fs/nfs/namespace.c - linux - Git at Google

 /*
  * 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/dcache.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 "internal.h"

 #define NFSDBG_FACILITY		NFSDBG_VFS

 static void nfs_expire_automounts(struct work_struct *work);

 LIST_HEAD(nfs_automount_list);
 static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
 int nfs_mountpoint_expiry_timeout = 500 * HZ;

 static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
 					const struct dentry *dentry,
 					struct nfs_fh *fh,
 					struct nfs_fattr *fattr);

 /*
  * nfs_path - reconstruct the path given an arbitrary dentry
  * @base - arbitrary string to prepend to the path
  * @droot - pointer to root dentry for mountpoint
  * @dentry - pointer to dentry
  * @buffer - result buffer
  * @buflen - length of buffer
  *
  * Helper function for constructing the path from the
  * root dentry to an 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.
  */
 char *nfs_path(const char *base,
 	       const struct dentry *droot,
 	       const struct dentry *dentry,
 	       char *buffer, ssize_t buflen)
 {
 	char *end = buffer+buflen;
 	int namelen;

 	*--end = '\0';
 	buflen--;
 	spin_lock(&dcache_lock);
 	while (!IS_ROOT(dentry) && dentry != droot) {
 		namelen = dentry->d_name.len;
 		buflen -= namelen + 1;
 		if (buflen < 0)
 			goto Elong_unlock;
 		end -= namelen;
 		memcpy(end, dentry->d_name.name, namelen);
 		*--end = '/';
 		dentry = dentry->d_parent;
 	}
 	spin_unlock(&dcache_lock);
 	namelen = strlen(base);
 	/* Strip off excess slashes in base string */
 	while (namelen > 0 && base[namelen - 1] == '/')
 		namelen--;
 	buflen -= namelen;
 	if (buflen < 0)
 		goto Elong;
 	end -= namelen;
 	memcpy(end, base, namelen);
 	return end;
 Elong_unlock:
 	spin_unlock(&dcache_lock);
 Elong:
 	return ERR_PTR(-ENAMETOOLONG);
 }

 /*
  * nfs_follow_mountpoint - handle crossing a mountpoint on the server
  * @dentry - dentry of mountpoint
  * @nd - nameidata info
  *
  * 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.
  */
 static void * nfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
 {
 	struct vfsmount *mnt;
 	struct nfs_server *server = NFS_SERVER(dentry->d_inode);
 	struct dentry *parent;
 	struct nfs_fh fh;
 	struct nfs_fattr fattr;
 	int err;

 	dprintk("--> nfs_follow_mountpoint()\n");

 	BUG_ON(IS_ROOT(dentry));
 	dprintk("%s: enter\n", __FUNCTION__);
 	dput(nd->path.dentry);
 	nd->path.dentry = dget(dentry);

 	/* Look it up again */
 	parent = dget_parent(nd->path.dentry);
 	err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
 						  &nd->path.dentry->d_name,
 						  &fh, &fattr);
 	dput(parent);
 	if (err != 0)
 		goto out_err;

 	if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL)
 		mnt = nfs_do_refmount(nd->path.mnt, nd->path.dentry);
 	else
 		mnt = nfs_do_submount(nd->path.mnt, nd->path.dentry, &fh,
 				      &fattr);
 	err = PTR_ERR(mnt);
 	if (IS_ERR(mnt))
 		goto out_err;

 	mntget(mnt);
 	err = do_add_mount(mnt, nd, nd->path.mnt->mnt_flags|MNT_SHRINKABLE,
 			   &nfs_automount_list);
 	if (err < 0) {
 		mntput(mnt);
 		if (err == -EBUSY)
 			goto out_follow;
 		goto out_err;
 	}
 	mntput(nd->path.mnt);
 	dput(nd->path.dentry);
 	nd->path.mnt = mnt;
 	nd->path.dentry = dget(mnt->mnt_root);
 	schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
 out:
 	dprintk("%s: done, returned %d\n", __FUNCTION__, err);

 	dprintk("<-- nfs_follow_mountpoint() = %d\n", err);
 	return ERR_PTR(err);
 out_err:
 	path_put(&nd->path);
 	goto out;
 out_follow:
 	while (d_mountpoint(nd->path.dentry) &&
 	       follow_down(&nd->path.mnt, &nd->path.dentry))
 		;
 	err = 0;
 	goto out;
 }

 const struct inode_operations nfs_mountpoint_inode_operations = {
 	.follow_link	= nfs_follow_mountpoint,
 	.getattr	= nfs_getattr,
 };

 const struct inode_operations nfs_referral_inode_operations = {
 	.follow_link	= nfs_follow_mountpoint,
 };

