Trond Myklebust | 55a9759 | 2006-06-09 09:34:19 -0400 | [diff] [blame^] | 1 | /* |
| 2 | * linux/fs/nfs/namespace.c |
| 3 | * |
| 4 | * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com> |
| 5 | * |
| 6 | * NFS namespace |
| 7 | */ |
| 8 | |
| 9 | #include <linux/config.h> |
| 10 | |
| 11 | #include <linux/dcache.h> |
| 12 | #include <linux/mount.h> |
| 13 | #include <linux/namei.h> |
| 14 | #include <linux/nfs_fs.h> |
| 15 | #include <linux/string.h> |
| 16 | #include <linux/sunrpc/clnt.h> |
| 17 | #include <linux/vfs.h> |
| 18 | |
| 19 | #define NFSDBG_FACILITY NFSDBG_VFS |
| 20 | |
| 21 | /* |
| 22 | * nfs_follow_mountpoint - handle crossing a mountpoint on the server |
| 23 | * @dentry - dentry of mountpoint |
| 24 | * @nd - nameidata info |
| 25 | * |
| 26 | * When we encounter a mountpoint on the server, we want to set up |
| 27 | * a mountpoint on the client too, to prevent inode numbers from |
| 28 | * colliding, and to allow "df" to work properly. |
| 29 | * On NFSv4, we also want to allow for the fact that different |
| 30 | * filesystems may be migrated to different servers in a failover |
| 31 | * situation, and that different filesystems may want to use |
| 32 | * different security flavours. |
| 33 | */ |
| 34 | static void * nfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd) |
| 35 | { |
| 36 | struct vfsmount *mnt; |
| 37 | struct nfs_server *server = NFS_SERVER(dentry->d_inode); |
| 38 | struct dentry *parent; |
| 39 | struct nfs_fh fh; |
| 40 | struct nfs_fattr fattr; |
| 41 | int err; |
| 42 | |
| 43 | BUG_ON(IS_ROOT(dentry)); |
| 44 | dprintk("%s: enter\n", __FUNCTION__); |
| 45 | dput(nd->dentry); |
| 46 | nd->dentry = dget(dentry); |
| 47 | if (d_mountpoint(nd->dentry)) |
| 48 | goto out_follow; |
| 49 | /* Look it up again */ |
| 50 | parent = dget_parent(nd->dentry); |
| 51 | err = server->rpc_ops->lookup(parent->d_inode, &nd->dentry->d_name, &fh, &fattr); |
| 52 | dput(parent); |
| 53 | if (err != 0) |
| 54 | goto out_err; |
| 55 | |
| 56 | mnt = nfs_do_submount(nd->mnt, nd->dentry, &fh, &fattr); |
| 57 | err = PTR_ERR(mnt); |
| 58 | if (IS_ERR(mnt)) |
| 59 | goto out_err; |
| 60 | |
| 61 | mntget(mnt); |
| 62 | err = do_add_mount(mnt, nd, nd->mnt->mnt_flags, NULL); |
| 63 | if (err < 0) { |
| 64 | mntput(mnt); |
| 65 | if (err == -EBUSY) |
| 66 | goto out_follow; |
| 67 | goto out_err; |
| 68 | } |
| 69 | mntput(nd->mnt); |
| 70 | dput(nd->dentry); |
| 71 | nd->mnt = mnt; |
| 72 | nd->dentry = dget(mnt->mnt_root); |
| 73 | out: |
| 74 | dprintk("%s: done, returned %d\n", __FUNCTION__, err); |
| 75 | return ERR_PTR(err); |
| 76 | out_err: |
| 77 | path_release(nd); |
| 78 | goto out; |
| 79 | out_follow: |
| 80 | while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry)) |
| 81 | ; |
| 82 | err = 0; |
| 83 | goto out; |
| 84 | } |
| 85 | |
| 86 | struct inode_operations nfs_mountpoint_inode_operations = { |
| 87 | .follow_link = nfs_follow_mountpoint, |
| 88 | .getattr = nfs_getattr, |
| 89 | }; |