/* getroot.c: get the root dentry for an NFS mount
 *
 * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/init.h>

#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/unistd.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/stats.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/lockd/bind.h>
#include <linux/seq_file.h>
#include <linux/mount.h>
#include <linux/vfs.h>
#include <linux/namei.h>
#include <linux/security.h>

#include <linux/uaccess.h>

#include "internal.h"

#define NFSDBG_FACILITY		NFSDBG_CLIENT

/*
 * Set the superblock root dentry.
 * Note that this function frees the inode in case of error.
 */
static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *inode)
{
	/* The mntroot acts as the dummy root dentry for this superblock */
	if (sb->s_root == NULL) {
		sb->s_root = d_make_root(inode);
		if (sb->s_root == NULL)
			return -ENOMEM;
		ihold(inode);
		/*
		 * Ensure that this dentry is invisible to d_find_alias().
		 * Otherwise, it may be spliced into the tree by
		 * d_splice_alias if a parent directory from the same
		 * filesystem gets mounted at a later time.
		 * This again causes shrink_dcache_for_umount_subtree() to
		 * Oops, since the test for IS_ROOT() will fail.
		 */
		spin_lock(&d_inode(sb->s_root)->i_lock);
		spin_lock(&sb->s_root->d_lock);
		hlist_del_init(&sb->s_root->d_u.d_alias);
		spin_unlock(&sb->s_root->d_lock);
		spin_unlock(&d_inode(sb->s_root)->i_lock);
	}
	return 0;
}

/*
 * get an NFS2/NFS3 root dentry from the root filehandle
 */
struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh,
			    const char *devname)
{
	struct nfs_server *server = NFS_SB(sb);
	struct nfs_fsinfo fsinfo;
	struct dentry *ret;
	struct inode *inode;
	void *name = kstrdup(devname, GFP_KERNEL);
	int error;

	if (!name)
		return ERR_PTR(-ENOMEM);

	/* get the actual root for this mount */
	fsinfo.fattr = nfs_alloc_fattr();
	if (fsinfo.fattr == NULL) {
		kfree(name);
		return ERR_PTR(-ENOMEM);
	}

	error = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo);
	if (error < 0) {
		dprintk("nfs_get_root: getattr error = %d\n", -error);
		ret = ERR_PTR(error);
		goto out;
	}

	inode = nfs_fhget(sb, mntfh, fsinfo.fattr, NULL);
	if (IS_ERR(inode)) {
		dprintk("nfs_get_root: get root inode failed\n");
		ret = ERR_CAST(inode);
		goto out;
	}

	error = nfs_superblock_set_dummy_root(sb, inode);
	if (error != 0) {
		ret = ERR_PTR(error);
		goto out;
	}

	/* root dentries normally start off anonymous and get spliced in later
	 * if the dentry tree reaches them; however if the dentry already
	 * exists, we'll pick it up at this point and use it as the root
	 */
	ret = d_obtain_root(inode);
	if (IS_ERR(ret)) {
		dprintk("nfs_get_root: get root dentry failed\n");
		goto out;
	}

