative (kernfs)? */
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err = -EINVAL;
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if (d_really_is_negative(work))
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goto out_dput;
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/*
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* Try to remove POSIX ACL xattrs from workdir. We are good if:
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*
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* a) success (there was a POSIX ACL xattr and was removed)
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* b) -ENODATA (there was no POSIX ACL xattr)
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* c) -EOPNOTSUPP (POSIX ACL xattrs are not supported)
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*
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* There are various other error values that could effectively
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* mean that the xattr doesn't exist (e.g. -ERANGE is returned
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* if the xattr name is too long), but the set of filesystems
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* allowed as upper are limited to "normal" ones, where checking
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* for the above two errors is sufficient.
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*/
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err = ovl_do_remove_acl(ofs, work, XATTR_NAME_POSIX_ACL_DEFAULT);
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if (err && err != -ENODATA && err != -EOPNOTSUPP)
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goto out_dput;
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err = ovl_do_remove_acl(ofs, work, XATTR_NAME_POSIX_ACL_ACCESS);
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if (err && err != -ENODATA && err != -EOPNOTSUPP)
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goto out_dput;
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/* Clear any inherited mode bits */
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inode_lock(work->d_inode);
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err = ovl_do_notify_change(ofs, work, &attr);
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inode_unlock(work->d_inode);
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if (err)
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goto out_dput;
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} else {
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err = PTR_ERR(work);
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goto out_err;
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}
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out_unlock:
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inode_unlock(dir);
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return work;
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out_dput:
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dput(work);
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out_err:
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pr_warn("failed to create directory %s/%s (errno: %i); mounting read-only\n",
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ofs->config.workdir, name, -err);
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work = NULL;
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goto out_unlock;
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}
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static int ovl_check_namelen(const struct path *path, struct ovl_fs *ofs,
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const char *name)
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{
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struct kstatfs statfs;
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int err = vfs_statfs(path, &statfs);
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if (err)
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pr_err("statfs failed on '%s'\n", name);
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else
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ofs->namelen = max(ofs->namelen, statfs.f_namelen);
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return err;
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}
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static int ovl_lower_dir(const char *name, struct path *path,
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struct ovl_fs *ofs, int *stack_depth)
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{
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int fh_type;
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int err;
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err = ovl_check_namelen(path, ofs, name);
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if (err)
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return err;
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*stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
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/*
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* The inodes index feature and NFS export need to encode and decode
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* file handles, so they require that all layers support them.
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*/
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fh_type = ovl_can_decode_fh(path->dentry->d_sb);
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if ((ofs->config.nfs_export ||
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(ofs->config.index && ofs->config.upperdir)) && !fh_type) {
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ofs->config.index = false;
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ofs->config.nfs_export = false;
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pr_warn("fs on '%s' does not support file handles, falling back to index=off,nfs_export=off.\n",
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name);
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}
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ofs->nofh |= !fh_type;
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/*
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* Decoding origin file handle is required for persistent st_ino.
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* Without persistent st_ino, xino=auto falls back to xino=off.
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*/
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if (ofs->config.xino == OVL_XINO_AUTO &&
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ofs->config.upperdir && !fh_type) {
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ofs->config.xino = OVL_XINO_OFF;
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pr_warn("fs on '%s' does not support file handles, falling back to xino=off.\n",
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name);
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}
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|
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/* Check if lower fs has 32bit inode numbers */
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if (fh_type != FILEID_INO32_GEN)
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ofs->xino_mode = -1;
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return 0;
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}
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|
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/* Workdir should not be subdir of upperdir and vice versa */
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static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
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{
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bool ok = false;
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|
|
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if (workdir != upperdir) {
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struct dentry *trap = lock_rename(workdir, upperdir);
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if (!IS_ERR(trap))
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unlock_rename(workdir, upperdir);
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ok = (trap == NULL);
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}
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return ok;
|
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}
|
|
|
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static int ovl_setup_trap(struct super_block *sb, struct dentry *dir,
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struct inode **ptrap, const char *name)
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{
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struct inode *trap;
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int err;
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trap = ovl_get_trap_inode(sb, dir);
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err = PTR_ERR_OR_ZERO(trap);
|
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if (err) {
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if (err == -ELOOP)
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pr_err("conflicting %s path\n", name);
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return err;
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}
|
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|
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*ptrap = trap;
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return 0;
|
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}
|
|
|
|
/*
|
|
* Determine how we treat concurrent use of upperdir/workdir based on the
|
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* index feature. This is papering over mount leaks of container runtimes,
|
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* for example, an old overlay mount is leaked and now its upperdir is
|
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* attempted to be used as a lower layer in a new overlay mount.
|
|
*/
|
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static int ovl_report_in_use(struct ovl_fs *ofs, const char *name)
|
|
{
|
|
if (ofs->config.index) {
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pr_err("%s is in-use as upperdir/workdir of another mount, mount with '-o index=off' to override exclusive upperdir protection.\n",
|
|
name);
|
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return -EBUSY;
|
|
} else {
|
|
pr_warn("%s is in-use as upperdir/workdir of another mount, accessing files from both mounts will result in undefined behavior.\n",
|
|
name);
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs,
|
|
struct ovl_layer *upper_layer,
|
|
const struct path *upperpath)
|
|
{
|
|
struct vfsmount *upper_mnt;
|
|
int err;
|
|
|
|
/* Upperdir path should not be r/o */
|
|
if (__mnt_is_readonly(upperpath->mnt)) {
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|
pr_err("upper fs is r/o, try multi-lower layers mount\n");
|
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err = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
err = ovl_check_namelen(upperpath, ofs, ofs->config.upperdir);
|
|
if (err)
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|
goto out;
|
|
|
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err = ovl_setup_trap(sb, upperpath->dentry, &upper_layer->trap,
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|
"upperdir");
|
|
if (err)
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|
goto out;
|
|
|
|
upper_mnt = clone_private_mount(upperpath);
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|
err = PTR_ERR(upper_mnt);
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|
if (IS_ERR(upper_mnt)) {
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|
pr_err("failed to clone upperpath\n");
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|
goto out;
|
|
}
|
|
|
|
/* Don't inherit atime flags */
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|
upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME);
|
|
upper_layer->mnt = upper_mnt;
|
|
upper_layer->idx = 0;
|
|
upper_layer->fsid = 0;
|
|
|
|
/*
|
|
* Inherit SB_NOSEC flag from upperdir.
