ovl: split super.c
fs/overlayfs/super.c is the biggest of the overlayfs source files and it contains various utility functions as well as the rather complicated lookup code. Split these parts out to separate files. Before: 1446 fs/overlayfs/super.c After: 919 fs/overlayfs/super.c 267 fs/overlayfs/namei.c 235 fs/overlayfs/util.c 51 fs/overlayfs/ovl_entry.h Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Miklos Szeredi
parent
2b8c30e9ef
commit
bbb1e54dd5
6 changed files with 572 additions and 546 deletions
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@ -4,4 +4,4 @@
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obj-$(CONFIG_OVERLAY_FS) += overlay.o
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overlay-objs := super.o inode.o dir.o readdir.o copy_up.o
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overlay-objs := super.o namei.o util.o inode.o dir.o readdir.o copy_up.o
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267
fs/overlayfs/namei.c
Normal file
267
fs/overlayfs/namei.c
Normal file
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@ -0,0 +1,267 @@
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/*
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* Copyright (C) 2011 Novell Inc.
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* Copyright (C) 2016 Red Hat, Inc.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*/
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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 "overlayfs.h"
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#include "ovl_entry.h"
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static struct dentry *ovl_lookup_real(struct dentry *dir,
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const struct qstr *name)
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{
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struct dentry *dentry;
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dentry = lookup_one_len_unlocked(name->name, dir, name->len);
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if (IS_ERR(dentry)) {
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if (PTR_ERR(dentry) == -ENOENT)
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dentry = NULL;
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} else if (!dentry->d_inode) {
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dput(dentry);
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dentry = NULL;
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} else if (ovl_dentry_weird(dentry)) {
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dput(dentry);
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/* Don't support traversing automounts and other weirdness */
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dentry = ERR_PTR(-EREMOTE);
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}
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return dentry;
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}
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static bool ovl_is_opaquedir(struct dentry *dentry)
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{
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int res;
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char val;
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if (!d_is_dir(dentry))
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return false;
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res = vfs_getxattr(dentry, OVL_XATTR_OPAQUE, &val, 1);
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if (res == 1 && val == 'y')
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return true;
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return false;
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}
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/*
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* Returns next layer in stack starting from top.
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* Returns -1 if this is the last layer.
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*/
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int ovl_path_next(int idx, struct dentry *dentry, struct path *path)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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BUG_ON(idx < 0);
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if (idx == 0) {
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ovl_path_upper(dentry, path);
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if (path->dentry)
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return oe->numlower ? 1 : -1;
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idx++;
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}
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BUG_ON(idx > oe->numlower);
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*path = oe->lowerstack[idx - 1];
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return (idx < oe->numlower) ? idx + 1 : -1;
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}
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struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
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unsigned int flags)
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{
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struct ovl_entry *oe;
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const struct cred *old_cred;
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struct ovl_entry *poe = dentry->d_parent->d_fsdata;
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struct path *stack = NULL;
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struct dentry *upperdir, *upperdentry = NULL;
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unsigned int ctr = 0;
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struct inode *inode = NULL;
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bool upperopaque = false;
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bool stop = false;
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bool isdir = false;
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struct dentry *this;
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unsigned int i;
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int err;
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old_cred = ovl_override_creds(dentry->d_sb);
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upperdir = ovl_upperdentry_dereference(poe);
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if (upperdir) {
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this = ovl_lookup_real(upperdir, &dentry->d_name);
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err = PTR_ERR(this);
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if (IS_ERR(this))
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goto out;
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if (this) {
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if (unlikely(ovl_dentry_remote(this))) {
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dput(this);
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err = -EREMOTE;
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goto out;
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}
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if (ovl_is_whiteout(this)) {
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dput(this);
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this = NULL;
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stop = upperopaque = true;
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} else if (!d_is_dir(this)) {
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stop = true;
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} else {
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isdir = true;
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if (poe->numlower && ovl_is_opaquedir(this))
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stop = upperopaque = true;
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}
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}
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upperdentry = this;
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}
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if (!stop && poe->numlower) {
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err = -ENOMEM;
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stack = kcalloc(poe->numlower, sizeof(struct path), GFP_KERNEL);
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if (!stack)
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goto out_put_upper;
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}
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for (i = 0; !stop && i < poe->numlower; i++) {
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struct path lowerpath = poe->lowerstack[i];
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this = ovl_lookup_real(lowerpath.dentry, &dentry->d_name);
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err = PTR_ERR(this);
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if (IS_ERR(this)) {
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/*
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* If it's positive, then treat ENAMETOOLONG as ENOENT.
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*/
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if (err == -ENAMETOOLONG && (upperdentry || ctr))
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continue;
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goto out_put;
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}
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if (!this)
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continue;
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if (ovl_is_whiteout(this)) {
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dput(this);
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break;
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}
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/*
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* If this is a non-directory then stop here.