	security_d_instantiate(ret, inode);
	spin_lock(&ret->d_lock);
	if (IS_ROOT(ret) && !ret->d_fsdata &&
	    !(ret->d_flags & DCACHE_NFSFS_RENAMED)) {
		ret->d_fsdata = name;
		name = NULL;
	}
	spin_unlock(&ret->d_lock);
out:
	kfree(name);
	nfs_free_fattr(fsinfo.fattr);
	return ret;
}
a1b4a'>net: ipv6: Change notifications for multipath add to RTA_MULTIPATH</a></td><td>David Ahern</td><td>1</td><td><span class='deletions'>-0</span>/<span class='insertions'>+1</span></td></tr>
<tr><td><span title='2017-02-04 19:58:14 -0500'>2017-02-04</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=0ae8133586ad1c9be894411aaf8b17bb58c8efe5'>net: ipv6: Allow shorthand delete of all nexthops in multipath route</a></td><td>David Ahern</td><td>1</td><td><span class='deletions'>-1</span>/<span class='insertions'>+3</span></td></tr>
<tr><td><span title='2017-02-03 17:28:29 -0500'>2017-02-03</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=79e7fff47b7bb4124ef970a13eac4fdeddd1fc25'>net: remove support for per driver ndo_busy_poll()</a></td><td>Eric Dumazet</td><td>2</td><td><span class='deletions'>-5</span>/<span class='insertions'>+0</span></td></tr>
<tr><td><span title='2017-02-03 16:58:20 -0500'>2017-02-03</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=52e01b84a244473074fc0612c169e2e043d58b01'>Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next</a></td><td>David S. Miller</td><td>11</td><td><span class='deletions'>-40</span>/<span class='insertions'>+60</span></td></tr>
<tr><td><span title='2017-02-03 16:35:43 -0500'>2017-02-03</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=69ca05ce9dec2cc95070df7f1f10ea6c9c12d237'>sched: cls_flower: expose priority to offloading netdevice</a></td><td>Jiri Pirko</td><td>1</td><td><span class='deletions'>-0</span>/<span class='insertions'>+1</span></td></tr>
<tr><td><span title='2017-02-03 16:35:42 -0500'>2017-02-03</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=44091d29f2075972aede47ef17e1e70db3d51190'>lib: Introduce priority array area manager</a></td><td>Jiri Pirko</td><td>1</td><td><span class='deletions'>-0</span>/<span class='insertions'>+76</span></td></tr>
<tr><td><span title='2017-02-03 16:35:42 -0500'>2017-02-03</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=b862815c3ee7b49ec20a9ab25da55a5f0bcbb95e'>list: introduce list_for_each_entry_from_reverse helper</a></td><td>Jiri Pirko</td><td>1</td><td><span class='deletions'>-0</span>/<span class='insertions'>+13</span></td></tr>
<tr><td><span title='2017-02-03 15:50:18 -0500'>2017-02-03</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=3898fac1f488c76e0eef5b5267b4ba8112a82ac4'>trace: rename trace_print_hex_seq arg and add kdoc</a></td><td>Daniel Borkmann</td><td>2</td><td><span class='deletions'>-3</span>/<span class='insertions'>+3</span></td></tr>
<tr><td><span title='2017-02-03 15:21:21 -0500'>2017-02-03</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=b3c7ef0adadc5768e0baa786213c6bd1ce521a77'>bridge: uapi: add per vlan tunnel info</a></td><td>Roopa Prabhu</td><td>3</td><td><span class='deletions'>-0</span>/<span class='insertions'>+13</span></td></tr>
<tr><td><span title='2017-02-03 15:21:21 -0500'>2017-02-03</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=3ad7a4b141ebd6091494913672d7166d5c2764e4'>vxlan: support fdb and learning in COLLECT_METADATA mode</a></td><td>Roopa Prabhu</td><td>1</td><td><span class='deletions'>-0</span>/<span class='insertions'>+1</span></td></tr>
<tr><td><span title='2017-02-03 15:21:21 -0500'>2017-02-03</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=f35581d64e55fc65753a62957b3b98127d560d07'>ip_tunnels: new IP_TUNNEL_INFO_BRIDGE flag for ip_tunnel_info mode</a></td><td>Roopa Prabhu</td><td>1</td><td><span class='deletions'>-0</span>/<span class='insertions'>+1</span></td></tr>
<tr><td><span title='2017-02-03 15:16:46 -0500'>2017-02-03</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=295a6e06d21e1f469c9f38b00125a13b60ad4e7c'>net/sched: act_ife: Change to use ife module</a></td><td>Yotam Gigi</td><td>2</td><td><span class='deletions'>-10</span>/<span class='insertions'>+1</span></td></tr>
<tr><td><span title='2017-02-03 15:16:45 -0500'>2017-02-03</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=1ce8460496c05379c66edc178c3c55ca4e953044'>net: Introduce ife encapsulation module</a></td><td>Yotam Gigi</td><td>3</td><td><span class='deletions'>-0</span>/<span class='insertions'>+70</span></td></tr>
<tr><td><span title='2017-02-03 15:16:45 -0500'>2017-02-03</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=1d5e7c859e81a66674d194c346119d154d31e9dc'>net/sched: act_ife: Unexport ife_tlv_meta_encode</a></td><td>Yotam Gigi</td><td>1</td><td><span class='deletions'>-2</span>/<span class='insertions'>+0</span></td></tr>