|
|
*
|
|
* This optimization changes behavior when a security related attribute
|
|
* (suid/sgid/security.*) is changed on an underlying layer. This is
|
|
* okay because we don't yet have guarantees in that case, but it will
|
|
* need careful treatment once we want to honour changes to underlying
|
|
* filesystems.
|
|
*/
|
|
if (upper_mnt->mnt_sb->s_flags & SB_NOSEC)
|
|
sb->s_flags |= SB_NOSEC;
|
|
|
|
if (ovl_inuse_trylock(ovl_upper_mnt(ofs)->mnt_root)) {
|
|
ofs->upperdir_locked = true;
|
|
} else {
|
|
err = ovl_report_in_use(ofs, "upperdir");
|
|
if (err)
|
|
goto out;
|
|
}
|
|
|
|
err = 0;
|
|
out:
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Returns 1 if RENAME_WHITEOUT is supported, 0 if not supported and
|
|
* negative values if error is encountered.
|
|
*/
|
|
static int ovl_check_rename_whiteout(struct ovl_fs *ofs)
|
|
{
|
|
struct dentry *workdir = ofs->workdir;
|
|
struct inode *dir = d_inode(workdir);
|
|
struct dentry *temp;
|
|
struct dentry *dest;
|
|
struct dentry *whiteout;
|
|
struct name_snapshot name;
|
|
int err;
|
|
|
|
inode_lock_nested(dir, I_MUTEX_PARENT);
|
|
|
|
temp = ovl_create_temp(ofs, workdir, OVL_CATTR(S_IFREG | 0));
|
|
err = PTR_ERR(temp);
|
|
if (IS_ERR(temp))
|
|
goto out_unlock;
|
|
|
|
dest = ovl_lookup_temp(ofs, workdir);
|
|
err = PTR_ERR(dest);
|
|
if (IS_ERR(dest)) {
|
|
dput(temp);
|
|
goto out_unlock;
|
|
}
|
|
|
|
/* Name is inline and stable - using snapshot as a copy helper */
|
|
take_dentry_name_snapshot(&name, temp);
|
|
err = ovl_do_rename(ofs, dir, temp, dir, dest, RENAME_WHITEOUT);
|
|
if (err) {
|
|
if (err == -EINVAL)
|
|
err = 0;
|
|
goto cleanup_temp;
|
|
}
|
|
|
|
whiteout = ovl_lookup_upper(ofs, name.name.name, workdir, name.name.len);
|
|
err = PTR_ERR(whiteout);
|
|
if (IS_ERR(whiteout))
|
|
goto cleanup_temp;
|
|
|
|
err = ovl_upper_is_whiteout(ofs, whiteout);
|
|
|
|
/* Best effort cleanup of whiteout and temp file */
|
|
if (err)
|
|
ovl_cleanup(ofs, dir, whiteout);
|
|
dput(whiteout);
|
|
|
|
cleanup_temp:
|
|
ovl_cleanup(ofs, dir, temp);
|
|
release_dentry_name_snapshot(&name);
|
|
dput(temp);
|
|
dput(dest);
|
|
|
|
out_unlock:
|
|
inode_unlock(dir);
|
|
|
|
return err;
|
|
}
|
|
|
|
static struct dentry *ovl_lookup_or_create(struct ovl_fs *ofs,
|
|
struct dentry *parent,
|
|
const char *name, umode_t mode)
|
|
{
|
|
size_t len = strlen(name);
|
|
struct dentry *child;
|
|
|
|
inode_lock_nested(parent->d_inode, I_MUTEX_PARENT);
|
|
child = ovl_lookup_upper(ofs, name, parent, len);
|
|
if (!IS_ERR(child) && !child->d_inode)
|
|
child = ovl_create_real(ofs, parent->d_inode, child,
|
|
OVL_CATTR(mode));
|
|
inode_unlock(parent->d_inode);
|
|
dput(parent);
|
|
|
|
return child;
|
|
}
|
|
|
|
/*
|
|
* Creates $workdir/work/incompat/volatile/dirty file if it is not already
|
|
* present.
