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
267
fs/overlayfs/namei.c
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267
fs/overlayfs/namei.c
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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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