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*/
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if (!d_is_dir(this)) {
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if (isdir) {
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dput(this);
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break;
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}
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stop = true;
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} else {
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/*
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* Only makes sense to check opaque dir if this is not
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* the lowermost layer.
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*/
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if (i < poe->numlower - 1 && ovl_is_opaquedir(this))
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stop = true;
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}
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stack[ctr].dentry = this;
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stack[ctr].mnt = lowerpath.mnt;
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ctr++;
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}
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oe = ovl_alloc_entry(ctr);
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err = -ENOMEM;
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if (!oe)
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goto out_put;
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if (upperdentry || ctr) {
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struct dentry *realdentry;
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struct inode *realinode;
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realdentry = upperdentry ? upperdentry : stack[0].dentry;
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realinode = d_inode(realdentry);
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err = -ENOMEM;
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if (upperdentry && !d_is_dir(upperdentry)) {
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inode = ovl_get_inode(dentry->d_sb, realinode);
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} else {
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inode = ovl_new_inode(dentry->d_sb, realinode->i_mode,
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realinode->i_rdev);
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if (inode)
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ovl_inode_init(inode, realinode, !!upperdentry);
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}
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if (!inode)
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goto out_free_oe;
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ovl_copyattr(realdentry->d_inode, inode);
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}
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revert_creds(old_cred);
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oe->opaque = upperopaque;
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oe->__upperdentry = upperdentry;
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memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr);
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kfree(stack);
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dentry->d_fsdata = oe;
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d_add(dentry, inode);
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return NULL;
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out_free_oe:
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kfree(oe);
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out_put:
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for (i = 0; i < ctr; i++)
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dput(stack[i].dentry);
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kfree(stack);
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out_put_upper:
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dput(upperdentry);
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out:
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revert_creds(old_cred);
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return ERR_PTR(err);
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}
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bool ovl_lower_positive(struct dentry *dentry)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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struct ovl_entry *poe = dentry->d_parent->d_fsdata;
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const struct qstr *name = &dentry->d_name;
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unsigned int i;
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bool positive = false;
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bool done = false;
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/*
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* If dentry is negative, then lower is positive iff this is a
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* whiteout.
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*/
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if (!dentry->d_inode)
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return oe->opaque;
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/* Negative upper -> positive lower */
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if (!oe->__upperdentry)
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return true;
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/* Positive upper -> have to look up lower to see whether it exists */
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for (i = 0; !done && !positive && i < poe->numlower; i++) {
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struct dentry *this;
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struct dentry *lowerdir = poe->lowerstack[i].dentry;
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this = lookup_one_len_unlocked(name->name, lowerdir,
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name->len);
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if (IS_ERR(this)) {
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switch (PTR_ERR(this)) {
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case -ENOENT:
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case -ENAMETOOLONG:
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break;
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default:
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/*
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* Assume something is there, we just couldn't
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* access it.
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*/
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positive = true;
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break;
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}
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} else {
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if (this->d_inode) {
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positive = !ovl_is_whiteout(this);
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done = true;
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}
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dput(this);
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}
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}
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return positive;
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}
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@ -9,8 +9,6 @@
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#include <linux/kernel.h>
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struct ovl_entry;
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enum ovl_path_type {
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__OVL_PATH_UPPER = (1 << 0),
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__OVL_PATH_MERGE = (1 << 1),
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@ -138,37 +136,39 @@ static inline struct inode *ovl_inode_real(struct inode *inode, bool *is_upper)
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return (struct inode *) (x & ~OVL_ISUPPER_MASK);
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}
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/* util.c */
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int ovl_want_write(struct dentry *dentry);
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void ovl_drop_write(struct dentry *dentry);
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struct dentry *ovl_workdir(struct dentry *dentry);
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const struct cred *ovl_override_creds(struct super_block *sb);
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struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
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bool ovl_dentry_remote(struct dentry *dentry);
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bool ovl_dentry_weird(struct dentry *dentry);
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enum ovl_path_type ovl_path_type(struct dentry *dentry);
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u64 ovl_dentry_version_get(struct dentry *dentry);
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void ovl_dentry_version_inc(struct dentry *dentry);
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void ovl_path_upper(struct dentry *dentry, struct path *path);
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void ovl_path_lower(struct dentry *dentry, struct path *path);
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enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
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int ovl_path_next(int idx, struct dentry *dentry, struct path *path);
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struct dentry *ovl_dentry_upper(struct dentry *dentry);
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struct dentry *ovl_dentry_lower(struct dentry *dentry);
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struct dentry *ovl_dentry_real(struct dentry *dentry);
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struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode,
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bool is_upper);
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struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry);