<tr><td><span title='2017-02-03 11:19:34 -0500'>2017-02-03</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=3541f9e8bdebce02458882b66b638d7302c1f616'>tcp: add tcp_mss_clamp() helper</a></td><td>Eric Dumazet</td><td>1</td><td><span class='deletions'>-0</span>/<span class='insertions'>+9</span></td></tr>
<tr><td><span title='2017-02-02 23:34:19 -0500'>2017-02-02</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=8fe809a992639b2013c0d8da2ba55cdea28a959a'>net: add LINUX_MIB_PFMEMALLOCDROP counter</a></td><td>Eric Dumazet</td><td>1</td><td><span class='deletions'>-0</span>/<span class='insertions'>+1</span></td></tr>
<tr><td><span title='2017-02-02 22:05:28 -0500'>2017-02-02</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=60f06fde4cff6f6134decbf09199b5e047bc3355'>net: phy: marvell: Add support for 88e1545 PHY</a></td><td>Andrew Lunn</td><td>1</td><td><span class='deletions'>-0</span>/<span class='insertions'>+1</span></td></tr>
<tr><td><span title='2017-02-02 21:58:02 -0500'>2017-02-02</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=ba94f3088b792b16ea576a256a6030feddc87f24'>unix: add ioctl to open a unix socket file with O_PATH</a></td><td>Andrey Vagin</td><td>1</td><td><span class='deletions'>-0</span>/<span class='insertions'>+2</span></td></tr>
<tr><td><span title='2017-02-02 21:50:51 -0500'>2017-02-02</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=e4cf8a38fc0d257b4070066e46a678f4777fecaa'>net: phy: Marvell: Add mv88e6390 internal PHY</a></td><td>Andrew Lunn</td><td>1</td><td><span class='deletions'>-0</span>/<span class='insertions'>+6</span></td></tr>
<tr><td><span title='2017-02-02 16:54:00 -0500'>2017-02-02</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=e2160156bf2a7d5018e99a9993fbcdda0abac09b'>Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net</a></td><td>David S. Miller</td><td>9</td><td><span class='deletions'>-30</span>/<span class='insertions'>+40</span></td></tr>
<tr><td><span title='2017-02-02 14:31:58 +0100'>2017-02-02</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=2851940ffee313e0ff12540a8e11a8c54dea9c65'>netfilter: allow logging from non-init namespaces</a></td><td>Michal Kubeček</td><td>1</td><td><span class='deletions'>-0</span>/<span class='insertions'>+3</span></td></tr>
<tr><td><span title='2017-02-02 14:31:57 +0100'>2017-02-02</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=90c1aff702d449a1a248c4829d51c0bc677f968e'>ipvs: free ip_vs_dest structs when refcnt=0</a></td><td>David Windsor</td><td>1</td><td><span class='deletions'>-1</span>/<span class='insertions'>+1</span></td></tr>
<tr><td><span title='2017-02-02 14:31:56 +0100'>2017-02-02</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=a9e419dc7be6997409dca6d1b9daf3cc7046902f'>netfilter: merge ctinfo into nfct pointer storage area</a></td><td>Florian Westphal</td><td>2</td><td><span class='deletions'>-17</span>/<span class='insertions'>+15</span></td></tr>
<tr><td><span title='2017-02-02 14:31:55 +0100'>2017-02-02</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=303223092081963513494b4377fa1ac9e362ed4b'>netfilter: guarantee 8 byte minalign for template addresses</a></td><td>Florian Westphal</td><td>1</td><td><span class='deletions'>-0</span>/<span class='insertions'>+2</span></td></tr>
<tr><td><span title='2017-02-02 14:31:54 +0100'>2017-02-02</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=c74454fadd5ea6fc866ffe2c417a0dba56b2bf1c'>netfilter: add and use nf_ct_set helper</a></td><td>Florian Westphal</td><td>2</td><td><span class='deletions'>-2</span>/<span class='insertions'>+9</span></td></tr>
<tr><td><span title='2017-02-02 14:31:53 +0100'>2017-02-02</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=cb9c68363efb6d1f950ec55fb06e031ee70db5fc'>skbuff: add and use skb_nfct helper</a></td><td>Florian Westphal</td><td>2</td><td><span class='deletions'>-4</span>/<span class='insertions'>+11</span></td></tr>
<tr><td><span title='2017-02-02 14:31:52 +0100'>2017-02-02</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=97a6ad13decc16c5adbf181283932daba7e17faf'>netfilter: reduce direct skb-&gt;nfct usage</a></td><td>Florian Westphal</td><td>1</td><td><span class='deletions'>-3</span>/<span class='insertions'>+6</span></td></tr>
<tr><td><span title='2017-02-02 14:31:51 +0100'>2017-02-02</span></td><td><a href='/cgit.cgi/linux/net-next.git/commit/include?h=nds-private-remove&amp;id=11df4b760f11ca7528c62b1c4b870735d1c62116'>netfilter: conntrack: no need to pass ctinfo to error handler</a></td><td>Florian Westphal</td><td>1</td><td><span class='deletions'>-1</span>/<span class='insertions'>+1</span></td></tr>