Fixed MTP to work with TWRP

fs/afs/cell.c

@@ -0,0 +1,460 @@
+/* AFS cell and server record management
+ *
+ * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/key.h>
+#include <linux/ctype.h>
+#include <linux/dns_resolver.h>
+#include <linux/sched.h>
+#include <keys/rxrpc-type.h>
+#include "internal.h"
+
+DECLARE_RWSEM(afs_proc_cells_sem);
+LIST_HEAD(afs_proc_cells);
+
+static LIST_HEAD(afs_cells);
+static DEFINE_RWLOCK(afs_cells_lock);
+static DECLARE_RWSEM(afs_cells_sem); /* add/remove serialisation */
+static DECLARE_WAIT_QUEUE_HEAD(afs_cells_freeable_wq);
+static struct afs_cell *afs_cell_root;
+
+/*
+ * allocate a cell record and fill in its name, VL server address list and
+ * allocate an anonymous key
+ */
+static struct afs_cell *afs_cell_alloc(const char *name, unsigned namelen,
+				       char *vllist)
+{
+	struct afs_cell *cell;
+	struct key *key;
+	char keyname[4 + AFS_MAXCELLNAME + 1], *cp, *dp, *next;
+	char  *dvllist = NULL, *_vllist = NULL;
+	char  delimiter = ':';
+	int ret;
+
+	_enter("%*.*s,%s", namelen, namelen, name ?: "", vllist);
+
+	BUG_ON(!name); /* TODO: want to look up "this cell" in the cache */
+
+	if (namelen > AFS_MAXCELLNAME) {
+		_leave(" = -ENAMETOOLONG");
+		return ERR_PTR(-ENAMETOOLONG);
+	}
+
+	/* allocate and initialise a cell record */
+	cell = kzalloc(sizeof(struct afs_cell) + namelen + 1, GFP_KERNEL);
+	if (!cell) {
+		_leave(" = -ENOMEM");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	memcpy(cell->name, name, namelen);
+	cell->name[namelen] = 0;
+
+	atomic_set(&cell->usage, 1);
+	INIT_LIST_HEAD(&cell->link);
+	rwlock_init(&cell->servers_lock);
+	INIT_LIST_HEAD(&cell->servers);
+	init_rwsem(&cell->vl_sem);
+	INIT_LIST_HEAD(&cell->vl_list);
+	spin_lock_init(&cell->vl_lock);
+
+	/* if the ip address is invalid, try dns query */
+	if (!vllist || strlen(vllist) < 7) {
+		ret = dns_query("afsdb", name, namelen, "ipv4", &dvllist, NULL);
+		if (ret < 0) {
+			if (ret == -ENODATA || ret == -EAGAIN || ret == -ENOKEY)
+				/* translate these errors into something
+				 * userspace might understand */
+				ret = -EDESTADDRREQ;
+			_leave(" = %d", ret);
+			return ERR_PTR(ret);
+		}
+		_vllist = dvllist;
+
+		/* change the delimiter for user-space reply */
+		delimiter = ',';
+
+	} else {
+		_vllist = vllist;
+	}
+
+	/* fill in the VL server list from the rest of the string */
+	do {
+		unsigned a, b, c, d;
+
+		next = strchr(_vllist, delimiter);
+		if (next)
+			*next++ = 0;
+
+		if (sscanf(_vllist, "%u.%u.%u.%u", &a, &b, &c, &d) != 4)
+			goto bad_address;
+
+		if (a > 255 || b > 255 || c > 255 || d > 255)
+			goto bad_address;
+
+		cell->vl_addrs[cell->vl_naddrs++].s_addr =
+			htonl((a << 24) | (b << 16) | (c << 8) | d);
+
+	} while (cell->vl_naddrs < AFS_CELL_MAX_ADDRS && (_vllist = next));
+
+	/* create a key to represent an anonymous user */
+	memcpy(keyname, "afs@", 4);
+	dp = keyname + 4;
+	cp = cell->name;
+	do {
+		*dp++ = toupper(*cp);
+	} while (*cp++);
+
+	key = rxrpc_get_null_key(keyname);
+	if (IS_ERR(key)) {
+		_debug("no key");
+		ret = PTR_ERR(key);
+		goto error;
+	}
+	cell->anonymous_key = key;
+
+	_debug("anon key %p{%x}",
+	       cell->anonymous_key, key_serial(cell->anonymous_key));
+
+	_leave(" = %p", cell);
+	return cell;
+
+bad_address:
+	printk(KERN_ERR "kAFS: bad VL server IP address\n");
+	ret = -EINVAL;
+error:
+	key_put(cell->anonymous_key);
+	kfree(dvllist);
+	kfree(cell);
+	_leave(" = %d", ret);
+	return ERR_PTR(ret);
+}
+
+/*
+ * afs_cell_crate() - create a cell record
+ * @name:	is the name of the cell.