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void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache);
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struct dentry *ovl_workdir(struct dentry *dentry);
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int ovl_want_write(struct dentry *dentry);
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void ovl_drop_write(struct dentry *dentry);
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bool ovl_dentry_is_opaque(struct dentry *dentry);
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bool ovl_lower_positive(struct dentry *dentry);
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bool ovl_dentry_is_whiteout(struct dentry *dentry);
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void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque);
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bool ovl_is_whiteout(struct dentry *dentry);
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const struct cred *ovl_override_creds(struct super_block *sb);
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void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry);
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void ovl_inode_init(struct inode *inode, struct inode *realinode,
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bool is_upper);
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void ovl_inode_update(struct inode *inode, struct inode *upperinode);
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struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
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unsigned int flags);
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void ovl_dentry_version_inc(struct dentry *dentry);
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u64 ovl_dentry_version_get(struct dentry *dentry);
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bool ovl_is_whiteout(struct dentry *dentry);
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struct file *ovl_path_open(struct path *path, int flags);
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struct dentry *ovl_upper_create(struct dentry *upperdir, struct dentry *dentry,
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struct kstat *stat, const char *link);
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/* namei.c */
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int ovl_path_next(int idx, struct dentry *dentry, struct path *path);
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struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags);
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bool ovl_lower_positive(struct dentry *dentry);
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/* readdir.c */
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extern const struct file_operations ovl_dir_operations;
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51
fs/overlayfs/ovl_entry.h
Normal file
51
fs/overlayfs/ovl_entry.h
Normal file
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@ -0,0 +1,51 @@
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/*
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*
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* Copyright (C) 2011 Novell Inc.
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* Copyright (C) 2016 Red Hat, Inc.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*/
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struct ovl_config {
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char *lowerdir;
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char *upperdir;
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char *workdir;
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bool default_permissions;
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};
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/* private information held for overlayfs's superblock */
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struct ovl_fs {
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struct vfsmount *upper_mnt;
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unsigned numlower;
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struct vfsmount **lower_mnt;
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struct dentry *workdir;
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long lower_namelen;
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/* pathnames of lower and upper dirs, for show_options */
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struct ovl_config config;
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/* creds of process who forced instantiation of super block */
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const struct cred *creator_cred;
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};
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/* private information held for every overlayfs dentry */
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struct ovl_entry {
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struct dentry *__upperdentry;
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struct ovl_dir_cache *cache;
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union {
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struct {
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u64 version;
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bool opaque;
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};
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struct rcu_head rcu;
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};
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unsigned numlower;
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struct path lowerstack[];
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};
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struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
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static inline struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe)
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{
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return lockless_dereference(oe->__upperdentry);
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}
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@ -9,283 +9,25 @@
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#include <linux/fs.h>
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#include <linux/namei.h>
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#include <linux/pagemap.h>
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#include <linux/xattr.h>
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#include <linux/security.h>
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#include <linux/mount.h>
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#include <linux/slab.h>
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#include <linux/parser.h>
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#include <linux/module.h>
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#include <linux/sched.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 "overlayfs.h"
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#include "ovl_entry.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_config {
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char *lowerdir;
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char *upperdir;
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char *workdir;
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bool default_permissions;
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};
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/* private information held for overlayfs's superblock */
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struct ovl_fs {
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struct vfsmount *upper_mnt;
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unsigned numlower;
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struct vfsmount **lower_mnt;
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struct dentry *workdir;
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long lower_namelen;
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/* pathnames of lower and upper dirs, for show_options */
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struct ovl_config config;
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/* creds of process who forced instantiation of super block */
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const struct cred *creator_cred;
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};
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struct ovl_dir_cache;
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/* private information held for every overlayfs dentry */
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struct ovl_entry {
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struct dentry *__upperdentry;
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struct ovl_dir_cache *cache;
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union {
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struct {
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u64 version;
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bool opaque;
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};
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struct rcu_head rcu;
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};
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unsigned numlower;
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struct path lowerstack[];
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};
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#define OVL_MAX_STACK 500
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static struct dentry *__ovl_dentry_lower(struct ovl_entry *oe)
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{
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return oe->numlower ? oe->lowerstack[0].dentry : NULL;
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}
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enum ovl_path_type ovl_path_type(struct dentry *dentry)
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{
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struct ovl_entry *oe = dentry->d_fsdata;
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enum ovl_path_type type = 0;
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if (oe->__upperdentry) {
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type = __OVL_PATH_UPPER;
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/*
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* Non-dir dentry can hold lower dentry from previous
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* location.
