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// SPDX-License-Identifier: GPL-2.0-or-later
/* vnode and volume validity verification.
*
* Copyright (C) 2023 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include "internal.h"
/*
* mark the data attached to an inode as obsolete due to a write on the server
* - might also want to ditch all the outstanding writes and dirty pages
*/
static void afs_zap_data(struct afs_vnode *vnode)
{
_enter("{%llx:%llu}", vnode->fid.vid, vnode->fid.vnode);
afs_invalidate_cache(vnode, 0);
/* nuke all the non-dirty pages that aren't locked, mapped or being
* written back in a regular file and completely discard the pages in a
* directory or symlink */
if (S_ISREG(vnode->netfs.inode.i_mode))
invalidate_remote_inode(&vnode->netfs.inode);
else
invalidate_inode_pages2(vnode->netfs.inode.i_mapping);
}
/*
* Check to see if we have a server currently serving this volume and that it
* hasn't been reinitialised or dropped from the list.
*/
static bool afs_check_server_good(struct afs_vnode *vnode)
{
struct afs_server_list *slist;
struct afs_server *server;
bool good;
int i;
if (vnode->cb_fs_s_break == atomic_read(&vnode->volume->cell->fs_s_break))
return true;
rcu_read_lock();
slist = rcu_dereference(vnode->volume->servers);
for (i = 0; i < slist->nr_servers; i++) {
server = slist->servers[i].server;
if (server == vnode->cb_server) {
good = (vnode->cb_s_break == server->cb_s_break);
rcu_read_unlock();
return good;
}
}
rcu_read_unlock();
return false;
}
/*
* Check the validity of a vnode/inode.
*/
bool afs_check_validity(struct afs_vnode *vnode)
{
enum afs_cb_break_reason need_clear = afs_cb_break_no_break;
time64_t now = ktime_get_real_seconds();
unsigned int cb_break;
int seq;
do {
seq = read_seqbegin(&vnode->cb_lock);
cb_break = vnode->cb_break;
if (test_bit(AFS_VNODE_CB_PROMISED, &vnode->flags)) {
if (vnode->cb_v_break != vnode->volume->cb_v_break)
need_clear = afs_cb_break_for_v_break;
else if (!afs_check_server_good(vnode))
need_clear = afs_cb_break_for_s_reinit;
else if (test_bit(AFS_VNODE_ZAP_DATA, &vnode->flags))
need_clear = afs_cb_break_for_zap;
else if (vnode->cb_expires_at - 10 <= now)
need_clear = afs_cb_break_for_lapsed;
} else if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
;
} else {
need_clear = afs_cb_break_no_promise;
}
} while (read_seqretry(&vnode->cb_lock, seq));
if (need_clear == afs_cb_break_no_break)
return true;
write_seqlock(&vnode->cb_lock);
if (need_clear == afs_cb_break_no_promise)
vnode->cb_v_break = vnode->volume->cb_v_break;
else if (cb_break == vnode->cb_break)
__afs_break_callback(vnode, need_clear);
else
trace_afs_cb_miss(&vnode->fid, need_clear);
write_sequnlock(&vnode->cb_lock);
return false;
}
/*
* Returns true if the pagecache is still valid. Does not sleep.
*/
bool afs_pagecache_valid(struct afs_vnode *vnode)
{
if (unlikely(test_bit(AFS_VNODE_DELETED, &vnode->flags))) {
if (vnode->netfs.inode.i_nlink)
clear_nlink(&vnode->netfs.inode);
return true;
}
if (test_bit(AFS_VNODE_CB_PROMISED, &vnode->flags) &&
afs_check_validity(vnode))
return true;
return false;
}
/*
* validate a vnode/inode
* - there are several things we need to check
* - parent dir data changes (rm, rmdir, rename, mkdir, create, link,
* symlink)
* - parent dir metadata changed (security changes)
* - dentry data changed (write, truncate)
* - dentry metadata changed (security changes)
*/
int afs_validate(struct afs_vnode *vnode, struct key *key)
{
int ret;
_enter("{v={%llx:%llu} fl=%lx},%x",
vnode->fid.vid, vnode->fid.vnode, vnode->flags,
key_serial(key));
if (afs_pagecache_valid(vnode))
goto valid;
down_write(&vnode->validate_lock);
/* if the promise has expired, we need to check the server again to get
* a new promise - note that if the (parent) directory's metadata was
* changed then the security may be different and we may no longer have
* access */
if (!test_bit(AFS_VNODE_CB_PROMISED, &vnode->flags)) {
_debug("not promised");
ret = afs_fetch_status(vnode, key, false, NULL);
if (ret < 0) {
if (ret == -ENOENT) {
set_bit(AFS_VNODE_DELETED, &vnode->flags);
ret = -ESTALE;
}
goto error_unlock;
}
_debug("new promise [fl=%lx]", vnode->flags);
}
if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
_debug("file already deleted");
ret = -ESTALE;
goto error_unlock;
}
/* if the vnode's data version number changed then its contents are
* different */
if (test_and_clear_bit(AFS_VNODE_ZAP_DATA, &vnode->flags))
afs_zap_data(vnode);
up_write(&vnode->validate_lock);
valid:
_leave(" = 0");
return 0;
error_unlock:
up_write(&vnode->validate_lock);
_leave(" = %d", ret);
return ret;
}
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