Merge branch 'afs-proc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull AFS updates from Al Viro:
"Assorted AFS stuff - ended up in vfs.git since most of that consists
of David's AFS-related followups to Christoph's procfs series"

* 'afs-proc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
afs: Optimise callback breaking by not repeating volume lookup
afs: Display manually added cells in dynamic root mount
afs: Enable IPv6 DNS lookups
afs: Show all of a server's addresses in /proc/fs/afs/servers
afs: Handle CONFIG_PROC_FS=n
proc: Make inline name size calculation automatic
afs: Implement network namespacing
afs: Mark afs_net::ws_cell as __rcu and set using rcu functions
afs: Fix a Sparse warning in xdr_decode_AFSFetchStatus()
proc: Add a way to make network proc files writable
afs: Rearrange fs/afs/proc.c to remove remaining predeclarations.
afs: Rearrange fs/afs/proc.c to move the show routines up
afs: Rearrange fs/afs/proc.c by moving fops and open functions down
afs: Move /proc management functions to the end of the file

fs/afs/Makefile

···
 
 afs-cache-$(CONFIG_AFS_FSCACHE) := cache.o
 
-kafs-objs := \
+kafs-y := \
 	$(afs-cache-y) \
 	addr_list.o \
 	callback.o \
···
 	main.o \
 	misc.o \
 	mntpt.o \
-	proc.o \
 	rotate.o \
 	rxrpc.o \
 	security.o \
···
 	write.o \
 	xattr.o
 
+kafs-$(CONFIG_PROC_FS) += proc.o
 obj-$(CONFIG_AFS_FS)  := kafs.o

fs/afs/addr_list.c

···
 	_enter("%s", cell->name);
 
 	ret = dns_query("afsdb", cell->name, cell->name_len,
-			"ipv4", &vllist, _expiry);
+			"", &vllist, _expiry);
 	if (ret < 0)
 		return ERR_PTR(ret);
 

fs/afs/callback.c

···
 #include "internal.h"
 
 /*
+ * Create volume and callback interests on a server.
+ */
+static struct afs_cb_interest *afs_create_interest(struct afs_server *server,
+						   struct afs_vnode *vnode)
+{
+	struct afs_vol_interest *new_vi, *vi;
+	struct afs_cb_interest *new;
+	struct hlist_node **pp;
+
+	new_vi = kzalloc(sizeof(struct afs_vol_interest), GFP_KERNEL);
+	if (!new_vi)
+		return NULL;
+
+	new = kzalloc(sizeof(struct afs_cb_interest), GFP_KERNEL);
+	if (!new) {
+		kfree(new_vi);
+		return NULL;
+	}
+
+	new_vi->usage = 1;
+	new_vi->vid = vnode->volume->vid;
+	INIT_HLIST_NODE(&new_vi->srv_link);
+	INIT_HLIST_HEAD(&new_vi->cb_interests);
+
+	refcount_set(&new->usage, 1);
+	new->sb = vnode->vfs_inode.i_sb;
+	new->vid = vnode->volume->vid;
+	new->server = afs_get_server(server);
+	INIT_HLIST_NODE(&new->cb_vlink);
+
+	write_lock(&server->cb_break_lock);
+
+	for (pp = &server->cb_volumes.first; *pp; pp = &(*pp)->next) {
+		vi = hlist_entry(*pp, struct afs_vol_interest, srv_link);
+		if (vi->vid < new_vi->vid)
+			continue;
+		if (vi->vid > new_vi->vid)
+			break;
+		vi->usage++;
+		goto found_vi;
+	}
+
+	new_vi->srv_link.pprev = pp;
+	new_vi->srv_link.next = *pp;
+	if (*pp)
+		(*pp)->pprev = &new_vi->srv_link.next;
+	*pp = &new_vi->srv_link;
+	vi = new_vi;
+	new_vi = NULL;
+found_vi:
+
+	new->vol_interest = vi;
+	hlist_add_head(&new->cb_vlink, &vi->cb_interests);
+
+	write_unlock(&server->cb_break_lock);
+	kfree(new_vi);
+	return new;
+}
+
+/*
  * Set up an interest-in-callbacks record for a volume on a server and
  * register it with the server.
  * - Called with vnode->io_lock held.
···
 	}
 
 	if (!cbi) {
-		new = kzalloc(sizeof(struct afs_cb_interest), GFP_KERNEL);
+		new = afs_create_interest(server, vnode);
 		if (!new)
 			return -ENOMEM;
-
-		refcount_set(&new->usage, 1);
-		new->sb = vnode->vfs_inode.i_sb;
-		new->vid = vnode->volume->vid;
-		new->server = afs_get_server(server);
-		INIT_LIST_HEAD(&new->cb_link);
-
-		write_lock(&server->cb_break_lock);
-		list_add_tail(&new->cb_link, &server->cb_interests);
-		write_unlock(&server->cb_break_lock);
 
 		write_lock(&slist->lock);
 		if (!entry->cb_interest) {
···
  */
 void afs_put_cb_interest(struct afs_net *net, struct afs_cb_interest *cbi)
 {
+	struct afs_vol_interest *vi;
+
 	if (cbi && refcount_dec_and_test(&cbi->usage)) {
-		if (!list_empty(&cbi->cb_link)) {
+		if (!hlist_unhashed(&cbi->cb_vlink)) {
 			write_lock(&cbi->server->cb_break_lock);
-			list_del_init(&cbi->cb_link);
+
+			hlist_del_init(&cbi->cb_vlink);
+			vi = cbi->vol_interest;
+			cbi->vol_interest = NULL;
+			if (--vi->usage == 0)
+				hlist_del(&vi->srv_link);
+			else
+				vi = NULL;
+
 			write_unlock(&cbi->server->cb_break_lock);
+			kfree(vi);
 			afs_put_server(net, cbi->server);
 		}
 		kfree(cbi);
···
 static void afs_break_one_callback(struct afs_server *server,
 				   struct afs_fid *fid)
 {
+	struct afs_vol_interest *vi;
 	struct afs_cb_interest *cbi;
 	struct afs_iget_data data;
 	struct afs_vnode *vnode;
 	struct inode *inode;
 
 	read_lock(&server->cb_break_lock);
+	hlist_for_each_entry(vi, &server->cb_volumes, srv_link) {
+		if (vi->vid < fid->vid)
+			continue;
+		if (vi->vid > fid->vid) {
+			vi = NULL;
+			break;
+		}
+		//atomic_inc(&vi->usage);
+		break;
+	}
+
+	/* TODO: Find all matching volumes if we couldn't match the server and
+	 * break them anyway.
+	 */
+	if (!vi)
+		goto out;
 
 	/* Step through all interested superblocks.  There may be more than one
 	 * because of cell aliasing.
 	 */
-	list_for_each_entry(cbi, &server->cb_interests, cb_link) {
-		if (cbi->vid != fid->vid)
-			continue;
-
+	hlist_for_each_entry(cbi, &vi->cb_interests, cb_vlink) {
 		if (fid->vnode == 0 && fid->unique == 0) {
 			/* The callback break applies to an entire volume. */
 			struct afs_super_info *as = AFS_FS_S(cbi->sb);
···
 		}
 	}
 
+out:
 	read_unlock(&server->cb_break_lock);
 }
 

fs/afs/cell.c

···
 #include <linux/dns_resolver.h>
 #include <linux/sched.h>
 #include <linux/inet.h>
+#include <linux/namei.h>
 #include <keys/rxrpc-type.h>
 #include "internal.h"
 
···
 
 	/* install the new cell */
 	write_seqlock(&net->cells_lock);
-	old_root = net->ws_cell;
-	net->ws_cell = new_root;
+	old_root = rcu_access_pointer(net->ws_cell);
+	rcu_assign_pointer(net->ws_cell, new_root);
 	write_sequnlock(&net->cells_lock);
 
 	afs_put_cell(net, old_root);
···
 					     NULL, 0,
 					     cell, 0, true);
 #endif
-	ret = afs_proc_cell_setup(net, cell);
+	ret = afs_proc_cell_setup(cell);
 	if (ret < 0)
 		return ret;
-	spin_lock(&net->proc_cells_lock);
+
+	mutex_lock(&net->proc_cells_lock);
 	list_add_tail(&cell->proc_link, &net->proc_cells);
-	spin_unlock(&net->proc_cells_lock);
+	afs_dynroot_mkdir(net, cell);
+	mutex_unlock(&net->proc_cells_lock);
 	return 0;
 }
 
···
 {
 	_enter("%s", cell->name);
 
-	afs_proc_cell_remove(net, cell);
+	afs_proc_cell_remove(cell);
 
-	spin_lock(&net->proc_cells_lock);
+	mutex_lock(&net->proc_cells_lock);
 	list_del_init(&cell->proc_link);
-	spin_unlock(&net->proc_cells_lock);
+	afs_dynroot_rmdir(net, cell);
+	mutex_unlock(&net->proc_cells_lock);
 
 #ifdef CONFIG_AFS_FSCACHE
 	fscache_relinquish_cookie(cell->cache, NULL, false);
···
 	_enter("");
 
 	write_seqlock(&net->cells_lock);
-	ws = net->ws_cell;
-	net->ws_cell = NULL;
+	ws = rcu_access_pointer(net->ws_cell);
+	RCU_INIT_POINTER(net->ws_cell, NULL);
 	write_sequnlock(&net->cells_lock);
 	afs_put_cell(net, ws);
 

fs/afs/cmservice.c

···
 	nifs = 0;
 	ifs = kcalloc(32, sizeof(*ifs), GFP_KERNEL);
 	if (ifs) {
-		nifs = afs_get_ipv4_interfaces(ifs, 32, false);
+		nifs = afs_get_ipv4_interfaces(call->net, ifs, 32, false);
 		if (nifs < 0) {
 			kfree(ifs);
 			ifs = NULL;

fs/afs/dynroot.c

···
-/* dir.c: AFS dynamic root handling
+/* AFS dynamic root handling
  *
  * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells ([e-mail])
···
 		return 0;
 	}
 