|
||||
*/
|
||||
if (oe->numlower && d_is_dir(dentry))
|
||||
type |= __OVL_PATH_MERGE;
|
||||
} else {
|
||||
if (oe->numlower > 1)
|
||||
type |= __OVL_PATH_MERGE;
|
||||
}
|
||||
return type;
|
||||
}
|
||||
|
||||
static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe)
|
||||
{
|
||||
return lockless_dereference(oe->__upperdentry);
|
||||
}
|
||||
|
||||
void ovl_path_upper(struct dentry *dentry, struct path *path)
|
||||
{
|
||||
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
|
||||
path->mnt = ofs->upper_mnt;
|
||||
path->dentry = ovl_upperdentry_dereference(oe);
|
||||
}
|
||||
|
||||
enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
|
||||
{
|
||||
enum ovl_path_type type = ovl_path_type(dentry);
|
||||
|
||||
if (!OVL_TYPE_UPPER(type))
|
||||
ovl_path_lower(dentry, path);
|
||||
else
|
||||
ovl_path_upper(dentry, path);
|
||||
|
||||
return type;
|
||||
}
|
||||
|
||||
struct dentry *ovl_dentry_upper(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
|
||||
return ovl_upperdentry_dereference(oe);
|
||||
}
|
||||
|
||||
struct dentry *ovl_dentry_lower(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
|
||||
return __ovl_dentry_lower(oe);
|
||||
}
|
||||
|
||||
struct dentry *ovl_dentry_real(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
struct dentry *realdentry;
|
||||
|
||||
realdentry = ovl_upperdentry_dereference(oe);
|
||||
if (!realdentry)
|
||||
realdentry = __ovl_dentry_lower(oe);
|
||||
|
||||
return realdentry;
|
||||
}
|
||||
|
||||
static void ovl_inode_init(struct inode *inode, struct inode *realinode,
|
||||
bool is_upper)
|
||||
{
|
||||
WRITE_ONCE(inode->i_private, (unsigned long) realinode |
|
||||
(is_upper ? OVL_ISUPPER_MASK : 0));
|
||||
}
|
||||
|
||||
struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode,
|
||||
bool is_upper)
|
||||
{
|
||||
if (is_upper) {
|
||||
struct ovl_fs *ofs = inode->i_sb->s_fs_info;
|
||||
|
||||
return ofs->upper_mnt;
|
||||
} else {
|
||||
return oe->numlower ? oe->lowerstack[0].mnt : NULL;
|
||||
}
|
||||
}
|
||||
|
||||
struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
|
||||
return oe->cache;
|
||||
}
|
||||
|
||||
void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
|
||||
oe->cache = cache;
|
||||
}
|
||||
|
||||
void ovl_path_lower(struct dentry *dentry, struct path *path)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
|
||||
*path = oe->numlower ? oe->lowerstack[0] : (struct path) { NULL, NULL };
|
||||
}
|
||||
|
||||
int ovl_want_write(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
|
||||
return mnt_want_write(ofs->upper_mnt);
|
||||
}
|
||||
|
||||
void ovl_drop_write(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
|
||||
mnt_drop_write(ofs->upper_mnt);
|
||||
}
|
||||
|
||||
struct dentry *ovl_workdir(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
|
||||
return ofs->workdir;
|
||||
}
|
||||
|
||||
bool ovl_dentry_is_opaque(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
return oe->opaque;
|
||||
}
|
||||
|
||||
bool ovl_dentry_is_whiteout(struct dentry *dentry)
|
||||
{
|
||||
return !dentry->d_inode && ovl_dentry_is_opaque(dentry);
|
||||
}
|
||||
|
||||
void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
oe->opaque = opaque;
|
||||
}
|
||||
|
||||
void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
|
||||
WARN_ON(!inode_is_locked(upperdentry->d_parent->d_inode));
|
||||
WARN_ON(oe->__upperdentry);
|
||||
/*
|
||||
* Make sure upperdentry is consistent before making it visible to
|
||||
* ovl_upperdentry_dereference().