|
|
*/
|
|
static int ovl_create_volatile_dirty(struct ovl_fs *ofs)
|
|
{
|
|
unsigned int ctr;
|
|
struct dentry *d = dget(ofs->workbasedir);
|
|
static const char *const volatile_path[] = {
|
|
OVL_WORKDIR_NAME, "incompat", "volatile", "dirty"
|
|
};
|
|
const char *const *name = volatile_path;
|
|
|
|
for (ctr = ARRAY_SIZE(volatile_path); ctr; ctr--, name++) {
|
|
d = ovl_lookup_or_create(ofs, d, *name, ctr > 1 ? S_IFDIR : S_IFREG);
|
|
if (IS_ERR(d))
|
|
return PTR_ERR(d);
|
|
}
|
|
dput(d);
|
|
return 0;
|
|
}
|
|
|
|
static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs,
|
|
const struct path *workpath)
|
|
{
|
|
struct vfsmount *mnt = ovl_upper_mnt(ofs);
|
|
struct dentry *workdir;
|
|
struct file *tmpfile;
|
|
bool rename_whiteout;
|
|
bool d_type;
|
|
int fh_type;
|
|
int err;
|
|
|
|
err = mnt_want_write(mnt);
|
|
if (err)
|
|
return err;
|
|
|
|
workdir = ovl_workdir_create(ofs, OVL_WORKDIR_NAME, false);
|
|
err = PTR_ERR(workdir);
|
|
if (IS_ERR_OR_NULL(workdir))
|
|
goto out;
|
|
|
|
ofs->workdir = workdir;
|
|
|
|
err = ovl_setup_trap(sb, ofs->workdir, &ofs->workdir_trap, "workdir");
|
|
if (err)
|
|
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;
|
|
|
|
d_type = err;
|
|
if (!d_type)
|
|
pr_warn("upper fs needs to support d_type.\n");
|
|
|
|
/* Check if upper/work fs supports O_TMPFILE */
|
|
tmpfile = ovl_do_tmpfile(ofs, ofs->workdir, S_IFREG | 0);
|
|
ofs->tmpfile = !IS_ERR(tmpfile);
|
|
if (ofs->tmpfile)
|
|
fput(tmpfile);
|
|
else
|
|
pr_warn("upper fs does not support tmpfile.\n");
|
|
|
|
|
|
/* Check if upper/work fs supports RENAME_WHITEOUT */
|
|
err = ovl_check_rename_whiteout(ofs);
|
|
if (err < 0)
|
|
goto out;
|
|
|
|
rename_whiteout = err;
|
|
if (!rename_whiteout)
|
|
pr_warn("upper fs does not support RENAME_WHITEOUT.\n");
|
|
|
|
/*
|
|
* Check if upper/work fs supports (trusted|user).overlay.* xattr
|
|
*/
|
|
err = ovl_setxattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE, "0", 1);
|
|
if (err) {
|
|
pr_warn("failed to set xattr on upper\n");
|
|
ofs->noxattr = true;
|
|
if (ovl_redirect_follow(ofs)) {
|
|
ofs->config.redirect_mode = OVL_REDIRECT_NOFOLLOW;
|
|
pr_warn("...falling back to redirect_dir=nofollow.\n");
|
|
}
|
|
if (ofs->config.metacopy) {
|
|
ofs->config.metacopy = false;
|
|
pr_warn("...falling back to metacopy=off.\n");
|
|
}
|
|
if (ofs->config.index) {
|
|
ofs->config.index = false;
|
|
pr_warn("...falling back to index=off.\n");
|
|
}
|
|
if (ovl_has_fsid(ofs)) {
|
|
ofs->config.uuid = OVL_UUID_NULL;
|
|
pr_warn("...falling back to uuid=null.\n");
|
|
}
|
|
/*
|
|
* xattr support is required for persistent st_ino.
|
|
* Without persistent st_ino, xino=auto falls back to xino=off.
|
|
*/
|
|
if (ofs->config.xino == OVL_XINO_AUTO) {
|
|
ofs->config.xino = OVL_XINO_OFF;
|
|
pr_warn("...falling back to xino=off.\n");
|
|
}
|
|
if (err == -EPERM && !ofs->config.userxattr)
|
|
pr_info("try mounting with 'userxattr' option\n");
|
|
err = 0;
|
|
} else {
|
|
ovl_removexattr(ofs, ofs->workdir, OVL_XATTR_OPAQUE);
|
|
}
|
|
|
|
/*
|
|
* We allowed sub-optimal upper fs configuration and don't want to break
|
|
* users over kernel upgrade, but we never allowed remote upper fs, so
|
|
* we can enforce strict requirements for remote upper fs.
|
|
*/
|
|
if (ovl_dentry_remote(ofs->workdir) &&
|
|
(!d_type || !rename_whiteout || ofs->noxattr)) {
|
|
pr_err("upper fs missing required features.\n");
|
|
err = -EINVAL;
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* For volatile mount, create a incompat/volatile/dirty file to keep
|
|
* track of it.
|
|
*/
|
|
if (ofs->config.ovl_volatile) {
|
|
err = ovl_create_volatile_dirty(ofs);
|
|
if (err < 0) {
|
|
pr_err("Failed to create volatile/dirty file.\n");
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
/* 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("upper fs does not support file handles, falling back to index=off.\n");
|
|
}
|
|
ofs->nofh |= !fh_type;
|
|
|
|
/* Check if upper fs has 32bit inode numbers */
|
|
if (fh_type != FILEID_INO32_GEN)
|
|
ofs->xino_mode = -1;
|
|
|
|
/* NFS export of r/w mount depends on index */
|
|
if (ofs->config.nfs_export && !ofs->config.index) {
|
|
pr_warn("NFS export requires \"index=on\", falling back to nfs_export=off.\n");
|
|
ofs->config.nfs_export = false;
|
|
}
|
|
out:
|
|
mnt_drop_write(mnt);
|
|
return err;
|
|
}
|
|
|
|
static int ovl_get_workdir(struct super_block *sb, struct ovl_fs *ofs,
|
|
const struct path *upperpath,
|
|
const struct path *workpath)
|
|
{
|
|
int err;
|
|
|
|
err = -EINVAL;
|
|
if (upperpath->mnt != workpath->mnt) {
|
|
pr_err("workdir and upperdir must reside under the same mount\n");
|
|
return err;
|
|
}
|
|
if (!ovl_workdir_ok(workpath->dentry, upperpath->dentry)) {
|
|
pr_err("workdir and upperdir must be separate subtrees\n");
|
|
return err;
|
|
}
|
|
|
|
ofs->workbasedir = dget(workpath->dentry);
|
|
|
|
if (ovl_inuse_trylock(ofs->workbasedir)) {