-	ret = dns_query("afsdb", name, len, "ipv4", NULL, NULL);
+	ret = dns_query("afsdb", name, len, "", NULL, NULL);
 	if (ret == -ENODATA)
 		ret = -EDESTADDRREQ;
 	return ret;
···
 	.d_release	= afs_d_release,
 	.d_automount	= afs_d_automount,
 };
+
+/*
+ * Create a manually added cell mount directory.
+ * - The caller must hold net->proc_cells_lock
+ */
+int afs_dynroot_mkdir(struct afs_net *net, struct afs_cell *cell)
+{
+	struct super_block *sb = net->dynroot_sb;
+	struct dentry *root, *subdir;
+	int ret;
+
+	if (!sb || atomic_read(&sb->s_active) == 0)
+		return 0;
+
+	/* Let the ->lookup op do the creation */
+	root = sb->s_root;
+	inode_lock(root->d_inode);
+	subdir = lookup_one_len(cell->name, root, cell->name_len);
+	if (IS_ERR(subdir)) {
+		ret = PTR_ERR(subdir);
+		goto unlock;
+	}
+
+	/* Note that we're retaining an extra ref on the dentry */
+	subdir->d_fsdata = (void *)1UL;
+	ret = 0;
+unlock:
+	inode_unlock(root->d_inode);
+	return ret;
+}
+
+/*
+ * Remove a manually added cell mount directory.
+ * - The caller must hold net->proc_cells_lock
+ */
+void afs_dynroot_rmdir(struct afs_net *net, struct afs_cell *cell)
+{
+	struct super_block *sb = net->dynroot_sb;
+	struct dentry *root, *subdir;
+
+	if (!sb || atomic_read(&sb->s_active) == 0)
+		return;
+
+	root = sb->s_root;
+	inode_lock(root->d_inode);
+
+	/* Don't want to trigger a lookup call, which will re-add the cell */
+	subdir = try_lookup_one_len(cell->name, root, cell->name_len);
+	if (IS_ERR_OR_NULL(subdir)) {
+		_debug("lookup %ld", PTR_ERR(subdir));
+		goto no_dentry;
+	}
+
+	_debug("rmdir %pd %u", subdir, d_count(subdir));
+
+	if (subdir->d_fsdata) {
+		_debug("unpin %u", d_count(subdir));
+		subdir->d_fsdata = NULL;
+		dput(subdir);
+	}
+	dput(subdir);
+no_dentry:
+	inode_unlock(root->d_inode);
+	_leave("");
+}
+
+/*
+ * Populate a newly created dynamic root with cell names.
+ */
+int afs_dynroot_populate(struct super_block *sb)
+{
+	struct afs_cell *cell;
+	struct afs_net *net = afs_sb2net(sb);
+	int ret;
+
+	if (mutex_lock_interruptible(&net->proc_cells_lock) < 0)
+		return -ERESTARTSYS;
+
+	net->dynroot_sb = sb;
+	list_for_each_entry(cell, &net->proc_cells, proc_link) {
+		ret = afs_dynroot_mkdir(net, cell);
+		if (ret < 0)
+			goto error;
+	}
+
+	ret = 0;
+out:
+	mutex_unlock(&net->proc_cells_lock);
+	return ret;
+
+error:
+	net->dynroot_sb = NULL;
+	goto out;
+}
+
+/*
+ * When a dynamic root that's in the process of being destroyed, depopulate it
+ * of pinned directories.
+ */
+void afs_dynroot_depopulate(struct super_block *sb)
+{
+	struct afs_net *net = afs_sb2net(sb);
+	struct dentry *root = sb->s_root, *subdir, *tmp;
+
+	/* Prevent more subdirs from being created */
+	mutex_lock(&net->proc_cells_lock);
+	if (net->dynroot_sb == sb)
+		net->dynroot_sb = NULL;
+	mutex_unlock(&net->proc_cells_lock);
+
+	inode_lock(root->d_inode);
+
+	/* Remove all the pins for dirs created for manually added cells */
+	list_for_each_entry_safe(subdir, tmp, &root->d_subdirs, d_child) {
+		if (subdir->d_fsdata) {
+			subdir->d_fsdata = NULL;
+			dput(subdir);
+		}
+	}
+
+	inode_unlock(root->d_inode);
+}

fs/afs/fsclient.c

···
 	u64 data_version, size;
 	u32 type, abort_code;
 	u8 flags = 0;
-	int ret;
-
-	if (vnode)
-		write_seqlock(&vnode->cb_lock);
 
 	abort_code = ntohl(xdr->abort_code);
 
···
 			 * case.
 			 */
 			status->abort_code = abort_code;
-			ret = 0;
-			goto out;
+			return 0;
 		}
 
 		pr_warn("Unknown AFSFetchStatus version %u\n", ntohl(xdr->if_version));
···
 
 	if (abort_code != 0 && inline_error) {
 		status->abort_code = abort_code;
-		ret = 0;
-		goto out;
+		return 0;
 	}
 
 	type = ntohl(xdr->type);
···
 					     flags);
 	}
 
-	ret = 0;
-
-out:
-	if (vnode)
-		write_sequnlock(&vnode->cb_lock);
-	return ret;
+	return 0;
 
 bad:
 	xdr_dump_bad(*_bp);
-	ret = afs_protocol_error(call, -EBADMSG);
-	goto out;
+	return afs_protocol_error(call, -EBADMSG);
+}
+
+/*
+ * Decode the file status.  We need to lock the target vnode if we're going to
+ * update its status so that stat() sees the attributes update atomically.
+ */
+static int afs_decode_status(struct afs_call *call,
+			     const __be32 **_bp,
+			     struct afs_file_status *status,
+			     struct afs_vnode *vnode,
+			     const afs_dataversion_t *expected_version,
+			     struct afs_read *read_req)
+{
+	int ret;
+
+	if (!vnode)
+		return xdr_decode_AFSFetchStatus(call, _bp, status, vnode,
+						 expected_version, read_req);
+
+	write_seqlock(&vnode->cb_lock);
+	ret = xdr_decode_AFSFetchStatus(call, _bp, status, vnode,
+					expected_version, read_req);
+	write_sequnlock(&vnode->cb_lock);
+	return ret;
 }
 
 /*
···
 
 	/* unmarshall the reply once we've received all of it */
 	bp = call->buffer;
-	if (xdr_decode_AFSFetchStatus(call, &bp, &vnode->status, vnode,
-				      &call->expected_version, NULL) < 0)
+	if (afs_decode_status(call, &bp, &vnode->status, vnode,
+			      &call->expected_version, NULL) < 0)
 		return afs_protocol_error(call, -EBADMSG);
 	xdr_decode_AFSCallBack(call, vnode, &bp);
 	if (call->reply[1])
···
 			return ret;
 
 		bp = call->buffer;
-		if (xdr_decode_AFSFetchStatus(call, &bp, &vnode->status, vnode,
-					      &vnode->status.data_version, req) < 0)
+		if (afs_decode_status(call, &bp, &vnode->status, vnode,
+				      &vnode->status.data_version, req) < 0)
 			return afs_protocol_error(call, -EBADMSG);
 		xdr_decode_AFSCallBack(call, vnode, &bp);
 		if (call->reply[1])
···
 	/* unmarshall the reply once we've received all of it */
 	bp = call->buffer;
 	xdr_decode_AFSFid(&bp, call->reply[1]);
-	if (xdr_decode_AFSFetchStatus(call, &bp, call->reply[2], NULL, NULL, NULL) < 0 ||
-	    xdr_decode_AFSFetchStatus(call, &bp, &vnode->status, vnode,
-				      &call->expected_version, NULL) < 0)
+	if (afs_decode_status(call, &bp, call->reply[2], NULL, NULL, NULL) < 0 ||
+	    afs_decode_status(call, &bp, &vnode->status, vnode,
+			      &call->expected_version, NULL) < 0)
 		return afs_protocol_error(call, -EBADMSG);
 	xdr_decode_AFSCallBack_raw(&bp, call->reply[3]);
 	/* xdr_decode_AFSVolSync(&bp, call->reply[X]); */
···
 
 	/* unmarshall the reply once we've received all of it */
 	bp = call->buffer;
-	if (xdr_decode_AFSFetchStatus(call, &bp, &vnode->status, vnode,
-				      &call->expected_version, NULL) < 0)
+	if (afs_decode_status(call, &bp, &vnode->status, vnode,
+			      &call->expected_version, NULL) < 0)
 		return afs_protocol_error(call, -EBADMSG);
 	/* xdr_decode_AFSVolSync(&bp, call->reply[X]); */
 
···
 
 	/* unmarshall the reply once we've received all of it */
 	bp = call->buffer;
-	if (xdr_decode_AFSFetchStatus(call, &bp, &vnode->status, vnode, NULL, NULL) < 0 ||
-	    xdr_decode_AFSFetchStatus(call, &bp, &dvnode->status, dvnode,
-				      &call->expected_version, NULL) < 0)
+	if (afs_decode_status(call, &bp, &vnode->status, vnode, NULL, NULL) < 0 ||
+	    afs_decode_status(call, &bp, &dvnode->status, dvnode,
+			      &call->expected_version, NULL) < 0)
 		return afs_protocol_error(call, -EBADMSG);
 	/* xdr_decode_AFSVolSync(&bp, call->reply[X]); */
 
···
 	/* unmarshall the reply once we've received all of it */
 	bp = call->buffer;
 	xdr_decode_AFSFid(&bp, call->reply[1]);
-	if (xdr_decode_AFSFetchStatus(call, &bp, call->reply[2], NULL, NULL, NULL) ||
-	    xdr_decode_AFSFetchStatus(call, &bp, &vnode->status, vnode,
-				      &call->expected_version, NULL) < 0)
+	if (afs_decode_status(call, &bp, call->reply[2], NULL, NULL, NULL) ||
+	    afs_decode_status(call, &bp, &vnode->status, vnode,
+			      &call->expected_version, NULL) < 0)
 		return afs_protocol_error(call, -EBADMSG);
 	/* xdr_decode_AFSVolSync(&bp, call->reply[X]); */
 
···
 
 	/* unmarshall the reply once we've received all of it */
 	bp = call->buffer;
-	if (xdr_decode_AFSFetchStatus(call, &bp, &orig_dvnode->status, orig_dvnode,
-				      &call->expected_version, NULL) < 0)
+	if (afs_decode_status(call, &bp, &orig_dvnode->status, orig_dvnode,
+			      &call->expected_version, NULL) < 0)
 		return afs_protocol_error(call, -EBADMSG);
 	if (new_dvnode != orig_dvnode &&
-	    xdr_decode_AFSFetchStatus(call, &bp, &new_dvnode->status, new_dvnode,
-				      &call->expected_version_2, NULL) < 0)
+	    afs_decode_status(call, &bp, &new_dvnode->status, new_dvnode,
+			      &call->expected_version_2, NULL) < 0)
 		return afs_protocol_error(call, -EBADMSG);
 	/* xdr_decode_AFSVolSync(&bp, call->reply[X]); */
 