|
||||
*/
|
||||
smp_wmb();
|
||||
oe->__upperdentry = upperdentry;
|
||||
}
|
||||
|
||||
void ovl_inode_update(struct inode *inode, struct inode *upperinode)
|
||||
{
|
||||
WARN_ON(!upperinode);
|
||||
WARN_ON(!inode_unhashed(inode));
|
||||
WRITE_ONCE(inode->i_private,
|
||||
(unsigned long) upperinode | OVL_ISUPPER_MASK);
|
||||
if (!S_ISDIR(upperinode->i_mode))
|
||||
__insert_inode_hash(inode, (unsigned long) upperinode);
|
||||
}
|
||||
|
||||
void ovl_dentry_version_inc(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
|
||||
WARN_ON(!inode_is_locked(dentry->d_inode));
|
||||
oe->version++;
|
||||
}
|
||||
|
||||
u64 ovl_dentry_version_get(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
|
||||
WARN_ON(!inode_is_locked(dentry->d_inode));
|
||||
return oe->version;
|
||||
}
|
||||
|
||||
bool ovl_is_whiteout(struct dentry *dentry)
|
||||
{
|
||||
struct inode *inode = dentry->d_inode;
|
||||
|
||||
return inode && IS_WHITEOUT(inode);
|
||||
}
|
||||
|
||||
const struct cred *ovl_override_creds(struct super_block *sb)
|
||||
{
|
||||
struct ovl_fs *ofs = sb->s_fs_info;
|
||||
|
||||
return override_creds(ofs->creator_cred);
|
||||
}
|
||||
|
||||
static bool ovl_is_opaquedir(struct dentry *dentry)
|
||||
{
|
||||
int res;
|
||||
char val;
|
||||
|
||||
if (!d_is_dir(dentry))
|
||||
return false;
|
||||
|
||||
res = vfs_getxattr(dentry, OVL_XATTR_OPAQUE, &val, 1);
|
||||
if (res == 1 && val == 'y')
|
||||
return true;
|
||||
|
||||
return false;
|
||||
}
|
||||
|
||||
static void ovl_dentry_release(struct dentry *dentry)
|
||||
{
|
||||
|
|
@ -395,275 +137,6 @@ static const struct dentry_operations ovl_reval_dentry_operations = {
|
|||
.d_weak_revalidate = ovl_dentry_weak_revalidate,
|
||||
};
|
||||
|
||||
static struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
|
||||
{
|
||||
size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
|
||||
struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
|
||||
|
||||
if (oe)
|
||||
oe->numlower = numlower;
|
||||
|
||||
return oe;
|
||||
}
|
||||
|
||||
static bool ovl_dentry_remote(struct dentry *dentry)
|
||||
{
|
||||
return dentry->d_flags &
|
||||
(DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE |
|
||||
DCACHE_OP_REAL);
|
||||
}
|
||||
|
||||
static bool ovl_dentry_weird(struct dentry *dentry)
|
||||
{
|
||||
return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
|
||||
DCACHE_MANAGE_TRANSIT |
|
||||
DCACHE_OP_HASH |
|
||||
DCACHE_OP_COMPARE);
|
||||
}
|
||||
|
||||
static inline struct dentry *ovl_lookup_real(struct dentry *dir,
|
||||
const struct qstr *name)
|
||||
{
|
||||
struct dentry *dentry;
|
||||
|
||||
dentry = lookup_one_len_unlocked(name->name, dir, name->len);
|
||||
if (IS_ERR(dentry)) {
|
||||
if (PTR_ERR(dentry) == -ENOENT)
|
||||
dentry = NULL;
|
||||
} else if (!dentry->d_inode) {
|
||||
dput(dentry);
|
||||
dentry = NULL;
|
||||
} else if (ovl_dentry_weird(dentry)) {
|
||||
dput(dentry);
|
||||
/* Don't support traversing automounts and other weirdness */
|
||||
dentry = ERR_PTR(-EREMOTE);
|
||||
}
|
||||
return dentry;
|
||||
}
|
||||
|
||||
/*
|
||||
* Returns next layer in stack starting from top.
|
||||
* Returns -1 if this is the last layer.
|
||||
*/
|
||||
int ovl_path_next(int idx, struct dentry *dentry, struct path *path)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
|
||||
BUG_ON(idx < 0);
|
||||
if (idx == 0) {
|
||||
ovl_path_upper(dentry, path);
|
||||
if (path->dentry)
|
||||
return oe->numlower ? 1 : -1;
|
||||
idx++;
|
||||
}
|
||||
BUG_ON(idx > oe->numlower);
|
||||
*path = oe->lowerstack[idx - 1];
|
||||
|
||||
return (idx < oe->numlower) ? idx + 1 : -1;
|
||||
}
|
||||
|
||||
struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
|
||||
unsigned int flags)
|
||||
{
|
||||
struct ovl_entry *oe;
|
||||
const struct cred *old_cred;
|
||||
struct ovl_entry *poe = dentry->d_parent->d_fsdata;
|
||||
struct path *stack = NULL;
|
