--- /dev/null
+/*
+ * linux/fs/nfs/namespace.c
+ *
+ * Copyright (C) 2005 Trond Myklebust <Trond.Myklebust@netapp.com>
+ * - Modified by David Howells <dhowells@redhat.com>
+ *
+ * NFS namespace
+ */
+
+#include <linux/module.h>
+#include <linux/dcache.h>
+#include <linux/gfp.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/nfs_fs.h>
+#include <linux/string.h>
+#include <linux/sunrpc/clnt.h>
+#include <linux/vfs.h>
+#include <linux/sunrpc/gss_api.h>
+#include "internal.h"
+
+#define NFSDBG_FACILITY NFSDBG_VFS
+
+static void nfs_expire_automounts(struct work_struct *work);
+
+static LIST_HEAD(nfs_automount_list);
+static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
+int nfs_mountpoint_expiry_timeout = 500 * HZ;
+
+/*
+ * nfs_path - reconstruct the path given an arbitrary dentry
+ * @base - used to return pointer to the end of devname part of path
+ * @dentry - pointer to dentry
+ * @buffer - result buffer
+ * @buflen - length of buffer
+ * @flags - options (see below)
+ *
+ * Helper function for constructing the server pathname
+ * by arbitrary hashed dentry.
+ *
+ * This is mainly for use in figuring out the path on the
+ * server side when automounting on top of an existing partition
+ * and in generating /proc/mounts and friends.
+ *
+ * Supported flags:
+ * NFS_PATH_CANONICAL: ensure there is exactly one slash after
+ * the original device (export) name
+ * (if unset, the original name is returned verbatim)
+ */
+char *nfs_path(char **p, struct dentry *dentry, char *buffer, ssize_t buflen,
+ unsigned flags)
+{
+ char *end;
+ int namelen;
+ unsigned seq;
+ const char *base;
+
+rename_retry:
+ end = buffer+buflen;
+ *--end = '\0';
+ buflen--;
+
+ seq = read_seqbegin(&rename_lock);
+ rcu_read_lock();
+ while (1) {
+ spin_lock(&dentry->d_lock);
+ if (IS_ROOT(dentry))
+ break;
+ namelen = dentry->d_name.len;
+ buflen -= namelen + 1;
+ if (buflen < 0)
+ goto Elong_unlock;
+ end -= namelen;
+ memcpy(end, dentry->d_name.name, namelen);
+ *--end = '/';
+ spin_unlock(&dentry->d_lock);
+ dentry = dentry->d_parent;
+ }
+ if (read_seqretry(&rename_lock, seq)) {
+ spin_unlock(&dentry->d_lock);
+ rcu_read_unlock();
+ goto rename_retry;
+ }
+ if ((flags & NFS_PATH_CANONICAL) && *end != '/') {
+ if (--buflen < 0) {
+ spin_unlock(&dentry->d_lock);
+ rcu_read_unlock();
+ goto Elong;
+ }
+ *--end = '/';
+ }
+ *p = end;
+ base = dentry->d_fsdata;
+ if (!base) {
+ spin_unlock(&dentry->d_lock);
+ rcu_read_unlock();
+ WARN_ON(1);
+ return end;
+ }
+ namelen = strlen(base);
+ if (flags & NFS_PATH_CANONICAL) {
+ /* Strip off excess slashes in base string */
+ while (namelen > 0 && base[namelen - 1] == '/')
+ namelen--;
+ }
+ buflen -= namelen;
+ if (buflen < 0) {
+ spin_unlock(&dentry->d_lock);
+ rcu_read_unlock();
+ goto Elong;
+ }
+ end -= namelen;
+ memcpy(end, base, namelen);
+ spin_unlock(&dentry->d_lock);
+ rcu_read_unlock();
+ return end;
+Elong_unlock:
+ spin_unlock(&dentry->d_lock);
+ rcu_read_unlock();
+ if (read_seqretry(&rename_lock, seq))
+ goto rename_retry;
+Elong:
+ return ERR_PTR(-ENAMETOOLONG);
+}
+EXPORT_SYMBOL_GPL(nfs_path);
+
+/*
+ * nfs_d_automount - Handle crossing a mountpoint on the server
+ * @path - The mountpoint
+ *
+ * When we encounter a mountpoint on the server, we want to set up
+ * a mountpoint on the client too, to prevent inode numbers from
+ * colliding, and to allow "df" to work properly.
+ * On NFSv4, we also want to allow for the fact that different
+ * filesystems may be migrated to different servers in a failover
+ * situation, and that different filesystems may want to use
+ * different security flavours.