 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)
 {
 #ifdef CONFIG_NFS_V4
 	struct vfsmount *mnt = NULL;
 	switch (server->nfs_client->rpc_ops->version) {
 		case 2:
 		case 3:
 			mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
 			break;
 		case 4:
 			mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
 	}
 	return mnt;
 #else
 	return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
 #endif
 }

 /**
  * nfs_do_submount - set up mountpoint when crossing a filesystem boundary
  * @mnt_parent - mountpoint of parent directory
  * @dentry - parent directory
  * @fh - filehandle for new root dentry
  * @fattr - attributes for new root inode
  *
  */
 static struct vfsmount *nfs_do_submount(const struct vfsmount *mnt_parent,
 					const struct dentry *dentry,
 					struct nfs_fh *fh,
 					struct nfs_fattr *fattr)
 {
 	struct nfs_clone_mount mountdata = {
 		.sb = mnt_parent->mnt_sb,
 		.dentry = dentry,
 		.fh = fh,
 		.fattr = fattr,
 	};
 	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 %s/%s\n", __FUNCTION__,
 			dentry->d_parent->d_name.name,
 			dentry->d_name.name);
 	if (page == NULL)
 		goto out;
 	devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
 	mnt = (struct vfsmount *)devname;
 	if (IS_ERR(devname))
 		goto free_page;
 	mnt = nfs_do_clone_mount(NFS_SB(mnt_parent->mnt_sb), devname, &mountdata);
 free_page:
 	free_page((unsigned long)page);
 out:
 	dprintk("%s: done\n", __FUNCTION__);

 	dprintk("<-- nfs_do_submount() = %p\n", mnt);
 	return mnt;
 }
	/*
	* 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/dcache.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 "internal.h"

	#define NFSDBG_FACILITY NFSDBG_VFS

	static void nfs_expire_automounts(struct work_struct *work);

	LIST_HEAD(nfs_automount_list);
	static DECLARE_DELAYED_WORK(nfs_automount_task, nfs_expire_automounts);
	int nfs_mountpoint_expiry_timeout = 500 * HZ;

	static struct vfsmount nfs_do_submount(const struct vfsmount mnt_parent,
	const struct dentry *dentry,
	struct nfs_fh *fh,
	struct nfs_fattr *fattr);

	/*
	* nfs_path - reconstruct the path given an arbitrary dentry
	* @base - arbitrary string to prepend to the path
	* @droot - pointer to root dentry for mountpoint
	* @dentry - pointer to dentry
	* @buffer - result buffer
	* @buflen - length of buffer
	*
	* Helper function for constructing the path from the
	* root dentry to an 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.
	*/
	char nfs_path(const char base,
	const struct dentry *droot,
	const struct dentry *dentry,
	char *buffer, ssize_t buflen)
	{
	char *end = buffer+buflen;
	int namelen;

	*--end = '\0';
	buflen--;
	spin_lock(&dcache_lock);
	while (!IS_ROOT(dentry) && dentry != droot) {
	namelen = dentry->d_name.len;
	buflen -= namelen + 1;
	if (buflen < 0)
	goto Elong_unlock;
	end -= namelen;
	memcpy(end, dentry->d_name.name, namelen);
	*--end = '/';
	dentry = dentry->d_parent;
	}
	spin_unlock(&dcache_lock);
	namelen = strlen(base);
	/* Strip off excess slashes in base string */
	while (namelen > 0 && base[namelen - 1] == '/')
	namelen--;
	buflen -= namelen;
	if (buflen < 0)
	goto Elong;
	end -= namelen;
	memcpy(end, base, namelen);
	return end;
	Elong_unlock:
	spin_unlock(&dcache_lock);
	Elong:
	return ERR_PTR(-ENAMETOOLONG);
	}