|
|
ofs->workdir_locked = true;
|
|
} else {
|
|
err = ovl_report_in_use(ofs, "workdir");
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
err = ovl_setup_trap(sb, ofs->workbasedir, &ofs->workbasedir_trap,
|
|
"workdir");
|
|
if (err)
|
|
return err;
|
|
|
|
return ovl_make_workdir(sb, ofs, workpath);
|
|
}
|
|
|
|
static int ovl_get_indexdir(struct super_block *sb, struct ovl_fs *ofs,
|
|
struct ovl_entry *oe, const struct path *upperpath)
|
|
{
|
|
struct vfsmount *mnt = ovl_upper_mnt(ofs);
|
|
struct dentry *indexdir;
|
|
struct dentry *origin = ovl_lowerstack(oe)->dentry;
|
|
const struct ovl_fh *fh;
|
|
int err;
|
|
|
|
fh = ovl_get_origin_fh(ofs, origin);
|
|
if (IS_ERR(fh))
|
|
return PTR_ERR(fh);
|
|
|
|
err = mnt_want_write(mnt);
|
|
if (err)
|
|
goto out_free_fh;
|
|
|
|
/* Verify lower root is upper root origin */
|
|
err = ovl_verify_origin_fh(ofs, upperpath->dentry, fh, true);
|
|
if (err) {
|
|
pr_err("failed to verify upper root origin\n");
|
|
goto out;
|
|
}
|
|
|
|
/* index dir will act also as workdir */
|
|
iput(ofs->workdir_trap);
|
|
ofs->workdir_trap = NULL;
|
|
dput(ofs->workdir);
|
|
ofs->workdir = NULL;
|
|
indexdir = ovl_workdir_create(ofs, OVL_INDEXDIR_NAME, true);
|
|
if (IS_ERR(indexdir)) {
|
|
err = PTR_ERR(indexdir);
|
|
} else if (indexdir) {
|
|
ofs->workdir = indexdir;
|
|
err = ovl_setup_trap(sb, indexdir, &ofs->workdir_trap,
|
|
"indexdir");
|
|
if (err)
|
|
goto out;
|
|
|
|
/*
|
|
* Verify upper root is exclusively associated with index dir.
|
|
* Older kernels stored upper fh in ".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
|
|
* ".overlay.upper" to indicate that index may have
|
|
* directory entries.
|
|
*/
|
|
if (ovl_check_origin_xattr(ofs, indexdir)) {
|
|
err = ovl_verify_origin_xattr(ofs, indexdir,
|
|
OVL_XATTR_ORIGIN,
|
|
upperpath->dentry, true,
|
|
false);
|
|
if (err)
|
|
pr_err("failed to verify index dir 'origin' xattr\n");
|
|
}
|
|
err = ovl_verify_upper(ofs, indexdir, upperpath->dentry, true);
|
|
if (err)
|
|
pr_err("failed to verify index dir 'upper' xattr\n");
|
|
|
|
/* Cleanup bad/stale/orphan index entries */
|
|
if (!err)
|
|
err = ovl_indexdir_cleanup(ofs);
|
|
}
|
|
if (err || !indexdir)
|
|
pr_warn("try deleting index dir or mounting with '-o index=off' to disable inodes index.\n");
|
|
|
|
out:
|
|
mnt_drop_write(mnt);
|
|
out_free_fh:
|
|
kfree(fh);
|
|
return err;
|
|
}
|
|
|
|
static bool ovl_lower_uuid_ok(struct ovl_fs *ofs, const uuid_t *uuid)
|
|
{
|
|
unsigned int i;
|
|
|
|
if (!ofs->config.nfs_export && !ovl_upper_mnt(ofs))
|
|
return true;
|
|
|
|
/*
|
|
* We allow using single lower with null uuid for index and nfs_export
|
|
* for example to support those features with single lower squashfs.
|
|
* To avoid regressions in setups of overlay with re-formatted lower
|
|
* squashfs, do not allow decoding origin with lower null uuid unless
|
|
* user opted-in to one of the new features that require following the
|
|
* lower inode of non-dir upper.
|
|
*/
|
|
if (ovl_allow_offline_changes(ofs) && uuid_is_null(uuid))
|
|
return false;
|
|
|
|
for (i = 0; i < ofs->numfs; i++) {
|
|
/*
|
|
* We use uuid to associate an overlay lower file handle with a
|
|
* lower layer, so we can accept lower fs with null uuid as long
|
|
* as all lower layers with null uuid are on the same fs.
|
|
* if we detect multiple lower fs with the same uuid, we
|
|
* disable lower file handle decoding on all of them.
|
|
*/
|
|
if (ofs->fs[i].is_lower &&
|
|
uuid_equal(&ofs->fs[i].sb->s_uuid, uuid)) {
|
|
ofs->fs[i].bad_uuid = true;
|
|
return false;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/* Get a unique fsid for the layer */
|
|
static int ovl_get_fsid(struct ovl_fs *ofs, const struct path *path)
|
|
{
|
|
struct super_block *sb = path->mnt->mnt_sb;
|
|
unsigned int i;
|
|
dev_t dev;
|
|
int err;
|
|
bool bad_uuid = false;
|
|
bool warn = false;
|
|
|
|
for (i = 0; i < ofs->numfs; i++) {
|
|
if (ofs->fs[i].sb == sb)
|
|
return i;
|
|
}
|
|
|
|
if (!ovl_lower_uuid_ok(ofs, &sb->s_uuid)) {
|
|
bad_uuid = true;
|
|
if (ofs->config.xino == OVL_XINO_AUTO) {
|
|
ofs->config.xino = OVL_XINO_OFF;
|
|
warn = true;
|
|
}
|
|
if (ofs->config.index || ofs->config.nfs_export) {
|
|
ofs->config.index = false;
|
|
ofs->config.nfs_export = false;
|
|
warn = true;
|
|
}
|
|
if (warn) {
|
|
pr_warn("%s uuid detected in lower fs '%pd2', falling back to xino=%s,index=off,nfs_export=off.\n",
|
|
uuid_is_null(&sb->s_uuid) ? "null" :
|
|
"conflicting",
|
|
path->dentry, ovl_xino_mode(&ofs->config));
|
|
}
|
|
}
|
|
|
|
err = get_anon_bdev(&dev);
|
|
if (err) {
|
|
pr_err("failed to get anonymous bdev for lowerpath\n");
|
|
return err;
|
|
}
|
|
|
|
ofs->fs[ofs->numfs].sb = sb;
|
|
ofs->fs[ofs->numfs].pseudo_dev = dev;
|
|
ofs->fs[ofs->numfs].bad_uuid = bad_uuid;
|
|
|
|
return ofs->numfs++;
|
|
}
|
|
|
|
/*
|
|
* The fsid after the last lower fsid is used for the data layers.