||||
struct dentry *upperdir, *upperdentry = NULL;
|
||||
unsigned int ctr = 0;
|
||||
struct inode *inode = NULL;
|
||||
bool upperopaque = false;
|
||||
bool stop = false;
|
||||
bool isdir = false;
|
||||
struct dentry *this;
|
||||
unsigned int i;
|
||||
int err;
|
||||
|
||||
old_cred = ovl_override_creds(dentry->d_sb);
|
||||
upperdir = ovl_upperdentry_dereference(poe);
|
||||
if (upperdir) {
|
||||
this = ovl_lookup_real(upperdir, &dentry->d_name);
|
||||
err = PTR_ERR(this);
|
||||
if (IS_ERR(this))
|
||||
goto out;
|
||||
|
||||
if (this) {
|
||||
if (unlikely(ovl_dentry_remote(this))) {
|
||||
dput(this);
|
||||
err = -EREMOTE;
|
||||
goto out;
|
||||
}
|
||||
if (ovl_is_whiteout(this)) {
|
||||
dput(this);
|
||||
this = NULL;
|
||||
stop = upperopaque = true;
|
||||
} else if (!d_is_dir(this)) {
|
||||
stop = true;
|
||||
} else {
|
||||
isdir = true;
|
||||
if (poe->numlower && ovl_is_opaquedir(this))
|
||||
stop = upperopaque = true;
|
||||
}
|
||||
}
|
||||
upperdentry = this;
|
||||
}
|
||||
|
||||
if (!stop && poe->numlower) {
|
||||
err = -ENOMEM;
|
||||
stack = kcalloc(poe->numlower, sizeof(struct path), GFP_KERNEL);
|
||||
if (!stack)
|
||||
goto out_put_upper;
|
||||
}
|
||||
|
||||
for (i = 0; !stop && i < poe->numlower; i++) {
|
||||
struct path lowerpath = poe->lowerstack[i];
|
||||
|
||||
this = ovl_lookup_real(lowerpath.dentry, &dentry->d_name);
|
||||
err = PTR_ERR(this);
|
||||
if (IS_ERR(this)) {
|
||||
/*
|
||||
* If it's positive, then treat ENAMETOOLONG as ENOENT.
|
||||
*/
|
||||
if (err == -ENAMETOOLONG && (upperdentry || ctr))
|
||||
continue;
|
||||
goto out_put;
|
||||
}
|
||||
if (!this)
|
||||
continue;
|
||||
if (ovl_is_whiteout(this)) {
|
||||
dput(this);
|
||||
break;
|
||||
}
|
||||
/*
|
||||
* If this is a non-directory then stop here.
|
||||
*/
|
||||
if (!d_is_dir(this)) {
|
||||
if (isdir) {
|
||||
dput(this);
|
||||
break;
|
||||
}
|
||||
stop = true;
|
||||
} else {
|
||||
/*
|
||||
* Only makes sense to check opaque dir if this is not
|
||||
* the lowermost layer.
|
||||
*/
|
||||
if (i < poe->numlower - 1 && ovl_is_opaquedir(this))
|
||||
stop = true;
|
||||
}
|
||||
|
||||
stack[ctr].dentry = this;
|
||||
stack[ctr].mnt = lowerpath.mnt;
|
||||
ctr++;
|
||||
}
|
||||
|
||||
oe = ovl_alloc_entry(ctr);
|
||||
err = -ENOMEM;
|
||||
if (!oe)
|
||||
goto out_put;
|
||||
|
||||
if (upperdentry || ctr) {
|
||||
struct dentry *realdentry;
|
||||
struct inode *realinode;
|
||||
|
||||
realdentry = upperdentry ? upperdentry : stack[0].dentry;
|
||||
realinode = d_inode(realdentry);
|
||||
|
||||
err = -ENOMEM;
|
||||
if (upperdentry && !d_is_dir(upperdentry)) {
|
||||
inode = ovl_get_inode(dentry->d_sb, realinode);
|
||||
} else {
|
||||
inode = ovl_new_inode(dentry->d_sb, realinode->i_mode,
|
||||
realinode->i_rdev);
|
||||
if (inode)
|
||||
ovl_inode_init(inode, realinode, !!upperdentry);
|
||||
}
|
||||
if (!inode)
|
||||
goto out_free_oe;
|
||||
ovl_copyattr(realdentry->d_inode, inode);
|
||||
}
|
||||
|
||||
revert_creds(old_cred);
|
||||
oe->opaque = upperopaque;
|
||||
oe->__upperdentry = upperdentry;
|
||||
memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr);
|
||||
kfree(stack);
|
||||
dentry->d_fsdata = oe;
|
||||
d_add(dentry, inode);
|
||||
|
||||
return NULL;
|
||||
|
||||
out_free_oe:
|
||||
kfree(oe);
|
||||
out_put:
|
||||
for (i = 0; i < ctr; i++)
|
||||
dput(stack[i].dentry);
|
||||
kfree(stack);
|
||||
out_put_upper:
|
||||
dput(upperdentry);
|
||||
out:
|
||||
revert_creds(old_cred);
|
||||
return ERR_PTR(err);
|
||||
}
|
||||
|
||||
bool ovl_lower_positive(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
struct ovl_entry *poe = dentry->d_parent->d_fsdata;
|
||||
const struct qstr *name = &dentry->d_name;
|
||||
unsigned int i;
|
||||
bool positive = false;
|
||||
bool done = false;
|
||||
|
||||
/*
|
||||
* If dentry is negative, then lower is positive iff this is a
|
||||
* whiteout.
