Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 490 insertions, 0 deletions

diff --git a/fs/afs/validation.c b/fs/afs/validation.c
new file mode 100644
index 000000000..e997563af
--- /dev/null
+++ b/fs/afs/validation.c
@@ -0,0 +1,490 @@
+// 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"
+
+/*
+ * Data validation is managed through a number of mechanisms from the server:
+ *
+ *  (1) On first contact with a server (such as if it has just been rebooted),
+ *      the server sends us a CB.InitCallBackState* request.
+ *
+ *  (2) On a RW volume, in response to certain vnode (inode)-accessing RPC
+ *      calls, the server maintains a time-limited per-vnode promise that it
+ *      will send us a CB.CallBack request if a third party alters the vnodes
+ *      accessed.
+ *
+ *      Note that a vnode-level callbacks may also be sent for other reasons,
+ *      such as filelock release.
+ *
+ *  (3) On a RO (or Backup) volume, in response to certain vnode-accessing RPC
+ *      calls, each server maintains a time-limited per-volume promise that it
+ *      will send us a CB.CallBack request if the RO volume is updated to a
+ *      snapshot of the RW volume ("vos release").  This is an atomic event
+ *      that cuts over all instances of the RO volume across multiple servers
+ *      simultaneously.
+ *
+ *	Note that a volume-level callbacks may also be sent for other reasons,
+ *	such as the volumeserver taking over control of the volume from the
+ *	fileserver.
+ *
+ *	Note also that each server maintains an independent time limit on an
+ *	independent callback.
+ *
+ *  (4) Certain RPC calls include a volume information record "VolSync" in
+ *      their reply.  This contains a creation date for the volume that should
+ *      remain unchanged for a RW volume (but will be changed if the volume is
+ *      restored from backup) or will be bumped to the time of snapshotting
+ *      when a RO volume is released.
+ *
+ * In order to track this events, the following are provided:
+ *
+ *	->cb_v_break.  A counter of events that might mean that the contents of
+ *	a volume have been altered since we last checked a vnode.
+ *
+ *	->cb_v_check.  A counter of the number of events that we've sent a
+ *	query to the server for.  Everything's up to date if this equals
+ *	cb_v_break.
+ *
+ *	->cb_scrub.  A counter of the number of regression events for which we
+ *	have to completely wipe the cache.
+ *
+ *	->cb_ro_snapshot.  A counter of the number of times that we've
+ *      recognised that a RO volume has been updated.
+ *
+ *	->cb_break.  A counter of events that might mean that the contents of a
+ *      vnode have been altered.
+ *
+ *	->cb_expires_at.  The time at which the callback promise expires or
+ *      AFS_NO_CB_PROMISE if we have no promise.
+ *
+ * The way we manage things is:
+ *
+ *  (1) When a volume-level CB.CallBack occurs, we increment ->cb_v_break on
+ *      the volume and reset ->cb_expires_at (ie. set AFS_NO_CB_PROMISE) on the
+ *      volume and volume's server record.
+ *
+ *  (2) When a CB.InitCallBackState occurs, we treat this as a volume-level
+ *	callback break on all the volumes that have been using that volume
+ *	(ie. increment ->cb_v_break and reset ->cb_expires_at).
+ *
+ *  (3) When a vnode-level CB.CallBack occurs, we increment ->cb_break on the
+ *	vnode and reset its ->cb_expires_at.  If the vnode is mmapped, we also
+ *	dispatch a work item to unmap all PTEs to the vnode's pagecache to
+ *	force reentry to the filesystem for revalidation.
+ *
+ *  (4) When entering the filesystem, we call afs_validate() to check the
+ *	validity of a vnode.  This first checks to see if ->cb_v_check and
+ *	->cb_v_break match, and if they don't, we lock volume->cb_check_lock
+ *	exclusively and perform an FS.FetchStatus on the vnode.
+ *
+ *	After checking the volume, we check the vnode.  If there's a mismatch
+ *	between the volume counters and the vnode's mirrors of those counters,
+ *	we lock vnode->validate_lock and issue an FS.FetchStatus on the vnode.
+ *
+ *  (5) When the reply from FS.FetchStatus arrives, the VolSync record is
+ *      parsed:
+ *
+ *	(A) If the Creation timestamp has changed on a RW volume or regressed
+ *	    on a RO volume, we try to increment ->cb_scrub; if it advances on a
+ *	    RO volume, we assume "vos release" happened and try to increment
+ *	    ->cb_ro_snapshot.
+ *
+ *      (B) If the Update timestamp has regressed, we try to increment
+ *	    ->cb_scrub.
+ *
+ *      Note that in both of these cases, we only do the increment if we can
+ *      cmpxchg the value of the timestamp from the value we noted before the
+ *      op.  This tries to prevent parallel ops from fighting one another.
+ *
+ *	volume->cb_v_check is then set to ->cb_v_break.
+ *
+ *  (6) The AFSCallBack record included in the FS.FetchStatus reply is also
+ *	parsed and used to set the promise in ->cb_expires_at for the vnode,
+ *	the volume and the volume's server record.