+ * @namsesz:	is the strlen of the cell name.
+ * @vllist:	is a colon separated list of IP addresses in "a.b.c.d" format.
+ * @retref:	is T to return the cell reference when the cell exists.
+ */
+struct afs_cell *afs_cell_create(const char *name, unsigned namesz,
+				 char *vllist, bool retref)
+{
+	struct afs_cell *cell;
+	int ret;
+
+	_enter("%*.*s,%s", namesz, namesz, name ?: "", vllist);
+
+	down_write(&afs_cells_sem);
+	read_lock(&afs_cells_lock);
+	list_for_each_entry(cell, &afs_cells, link) {
+		if (strncasecmp(cell->name, name, namesz) == 0)
+			goto duplicate_name;
+	}
+	read_unlock(&afs_cells_lock);
+
+	cell = afs_cell_alloc(name, namesz, vllist);
+	if (IS_ERR(cell)) {
+		_leave(" = %ld", PTR_ERR(cell));
+		up_write(&afs_cells_sem);
+		return cell;
+	}
+
+	/* add a proc directory for this cell */
+	ret = afs_proc_cell_setup(cell);
+	if (ret < 0)
+		goto error;
+
+#ifdef CONFIG_AFS_FSCACHE
+	/* put it up for caching (this never returns an error) */
+	cell->cache = fscache_acquire_cookie(afs_cache_netfs.primary_index,
+					     &afs_cell_cache_index_def,
+					     cell, true);
+#endif
+
+	/* add to the cell lists */
+	write_lock(&afs_cells_lock);
+	list_add_tail(&cell->link, &afs_cells);
+	write_unlock(&afs_cells_lock);
+
+	down_write(&afs_proc_cells_sem);
+	list_add_tail(&cell->proc_link, &afs_proc_cells);
+	up_write(&afs_proc_cells_sem);
+	up_write(&afs_cells_sem);
+
+	_leave(" = %p", cell);
+	return cell;
+
+error:
+	up_write(&afs_cells_sem);
+	key_put(cell->anonymous_key);
+	kfree(cell);
+	_leave(" = %d", ret);
+	return ERR_PTR(ret);
+
+duplicate_name:
+	if (retref && !IS_ERR(cell))
+		afs_get_cell(cell);
+
+	read_unlock(&afs_cells_lock);
+	up_write(&afs_cells_sem);
+
+	if (retref) {
+		_leave(" = %p", cell);
+		return cell;
+	}
+
+	_leave(" = -EEXIST");
+	return ERR_PTR(-EEXIST);
+}
+
+/*
+ * set the root cell information
+ * - can be called with a module parameter string
+ * - can be called from a write to /proc/fs/afs/rootcell
+ */
+int afs_cell_init(char *rootcell)
+{
+	struct afs_cell *old_root, *new_root;
+	char *cp;
+
+	_enter("");
+
+	if (!rootcell) {
+		/* module is loaded with no parameters, or built statically.
+		 * - in the future we might initialize cell DB here.
+		 */
+		_leave(" = 0 [no root]");
+		return 0;
+	}
+
+	cp = strchr(rootcell, ':');
+	if (!cp)
+		_debug("kAFS: no VL server IP addresses specified");
+	else
+		*cp++ = 0;
+
+	/* allocate a cell record for the root cell */
+	new_root = afs_cell_create(rootcell, strlen(rootcell), cp, false);
+	if (IS_ERR(new_root)) {
+		_leave(" = %ld", PTR_ERR(new_root));
+		return PTR_ERR(new_root);
+	}
+
+	/* install the new cell */
+	write_lock(&afs_cells_lock);
+	old_root = afs_cell_root;
+	afs_cell_root = new_root;
+	write_unlock(&afs_cells_lock);
+	afs_put_cell(old_root);
+
+	_leave(" = 0");
+	return 0;
+}
+
+/*
+ * lookup a cell record
+ */
+struct afs_cell *afs_cell_lookup(const char *name, unsigned namesz,
+				 bool dns_cell)
+{
+	struct afs_cell *cell;
+
+	_enter("\"%*.*s\",", namesz, namesz, name ?: "");
+
+	down_read(&afs_cells_sem);
+	read_lock(&afs_cells_lock);
+
+	if (name) {
+		/* if the cell was named, look for it in the cell record list */
+		list_for_each_entry(cell, &afs_cells, link) {
+			if (strncmp(cell->name, name, namesz) == 0) {
+				afs_get_cell(cell);
+				goto found;
+			}
+		}
+		cell = ERR_PTR(-ENOENT);
+		if (dns_cell)
+			goto create_cell;
+	found:
+		;
+	} else {
+		cell = afs_cell_root;
+		if (!cell) {
+			/* this should not happen unless user tries to mount
+			 * when root cell is not set. Return an impossibly
+			 * bizarre errno to alert the user. Things like
+			 * ENOENT might be "more appropriate" but they happen
+			 * for other reasons.