···
 
 	/* unmarshall the reply once we've received all of it */
 	bp = call->buffer;
-	if (xdr_decode_AFSFetchStatus(call, &bp, &vnode->status, vnode,
-				      &call->expected_version, NULL) < 0)
+	if (afs_decode_status(call, &bp, &vnode->status, vnode,
+			      &call->expected_version, NULL) < 0)
 		return afs_protocol_error(call, -EBADMSG);
 	/* xdr_decode_AFSVolSync(&bp, call->reply[X]); */
 
···
 
 	/* unmarshall the reply once we've received all of it */
 	bp = call->buffer;
-	if (xdr_decode_AFSFetchStatus(call, &bp, &vnode->status, vnode,
-				      &call->expected_version, NULL) < 0)
+	if (afs_decode_status(call, &bp, &vnode->status, vnode,
+			      &call->expected_version, NULL) < 0)
 		return afs_protocol_error(call, -EBADMSG);
 	/* xdr_decode_AFSVolSync(&bp, call->reply[X]); */
 
···
 
 	/* unmarshall the reply once we've received all of it */
 	bp = call->buffer;
-	xdr_decode_AFSFetchStatus(call, &bp, status, vnode,
-				  &call->expected_version, NULL);
+	afs_decode_status(call, &bp, status, vnode,
+			  &call->expected_version, NULL);
 	callback[call->count].version	= ntohl(bp[0]);
 	callback[call->count].expiry	= ntohl(bp[1]);
 	callback[call->count].type	= ntohl(bp[2]);
···
 
 		bp = call->buffer;
 		statuses = call->reply[1];
-		if (xdr_decode_AFSFetchStatus(call, &bp, &statuses[call->count],
-					      call->count == 0 ? vnode : NULL,
-					      NULL, NULL) < 0)
+		if (afs_decode_status(call, &bp, &statuses[call->count],
+				      call->count == 0 ? vnode : NULL,
+				      NULL, NULL) < 0)
 			return afs_protocol_error(call, -EBADMSG);
 
 		call->count++;

fs/afs/internal.h

···
 #include <linux/backing-dev.h>
 #include <linux/uuid.h>
 #include <net/net_namespace.h>
+#include <net/netns/generic.h>
+#include <net/sock.h>
 #include <net/af_rxrpc.h>
 
 #include "afs.h"
···
 	afs_voltype_t		type;		/* type of volume requested */
 	int			volnamesz;	/* size of volume name */
 	const char		*volname;	/* name of volume to mount */
-	struct afs_net		*net;		/* Network namespace in effect */
+	struct net		*net_ns;	/* Network namespace in effect */
+	struct afs_net		*net;		/* the AFS net namespace stuff */
 	struct afs_cell		*cell;		/* cell in which to find volume */
 	struct afs_volume	*volume;	/* volume record */
 	struct key		*key;		/* key to use for secure mounting */
···
  * - there's one superblock per volume
  */
 struct afs_super_info {
-	struct afs_net		*net;		/* Network namespace */
+	struct net		*net_ns;	/* Network namespace */
 	struct afs_cell		*cell;		/* The cell in which the volume resides */
 	struct afs_volume	*volume;	/* volume record */
 	bool			dyn_root;	/* True if dynamic root */
···
 	char			*subs[AFS_NR_SYSNAME];
 	refcount_t		usage;
 	unsigned short		nr;
-	short			error;
 	char			blank[1];
 };
 
···
  * AFS network namespace record.
  */
 struct afs_net {
+	struct net		*net;		/* Backpointer to the owning net namespace */
 	struct afs_uuid		uuid;
 	bool			live;		/* F if this namespace is being removed */
 
···
 
 	/* Cell database */
 	struct rb_root		cells;
-	struct afs_cell		*ws_cell;
+	struct afs_cell __rcu	*ws_cell;
 	struct work_struct	cells_manager;
 	struct timer_list	cells_timer;
 	atomic_t		cells_outstanding;
 	seqlock_t		cells_lock;
 
-	spinlock_t		proc_cells_lock;
+	struct mutex		proc_cells_lock;
 	struct list_head	proc_cells;
 
 	/* Known servers.  Theoretically each fileserver can only be in one
···
 	struct mutex		lock_manager_mutex;
 
 	/* Misc */
+	struct super_block	*dynroot_sb;	/* Dynamic root mount superblock */
 	struct proc_dir_entry	*proc_afs;	/* /proc/net/afs directory */
 	struct afs_sysnames	*sysnames;
 	rwlock_t		sysnames_lock;
···
 };
 
 extern const char afs_init_sysname[];
-extern struct afs_net __afs_net;// Dummy AFS network namespace; TODO: replace with real netns
 
 enum afs_cell_state {
 	AFS_CELL_UNSET,
···
 	rwlock_t		fs_lock;	/* access lock */
 
 	/* callback promise management */
-	struct list_head	cb_interests;	/* List of superblocks using this server */
+	struct hlist_head	cb_volumes;	/* List of volume interests on this server */
 	unsigned		cb_s_break;	/* Break-everything counter. */
 	rwlock_t		cb_break_lock;	/* Volume finding lock */
+};
+
+/*
+ * Volume collation in the server's callback interest list.
+ */
+struct afs_vol_interest {
+	struct hlist_node	srv_link;	/* Link in server->cb_volumes */
+	struct hlist_head	cb_interests;	/* List of callback interests on the server */
+	afs_volid_t		vid;		/* Volume ID to match */
+	unsigned int		usage;
 };
 
 /*
  * Interest by a superblock on a server.
  */
 struct afs_cb_interest {
-	struct list_head	cb_link;	/* Link in server->cb_interests */
+	struct hlist_node	cb_vlink;	/* Link in vol_interest->cb_interests */
+	struct afs_vol_interest	*vol_interest;
 	struct afs_server	*server;	/* Server on which this interest resides */
 	struct super_block	*sb;		/* Superblock on which inodes reside */
 	afs_volid_t		vid;		/* Volume ID to match */
···
 extern const struct dentry_operations afs_dynroot_dentry_operations;
 
 extern struct inode *afs_try_auto_mntpt(struct dentry *, struct inode *);
+extern int afs_dynroot_mkdir(struct afs_net *, struct afs_cell *);
+extern void afs_dynroot_rmdir(struct afs_net *, struct afs_cell *);
+extern int afs_dynroot_populate(struct super_block *);
+extern void afs_dynroot_depopulate(struct super_block *);
 
 /*
  * file.c
···
  * main.c
  */
 extern struct workqueue_struct *afs_wq;
+extern int afs_net_id;
+
+static inline struct afs_net *afs_net(struct net *net)
+{
+	return net_generic(net, afs_net_id);
+}
+
+static inline struct afs_net *afs_sb2net(struct super_block *sb)
+{
+	return afs_net(AFS_FS_S(sb)->net_ns);
+}
 
 static inline struct afs_net *afs_d2net(struct dentry *dentry)
 {
-	return &__afs_net;
+	return afs_sb2net(dentry->d_sb);
 }
 
 static inline struct afs_net *afs_i2net(struct inode *inode)
 {
-	return &__afs_net;
+	return afs_sb2net(inode->i_sb);
 }
 
 static inline struct afs_net *afs_v2net(struct afs_vnode *vnode)
 {
-	return &__afs_net;
+	return afs_i2net(&vnode->vfs_inode);
 }
 
 static inline struct afs_net *afs_sock2net(struct sock *sk)
 {
-	return &__afs_net;
-}
-
-static inline struct afs_net *afs_get_net(struct afs_net *net)
-{
-	return net;
-}
-
-static inline void afs_put_net(struct afs_net *net)
-{
+	return net_generic(sock_net(sk), afs_net_id);
 }
 
 static inline void __afs_stat(atomic_t *s)
···
 /*
  * netdevices.c
  */
-extern int afs_get_ipv4_interfaces(struct afs_interface *, size_t, bool);
+extern int afs_get_ipv4_interfaces(struct afs_net *, struct afs_interface *,
+				   size_t, bool);
 
 /*
  * proc.c
  */
+#ifdef CONFIG_PROC_FS
 extern int __net_init afs_proc_init(struct afs_net *);
 extern void __net_exit afs_proc_cleanup(struct afs_net *);
-extern int afs_proc_cell_setup(struct afs_net *, struct afs_cell *);
-extern void afs_proc_cell_remove(struct afs_net *, struct afs_cell *);
+extern int afs_proc_cell_setup(struct afs_cell *);
+extern void afs_proc_cell_remove(struct afs_cell *);
 extern void afs_put_sysnames(struct afs_sysnames *);
+#else
+static inline int afs_proc_init(struct afs_net *net) { return 0; }
+static inline void afs_proc_cleanup(struct afs_net *net) {}
+static inline int afs_proc_cell_setup(struct afs_cell *cell) { return 0; }
+static inline void afs_proc_cell_remove(struct afs_cell *cell) {}
+static inline void afs_put_sysnames(struct afs_sysnames *sysnames) {}
+#endif
 
 /*
  * rotate.c
···
  * super.c
  */
 extern int __init afs_fs_init(void);
-extern void __exit afs_fs_exit(void);
+extern void afs_fs_exit(void);
 
 /*
  * vlclient.c

fs/afs/main.c

···
 #include <linux/completion.h>
 #include <linux/sched.h>
 #include <linux/random.h>
+#include <linux/proc_fs.h>
 #define CREATE_TRACE_POINTS
 #include "internal.h"
 
···
 MODULE_PARM_DESC(rootcell, "root AFS cell name and VL server IP addr list");
 
 struct workqueue_struct *afs_wq;
-struct afs_net __afs_net;
+static struct proc_dir_entry *afs_proc_symlink;
 
 #if defined(CONFIG_ALPHA)
 const char afs_init_sysname[] = "alpha_linux26";
···
 /*
  * Initialise an AFS network namespace record.
  */
-static int __net_init afs_net_init(struct afs_net *net)
+static int __net_init afs_net_init(struct net *net_ns)
 {
 	struct afs_sysnames *sysnames;
+	struct afs_net *net = afs_net(net_ns);
 	int ret;
 
+	net->net = net_ns;
 	net->live = true;
 	generate_random_uuid((unsigned char *)&net->uuid);
 
···
 	INIT_WORK(&net->cells_manager, afs_manage_cells);
 	timer_setup(&net->cells_timer, afs_cells_timer, 0);
 