|
|
* It is a "null fs" with a null sb, null uuid, and no pseudo dev.
|
|
*/
|
|
static int ovl_get_data_fsid(struct ovl_fs *ofs)
|
|
{
|
|
return ofs->numfs;
|
|
}
|
|
|
|
|
|
static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
|
|
struct ovl_fs_context *ctx, struct ovl_layer *layers)
|
|
{
|
|
int err;
|
|
unsigned int i;
|
|
size_t nr_merged_lower;
|
|
|
|
ofs->fs = kcalloc(ctx->nr + 2, sizeof(struct ovl_sb), GFP_KERNEL);
|
|
if (ofs->fs == NULL)
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* idx/fsid 0 are reserved for upper fs even with lower only overlay
|
|
* and the last fsid is reserved for "null fs" of the data layers.
|
|
*/
|
|
ofs->numfs++;
|
|
|
|
/*
|
|
* All lower layers that share the same fs as upper layer, use the same
|
|
* pseudo_dev as upper layer. Allocate fs[0].pseudo_dev even for lower
|
|
* only overlay to simplify ovl_fs_free().
|
|
* is_lower will be set if upper fs is shared with a lower layer.
|
|
*/
|
|
err = get_anon_bdev(&ofs->fs[0].pseudo_dev);
|
|
if (err) {
|
|
pr_err("failed to get anonymous bdev for upper fs\n");
|
|
return err;
|
|
}
|
|
|
|
if (ovl_upper_mnt(ofs)) {
|
|
ofs->fs[0].sb = ovl_upper_mnt(ofs)->mnt_sb;
|
|
ofs->fs[0].is_lower = false;
|
|
}
|
|
|
|
nr_merged_lower = ctx->nr - ctx->nr_data;
|
|
for (i = 0; i < ctx->nr; i++) {
|
|
struct ovl_fs_context_layer *l = &ctx->lower[i];
|
|
struct vfsmount *mnt;
|
|
struct inode *trap;
|
|
int fsid;
|
|
|
|
if (i < nr_merged_lower)
|
|
fsid = ovl_get_fsid(ofs, &l->path);
|
|
else
|
|
fsid = ovl_get_data_fsid(ofs);
|
|
if (fsid < 0)
|
|
return fsid;
|
|
|
|
/*
|
|
* Check if lower root conflicts with this overlay layers before
|
|
* checking if it is in-use as upperdir/workdir of "another"
|
|
* mount, because we do not bother to check in ovl_is_inuse() if
|
|
* the upperdir/workdir is in fact in-use by our
|
|
* upperdir/workdir.
|
|
*/
|
|
err = ovl_setup_trap(sb, l->path.dentry, &trap, "lowerdir");
|
|
if (err)
|
|
return err;
|
|
|
|
if (ovl_is_inuse(l->path.dentry)) {
|
|
err = ovl_report_in_use(ofs, "lowerdir");
|
|
if (err) {
|
|
iput(trap);
|
|
return err;
|
|
}
|
|
}
|
|
|
|
mnt = clone_private_mount(&l->path);
|
|
err = PTR_ERR(mnt);
|
|
if (IS_ERR(mnt)) {
|
|
pr_err("failed to clone lowerpath\n");
|
|
iput(trap);
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Make lower layers R/O. That way fchmod/fchown on lower file
|
|
* will fail instead of modifying lower fs.
|
|
*/
|
|
mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME;
|
|
|
|
layers[ofs->numlayer].trap = trap;
|
|
layers[ofs->numlayer].mnt = mnt;
|
|
layers[ofs->numlayer].idx = ofs->numlayer;
|
|
layers[ofs->numlayer].fsid = fsid;
|
|
layers[ofs->numlayer].fs = &ofs->fs[fsid];
|
|
/* Store for printing lowerdir=... in ovl_show_options() */
|
|
ofs->config.lowerdirs[ofs->numlayer] = l->name;
|
|
l->name = NULL;
|
|
ofs->numlayer++;
|
|
ofs->fs[fsid].is_lower = true;
|
|
}
|
|
|
|
/*
|
|
* When all layers on same fs, overlay can use real inode numbers.
|
|
* With mount option "xino=<on|auto>", mounter declares that there are
|
|
* enough free high bits in underlying fs to hold the unique fsid.
|
|
* If overlayfs does encounter underlying inodes using the high xino
|
|
* bits reserved for fsid, it emits a warning and uses the original
|
|
* inode number or a non persistent inode number allocated from a
|
|
* dedicated range.