+			 */
+			cell = ERR_PTR(-EDESTADDRREQ);
+		} else {
+			afs_get_cell(cell);
+		}
+
+	}
+
+	read_unlock(&afs_cells_lock);
+	up_read(&afs_cells_sem);
+	_leave(" = %p", cell);
+	return cell;
+
+create_cell:
+	read_unlock(&afs_cells_lock);
+	up_read(&afs_cells_sem);
+
+	cell = afs_cell_create(name, namesz, NULL, true);
+
+	_leave(" = %p", cell);
+	return cell;
+}
+
+#if 0
+/*
+ * try and get a cell record
+ */
+struct afs_cell *afs_get_cell_maybe(struct afs_cell *cell)
+{
+	write_lock(&afs_cells_lock);
+
+	if (cell && !list_empty(&cell->link))
+		afs_get_cell(cell);
+	else
+		cell = NULL;
+
+	write_unlock(&afs_cells_lock);
+	return cell;
+}
+#endif  /*  0  */
+
+/*
+ * destroy a cell record
+ */
+void afs_put_cell(struct afs_cell *cell)
+{
+	if (!cell)
+		return;
+
+	_enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name);
+
+	ASSERTCMP(atomic_read(&cell->usage), >, 0);
+
+	/* to prevent a race, the decrement and the dequeue must be effectively
+	 * atomic */
+	write_lock(&afs_cells_lock);
+
+	if (likely(!atomic_dec_and_test(&cell->usage))) {
+		write_unlock(&afs_cells_lock);
+		_leave("");
+		return;
+	}
+
+	ASSERT(list_empty(&cell->servers));
+	ASSERT(list_empty(&cell->vl_list));
+
+	write_unlock(&afs_cells_lock);
+
+	wake_up(&afs_cells_freeable_wq);
+
+	_leave(" [unused]");
+}
+
+/*
+ * destroy a cell record
+ * - must be called with the afs_cells_sem write-locked
+ * - cell->link should have been broken by the caller
+ */
+static void afs_cell_destroy(struct afs_cell *cell)
+{
+	_enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name);
+
+	ASSERTCMP(atomic_read(&cell->usage), >=, 0);
+	ASSERT(list_empty(&cell->link));
+
+	/* wait for everyone to stop using the cell */
+	if (atomic_read(&cell->usage) > 0) {
+		DECLARE_WAITQUEUE(myself, current);
+
+		_debug("wait for cell %s", cell->name);
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		add_wait_queue(&afs_cells_freeable_wq, &myself);
+
+		while (atomic_read(&cell->usage) > 0) {
+			schedule();
+			set_current_state(TASK_UNINTERRUPTIBLE);
+		}
+
+		remove_wait_queue(&afs_cells_freeable_wq, &myself);
+		set_current_state(TASK_RUNNING);
+	}
+
+	_debug("cell dead");
+	ASSERTCMP(atomic_read(&cell->usage), ==, 0);
+	ASSERT(list_empty(&cell->servers));
+	ASSERT(list_empty(&cell->vl_list));
+
+	afs_proc_cell_remove(cell);
+
+	down_write(&afs_proc_cells_sem);
+	list_del_init(&cell->proc_link);
+	up_write(&afs_proc_cells_sem);
+
+#ifdef CONFIG_AFS_FSCACHE
+	fscache_relinquish_cookie(cell->cache, 0);
+#endif
+	key_put(cell->anonymous_key);
+	kfree(cell);
+
+	_leave(" [destroyed]");
+}
+
+/*
+ * purge in-memory cell database on module unload or afs_init() failure
+ * - the timeout daemon is stopped before calling this
+ */
+void afs_cell_purge(void)
+{
+	struct afs_cell *cell;
+
+	_enter("");
+
+	afs_put_cell(afs_cell_root);
+
+	down_write(&afs_cells_sem);
+
+	while (!list_empty(&afs_cells)) {
+		cell = NULL;
+
+		/* remove the next cell from the front of the list */
+		write_lock(&afs_cells_lock);
+
+		if (!list_empty(&afs_cells)) {
+			cell = list_entry(afs_cells.next,
+					  struct afs_cell, link);
+			list_del_init(&cell->link);
+		}
+
+		write_unlock(&afs_cells_lock);
+
+		if (cell) {
+			_debug("PURGING CELL %s (%d)",
+			       cell->name, atomic_read(&cell->usage));
+
+			/* now the cell should be left with no references */
+			afs_cell_destroy(cell);
+		}
+	}
+
+	up_write(&afs_cells_sem);
+	_leave("");
+}