-	spin_lock_init(&net->proc_cells_lock);
+	mutex_init(&net->proc_cells_lock);
 	INIT_LIST_HEAD(&net->proc_cells);
 
 	seqlock_init(&net->fs_lock);
···
 /*
  * Clean up and destroy an AFS network namespace record.
  */
-static void __net_exit afs_net_exit(struct afs_net *net)
+static void __net_exit afs_net_exit(struct net *net_ns)
 {
+	struct afs_net *net = afs_net(net_ns);
+
 	net->live = false;
 	afs_cell_purge(net);
 	afs_purge_servers(net);
···
 	afs_proc_cleanup(net);
 	afs_put_sysnames(net->sysnames);
 }
+
+static struct pernet_operations afs_net_ops = {
+	.init	= afs_net_init,
+	.exit	= afs_net_exit,
+	.id	= &afs_net_id,
+	.size	= sizeof(struct afs_net),
+};
 
 /*
  * initialise the AFS client FS module
···
 		goto error_cache;
 #endif
 
-	ret = afs_net_init(&__afs_net);
+	ret = register_pernet_subsys(&afs_net_ops);
 	if (ret < 0)
 		goto error_net;
 
···
 	if (ret < 0)
 		goto error_fs;
 
+	afs_proc_symlink = proc_symlink("fs/afs", NULL, "../self/net/afs");
+	if (IS_ERR(afs_proc_symlink)) {
+		ret = PTR_ERR(afs_proc_symlink);
+		goto error_proc;
+	}
+
 	return ret;
 
+error_proc:
+	afs_fs_exit();
 error_fs:
-	afs_net_exit(&__afs_net);
+	unregister_pernet_subsys(&afs_net_ops);
 error_net:
 #ifdef CONFIG_AFS_FSCACHE
 	fscache_unregister_netfs(&afs_cache_netfs);
···
 {
 	printk(KERN_INFO "kAFS: Red Hat AFS client v0.1 unregistering.\n");
 
+	proc_remove(afs_proc_symlink);
 	afs_fs_exit();
-	afs_net_exit(&__afs_net);
+	unregister_pernet_subsys(&afs_net_ops);
 #ifdef CONFIG_AFS_FSCACHE
 	fscache_unregister_netfs(&afs_cache_netfs);
 #endif

fs/afs/netdevices.c

···
  * - maxbufs must be at least 1
  * - returns the number of interface records in the buffer
  */
-int afs_get_ipv4_interfaces(struct afs_interface *bufs, size_t maxbufs,
-			    bool wantloopback)
+int afs_get_ipv4_interfaces(struct afs_net *net, struct afs_interface *bufs,
+			    size_t maxbufs, bool wantloopback)
 {
 	struct net_device *dev;
 	struct in_device *idev;
···
 	ASSERT(maxbufs > 0);
 
 	rtnl_lock();
-	for_each_netdev(&init_net, dev) {
+	for_each_netdev(net->net, dev) {
 		if (dev->type == ARPHRD_LOOPBACK && !wantloopback)
 			continue;
 		idev = __in_dev_get_rtnl(dev);

fs/afs/proc.c

···
 #include <linux/uaccess.h>
 #include "internal.h"
 
-static inline struct afs_net *afs_proc2net(struct file *f)
-{
-	return &__afs_net;
-}
-
 static inline struct afs_net *afs_seq2net(struct seq_file *m)
 {
-	return &__afs_net; // TODO: use seq_file_net(m)
+	return afs_net(seq_file_net(m));
 }
 
-static int afs_proc_cells_open(struct inode *inode, struct file *file);
-static void *afs_proc_cells_start(struct seq_file *p, loff_t *pos);
-static void *afs_proc_cells_next(struct seq_file *p, void *v, loff_t *pos);
-static void afs_proc_cells_stop(struct seq_file *p, void *v);
-static int afs_proc_cells_show(struct seq_file *m, void *v);
-static ssize_t afs_proc_cells_write(struct file *file, const char __user *buf,
-				    size_t size, loff_t *_pos);
-
-static const struct seq_operations afs_proc_cells_ops = {
-	.start	= afs_proc_cells_start,
-	.next	= afs_proc_cells_next,
-	.stop	= afs_proc_cells_stop,
-	.show	= afs_proc_cells_show,
-};
-
-static const struct file_operations afs_proc_cells_fops = {
-	.open		= afs_proc_cells_open,
-	.read		= seq_read,
-	.write		= afs_proc_cells_write,
-	.llseek		= seq_lseek,
-	.release	= seq_release,
-};
-
-static ssize_t afs_proc_rootcell_read(struct file *file, char __user *buf,
-				      size_t size, loff_t *_pos);
-static ssize_t afs_proc_rootcell_write(struct file *file,
-				       const char __user *buf,
-				       size_t size, loff_t *_pos);
-
-static const struct file_operations afs_proc_rootcell_fops = {
-	.read		= afs_proc_rootcell_read,
-	.write		= afs_proc_rootcell_write,
-	.llseek		= no_llseek,
-};
-
-static void *afs_proc_cell_volumes_start(struct seq_file *p, loff_t *pos);
-static void *afs_proc_cell_volumes_next(struct seq_file *p, void *v,
-					loff_t *pos);
-static void afs_proc_cell_volumes_stop(struct seq_file *p, void *v);
-static int afs_proc_cell_volumes_show(struct seq_file *m, void *v);
-
-static const struct seq_operations afs_proc_cell_volumes_ops = {
-	.start	= afs_proc_cell_volumes_start,
-	.next	= afs_proc_cell_volumes_next,
-	.stop	= afs_proc_cell_volumes_stop,
-	.show	= afs_proc_cell_volumes_show,
-};
-
-static void *afs_proc_cell_vlservers_start(struct seq_file *p, loff_t *pos);
-static void *afs_proc_cell_vlservers_next(struct seq_file *p, void *v,
-					  loff_t *pos);
-static void afs_proc_cell_vlservers_stop(struct seq_file *p, void *v);
-static int afs_proc_cell_vlservers_show(struct seq_file *m, void *v);
-
-static const struct seq_operations afs_proc_cell_vlservers_ops = {
-	.start	= afs_proc_cell_vlservers_start,
-	.next	= afs_proc_cell_vlservers_next,
-	.stop	= afs_proc_cell_vlservers_stop,
-	.show	= afs_proc_cell_vlservers_show,
-};
-
-static void *afs_proc_servers_start(struct seq_file *p, loff_t *pos);
-static void *afs_proc_servers_next(struct seq_file *p, void *v,
-					loff_t *pos);
-static void afs_proc_servers_stop(struct seq_file *p, void *v);
-static int afs_proc_servers_show(struct seq_file *m, void *v);
-
-static const struct seq_operations afs_proc_servers_ops = {
-	.start	= afs_proc_servers_start,
-	.next	= afs_proc_servers_next,
-	.stop	= afs_proc_servers_stop,
-	.show	= afs_proc_servers_show,
-};
-
-static int afs_proc_sysname_open(struct inode *inode, struct file *file);
-static int afs_proc_sysname_release(struct inode *inode, struct file *file);
-static void *afs_proc_sysname_start(struct seq_file *p, loff_t *pos);
-static void *afs_proc_sysname_next(struct seq_file *p, void *v,
-					loff_t *pos);
-static void afs_proc_sysname_stop(struct seq_file *p, void *v);
-static int afs_proc_sysname_show(struct seq_file *m, void *v);
-static ssize_t afs_proc_sysname_write(struct file *file,
-				      const char __user *buf,
-				      size_t size, loff_t *_pos);
-
-static const struct seq_operations afs_proc_sysname_ops = {
-	.start	= afs_proc_sysname_start,
-	.next	= afs_proc_sysname_next,
-	.stop	= afs_proc_sysname_stop,
-	.show	= afs_proc_sysname_show,
-};
-
-static const struct file_operations afs_proc_sysname_fops = {
-	.open		= afs_proc_sysname_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= afs_proc_sysname_release,
-	.write		= afs_proc_sysname_write,
-};
-
-static int afs_proc_stats_show(struct seq_file *m, void *v);
-
-/*
- * initialise the /proc/fs/afs/ directory
- */
-int afs_proc_init(struct afs_net *net)
+static inline struct afs_net *afs_seq2net_single(struct seq_file *m)
 {
-	_enter("");
-
-	net->proc_afs = proc_mkdir("fs/afs", NULL);
-	if (!net->proc_afs)
-		goto error_dir;
-
-	if (!proc_create("cells", 0644, net->proc_afs, &afs_proc_cells_fops) ||
-	    !proc_create("rootcell", 0644, net->proc_afs, &afs_proc_rootcell_fops) ||
-	    !proc_create_seq("servers", 0644, net->proc_afs, &afs_proc_servers_ops) ||
-	    !proc_create_single("stats", 0644, net->proc_afs, afs_proc_stats_show) ||
-	    !proc_create("sysname", 0644, net->proc_afs, &afs_proc_sysname_fops))
-		goto error_tree;
-
-	_leave(" = 0");
-	return 0;
-
-error_tree:
-	proc_remove(net->proc_afs);
-error_dir:
-	_leave(" = -ENOMEM");
-	return -ENOMEM;
+	return afs_net(seq_file_single_net(m));
 }
 
 /*
- * clean up the /proc/fs/afs/ directory
- */
-void afs_proc_cleanup(struct afs_net *net)
-{
-	proc_remove(net->proc_afs);
-	net->proc_afs = NULL;
-}
-
-/*
- * open "/proc/fs/afs/cells" which provides a summary of extant cells
- */
-static int afs_proc_cells_open(struct inode *inode, struct file *file)
-{
-	return seq_open(file, &afs_proc_cells_ops);
-}
-
-/*
- * set up the iterator to start reading from the cells list and return the
- * first item
- */
-static void *afs_proc_cells_start(struct seq_file *m, loff_t *_pos)
-	__acquires(rcu)
-{
-	struct afs_net *net = afs_seq2net(m);
-
-	rcu_read_lock();
-	return seq_list_start_head(&net->proc_cells, *_pos);
-}
-
-/*
- * move to next cell in cells list
- */
-static void *afs_proc_cells_next(struct seq_file *m, void *v, loff_t *pos)
-{
-	struct afs_net *net = afs_seq2net(m);
-
-	return seq_list_next(v, &net->proc_cells, pos);
-}
-
-/*
- * clean up after reading from the cells list
- */
-static void afs_proc_cells_stop(struct seq_file *m, void *v)
-	__releases(rcu)
-{
-	rcu_read_unlock();
-}
-
-/*
- * display a header line followed by a load of cell lines
+ * Display the list of cells known to the namespace.
  */
 static int afs_proc_cells_show(struct seq_file *m, void *v)
 {
···
 	return 0;
 }
 
