diff options
Diffstat (limited to 'fs/afs/validation.c')
| -rw-r--r-- | fs/afs/validation.c | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/fs/afs/validation.c b/fs/afs/validation.c new file mode 100644 index 000000000000..18ba2c5e8ead --- /dev/null +++ b/fs/afs/validation.c @@ -0,0 +1,183 @@ +// 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; +} |