|
|
*/
|
|
if (ofs->numfs - !ovl_upper_mnt(ofs) == 1) {
|
|
if (ofs->config.xino == OVL_XINO_ON)
|
|
pr_info("\"xino=on\" is useless with all layers on same fs, ignore.\n");
|
|
ofs->xino_mode = 0;
|
|
} else if (ofs->config.xino == OVL_XINO_OFF) {
|
|
ofs->xino_mode = -1;
|
|
} else if (ofs->xino_mode < 0) {
|
|
/*
|
|
* This is a roundup of number of bits needed for encoding
|
|
* fsid, where fsid 0 is reserved for upper fs (even with
|
|
* lower only overlay) +1 extra bit is reserved for the non
|
|
* persistent inode number range that is used for resolving
|
|
* xino lower bits overflow.
|
|
*/
|
|
BUILD_BUG_ON(ilog2(OVL_MAX_STACK) > 30);
|
|
ofs->xino_mode = ilog2(ofs->numfs - 1) + 2;
|
|
}
|
|
|
|
if (ofs->xino_mode > 0) {
|
|
pr_info("\"xino\" feature enabled using %d upper inode bits.\n",
|
|
ofs->xino_mode);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
|
|
struct ovl_fs_context *ctx,
|
|
struct ovl_fs *ofs,
|
|
struct ovl_layer *layers)
|
|
{
|
|
int err;
|
|
unsigned int i;
|
|
size_t nr_merged_lower;
|
|
struct ovl_entry *oe;
|
|
struct ovl_path *lowerstack;
|
|
|
|
struct ovl_fs_context_layer *l;
|
|
|
|
if (!ofs->config.upperdir && ctx->nr == 1) {
|
|
pr_err("at least 2 lowerdir are needed while upperdir nonexistent\n");
|
|
return ERR_PTR(-EINVAL);
|
|
}
|
|
|
|
err = -EINVAL;
|
|
for (i = 0; i < ctx->nr; i++) {
|
|
l = &ctx->lower[i];
|
|
|
|
err = ovl_lower_dir(l->name, &l->path, ofs, &sb->s_stack_depth);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
err = -EINVAL;
|
|
sb->s_stack_depth++;
|
|
if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
|
|
pr_err("maximum fs stacking depth exceeded\n");
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
err = ovl_get_layers(sb, ofs, ctx, layers);
|
|
if (err)
|
|
return ERR_PTR(err);
|
|
|
|
err = -ENOMEM;
|
|
/* Data-only layers are not merged in root directory */
|
|
nr_merged_lower = ctx->nr - ctx->nr_data;
|
|
oe = ovl_alloc_entry(nr_merged_lower);
|
|
if (!oe)
|
|
return ERR_PTR(err);
|
|
|
|
lowerstack = ovl_lowerstack(oe);
|
|
for (i = 0; i < nr_merged_lower; i++) {
|
|
l = &ctx->lower[i];
|
|
lowerstack[i].dentry = dget(l->path.dentry);
|
|
lowerstack[i].layer = &ofs->layers[i + 1];
|
|
}
|
|
ofs->numdatalayer = ctx->nr_data;
|
|
|
|
return oe;
|
|
}
|
|
|
|
/*
|
|
* Check if this layer root is a descendant of:
|
|
* - another layer of this overlayfs instance
|
|
* - upper/work dir of any overlayfs instance
|
|
*/
|
|
static int ovl_check_layer(struct super_block *sb, struct ovl_fs *ofs,
|
|
struct dentry *dentry, const char *name,
|
|
bool is_lower)
|
|
{
|
|
struct dentry *next = dentry, *parent;
|
|
int err = 0;
|
|
|
|
if (!dentry)
|
|
return 0;
|
|
|
|
parent = dget_parent(next);
|
|
|
|
/* Walk back ancestors to root (inclusive) looking for traps */
|
|
while (!err && parent != next) {
|
|
if (is_lower && ovl_lookup_trap_inode(sb, parent)) {
|
|
err = -ELOOP;
|
|
pr_err("overlapping %s path\n", name);
|
|
} else if (ovl_is_inuse(parent)) {
|
|
err = ovl_report_in_use(ofs, name);
|
|
}
|
|
next = parent;
|
|
parent = dget_parent(next);
|
|
dput(next);
|
|
}
|
|
|
|
dput(parent);
|
|
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Check if any of the layers or work dirs overlap.
|
|
*/
|
|
static int ovl_check_overlapping_layers(struct super_block *sb,
|
|
struct ovl_fs *ofs)
|
|
{
|
|
int i, err;
|
|
|
|
if (ovl_upper_mnt(ofs)) {
|
|
err = ovl_check_layer(sb, ofs, ovl_upper_mnt(ofs)->mnt_root,
|
|
"upperdir", false);
|
|
if (err)
|
|
return err;
|
|
|
|
/*
|
|
* Checking workbasedir avoids hitting ovl_is_inuse(parent) of
|
|
* this instance and covers overlapping work and index dirs,
|
|
* unless work or index dir have been moved since created inside
|
|
* workbasedir. In that case, we already have their traps in
|
|
* inode cache and we will catch that case on lookup.