+static void *afs_proc_cells_start(struct seq_file *m, loff_t *_pos)
+	__acquires(rcu)
+{
+	rcu_read_lock();
+	return seq_list_start_head(&afs_seq2net(m)->proc_cells, *_pos);
+}
+
+static void *afs_proc_cells_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	return seq_list_next(v, &afs_seq2net(m)->proc_cells, pos);
+}
+
+static void afs_proc_cells_stop(struct seq_file *m, void *v)
+	__releases(rcu)
+{
+	rcu_read_unlock();
+}
+
+static const struct seq_operations afs_proc_cells_ops = {
+	.start	= afs_proc_cells_start,
+	.next	= afs_proc_cells_next,
+	.stop	= afs_proc_cells_stop,
+	.show	= afs_proc_cells_show,
+};
+
 /*
  * handle writes to /proc/fs/afs/cells
  * - to add cells: echo "add <cellname> <IP>[:<IP>][:<IP>]"
  */
-static ssize_t afs_proc_cells_write(struct file *file, const char __user *buf,
-				    size_t size, loff_t *_pos)
+static int afs_proc_cells_write(struct file *file, char *buf, size_t size)
 {
-	struct afs_net *net = afs_proc2net(file);
-	char *kbuf, *name, *args;
+	struct seq_file *m = file->private_data;
+	struct afs_net *net = afs_seq2net(m);
+	char *name, *args;
 	int ret;
 
-	/* start by dragging the command into memory */
-	if (size <= 1 || size >= PAGE_SIZE)
-		return -EINVAL;
-
-	kbuf = memdup_user_nul(buf, size);
-	if (IS_ERR(kbuf))
-		return PTR_ERR(kbuf);
-
 	/* trim to first NL */
-	name = memchr(kbuf, '\n', size);
+	name = memchr(buf, '\n', size);
 	if (name)
 		*name = 0;
 
 	/* split into command, name and argslist */
-	name = strchr(kbuf, ' ');
+	name = strchr(buf, ' ');
 	if (!name)
 		goto inval;
 	do {
···
 		goto inval;
 
 	/* determine command to perform */
-	_debug("cmd=%s name=%s args=%s", kbuf, name, args);
+	_debug("cmd=%s name=%s args=%s", buf, name, args);
 
-	if (strcmp(kbuf, "add") == 0) {
+	if (strcmp(buf, "add") == 0) {
 		struct afs_cell *cell;
 
 		cell = afs_lookup_cell(net, name, strlen(name), args, true);
···
 		goto inval;
 	}
 
-	ret = size;
+	ret = 0;
 
 done:
-	kfree(kbuf);
 	_leave(" = %d", ret);
 	return ret;
 
···
 	goto done;
 }
 
-static ssize_t afs_proc_rootcell_read(struct file *file, char __user *buf,
-				      size_t size, loff_t *_pos)
+/*
+ * Display the name of the current workstation cell.
+ */
+static int afs_proc_rootcell_show(struct seq_file *m, void *v)
 {
 	struct afs_cell *cell;
-	struct afs_net *net = afs_proc2net(file);
-	unsigned int seq = 0;
-	char name[AFS_MAXCELLNAME + 1];
-	int len;
+	struct afs_net *net;
 
-	if (*_pos > 0)
-		return 0;
-	if (!net->ws_cell)
-		return 0;
-
-	rcu_read_lock();
-	do {
-		read_seqbegin_or_lock(&net->cells_lock, &seq);
-		len = 0;
-		cell = rcu_dereference_raw(net->ws_cell);
-		if (cell) {
-			len = cell->name_len;
-			memcpy(name, cell->name, len);
-		}
-	} while (need_seqretry(&net->cells_lock, seq));
-	done_seqretry(&net->cells_lock, seq);
-	rcu_read_unlock();
-
-	if (!len)
-		return 0;
-
-	name[len++] = '\n';
-	if (len > size)
-		len = size;
-	if (copy_to_user(buf, name, len) != 0)
-		return -EFAULT;
-	*_pos = 1;
-	return len;
+	net = afs_seq2net_single(m);
+	if (rcu_access_pointer(net->ws_cell)) {
+		rcu_read_lock();
+		cell = rcu_dereference(net->ws_cell);
+		if (cell)
+			seq_printf(m, "%s\n", cell->name);
+		rcu_read_unlock();
+	}
+	return 0;
 }
 
 /*
- * handle writes to /proc/fs/afs/rootcell
- * - to initialize rootcell: echo "cell.name:192.168.231.14"
+ * Set the current workstation cell and optionally supply its list of volume
+ * location servers.
+ *
+ *	echo "cell.name:192.168.231.14" >/proc/fs/afs/rootcell
  */
-static ssize_t afs_proc_rootcell_write(struct file *file,
-				       const char __user *buf,
-				       size_t size, loff_t *_pos)
+static int afs_proc_rootcell_write(struct file *file, char *buf, size_t size)
 {
-	struct afs_net *net = afs_proc2net(file);
-	char *kbuf, *s;
+	struct seq_file *m = file->private_data;
+	struct afs_net *net = afs_seq2net_single(m);
+	char *s;
 	int ret;
 
-	/* start by dragging the command into memory */
-	if (size <= 1 || size >= PAGE_SIZE)
-		return -EINVAL;
-
-	kbuf = memdup_user_nul(buf, size);
-	if (IS_ERR(kbuf))
-		return PTR_ERR(kbuf);
-
 	ret = -EINVAL;
-	if (kbuf[0] == '.')
+	if (buf[0] == '.')
 		goto out;
-	if (memchr(kbuf, '/', size))
+	if (memchr(buf, '/', size))
 		goto out;
 
 	/* trim to first NL */
-	s = memchr(kbuf, '\n', size);
+	s = memchr(buf, '\n', size);
 	if (s)
 		*s = 0;
 
 	/* determine command to perform */
-	_debug("rootcell=%s", kbuf);
+	_debug("rootcell=%s", buf);
 
-	ret = afs_cell_init(net, kbuf);
-	if (ret >= 0)
-		ret = size;	/* consume everything, always */
+	ret = afs_cell_init(net, buf);
 
 out:
-	kfree(kbuf);
 	_leave(" = %d", ret);
 	return ret;
-}
-
-/*
- * initialise /proc/fs/afs/<cell>/
- */
-int afs_proc_cell_setup(struct afs_net *net, struct afs_cell *cell)
-{
-	struct proc_dir_entry *dir;
-
-	_enter("%p{%s},%p", cell, cell->name, net->proc_afs);
-
-	dir = proc_mkdir(cell->name, net->proc_afs);
-	if (!dir)
-		goto error_dir;
-
-	if (!proc_create_seq_data("vlservers", 0, dir,
-			&afs_proc_cell_vlservers_ops, cell))
-		goto error_tree;
-	if (!proc_create_seq_data("volumes", 0, dir, &afs_proc_cell_volumes_ops,
-			cell))
-		goto error_tree;
-
-	_leave(" = 0");
-	return 0;
-
-error_tree:
-	remove_proc_subtree(cell->name, net->proc_afs);
-error_dir:
-	_leave(" = -ENOMEM");
-	return -ENOMEM;
-}
-
-/*
- * remove /proc/fs/afs/<cell>/
- */
-void afs_proc_cell_remove(struct afs_net *net, struct afs_cell *cell)
-{
-	_enter("");
-
-	remove_proc_subtree(cell->name, net->proc_afs);
-
-	_leave("");
-}
-
-/*
- * set up the iterator to start reading from the cells list and return the
- * first item
- */
-static void *afs_proc_cell_volumes_start(struct seq_file *m, loff_t *_pos)
-	__acquires(cell->proc_lock)
-{
-	struct afs_cell *cell = PDE_DATA(file_inode(m->file));
-
-	_enter("cell=%p pos=%Ld", cell, *_pos);
-
-	read_lock(&cell->proc_lock);
-	return seq_list_start_head(&cell->proc_volumes, *_pos);
-}
-
-/*
- * move to next cell in cells list
- */
-static void *afs_proc_cell_volumes_next(struct seq_file *p, void *v,
-					loff_t *_pos)
-{
-	struct afs_cell *cell = PDE_DATA(file_inode(p->file));
-
-	_enter("cell=%p pos=%Ld", cell, *_pos);
-	return seq_list_next(v, &cell->proc_volumes, _pos);
-}
-
-/*
- * clean up after reading from the cells list
- */
-static void afs_proc_cell_volumes_stop(struct seq_file *p, void *v)
-	__releases(cell->proc_lock)
-{
-	struct afs_cell *cell = PDE_DATA(file_inode(p->file));
-
-	read_unlock(&cell->proc_lock);
 }
 
 static const char afs_vol_types[3][3] = {
···
 };
 
 /*
- * display a header line followed by a load of volume lines
+ * Display the list of volumes known to a cell.
  */
 static int afs_proc_cell_volumes_show(struct seq_file *m, void *v)
 {
···
 	return 0;
 }
 
+static void *afs_proc_cell_volumes_start(struct seq_file *m, loff_t *_pos)
+	__acquires(cell->proc_lock)
+{
+	struct afs_cell *cell = PDE_DATA(file_inode(m->file));
+
+	read_lock(&cell->proc_lock);
+	return seq_list_start_head(&cell->proc_volumes, *_pos);
+}
+
+static void *afs_proc_cell_volumes_next(struct seq_file *m, void *v,
+					loff_t *_pos)
+{
+	struct afs_cell *cell = PDE_DATA(file_inode(m->file));
+
+	return seq_list_next(v, &cell->proc_volumes, _pos);
+}
+
+static void afs_proc_cell_volumes_stop(struct seq_file *m, void *v)
+	__releases(cell->proc_lock)
+{
+	struct afs_cell *cell = PDE_DATA(file_inode(m->file));
+
+	read_unlock(&cell->proc_lock);
+}
+
+static const struct seq_operations afs_proc_cell_volumes_ops = {
+	.start	= afs_proc_cell_volumes_start,
+	.next	= afs_proc_cell_volumes_next,
+	.stop	= afs_proc_cell_volumes_stop,
+	.show	= afs_proc_cell_volumes_show,
+};
+
 /*
- * set up the iterator to start reading from the cells list and return the
- * first item
+ * Display the list of Volume Location servers we're using for a cell.
  */
+static int afs_proc_cell_vlservers_show(struct seq_file *m, void *v)
+{
+	struct sockaddr_rxrpc *addr = v;
+
+	/* display header on line 1 */
+	if (v == (void *)1) {
+		seq_puts(m, "ADDRESS\n");
+		return 0;
+	}
+
+	/* display one cell per line on subsequent lines */
+	seq_printf(m, "%pISp\n", &addr->transport);
+	return 0;
+}
+
 static void *afs_proc_cell_vlservers_start(struct seq_file *m, loff_t *_pos)
 	__acquires(rcu)
 {
···
 	return alist->addrs + pos;
 }
 
