154ceac45SDavid Howells /* getroot.c: get the root dentry for an NFS mount 254ceac45SDavid Howells * 354ceac45SDavid Howells * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved. 454ceac45SDavid Howells * Written by David Howells (dhowells@redhat.com) 554ceac45SDavid Howells * 654ceac45SDavid Howells * This program is free software; you can redistribute it and/or 754ceac45SDavid Howells * modify it under the terms of the GNU General Public License 854ceac45SDavid Howells * as published by the Free Software Foundation; either version 954ceac45SDavid Howells * 2 of the License, or (at your option) any later version. 1054ceac45SDavid Howells */ 1154ceac45SDavid Howells 1254ceac45SDavid Howells #include <linux/module.h> 1354ceac45SDavid Howells #include <linux/init.h> 1454ceac45SDavid Howells 1554ceac45SDavid Howells #include <linux/time.h> 1654ceac45SDavid Howells #include <linux/kernel.h> 1754ceac45SDavid Howells #include <linux/mm.h> 1854ceac45SDavid Howells #include <linux/string.h> 1954ceac45SDavid Howells #include <linux/stat.h> 2054ceac45SDavid Howells #include <linux/errno.h> 2154ceac45SDavid Howells #include <linux/unistd.h> 2254ceac45SDavid Howells #include <linux/sunrpc/clnt.h> 2354ceac45SDavid Howells #include <linux/sunrpc/stats.h> 2454ceac45SDavid Howells #include <linux/nfs_fs.h> 2554ceac45SDavid Howells #include <linux/nfs_mount.h> 2654ceac45SDavid Howells #include <linux/nfs4_mount.h> 2754ceac45SDavid Howells #include <linux/lockd/bind.h> 2854ceac45SDavid Howells #include <linux/seq_file.h> 2954ceac45SDavid Howells #include <linux/mount.h> 3054ceac45SDavid Howells #include <linux/nfs_idmap.h> 3154ceac45SDavid Howells #include <linux/vfs.h> 3254ceac45SDavid Howells #include <linux/namei.h> 33738a3519SDavid Howells #include <linux/security.h> 3454ceac45SDavid Howells 3554ceac45SDavid Howells #include <asm/system.h> 3654ceac45SDavid Howells #include <asm/uaccess.h> 3754ceac45SDavid Howells 3854ceac45SDavid Howells #include "nfs4_fs.h" 3954ceac45SDavid Howells #include "delegation.h" 4054ceac45SDavid Howells #include "internal.h" 4154ceac45SDavid Howells 4254ceac45SDavid Howells #define NFSDBG_FACILITY NFSDBG_CLIENT 4354ceac45SDavid Howells 4454ceac45SDavid Howells /* 45b09b9417STrond Myklebust * Set the superblock root dentry. 46b09b9417STrond Myklebust * Note that this function frees the inode in case of error. 47b09b9417STrond Myklebust */ 48b09b9417STrond Myklebust static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *inode) 49b09b9417STrond Myklebust { 50b09b9417STrond Myklebust /* The mntroot acts as the dummy root dentry for this superblock */ 51b09b9417STrond Myklebust if (sb->s_root == NULL) { 52b09b9417STrond Myklebust sb->s_root = d_alloc_root(inode); 53b09b9417STrond Myklebust if (sb->s_root == NULL) { 54b09b9417STrond Myklebust iput(inode); 55b09b9417STrond Myklebust return -ENOMEM; 56b09b9417STrond Myklebust } 57b09b9417STrond Myklebust /* Circumvent igrab(): we know the inode is not being freed */ 58b09b9417STrond Myklebust atomic_inc(&inode->i_count); 59a10db50aSTrond Myklebust /* 60a10db50aSTrond Myklebust * Ensure that this dentry is invisible to d_find_alias(). 61a10db50aSTrond Myklebust * Otherwise, it may be spliced into the tree by 62a10db50aSTrond Myklebust * d_materialise_unique if a parent directory from the same 63a10db50aSTrond Myklebust * filesystem gets mounted at a later time. 64a10db50aSTrond Myklebust * This again causes shrink_dcache_for_umount_subtree() to 65a10db50aSTrond Myklebust * Oops, since the test for IS_ROOT() will fail. 66a10db50aSTrond Myklebust */ 67a10db50aSTrond Myklebust spin_lock(&dcache_lock); 68a10db50aSTrond Myklebust list_del_init(&sb->s_root->d_alias); 69a10db50aSTrond Myklebust spin_unlock(&dcache_lock); 70b09b9417STrond Myklebust } 71b09b9417STrond