|
|
*/
|
|
err = ovl_check_layer(sb, ofs, ofs->workbasedir, "workdir",
|
|
false);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
for (i = 1; i < ofs->numlayer; i++) {
|
|
err = ovl_check_layer(sb, ofs,
|
|
ofs->layers[i].mnt->mnt_root,
|
|
"lowerdir", true);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static struct dentry *ovl_get_root(struct super_block *sb,
|
|
struct dentry *upperdentry,
|
|
struct ovl_entry *oe)
|
|
{
|
|
struct dentry *root;
|
|
struct ovl_fs *ofs = OVL_FS(sb);
|
|
struct ovl_path *lowerpath = ovl_lowerstack(oe);
|
|
unsigned long ino = d_inode(lowerpath->dentry)->i_ino;
|
|
int fsid = lowerpath->layer->fsid;
|
|
struct ovl_inode_params oip = {
|
|
.upperdentry = upperdentry,
|
|
.oe = oe,
|
|
};
|
|
|
|
root = d_make_root(ovl_new_inode(sb, S_IFDIR, 0));
|
|
if (!root)
|
|
return NULL;
|
|
|
|
if (upperdentry) {
|
|
/* Root inode uses upper st_ino/i_ino */
|
|
ino = d_inode(upperdentry)->i_ino;
|
|
fsid = 0;
|
|
ovl_dentry_set_upper_alias(root);
|
|
if (ovl_is_impuredir(sb, upperdentry))
|
|
ovl_set_flag(OVL_IMPURE, d_inode(root));
|
|
}
|
|
|
|
/* Look for xwhiteouts marker except in the lowermost layer */
|
|
for (int i = 0; i < ovl_numlower(oe) - 1; i++, lowerpath++) {
|
|
struct path path = {
|
|
.mnt = lowerpath->layer->mnt,
|
|
.dentry = lowerpath->dentry,
|
|
};
|
|
|
|
/* overlay.opaque=x means xwhiteouts directory */
|
|
if (ovl_get_opaquedir_val(ofs, &path) == 'x') {
|
|
ovl_layer_set_xwhiteouts(ofs, lowerpath->layer);
|
|
ovl_dentry_set_xwhiteouts(root);
|
|
}
|
|
}
|
|
|
|
/* Root is always merge -> can have whiteouts */
|
|
ovl_set_flag(OVL_WHITEOUTS, d_inode(root));
|
|
ovl_dentry_set_flag(OVL_E_CONNECTED, root);
|
|
ovl_set_upperdata(d_inode(root));
|
|
ovl_inode_init(d_inode(root), &oip, ino, fsid);
|
|
ovl_dentry_init_flags(root, upperdentry, oe, DCACHE_OP_WEAK_REVALIDATE);
|
|
/* root keeps a reference of upperdentry */
|
|
dget(upperdentry);
|
|
|
|
return root;
|
|
}
|
|
|
|
int ovl_fill_super(struct super_block *sb, struct fs_context *fc)
|
|
{
|
|
struct ovl_fs *ofs = sb->s_fs_info;
|
|
struct ovl_fs_context *ctx = fc->fs_private;
|
|
struct dentry *root_dentry;
|
|
struct ovl_entry *oe;
|
|
struct ovl_layer *layers;
|
|
struct cred *cred;
|
|
int err;
|
|
|
|
err = -EIO;
|
|
if (WARN_ON(fc->user_ns != current_user_ns()))
|
|
goto out_err;
|
|
|
|
sb->s_d_op = &ovl_dentry_operations;
|
|
|
|
err = -ENOMEM;
|
|
ofs->creator_cred = cred = prepare_creds();
|
|
if (!cred)
|
|
goto out_err;
|
|
|
|
err = ovl_fs_params_verify(ctx, &ofs->config);
|
|
if (err)
|
|
goto out_err;
|
|
|
|
err = -EINVAL;
|
|
if (ctx->nr == 0) {
|
|
if (!(fc->sb_flags & SB_SILENT))
|
|
pr_err("missing 'lowerdir'\n");
|
|
goto out_err;
|
|
}
|
|
|
|
err = -ENOMEM;
|
|
layers = kcalloc(ctx->nr + 1, sizeof(struct ovl_layer), GFP_KERNEL);
|
|
if (!layers)
|
|
goto out_err;
|
|
|
|
ofs->config.lowerdirs = kcalloc(ctx->nr + 1, sizeof(char *), GFP_KERNEL);
|
|
if (!ofs->config.lowerdirs) {
|
|
kfree(layers);
|
|
goto out_err;
|
|
}
|
|
ofs->layers = layers;
|
|
/*
|
|
* Layer 0 is reserved for upper even if there's no upper.
|
|
* config.lowerdirs[0] is used for storing the user provided colon
|
|
* separated lowerdir string.
|
|
*/
|
|
ofs->config.lowerdirs[0] = ctx->lowerdir_all;
|
|
ctx->lowerdir_all = NULL;
|
|
ofs->numlayer = 1;
|
|
|
|
sb->s_stack_depth = 0;
|
|
sb->s_maxbytes = MAX_LFS_FILESIZE;
|
|
atomic_long_set(&ofs->last_ino, 1);
|
|
/* Assume underlying fs uses 32bit inodes unless proven otherwise */
|
|
if (ofs->config.xino != OVL_XINO_OFF) {
|
|
ofs->xino_mode = BITS_PER_LONG - 32;
|
|
if (!ofs->xino_mode) {
|
|
pr_warn("xino not supported on 32bit kernel, falling back to xino=off.\n");
|
|
ofs->config.xino = OVL_XINO_OFF;
|
|
}
|
|
}
|
|
|
|
/* alloc/destroy_inode needed for setting up traps in inode cache */
|
|
sb->s_op = &ovl_super_operations;
|
|
|
|
if (ofs->config.upperdir) {
|
|
struct super_block *upper_sb;
|
|
|
|
err = -EINVAL;
|
|
if (!ofs->config.workdir) {
|
|
pr_err("missing 'workdir'\n");
|
|
goto out_err;
|
|
}
|
|
|
|
err = ovl_get_upper(sb, ofs, &layers[0], &ctx->upper);
|
|
if (err)
|
|
goto out_err;
|
|
|
|
upper_sb = ovl_upper_mnt(ofs)->mnt_sb;