|
||||
*/
|
||||
if (!dentry->d_inode)
|
||||
return oe->opaque;
|
||||
|
||||
/* Negative upper -> positive lower */
|
||||
if (!oe->__upperdentry)
|
||||
return true;
|
||||
|
||||
/* Positive upper -> have to look up lower to see whether it exists */
|
||||
for (i = 0; !done && !positive && i < poe->numlower; i++) {
|
||||
struct dentry *this;
|
||||
struct dentry *lowerdir = poe->lowerstack[i].dentry;
|
||||
|
||||
this = lookup_one_len_unlocked(name->name, lowerdir,
|
||||
name->len);
|
||||
if (IS_ERR(this)) {
|
||||
switch (PTR_ERR(this)) {
|
||||
case -ENOENT:
|
||||
case -ENAMETOOLONG:
|
||||
break;
|
||||
|
||||
default:
|
||||
/*
|
||||
* Assume something is there, we just couldn't
|
||||
* access it.
|
||||
*/
|
||||
positive = true;
|
||||
break;
|
||||
}
|
||||
} else {
|
||||
if (this->d_inode) {
|
||||
positive = !ovl_is_whiteout(this);
|
||||
done = true;
|
||||
}
|
||||
dput(this);
|
||||
}
|
||||
}
|
||||
|
||||
return positive;
|
||||
}
|
||||
|
||||
struct file *ovl_path_open(struct path *path, int flags)
|
||||
{
|
||||
return dentry_open(path, flags | O_NOATIME, current_cred());
|
||||
}
|
||||
|
||||
static void ovl_put_super(struct super_block *sb)
|
||||
{
|
||||
struct ovl_fs *ufs = sb->s_fs_info;
|
||||
|
|
|
|||
235
fs/overlayfs/util.c
Normal file
235
fs/overlayfs/util.c
Normal file
|
|
@ -0,0 +1,235 @@
|
|||
/*
|
||||
* Copyright (C) 2011 Novell Inc.
|
||||
* Copyright (C) 2016 Red Hat, Inc.
|
||||
*
|
||||
* This program is free software; you can redistribute it and/or modify it
|
||||
* under the terms of the GNU General Public License version 2 as published by
|
||||
* the Free Software Foundation.
|
||||
*/
|
||||
|
||||
#include <linux/fs.h>
|
||||
#include <linux/mount.h>
|
||||
#include <linux/slab.h>
|
||||
#include <linux/xattr.h>
|
||||
#include "overlayfs.h"
|
||||
#include "ovl_entry.h"
|
||||
|
||||
int ovl_want_write(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
|
||||
return mnt_want_write(ofs->upper_mnt);
|
||||
}
|
||||
|
||||
void ovl_drop_write(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
|
||||
mnt_drop_write(ofs->upper_mnt);
|
||||
}
|
||||
|
||||
struct dentry *ovl_workdir(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
|
||||
return ofs->workdir;
|
||||
}
|
||||
|
||||
const struct cred *ovl_override_creds(struct super_block *sb)
|
||||
{
|
||||
struct ovl_fs *ofs = sb->s_fs_info;
|
||||
|
||||
return override_creds(ofs->creator_cred);
|
||||
}
|
||||
|
||||
struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
|
||||
{
|
||||
size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
|
||||
struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
|
||||
|
||||
if (oe)
|
||||
oe->numlower = numlower;
|
||||
|
||||
return oe;
|
||||
}
|
||||
|
||||
bool ovl_dentry_remote(struct dentry *dentry)
|
||||
{
|
||||
return dentry->d_flags &
|
||||
(DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE |
|
||||
DCACHE_OP_REAL);
|
||||
}
|
||||
|
||||
bool ovl_dentry_weird(struct dentry *dentry)
|
||||
{
|
||||
return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
|
||||
DCACHE_MANAGE_TRANSIT |
|
||||
DCACHE_OP_HASH |
|
||||
DCACHE_OP_COMPARE);
|
||||
}
|
||||
|
||||
enum ovl_path_type ovl_path_type(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
enum ovl_path_type type = 0;
|
||||
|
||||
if (oe->__upperdentry) {
|
||||
type = __OVL_PATH_UPPER;
|
||||
|
||||
/*
|
||||
* Non-dir dentry can hold lower dentry from previous
|
||||
* location.