Myklebust return 0; 72b09b9417STrond Myklebust } 73b09b9417STrond Myklebust 74b09b9417STrond Myklebust /* 7554ceac45SDavid Howells * get an NFS2/NFS3 root dentry from the root filehandle 7654ceac45SDavid Howells */ 7754ceac45SDavid Howells struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh) 7854ceac45SDavid Howells { 7954ceac45SDavid Howells struct nfs_server *server = NFS_SB(sb); 8054ceac45SDavid Howells struct nfs_fsinfo fsinfo; 8154ceac45SDavid Howells struct nfs_fattr fattr; 8254ceac45SDavid Howells struct dentry *mntroot; 8354ceac45SDavid Howells struct inode *inode; 8454ceac45SDavid Howells int error; 8554ceac45SDavid Howells 8654ceac45SDavid Howells /* get the actual root for this mount */ 8754ceac45SDavid Howells fsinfo.fattr = &fattr; 8854ceac45SDavid Howells 8954ceac45SDavid Howells error = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo); 9054ceac45SDavid Howells if (error < 0) { 9154ceac45SDavid Howells dprintk("nfs_get_root: getattr error = %d\n", -error); 9254ceac45SDavid Howells return ERR_PTR(error); 9354ceac45SDavid Howells } 9454ceac45SDavid Howells 9554ceac45SDavid Howells inode = nfs_fhget(sb, mntfh, fsinfo.fattr); 9654ceac45SDavid Howells if (IS_ERR(inode)) { 9754ceac45SDavid Howells dprintk("nfs_get_root: get root inode failed\n"); 98e231c2eeSDavid Howells return ERR_CAST(inode); 9954ceac45SDavid Howells } 10054ceac45SDavid Howells 101b09b9417STrond Myklebust error = nfs_superblock_set_dummy_root(sb, inode); 102b09b9417STrond Myklebust if (error != 0) 103b09b9417STrond Myklebust return ERR_PTR(error); 104b09b9417STrond Myklebust 10554ceac45SDavid Howells /* root dentries normally start off anonymous and get spliced in later 10654ceac45SDavid Howells * if the dentry tree reaches them; however if the dentry already 10754ceac45SDavid Howells * exists, we'll pick it up at this point and use it as the root 10854ceac45SDavid Howells */ 10944003728SChristoph Hellwig mntroot = d_obtain_alias(inode); 11044003728SChristoph Hellwig if (IS_ERR(mntroot)) { 11154ceac45SDavid Howells dprintk("nfs_get_root: get root dentry failed\n"); 11244003728SChristoph Hellwig return mntroot; 11354ceac45SDavid Howells } 11454ceac45SDavid Howells 115738a3519SDavid Howells security_d_instantiate(mntroot, inode); 116738a3519SDavid Howells 11754ceac45SDavid Howells if (!mntroot->d_op) 11854ceac45SDavid Howells mntroot->d_op = server->nfs_client->rpc_ops->dentry_ops; 11954ceac45SDavid Howells 12054ceac45SDavid Howells return mntroot; 12154ceac45SDavid Howells } 12254ceac45SDavid Howells 12354ceac45SDavid Howells #ifdef CONFIG_NFS_V4 12454ceac45SDavid Howells 125815409d2STrond Myklebust int nfs4_get_rootfh(struct nfs_server *server, struct nfs_fh *mntfh) 12654ceac45SDavid Howells { 12754ceac45SDavid Howells struct nfs_fsinfo fsinfo; 128815409d2STrond Myklebust int ret = -ENOMEM; 12954ceac45SDavid Howells 130815409d2STrond Myklebust dprintk("--> nfs4_get_rootfh()\n"); 13154ceac45SDavid Howells 132815409d2STrond Myklebust fsinfo.fattr = nfs_alloc_fattr(); 133815409d2STrond Myklebust if (fsinfo.fattr == NULL) 134815409d2STrond Myklebust goto out; 13554ceac45SDavid Howells 13654ceac45SDavid Howells /* Start by getting the root filehandle from the server */ 13754ceac45SDavid Howells ret = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo); 13854ceac45SDavid Howells if (ret < 0) { 139815409d2STrond Myklebust dprintk("nfs4_get_rootfh: getroot error = %d\n", -ret); 140815409d2STrond Myklebust goto out; 14154ceac45SDavid Howells } 14254ceac45SDavid Howells 143815409d2STrond Myklebust if (!