-/*
- * move to next cell in cells list
- */
-static void *afs_proc_cell_vlservers_next(struct seq_file *p, void *v,
+static void *afs_proc_cell_vlservers_next(struct seq_file *m, void *v,
 					  loff_t *_pos)
 {
 	struct afs_addr_list *alist;
-	struct afs_cell *cell = PDE_DATA(file_inode(p->file));
+	struct afs_cell *cell = PDE_DATA(file_inode(m->file));
 	loff_t pos;
 
 	alist = rcu_dereference(cell->vl_addrs);
···
 	return alist->addrs + pos;
 }
 
-/*
- * clean up after reading from the cells list
- */
-static void afs_proc_cell_vlservers_stop(struct seq_file *p, void *v)
+static void afs_proc_cell_vlservers_stop(struct seq_file *m, void *v)
 	__releases(rcu)
 {
 	rcu_read_unlock();
 }
 
-/*
- * display a header line followed by a load of volume lines
- */
-static int afs_proc_cell_vlservers_show(struct seq_file *m, void *v)
-{
-	struct sockaddr_rxrpc *addr = v;
-
-	/* display header on line 1 */
-	if (v == (void *)1) {
-		seq_puts(m, "ADDRESS\n");
-		return 0;
-	}
-
-	/* display one cell per line on subsequent lines */
-	seq_printf(m, "%pISp\n", &addr->transport);
-	return 0;
-}
+static const struct seq_operations afs_proc_cell_vlservers_ops = {
+	.start	= afs_proc_cell_vlservers_start,
+	.next	= afs_proc_cell_vlservers_next,
+	.stop	= afs_proc_cell_vlservers_stop,
+	.show	= afs_proc_cell_vlservers_show,
+};
 
 /*
- * Set up the iterator to start reading from the server list and return the
- * first item.
- */
-static void *afs_proc_servers_start(struct seq_file *m, loff_t *_pos)
-	__acquires(rcu)
-{
-	struct afs_net *net = afs_seq2net(m);
-
-	rcu_read_lock();
-	return seq_hlist_start_head_rcu(&net->fs_proc, *_pos);
-}
-
-/*
- * move to next cell in cells list
- */
-static void *afs_proc_servers_next(struct seq_file *m, void *v, loff_t *_pos)
-{
-	struct afs_net *net = afs_seq2net(m);
-
-	return seq_hlist_next_rcu(v, &net->fs_proc, _pos);
-}
-
-/*
- * clean up after reading from the cells list
- */
-static void afs_proc_servers_stop(struct seq_file *p, void *v)
-	__releases(rcu)
-{
-	rcu_read_unlock();
-}
-
-/*
- * display a header line followed by a load of volume lines
+ * Display the list of fileservers we're using within a namespace.
  */
 static int afs_proc_servers_show(struct seq_file *m, void *v)
 {
 	struct afs_server *server;
 	struct afs_addr_list *alist;
+	int i;
 
 	if (v == SEQ_START_TOKEN) {
 		seq_puts(m, "UUID                                 USE ADDR\n");
···
 
 	server = list_entry(v, struct afs_server, proc_link);
 	alist = rcu_dereference(server->addresses);
-	seq_printf(m, "%pU %3d %pISp\n",
+	seq_printf(m, "%pU %3d %pISpc%s\n",
 		   &server->uuid,
 		   atomic_read(&server->usage),
-		   &alist->addrs[alist->index].transport);
+		   &alist->addrs[0].transport,
+		   alist->index == 0 ? "*" : "");
+	for (i = 1; i < alist->nr_addrs; i++)
+		seq_printf(m, "                                         %pISpc%s\n",
+			   &alist->addrs[i].transport,
+			   alist->index == i ? "*" : "");
 	return 0;
 }
 
-void afs_put_sysnames(struct afs_sysnames *sysnames)
+static void *afs_proc_servers_start(struct seq_file *m, loff_t *_pos)
+	__acquires(rcu)
 {
-	int i;
-
-	if (sysnames && refcount_dec_and_test(&sysnames->usage)) {
-		for (i = 0; i < sysnames->nr; i++)
-			if (sysnames->subs[i] != afs_init_sysname &&
-			    sysnames->subs[i] != sysnames->blank)
-				kfree(sysnames->subs[i]);
-	}
+	rcu_read_lock();
+	return seq_hlist_start_head_rcu(&afs_seq2net(m)->fs_proc, *_pos);
 }
 
-/*
- * Handle opening of /proc/fs/afs/sysname.  If it is opened for writing, we
- * assume the caller wants to change the substitution list and we allocate a
- * buffer to hold the list.
- */
-static int afs_proc_sysname_open(struct inode *inode, struct file *file)
+static void *afs_proc_servers_next(struct seq_file *m, void *v, loff_t *_pos)
 {
-	struct afs_sysnames *sysnames;
-	struct seq_file *m;
-	int ret;
+	return seq_hlist_next_rcu(v, &afs_seq2net(m)->fs_proc, _pos);
+}
 
-	ret = seq_open(file, &afs_proc_sysname_ops);
-	if (ret < 0)
-		return ret;
+static void afs_proc_servers_stop(struct seq_file *m, void *v)
+	__releases(rcu)
+{
+	rcu_read_unlock();
+}
 
-	if (file->f_mode & FMODE_WRITE) {
-		sysnames = kzalloc(sizeof(*sysnames), GFP_KERNEL);
-		if (!sysnames) {
-			seq_release(inode, file);
-			return -ENOMEM;
-		}
+static const struct seq_operations afs_proc_servers_ops = {
+	.start	= afs_proc_servers_start,
+	.next	= afs_proc_servers_next,
+	.stop	= afs_proc_servers_stop,
+	.show	= afs_proc_servers_show,
+};
 
-		refcount_set(&sysnames->usage, 1);
-		m = file->private_data;
-		m->private = sysnames;
-	}
+/*
+ * Display the list of strings that may be substituted for the @sys pathname
+ * macro.
+ */
+static int afs_proc_sysname_show(struct seq_file *m, void *v)
+{
+	struct afs_net *net = afs_seq2net(m);
+	struct afs_sysnames *sysnames = net->sysnames;
+	unsigned int i = (unsigned long)v - 1;
 
+	if (i < sysnames->nr)
+		seq_printf(m, "%s\n", sysnames->subs[i]);
 	return 0;
 }
 
-/*
- * Handle writes to /proc/fs/afs/sysname to set the @sys substitution.
- */
-static ssize_t afs_proc_sysname_write(struct file *file,
-				      const char __user *buf,
-				      size_t size, loff_t *_pos)
+static void *afs_proc_sysname_start(struct seq_file *m, loff_t *pos)
+	__acquires(&net->sysnames_lock)
 {
-	struct afs_sysnames *sysnames;
+	struct afs_net *net = afs_seq2net(m);
+	struct afs_sysnames *names;
+
+	read_lock(&net->sysnames_lock);
+
+	names = net->sysnames;
+	if (*pos >= names->nr)
+		return NULL;
+	return (void *)(unsigned long)(*pos + 1);
+}
+
+static void *afs_proc_sysname_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	struct afs_net *net = afs_seq2net(m);
+	struct afs_sysnames *names = net->sysnames;
+
+	*pos += 1;
+	if (*pos >= names->nr)
+		return NULL;
+	return (void *)(unsigned long)(*pos + 1);
+}
+
+static void afs_proc_sysname_stop(struct seq_file *m, void *v)
+	__releases(&net->sysnames_lock)
+{
+	struct afs_net *net = afs_seq2net(m);
+
+	read_unlock(&net->sysnames_lock);
+}
+
+static const struct seq_operations afs_proc_sysname_ops = {
+	.start	= afs_proc_sysname_start,
+	.next	= afs_proc_sysname_next,
+	.stop	= afs_proc_sysname_stop,
+	.show	= afs_proc_sysname_show,
+};
+
+/*
+ * Allow the @sys substitution to be configured.
+ */
+static int afs_proc_sysname_write(struct file *file, char *buf, size_t size)
+{
+	struct afs_sysnames *sysnames, *kill;
 	struct seq_file *m = file->private_data;
-	char *kbuf = NULL, *s, *p, *sub;
+	struct afs_net *net = afs_seq2net(m);
+	char *s, *p, *sub;
 	int ret, len;
 
-	sysnames = m->private;
+	sysnames = kzalloc(sizeof(*sysnames), GFP_KERNEL);
 	if (!sysnames)
-		return -EINVAL;
-	if (sysnames->error)
-		return sysnames->error;
+		return -ENOMEM;
+	refcount_set(&sysnames->usage, 1);
+	kill = sysnames;
 
-	if (size >= PAGE_SIZE - 1) {
-		sysnames->error = -EINVAL;
-		return -EINVAL;
-	}
-	if (size == 0)
-		return 0;
-
-	kbuf = memdup_user_nul(buf, size);
-	if (IS_ERR(kbuf))
-		return PTR_ERR(kbuf);
-
-	inode_lock(file_inode(file));
-
-	p = kbuf;
+	p = buf;
 	while ((s = strsep(&p, " \t\n"))) {
 		len = strlen(s);
 		if (len == 0)
···
 		sysnames->nr++;
 	}
 
-	ret = size;	/* consume everything, always */
+	if (sysnames->nr == 0) {
+		sysnames->subs[0] = sysnames->blank;
+		sysnames->nr++;
+	}
+
+	write_lock(&net->sysnames_lock);
+	kill = net->sysnames;
+	net->sysnames = sysnames;
+	write_unlock(&net->sysnames_lock);
+	ret = 0;
 out:
-	inode_unlock(file_inode(file));
-	kfree(kbuf);
+	afs_put_sysnames(kill);
 	return ret;
 
 invalid:
 	ret = -EINVAL;
 error:
-	sysnames->error = ret;
 	goto out;
 }
 
-static int afs_proc_sysname_release(struct inode *inode, struct file *file)
+void afs_put_sysnames(struct afs_sysnames *sysnames)
 {
-	struct afs_sysnames *sysnames, *kill = NULL;
-	struct seq_file *m = file->private_data;
-	struct afs_net *net = afs_seq2net(m);
+	int i;
 