|
||||
*/
|
||||
if (oe->numlower && d_is_dir(dentry))
|
||||
type |= __OVL_PATH_MERGE;
|
||||
} else {
|
||||
if (oe->numlower > 1)
|
||||
type |= __OVL_PATH_MERGE;
|
||||
}
|
||||
return type;
|
||||
}
|
||||
|
||||
void ovl_path_upper(struct dentry *dentry, struct path *path)
|
||||
{
|
||||
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
|
||||
path->mnt = ofs->upper_mnt;
|
||||
path->dentry = ovl_upperdentry_dereference(oe);
|
||||
}
|
||||
|
||||
void ovl_path_lower(struct dentry *dentry, struct path *path)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
|
||||
*path = oe->numlower ? oe->lowerstack[0] : (struct path) { NULL, NULL };
|
||||
}
|
||||
|
||||
enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
|
||||
{
|
||||
enum ovl_path_type type = ovl_path_type(dentry);
|
||||
|
||||
if (!OVL_TYPE_UPPER(type))
|
||||
ovl_path_lower(dentry, path);
|
||||
else
|
||||
ovl_path_upper(dentry, path);
|
||||
|
||||
return type;
|
||||
}
|
||||
|
||||
struct dentry *ovl_dentry_upper(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
|
||||
return ovl_upperdentry_dereference(oe);
|
||||
}
|
||||
|
||||
static struct dentry *__ovl_dentry_lower(struct ovl_entry *oe)
|
||||
{
|
||||
return oe->numlower ? oe->lowerstack[0].dentry : NULL;
|
||||
}
|
||||
|
||||
struct dentry *ovl_dentry_lower(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
|
||||
return __ovl_dentry_lower(oe);
|
||||
}
|
||||
|
||||
struct dentry *ovl_dentry_real(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
struct dentry *realdentry;
|
||||
|
||||
realdentry = ovl_upperdentry_dereference(oe);
|
||||
if (!realdentry)
|
||||
realdentry = __ovl_dentry_lower(oe);
|
||||
|
||||
return realdentry;
|
||||
}
|
||||
|
||||
struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
|
||||
return oe->cache;
|
||||
}
|
||||
|
||||
void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
|
||||
oe->cache = cache;
|
||||
}
|
||||
|
||||
bool ovl_dentry_is_opaque(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
return oe->opaque;
|
||||
}
|
||||
|
||||
bool ovl_dentry_is_whiteout(struct dentry *dentry)
|
||||
{
|
||||
return !dentry->d_inode && ovl_dentry_is_opaque(dentry);
|
||||
}
|
||||
|
||||
void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
oe->opaque = opaque;
|
||||
}
|
||||
|
||||
void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
|
||||
WARN_ON(!inode_is_locked(upperdentry->d_parent->d_inode));
|
||||
WARN_ON(oe->__upperdentry);
|
||||
/*
|
||||
* Make sure upperdentry is consistent before making it visible to
|
||||
* ovl_upperdentry_dereference().
|
||||
*/
|
||||
smp_wmb();
|
||||
oe->__upperdentry = upperdentry;
|
||||
}
|
||||
|
||||
void ovl_inode_init(struct inode *inode, struct inode *realinode, bool is_upper)
|
||||
{
|
||||
WRITE_ONCE(inode->i_private, (unsigned long) realinode |
|
||||
(is_upper ? OVL_ISUPPER_MASK : 0));
|
||||
}
|
||||
|
||||
void ovl_inode_update(struct inode *inode, struct inode *upperinode)
|
||||
{
|
||||
WARN_ON(!upperinode);
|
||||
WARN_ON(!inode_unhashed(inode));
|
||||
WRITE_ONCE(inode->i_private,
|
||||
(unsigned long) upperinode | OVL_ISUPPER_MASK);
|
||||
if (!S_ISDIR(upperinode->i_mode))
|
||||
__insert_inode_hash(inode, (unsigned long) upperinode);
|
||||
}
|
||||
|
||||
void ovl_dentry_version_inc(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
|
||||
WARN_ON(!inode_is_locked(dentry->d_inode));
|
||||
oe->version++;
|
||||
}
|
||||
|
||||
u64 ovl_dentry_version_get(struct dentry *dentry)
|
||||
{
|
||||
struct ovl_entry *oe = dentry->d_fsdata;
|
||||
|
||||
WARN_ON(!inode_is_locked(dentry->d_inode));
|
||||
return oe->version;
|
||||
}
|
||||
|
||||
bool ovl_is_whiteout(struct dentry *dentry)
|
||||
{
|
||||
struct inode *inode = dentry->d_inode;
|
||||
|
||||
return inode && IS_WHITEOUT(inode);
|
||||
}
|
||||
|
||||
struct file *ovl_path_open(struct path *path, int flags)
|
||||
{
|
||||
return dentry_open(path, flags | O_NOATIME, current_cred());
|
||||
}
|
||||
Loading…
Reference in a new issue