|
|
if (!ovl_should_sync(ofs)) {
|
|
ofs->errseq = errseq_sample(&upper_sb->s_wb_err);
|
|
if (errseq_check(&upper_sb->s_wb_err, ofs->errseq)) {
|
|
err = -EIO;
|
|
pr_err("Cannot mount volatile when upperdir has an unseen error. Sync upperdir fs to clear state.\n");
|
|
goto out_err;
|
|
}
|
|
}
|
|
|
|
err = ovl_get_workdir(sb, ofs, &ctx->upper, &ctx->work);
|
|
if (err)
|
|
goto out_err;
|
|
|
|
if (!ofs->workdir)
|
|
sb->s_flags |= SB_RDONLY;
|
|
|
|
sb->s_stack_depth = upper_sb->s_stack_depth;
|
|
sb->s_time_gran = upper_sb->s_time_gran;
|
|
}
|
|
oe = ovl_get_lowerstack(sb, ctx, ofs, layers);
|
|
err = PTR_ERR(oe);
|
|
if (IS_ERR(oe))
|
|
goto out_err;
|
|
|
|
/* If the upper fs is nonexistent, we mark overlayfs r/o too */
|
|
if (!ovl_upper_mnt(ofs))
|
|
sb->s_flags |= SB_RDONLY;
|
|
|
|
if (!ovl_origin_uuid(ofs) && ofs->numfs > 1) {
|
|
pr_warn("The uuid=off requires a single fs for lower and upper, falling back to uuid=null.\n");
|
|
ofs->config.uuid = OVL_UUID_NULL;
|
|
} else if (ovl_has_fsid(ofs) && ovl_upper_mnt(ofs)) {
|
|
/* Use per instance persistent uuid/fsid */
|
|
ovl_init_uuid_xattr(sb, ofs, &ctx->upper);
|
|
}
|
|
|
|
if (!ovl_force_readonly(ofs) && ofs->config.index) {
|
|
err = ovl_get_indexdir(sb, ofs, oe, &ctx->upper);
|
|
if (err)
|
|
goto out_free_oe;
|
|
|
|
/* Force r/o mount with no index dir */
|
|
if (!ofs->workdir)
|
|
sb->s_flags |= SB_RDONLY;
|
|
}
|
|
|
|
err = ovl_check_overlapping_layers(sb, ofs);
|
|
if (err)
|
|
goto out_free_oe;
|
|
|
|
/* Show index=off in /proc/mounts for forced r/o mount */
|
|
if (!ofs->workdir) {
|
|
ofs->config.index = false;
|
|
if (ovl_upper_mnt(ofs) && ofs->config.nfs_export) {
|
|
pr_warn("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("NFS export is not supported with metadata only copy up, falling back to nfs_export=off.\n");
|
|
ofs->config.nfs_export = false;
|
|
}
|
|
|
|
/*
|
|
* Support encoding decodable file handles with nfs_export=on
|
|
* and encoding non-decodable file handles with nfs_export=off
|
|
* if all layers support file handles.
|
|
*/
|
|
if (ofs->config.nfs_export)
|
|
sb->s_export_op = &ovl_export_operations;
|
|
else if (!ofs->nofh)
|
|
sb->s_export_op = &ovl_export_fid_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_xattr = ovl_xattr_handlers(ofs);
|
|
sb->s_fs_info = ofs;
|
|
#ifdef CONFIG_FS_POSIX_ACL
|
|
sb->s_flags |= SB_POSIXACL;
|
|
#endif
|
|
sb->s_iflags |= SB_I_SKIP_SYNC;
|
|
/*
|
|
* Ensure that umask handling is done by the filesystems used
|
|
* for the the upper layer instead of overlayfs as that would
|
|
* lead to unexpected results.
|
|
*/
|
|
sb->s_iflags |= SB_I_NOUMASK;
|
|
sb->s_iflags |= SB_I_EVM_HMAC_UNSUPPORTED;
|
|
|
|
err = -ENOMEM;
|
|
root_dentry = ovl_get_root(sb, ctx->upper.dentry, oe);
|
|
if (!root_dentry)
|
|
goto out_free_oe;
|
|
|
|
sb->s_root = root_dentry;
|
|
|
|
return 0;
|
|
|
|
out_free_oe:
|
|
ovl_free_entry(oe);
|
|
out_err:
|
|
ovl_free_fs(ofs);
|
|
sb->s_fs_info = NULL;
|
|
return err;
|
|
}
|
|
|
|
struct file_system_type ovl_fs_type = {
|
|
.owner = THIS_MODULE,
|
|
.name = "overlay",
|
|
.init_fs_context = ovl_init_fs_context,
|
|
.parameters = ovl_parameter_spec,
|
|
.fs_flags = FS_USERNS_MOUNT,
|
|
.kill_sb = kill_anon_super,
|
|
};
|
|
MODULE_ALIAS_FS("overlay");
|
|
|
|
static void ovl_inode_init_once(void *foo)
|
|
{
|
|
struct ovl_inode *oi = foo;
|
|
|
|
inode_init_once(&oi->vfs_inode);
|
|
}
|
|
|
|
static int __init ovl_init(void)
|
|
{
|
|
int err;
|
|
|
|
ovl_inode_cachep = kmem_cache_create("ovl_inode",
|
|
sizeof(struct ovl_inode), 0,
|
|
(SLAB_RECLAIM_ACCOUNT|
|
|
SLAB_ACCOUNT),
|
|
ovl_inode_init_once);
|
|
if (ovl_inode_cachep == NULL)
|
|
return -ENOMEM;
|
|
|
|
err = register_filesystem(&ovl_fs_type);
|
|
if (!err)
|
|
return 0;
|
|
|
|
kmem_cache_destroy(ovl_inode_cachep);
|
|
|
|
return err;
|
|
}
|
|
|
|
static void __exit ovl_exit(void)
|
|
{
|
|
unregister_filesystem(&ovl_fs_type);
|
|
|
|
/*
|
|
* Make sure all delayed rcu free inodes are flushed before we
|
|
* destroy cache.
|
|
*/
|
|
rcu_barrier();
|
|
kmem_cache_destroy(ovl_inode_cachep);
|
|
}
|
|
|
|
module_init(ovl_init);
|
|
module_exit(ovl_exit);
|