-	sysnames = m->private;
-	if (sysnames) {
-		if (!sysnames->error) {
-			kill = sysnames;
-			if (sysnames->nr == 0) {
-				sysnames->subs[0] = sysnames->blank;
-				sysnames->nr++;
-			}
-			write_lock(&net->sysnames_lock);
-			kill = net->sysnames;
-			net->sysnames = sysnames;
-			write_unlock(&net->sysnames_lock);
-		}
-		afs_put_sysnames(kill);
+	if (sysnames && refcount_dec_and_test(&sysnames->usage)) {
+		for (i = 0; i < sysnames->nr; i++)
+			if (sysnames->subs[i] != afs_init_sysname &&
+			    sysnames->subs[i] != sysnames->blank)
+				kfree(sysnames->subs[i]);
 	}
-
-	return seq_release(inode, file);
-}
-
-static void *afs_proc_sysname_start(struct seq_file *m, loff_t *pos)
-	__acquires(&net->sysnames_lock)
-{
-	struct afs_net *net = afs_seq2net(m);
-	struct afs_sysnames *names = net->sysnames;
-
-	read_lock(&net->sysnames_lock);
-
-	if (*pos >= names->nr)
-		return NULL;
-	return (void *)(unsigned long)(*pos + 1);
-}
-
-static void *afs_proc_sysname_next(struct seq_file *m, void *v, loff_t *pos)
-{
-	struct afs_net *net = afs_seq2net(m);
-	struct afs_sysnames *names = net->sysnames;
-
-	*pos += 1;
-	if (*pos >= names->nr)
-		return NULL;
-	return (void *)(unsigned long)(*pos + 1);
-}
-
-static void afs_proc_sysname_stop(struct seq_file *m, void *v)
-	__releases(&net->sysnames_lock)
-{
-	struct afs_net *net = afs_seq2net(m);
-
-	read_unlock(&net->sysnames_lock);
-}
-
-static int afs_proc_sysname_show(struct seq_file *m, void *v)
-{
-	struct afs_net *net = afs_seq2net(m);
-	struct afs_sysnames *sysnames = net->sysnames;
-	unsigned int i = (unsigned long)v - 1;
-
-	if (i < sysnames->nr)
-		seq_printf(m, "%s\n", sysnames->subs[i]);
-	return 0;
 }
 
 /*
···
  */
 static int afs_proc_stats_show(struct seq_file *m, void *v)
 {
-	struct afs_net *net = afs_seq2net(m);
+	struct afs_net *net = afs_seq2net_single(m);
 
 	seq_puts(m, "kAFS statistics\n");
 
···
 		   atomic_read(&net->n_stores),
 		   atomic_long_read(&net->n_store_bytes));
 	return 0;
+}
+
+/*
+ * initialise /proc/fs/afs/<cell>/
+ */
+int afs_proc_cell_setup(struct afs_cell *cell)
+{
+	struct proc_dir_entry *dir;
+	struct afs_net *net = cell->net;
+
+	_enter("%p{%s},%p", cell, cell->name, net->proc_afs);
+
+	dir = proc_net_mkdir(net->net, cell->name, net->proc_afs);
+	if (!dir)
+		goto error_dir;
+
+	if (!proc_create_net_data("vlservers", 0444, dir,
+				  &afs_proc_cell_vlservers_ops,
+				  sizeof(struct seq_net_private),
+				  cell) ||
+	    !proc_create_net_data("volumes", 0444, dir,
+				  &afs_proc_cell_volumes_ops,
+				  sizeof(struct seq_net_private),
+				  cell))
+		goto error_tree;
+
+	_leave(" = 0");
+	return 0;
+
+error_tree:
+	remove_proc_subtree(cell->name, net->proc_afs);
+error_dir:
+	_leave(" = -ENOMEM");
+	return -ENOMEM;
+}
+
+/*
+ * remove /proc/fs/afs/<cell>/
+ */
+void afs_proc_cell_remove(struct afs_cell *cell)
+{
+	struct afs_net *net = cell->net;
+
+	_enter("");
+	remove_proc_subtree(cell->name, net->proc_afs);
+	_leave("");
+}
+
+/*
+ * initialise the /proc/fs/afs/ directory
+ */
+int afs_proc_init(struct afs_net *net)
+{
+	struct proc_dir_entry *p;
+
+	_enter("");
+
+	p = proc_net_mkdir(net->net, "afs", net->net->proc_net);
+	if (!p)
+		goto error_dir;
+
+	if (!proc_create_net_data_write("cells", 0644, p,
+					&afs_proc_cells_ops,
+					afs_proc_cells_write,
+					sizeof(struct seq_net_private),
+					NULL) ||
+	    !proc_create_net_single_write("rootcell", 0644, p,
+					  afs_proc_rootcell_show,
+					  afs_proc_rootcell_write,
+					  NULL) ||
+	    !proc_create_net("servers", 0444, p, &afs_proc_servers_ops,
+			     sizeof(struct seq_net_private)) ||
+	    !proc_create_net_single("stats", 0444, p, afs_proc_stats_show, NULL) ||
+	    !proc_create_net_data_write("sysname", 0644, p,
+					&afs_proc_sysname_ops,
+					afs_proc_sysname_write,
+					sizeof(struct seq_net_private),
+					NULL))
+		goto error_tree;
+
+	net->proc_afs = p;
+	_leave(" = 0");
+	return 0;
+
+error_tree:
+	proc_remove(p);
+error_dir:
+	_leave(" = -ENOMEM");
+	return -ENOMEM;
+}
+
+/*
+ * clean up the /proc/fs/afs/ directory
+ */
+void afs_proc_cleanup(struct afs_net *net)
+{
+	proc_remove(net->proc_afs);
+	net->proc_afs = NULL;
 }

fs/afs/rxrpc.c

···
 
 	_enter("");
 
-	ret = sock_create_kern(&init_net, AF_RXRPC, SOCK_DGRAM, PF_INET6, &socket);
+	ret = sock_create_kern(net->net, AF_RXRPC, SOCK_DGRAM, PF_INET6, &socket);
 	if (ret < 0)
 		goto error_1;
 

fs/afs/server.c

···
 	server->flags = (1UL << AFS_SERVER_FL_NEW);
 	server->update_at = ktime_get_real_seconds() + afs_server_update_delay;
 	rwlock_init(&server->fs_lock);
-	INIT_LIST_HEAD(&server->cb_interests);
+	INIT_HLIST_HEAD(&server->cb_volumes);
 	rwlock_init(&server->cb_break_lock);
 
 	afs_inc_servers_outstanding(net);

fs/afs/super.c

···
 };
 MODULE_ALIAS_FS("afs");
 
+int afs_net_id;
+
 static const struct super_operations afs_super_ops = {
 	.statfs		= afs_statfs,
 	.alloc_inode	= afs_alloc_inode,
···
 /*
  * clean up the filesystem
  */
-void __exit afs_fs_exit(void)
+void afs_fs_exit(void)
 {
 	_enter("");
 
···
 	struct afs_super_info *as1 = data;
 	struct afs_super_info *as = AFS_FS_S(sb);
 
-	return (as->net == as1->net &&
+	return (as->net_ns == as1->net_ns &&
 		as->volume &&
-		as->volume->vid == as1->volume->vid);
+		as->volume->vid == as1->volume->vid &&
+		!as->dyn_root);
 }
 
 static int afs_dynroot_test_super(struct super_block *sb, void *data)
 {
-	return false;
+	struct afs_super_info *as1 = data;
+	struct afs_super_info *as = AFS_FS_S(sb);
+
+	return (as->net_ns == as1->net_ns &&
+		as->dyn_root);
 }
 
 static int afs_set_super(struct super_block *sb, void *data)
···
 	if (!sb->s_root)
 		goto error;
 
-	if (params->dyn_root)
+	if (as->dyn_root) {
 		sb->s_d_op = &afs_dynroot_dentry_operations;
-	else
+		ret = afs_dynroot_populate(sb);
+		if (ret < 0)
+			goto error;
+	} else {
 		sb->s_d_op = &afs_fs_dentry_operations;
+	}
 
 	_leave(" = 0");
 	return 0;
···
 
 	as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
 	if (as) {
-		as->net = afs_get_net(params->net);
+		as->net_ns = get_net(params->net_ns);
 		if (params->dyn_root)
 			as->dyn_root = true;
 		else
···
 {
 	if (as) {
 		afs_put_volume(as->cell, as->volume);
-		afs_put_cell(as->net, as->cell);
-		afs_put_net(as->net);
+		afs_put_cell(afs_net(as->net_ns), as->cell);
+		put_net(as->net_ns);
 		kfree(as);
 	}
+}
+
+static void afs_kill_super(struct super_block *sb)
+{
+	struct afs_super_info *as = AFS_FS_S(sb);
+	struct afs_net *net = afs_net(as->net_ns);
+
+	if (as->dyn_root)
+		afs_dynroot_depopulate(sb);
+	
+	/* Clear the callback interests (which will do ilookup5) before
+	 * deactivating the superblock.
+	 */
+	if (as->volume)
+		afs_clear_callback_interests(net, as->volume->servers);
+	kill_anon_super(sb);
+	if (as->volume)
+		afs_deactivate_volume(as->volume);
+	afs_destroy_sbi(as);
 }
 
 /*
···
 	_enter(",,%s,%p", dev_name, options);
 
 	memset(&params, 0, sizeof(params));
-	params.net = &__afs_net;
 
 	ret = -EINVAL;
 	if (current->nsproxy->net_ns != &init_net)
 		goto error;
-
+	params.net_ns = current->nsproxy->net_ns;
+	params.net = afs_net(params.net_ns);
+	
 	/* parse the options and device name */
 	if (options) {
 		ret = afs_parse_options(&params, options, &dev_name);
···
 	afs_put_cell(params.net, params.cell);
 	_leave(" = %d", ret);
 	return ERR_PTR(ret);
-}
-
-static void afs_kill_super(struct super_block *sb)
-{
-	struct afs_super_info *as = AFS_FS_S(sb);
-
-	/* Clear the callback interests (which will do ilookup5) before
-	 * deactivating the superblock.
-	 */
-	if (as->volume)
-		afs_clear_callback_interests(as->net, as->volume->servers);
-	kill_anon_super(sb);
-	if (as->volume)
-		afs_deactivate_volume(as->volume);
-	afs_destroy_sbi(as);
 }
 