	/*
	* nfs_follow_mountpoint - handle crossing a mountpoint on the server
	* @dentry - dentry of mountpoint
	* @nd - nameidata info
	*
	* 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.
	*/
	static void * nfs_follow_mountpoint(struct dentry dentry, struct nameidata nd)
	{
	struct vfsmount *mnt;
	struct nfs_server *server = NFS_SERVER(dentry->d_inode);
	struct dentry *parent;
	struct nfs_fh fh;
	struct nfs_fattr fattr;
	int err;

	dprintk("--> nfs_follow_mountpoint()\n");

	BUG_ON(IS_ROOT(dentry));
	dprintk("%s: enter\n", __FUNCTION__);
	dput(nd->path.dentry);
	nd->path.dentry = dget(dentry);

	/* Look it up again */
	parent = dget_parent(nd->path.dentry);
	err = server->nfs_client->rpc_ops->lookup(parent->d_inode,
	&nd->path.dentry->d_name,
	&fh, &fattr);
	dput(parent);
	if (err != 0)
	goto out_err;

	if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL)
	mnt = nfs_do_refmount(nd->path.mnt, nd->path.dentry);
	else
	mnt = nfs_do_submount(nd->path.mnt, nd->path.dentry, &fh,
	&fattr);
	err = PTR_ERR(mnt);
	if (IS_ERR(mnt))
	goto out_err;

	mntget(mnt);
	err = do_add_mount(mnt, nd, nd->path.mnt->mnt_flags\|MNT_SHRINKABLE,
	&nfs_automount_list);
	if (err < 0) {
	mntput(mnt);
	if (err == -EBUSY)
	goto out_follow;
	goto out_err;
	}
	mntput(nd->path.mnt);
	dput(nd->path.dentry);
	nd->path.mnt = mnt;
	nd->path.dentry = dget(mnt->mnt_root);
	schedule_delayed_work(&nfs_automount_task, nfs_mountpoint_expiry_timeout);
	out:
	dprintk("%s: done, returned %d\n", __FUNCTION__, err);

	dprintk("<-- nfs_follow_mountpoint() = %d\n", err);
	return ERR_PTR(err);
	out_err:
	path_put(&nd->path);
	goto out;
	out_follow:
	while (d_mountpoint(nd->path.dentry) &&
	follow_down(&nd->path.mnt, &nd->path.dentry))
	;
	err = 0;
	goto out;
	}

	const struct inode_operations nfs_mountpoint_inode_operations = {
	.follow_link = nfs_follow_mountpoint,
	.getattr = nfs_getattr,
	};

	const struct inode_operations nfs_referral_inode_operations = {
	.follow_link = nfs_follow_mountpoint,
	};

	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)
	{
	#ifdef CONFIG_NFS_V4
	struct vfsmount *mnt = NULL;
	switch (server->nfs_client->rpc_ops->version) {
	case 2:
	case 3:
	mnt = vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
	break;
	case 4:
	mnt = vfs_kern_mount(&nfs4_xdev_fs_type, 0, devname, mountdata);
	}
	return mnt;
	#else
	return vfs_kern_mount(&nfs_xdev_fs_type, 0, devname, mountdata);
	#endif
	}

	/**
	* nfs_do_submount - set up mountpoint when crossing a filesystem boundary
	* @mnt_parent - mountpoint of parent directory
	* @dentry - parent directory
	* @fh - filehandle for new root dentry
	* @fattr - attributes for new root inode
	*
	*/
	static struct vfsmount nfs_do_submount(const struct vfsmount mnt_parent,
	const struct dentry *dentry,
	struct nfs_fh *fh,
	struct nfs_fattr *fattr)
	{
	struct nfs_clone_mount mountdata = {
	.sb = mnt_parent->mnt_sb,
	.dentry = dentry,
	.fh = fh,
	.fattr = fattr,
	};
	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 %s/%s\n", __FUNCTION__,
	dentry->d_parent->d_name.name,
	dentry->d_name.name);
	if (page == NULL)
	goto out;
	devname = nfs_devname(mnt_parent, dentry, page, PAGE_SIZE);
	mnt = (struct vfsmount *)devname;
	if (IS_ERR(devname))
	goto free_page;
	mnt = nfs_do_clone_mount(NFS_SB(mnt_parent->mnt_sb), devname, &mountdata);
	free_page:
	free_page((unsigned long)page);
	out:
	dprintk("%s: done\n", __FUNCTION__);

	dprintk("<-- nfs_do_submount() = %p\n", mnt);
	return mnt;
	}