+ */
+struct vfsmount *nfs_d_automount(struct path *path)
+{
+ struct vfsmount *mnt;
+ struct nfs_server *server = NFS_SERVER(d_inode(path->dentry));
+ struct nfs_fh *fh = NULL;
+ struct nfs_fattr *fattr = NULL;
+
+ dprintk("--> nfs_d_automount()\n");
+
+ mnt = ERR_PTR(-ESTALE);
+ if (IS_ROOT(path->dentry))
+ goto out_nofree;
+
+ mnt = ERR_PTR(-ENOMEM);
+ fh = nfs_alloc_fhandle();
+ fattr = nfs_alloc_fattr();
+ if (fh == NULL || fattr == NULL)
+ goto out;
+
+ dprintk("%s: enter\n", __func__);
+
+ mnt = server->nfs_client->rpc_ops->submount(server, path->dentry, fh, fattr);
+ if (IS_ERR(mnt))
+ goto out;
+
+ dprintk("%s: done, success\n", __func__);
+ mntget(mnt); /* prevent immediate expiration */
+ mnt_set_expiry(mnt, &nfs_automount_list);
+ schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
+
+out:
+ nfs_free_fattr(fattr);
+ nfs_free_fhandle(fh);
+out_nofree:
+ if (IS_ERR(mnt))
+ dprintk("<-- %s(): error %ld\n", __func__, PTR_ERR(mnt));
+ else
+ dprintk("<-- %s() = %p\n", __func__, mnt);
+ return mnt;
+}
+
+static int
+nfs_namespace_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
+{
+ if (NFS_FH(d_inode(dentry))->size != 0)
+ return nfs_getattr(mnt, dentry, stat);
+ generic_fillattr(d_inode(dentry), stat);
+ return 0;
+}
+
+static int
+nfs_namespace_setattr(struct dentry *dentry, struct iattr *attr)
+{
+ if (NFS_FH(d_inode(dentry))->size != 0)
+ return nfs_setattr(dentry, attr);
+ return -EACCES;
+}
+
+const struct inode_operations nfs_mountpoint_inode_operations = {
+ .getattr = nfs_getattr,
+ .setattr = nfs_setattr,
+};
+
+const struct inode_operations nfs_referral_inode_operations = {
+ .getattr = nfs_namespace_getattr,
+ .setattr = nfs_namespace_setattr,
+};
+
+static void nfs_expire_automounts(struct work_struct *work)
+{
+ struct list_head *list = &nfs_automount_list;
+
+ mark_mounts_for_expiry(list);
+ if (!list_empty(list))
+ schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
+}
+
+void nfs_release_automount_timer(void)
+{
+ if (list_empty(&nfs_automount_list))
+ cancel_delayed_work(&nfs_automount_task);
+}
+
+/*
+ * Clone a mountpoint of the appropriate type
+ */
+static struct vfsmount *nfs_do_clone_mount(struct nfs_server *server,
+ const char *devname,
+ struct nfs_clone_mount *mountdata)
+{
+ return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
+}
+
+/**
+ * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
+ * @dentry - parent directory
+ * @fh - filehandle for new root dentry
+ * @fattr - attributes for new root inode
+ * @authflavor - security flavor to use when performing the mount
+ *
+ */
+struct vfsmount *nfs_do_submount(struct dentry *dentry, struct nfs_fh *fh,
+ struct nfs_fattr *fattr, rpc_authflavor_t authflavor)
+{
+ struct nfs_clone_mount mountdata = {
+ .sb = dentry->d_sb,
+ .dentry = dentry,
+ .fh = fh,
+ .fattr = fattr,
+ .authflavor = authflavor,
+ };
+ struct vfsmount *mnt = ERR_PTR(-ENOMEM);
+ char *page = (char *) __get_free_page(GFP_USER);
+ char *devname;
+
+ dprintk("--> nfs_do_submount()\n");
+
+ dprintk("%s: submounting on %pd2\n", __func__,
+ dentry);
+ if (page == NULL)
+ goto out;
+ devname = nfs_devname(dentry, page, PAGE_SIZE);
+ mnt = (struct vfsmount *)devname;
+ if (IS_ERR(devname))
+ goto free_page;
+ mnt = nfs_do_clone_mount(NFS_SB(dentry->d_sb), devname, &mountdata);
+free_page:
+ free_page((unsigned long)page);
+out:
+ dprintk("%s: done\n", __func__);
+
+ dprintk("<-- nfs_do_submount() = %p\n", mnt);
+ return mnt;
+}
+EXPORT_SYMBOL_GPL(nfs_do_submount);
+
+struct vfsmount *nfs_submount(struct nfs_server *server, struct dentry *dentry,
+ struct nfs_fh *fh, struct nfs_fattr *fattr)
+{
+ int err;
+ struct dentry *parent = dget_parent(dentry);
+
+ /* Look it up again to get its attributes */
+ err = server->nfs_client->rpc_ops->lookup(d_inode(parent), &dentry->d_name, fh, fattr, NULL);
+ dput(parent);
+ if (err != 0)
+ return ERR_PTR(err);
+
+ return nfs_do_submount(dentry, fh, fattr, server->client->cl_auth->au_flavor);
+}
+EXPORT_SYMBOL_GPL(nfs_submount);
Code Review / kvmfornfv.git / blobdiff