(fsinfo.fattr->valid & NFS_ATTR_FATTR_MODE) 144815409d2STrond Myklebust || !S_ISDIR(fsinfo.fattr->mode)) { 145815409d2STrond Myklebust printk(KERN_ERR "nfs4_get_rootfh:" 14654ceac45SDavid Howells " getroot encountered non-directory\n"); 147815409d2STrond Myklebust ret = -ENOTDIR; 148815409d2STrond Myklebust goto out; 14954ceac45SDavid Howells } 15054ceac45SDavid Howells 151815409d2STrond Myklebust if (fsinfo.fattr->valid & NFS_ATTR_FATTR_V4_REFERRAL) { 152815409d2STrond Myklebust printk(KERN_ERR "nfs4_get_rootfh:" 15354ceac45SDavid Howells " getroot obtained referral\n"); 154815409d2STrond Myklebust ret = -EREMOTE; 155815409d2STrond Myklebust goto out; 15654ceac45SDavid Howells } 15754ceac45SDavid Howells 158815409d2STrond Myklebust memcpy(&server->fsid, &fsinfo.fattr->fsid, sizeof(server->fsid)); 159815409d2STrond Myklebust out: 160815409d2STrond Myklebust nfs_free_fattr(fsinfo.fattr); 161815409d2STrond Myklebust dprintk("<-- nfs4_get_rootfh() = %d\n", ret); 16254ceac45SDavid Howells return ret; 16354ceac45SDavid Howells } 16454ceac45SDavid Howells 16554ceac45SDavid Howells /* 16654ceac45SDavid Howells * get an NFS4 root dentry from the root filehandle 16754ceac45SDavid Howells */ 16854ceac45SDavid Howells struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh) 16954ceac45SDavid Howells { 17054ceac45SDavid Howells struct nfs_server *server = NFS_SB(sb); 17154ceac45SDavid Howells struct nfs_fattr fattr; 17254ceac45SDavid Howells struct dentry *mntroot; 17354ceac45SDavid Howells struct inode *inode; 17454ceac45SDavid Howells int error; 17554ceac45SDavid Howells 17654ceac45SDavid Howells dprintk("--> nfs4_get_root()\n"); 17754ceac45SDavid Howells 17854ceac45SDavid Howells /* get the info about the server and filesystem */ 17954ceac45SDavid Howells error = nfs4_server_capabilities(server, mntfh); 18054ceac45SDavid Howells if (error < 0) { 18154ceac45SDavid Howells dprintk("nfs_get_root: getcaps error = %d\n", 18254ceac45SDavid Howells -error); 18354ceac45SDavid Howells return ERR_PTR(error); 18454ceac45SDavid Howells } 18554ceac45SDavid Howells 18654ceac45SDavid Howells /* get the actual root for this mount */ 18754ceac45SDavid Howells error = server->nfs_client->rpc_ops->getattr(server, mntfh, &fattr); 18854ceac45SDavid Howells if (error < 0) { 18954ceac45SDavid Howells dprintk("nfs_get_root: getattr error = %d\n", -error); 19054ceac45SDavid Howells return ERR_PTR(error); 19154ceac45SDavid Howells } 19254ceac45SDavid Howells 19354ceac45SDavid Howells inode = nfs_fhget(sb, mntfh, &fattr); 19454ceac45SDavid Howells if (IS_ERR(inode)) { 19554ceac45SDavid Howells dprintk("nfs_get_root: get root inode failed\n"); 196e231c2eeSDavid Howells return ERR_CAST(inode); 19754ceac45SDavid Howells } 19854ceac45SDavid Howells 199b09b9417STrond Myklebust error = nfs_superblock_set_dummy_root(sb, inode); 200b09b9417STrond Myklebust if (error != 0) 201b09b9417STrond Myklebust return ERR_PTR(error); 202b09b9417STrond Myklebust 20354ceac45SDavid Howells /* root dentries normally start off anonymous and get spliced in later 20454ceac45SDavid Howells * if the dentry tree reaches them; however if the dentry already 20554ceac45SDavid Howells * exists, we'll pick it up at this point and use it as the root 20654ceac45SDavid Howells */ 20744003728SChristoph Hellwig mntroot = d_obtain_alias(inode); 20844003728SChristoph Hellwig if (IS_ERR(mntroot)) { 20954ceac45SDavid Howells dprintk("nfs_get_root: get root dentry failed\n"); 21044003728SChristoph Hellwig return mntroot; 21154ceac45SDavid Howells } 21254ceac45SDavid Howells 213738a3519SDavid Howells security_d_instantiate(mntroot, inode); 214738a3519SDavid Howells 21554ceac45SDavid Howells if (!mntroot->d_op) 21654ceac45SDavid Howells mntroot->d_op = server->nfs_client->rpc_ops->dentry_ops; 21754ceac45SDavid Howells 21854ceac45SDavid Howells dprintk("<-- nfs4_get_root()\n"); 21954ceac45SDavid Howells return mntroot; 22054ceac45SDavid Howells } 22154ceac45SDavid Howells 22254ceac45SDavid Howells #endif /* CONFIG_NFS_V4 */ 223