 /*

fs/namei.c

···
 }
 
 /**
+ * try_lookup_one_len - filesystem helper to lookup single pathname component
+ * @name:	pathname component to lookup
+ * @base:	base directory to lookup from
+ * @len:	maximum length @len should be interpreted to
+ *
+ * Look up a dentry by name in the dcache, returning NULL if it does not
+ * currently exist.  The function does not try to create a dentry.
+ *
+ * Note that this routine is purely a helper for filesystem usage and should
+ * not be called by generic code.
+ *
+ * The caller must hold base->i_mutex.
+ */
+struct dentry *try_lookup_one_len(const char *name, struct dentry *base, int len)
+{
+	struct qstr this;
+	int err;
+
+	WARN_ON_ONCE(!inode_is_locked(base->d_inode));
+
+	err = lookup_one_len_common(name, base, len, &this);
+	if (err)
+		return ERR_PTR(err);
+
+	return lookup_dcache(&this, base, 0);
+}
+EXPORT_SYMBOL(try_lookup_one_len);
+
+/**
  * lookup_one_len - filesystem helper to lookup single pathname component
  * @name:	pathname component to lookup
  * @base:	base directory to lookup from

fs/proc/generic.c

···
 	if (!ent)
 		goto out;
 
-	if (qstr.len + 1 <= sizeof(ent->inline_name)) {
+	if (qstr.len + 1 <= SIZEOF_PDE_INLINE_NAME) {
 		ent->name = ent->inline_name;
 	} else {
 		ent->name = kmalloc(qstr.len + 1, GFP_KERNEL);
···
 	return __PDE_DATA(inode);
 }
 EXPORT_SYMBOL(PDE_DATA);
+
+/*
+ * Pull a user buffer into memory and pass it to the file's write handler if
+ * one is supplied.  The ->write() method is permitted to modify the
+ * kernel-side buffer.
+ */
+ssize_t proc_simple_write(struct file *f, const char __user *ubuf, size_t size,
+			  loff_t *_pos)
+{
+	struct proc_dir_entry *pde = PDE(file_inode(f));
+	char *buf;
+	int ret;
+
+	if (!pde->write)
+		return -EACCES;
+	if (size == 0 || size > PAGE_SIZE - 1)
+		return -EINVAL;
+	buf = memdup_user_nul(ubuf, size);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
+	ret = pde->write(f, buf, size);
+	kfree(buf);
+	return ret == 0 ? size : ret;
+}

fs/proc/inode.c

···
 		kmem_cache_create("pde_opener", sizeof(struct pde_opener), 0,
 				  SLAB_ACCOUNT|SLAB_PANIC, NULL);
 	proc_dir_entry_cache = kmem_cache_create_usercopy(
-		"proc_dir_entry", sizeof(struct proc_dir_entry), 0, SLAB_PANIC,
-		offsetof(struct proc_dir_entry, inline_name),
-		sizeof_field(struct proc_dir_entry, inline_name), NULL);
+		"proc_dir_entry", SIZEOF_PDE_SLOT, 0, SLAB_PANIC,
+		OFFSETOF_PDE_NAME, SIZEOF_PDE_INLINE_NAME, NULL);
 }
 
 static int proc_show_options(struct seq_file *seq, struct dentry *root)

fs/proc/internal.h

···
 		const struct seq_operations *seq_ops;
 		int (*single_show)(struct seq_file *, void *);
 	};
+	proc_write_t write;
 	void *data;
 	unsigned int state_size;
 	unsigned int low_ino;
···
 	char *name;
 	umode_t mode;
 	u8 namelen;
-#ifdef CONFIG_64BIT
-#define SIZEOF_PDE_INLINE_NAME	(192-155)
-#else
-#define SIZEOF_PDE_INLINE_NAME	(128-95)
-#endif
-	char inline_name[SIZEOF_PDE_INLINE_NAME];
+	char inline_name[];
 } __randomize_layout;
+
+#define OFFSETOF_PDE_NAME offsetof(struct proc_dir_entry, inline_name)
+#define SIZEOF_PDE_SLOT					\
+	(OFFSETOF_PDE_NAME + 34 <= 64 ? 64 :		\
+	 OFFSETOF_PDE_NAME + 34 <= 128 ? 128 :		\
+	 OFFSETOF_PDE_NAME + 34 <= 192 ? 192 :		\
+	 OFFSETOF_PDE_NAME + 34 <= 256 ? 256 :		\
+	 OFFSETOF_PDE_NAME + 34 <= 512 ? 512 :		\
+	 0)
+
+#define SIZEOF_PDE_INLINE_NAME (SIZEOF_PDE_SLOT - OFFSETOF_PDE_NAME)
 
 extern struct kmem_cache *proc_dir_entry_cache;
 void pde_free(struct proc_dir_entry *pde);
···
 {
 	return S_ISDIR(pde->mode) && !pde->proc_iops;
 }
+extern ssize_t proc_simple_write(struct file *, const char __user *, size_t, loff_t *);
 
 /*
  * inode.c

fs/proc/proc_net.c

···
 
 	WARN_ON_ONCE(state_size < sizeof(*p));
 
+	if (file->f_mode & FMODE_WRITE && !PDE(inode)->write)
+		return -EACCES;
+
 	net = get_proc_net(inode);
 	if (!net)
 		return -ENXIO;
···
 static const struct file_operations proc_net_seq_fops = {
 	.open		= seq_open_net,
 	.read		= seq_read,
+	.write		= proc_simple_write,
 	.llseek		= seq_lseek,
 	.release	= seq_release_net,
 };
···
 	return proc_register(parent, p);
 }
 EXPORT_SYMBOL_GPL(proc_create_net_data);
+
+/**
+ * proc_create_net_data_write - Create a writable net_ns-specific proc file
+ * @name: The name of the file.
+ * @mode: The file's access mode.
+ * @parent: The parent directory in which to create.
+ * @ops: The seq_file ops with which to read the file.
+ * @write: The write method which which to 'modify' the file.
+ * @data: Data for retrieval by PDE_DATA().
+ *
+ * Create a network namespaced proc file in the @parent directory with the
+ * specified @name and @mode that allows reading of a file that displays a
+ * series of elements and also provides for the file accepting writes that have
+ * some arbitrary effect.
+ *
+ * The functions in the @ops table are used to iterate over items to be
+ * presented and extract the readable content using the seq_file interface.
+ *
+ * The @write function is called with the data copied into a kernel space
+ * scratch buffer and has a NUL appended for convenience.  The buffer may be
+ * modified by the @write function.  @write should return 0 on success.
+ *
+ * The @data value is accessible from the @show and @write functions by calling
+ * PDE_DATA() on the file inode.  The network namespace must be accessed by
+ * calling seq_file_net() on the seq_file struct.
+ */
+struct proc_dir_entry *proc_create_net_data_write(const char *name, umode_t mode,
+						  struct proc_dir_entry *parent,
+						  const struct seq_operations *ops,
+						  proc_write_t write,
+						  unsigned int state_size, void *data)
+{
+	struct proc_dir_entry *p;
+
+	p = proc_create_reg(name, mode, &parent, data);
+	if (!p)
+		return NULL;
+	p->proc_fops = &proc_net_seq_fops;
+	p->seq_ops = ops;
+	p->state_size = state_size;
+	p->write = write;
+	return proc_register(parent, p);
+}
+EXPORT_SYMBOL_GPL(proc_create_net_data_write);
 
 static int single_open_net(struct inode *inode, struct file *file)
 {
···
 static const struct file_operations proc_net_single_fops = {
 	.open		= single_open_net,
 	.read		= seq_read,
+	.write		= proc_simple_write,
 	.llseek		= seq_lseek,
 	.release	= single_release_net,
 };
···
 	return proc_register(parent, p);
 }
 EXPORT_SYMBOL_GPL(proc_create_net_single);
+
+/**
+ * proc_create_net_single_write - Create a writable net_ns-specific proc file
+ * @name: The name of the file.
+ * @mode: The file's access mode.
+ * @parent: The parent directory in which to create.
+ * @show: The seqfile show method with which to read the file.
+ * @write: The write method which which to 'modify' the file.
+ * @data: Data for retrieval by PDE_DATA().
+ *
+ * Create a network-namespaced proc file in the @parent directory with the
+ * specified @name and @mode that allows reading of a file that displays a
+ * single element rather than a series and also provides for the file accepting
+ * writes that have some arbitrary effect.
+ *
+ * The @show function is called to extract the readable content via the
+ * seq_file interface.
+ *
+ * The @write function is called with the data copied into a kernel space
+ * scratch buffer and has a NUL appended for convenience.  The buffer may be
+ * modified by the @write function.  @write should return 0 on success.
+ *
+ * The @data value is accessible from the @show and @write functions by calling
+ * PDE_DATA() on the file inode.  The network namespace must be accessed by
+ * calling seq_file_single_net() on the seq_file struct.
+ */
+struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mode,
+						    struct proc_dir_entry *parent,
+						    int (*show)(struct seq_file *, void *),
+						    proc_write_t write,
+						    void *data)
+{
+	struct proc_dir_entry *p;
+
+	p = proc_create_reg(name, mode, &parent, data);
+	if (!p)
+		return NULL;
+	p->proc_fops = &proc_net_single_fops;
+	p->single_show = show;
+	p->write = write;
+	return proc_register(parent, p);
+}
+EXPORT_SYMBOL_GPL(proc_create_net_single_write);
 
 static struct net *get_proc_task_net(struct inode *dir)
 {

fs/proc/root.c

···
 	.proc_fops	= &proc_root_operations,
 	.parent		= &proc_root,
 	.subdir		= RB_ROOT,
-	.name		= proc_root.inline_name,
-	.inline_name	= "/proc",
+	.name		= "/proc",
 };
 
 int pid_ns_prepare_proc(struct pid_namespace *ns)

include/linux/namei.h

···
 extern struct dentry *kern_path_locked(const char *, struct path *);
 extern int kern_path_mountpoint(int, const char *, struct path *, unsigned int);
 
+extern struct dentry *try_lookup_one_len(const char *, struct dentry *, int);
 extern struct dentry *lookup_one_len(const char *, struct dentry *, int);
 extern struct dentry *lookup_one_len_unlocked(const char *, struct dentry *, int);
 

include/linux/proc_fs.h

···
 
 #ifdef CONFIG_PROC_FS
 
+typedef int (*proc_write_t)(struct file *, char *, size_t);
+
 extern void proc_root_init(void);
 extern void proc_flush_task(struct task_struct *);
 
···
 struct proc_dir_entry *proc_create_net_single(const char *name, umode_t mode,
 		struct proc_dir_entry *parent,
 		int (*show)(struct seq_file *, void *), void *data);
+struct proc_dir_entry *proc_create_net_data_write(const char *name, umode_t mode,
+						  struct proc_dir_entry *parent,
+						  const struct seq_operations *ops,
+						  proc_write_t write,
+						  unsigned int state_size, void *data);
+struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mode,
+						    struct proc_dir_entry *parent,
+						    int (*show)(struct seq_file *, void *),
+						    proc_write_t write,
+						    void *data);
 
 #else /* CONFIG_PROC_FS */