+ *
+ *  (7) If ->cb_scrub is seen to have advanced, we invalidate the pagecache for
+ *      the vnode.
+ */
+
+/*
+ * Check the validity of a vnode/inode and its parent volume.
+ */
+bool afs_check_validity(const struct afs_vnode *vnode)
+{
+	const struct afs_volume *volume = vnode->volume;
+	enum afs_vnode_invalid_trace trace = afs_vnode_valid_trace;
+	time64_t cb_expires_at = atomic64_read(&vnode->cb_expires_at);
+	time64_t deadline = ktime_get_real_seconds() + 10;
+
+	if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
+		return true;
+
+	if (atomic_read(&volume->cb_v_check) != atomic_read(&volume->cb_v_break))
+		trace = afs_vnode_invalid_trace_cb_v_break;
+	else if (cb_expires_at == AFS_NO_CB_PROMISE)
+		trace = afs_vnode_invalid_trace_no_cb_promise;
+	else if (cb_expires_at <= deadline)
+		trace = afs_vnode_invalid_trace_expired;
+	else if (volume->cb_expires_at <= deadline)
+		trace = afs_vnode_invalid_trace_vol_expired;
+	else if (vnode->cb_ro_snapshot != atomic_read(&volume->cb_ro_snapshot))
+		trace = afs_vnode_invalid_trace_cb_ro_snapshot;
+	else if (vnode->cb_scrub != atomic_read(&volume->cb_scrub))
+		trace = afs_vnode_invalid_trace_cb_scrub;
+	else if (test_bit(AFS_VNODE_ZAP_DATA, &vnode->flags))
+		trace = afs_vnode_invalid_trace_zap_data;
+	else
+		return true;
+	trace_afs_vnode_invalid(vnode, trace);
+	return false;
+}
+
+/*
+ * See if the server we've just talked to is currently excluded.
+ */
+static bool __afs_is_server_excluded(struct afs_operation *op, struct afs_volume *volume)
+{
+	const struct afs_server_entry *se;
+	const struct afs_server_list *slist;
+	bool is_excluded = true;
+	int i;
+
+	rcu_read_lock();
+
+	slist = rcu_dereference(volume->servers);
+	for (i = 0; i < slist->nr_servers; i++) {
+		se = &slist->servers[i];
+		if (op->server == se->server) {
+			is_excluded = test_bit(AFS_SE_EXCLUDED, &se->flags);
+			break;
+		}
+	}
+
+	rcu_read_unlock();
+	return is_excluded;
+}
+
+/*
+ * Update the volume's server list when the creation time changes and see if
+ * the server we've just talked to is currently excluded.
+ */
+static int afs_is_server_excluded(struct afs_operation *op, struct afs_volume *volume)
+{
+	int ret;
+
+	if (__afs_is_server_excluded(op, volume))
+		return 1;
+
+	set_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);
+	ret = afs_check_volume_status(op->volume, op);
+	if (ret < 0)
+		return ret;
+
+	return __afs_is_server_excluded(op, volume);
+}
+
+/*
+ * Handle a change to the volume creation time in the VolSync record.
+ */
+static int afs_update_volume_creation_time(struct afs_operation *op, struct afs_volume *volume)
+{
+	unsigned int snap;
+	time64_t cur = volume->creation_time;
+	time64_t old = op->pre_volsync.creation;
+	time64_t new = op->volsync.creation;
+	int ret;
+
+	_enter("%llx,%llx,%llx->%llx", volume->vid, cur, old, new);
+
+	if (cur == TIME64_MIN) {
+		volume->creation_time = new;
+		return 0;
+	}
+
+	if (new == cur)
+		return 0;
+
+	/* Try to advance the creation timestamp from what we had before the
+	 * operation to what we got back from the server.  This should
+	 * hopefully ensure that in a race between multiple operations only one
+	 * of them will do this.
+	 */
+	if (cur != old)
+		return 0;
+
+	/* If the creation time changes in an unexpected way, we need to scrub
+	 * our caches.  For a RW vol, this will only change if the volume is
+	 * restored from a backup; for a RO/Backup vol, this will advance when
+	 * the volume is updated to a new snapshot (eg. "vos release").
+	 */
+	if (volume->type == AFSVL_RWVOL)
+		goto regressed;
+	if (volume->type == AFSVL_BACKVOL) {
+		if (new < old)
+			goto regressed;
+		goto advance;
+	}
+
+	/* We have an RO volume, we need to query the VL server and look at the
+	 * server flags to see if RW->RO replication is in progress.
+	 */
+	ret = afs_is_server_excluded(op, volume);
+	if (ret < 0)
+		return ret;
+	if (ret > 0) {
+		snap = atomic_read(&volume->cb_ro_snapshot);
+		trace_afs_cb_v_break(volume->vid, snap, afs_cb_break_volume_excluded);
+		return ret;
+	}
+
+advance:
+	snap = atomic_inc_return(&volume->cb_ro_snapshot);
+	trace_afs_cb_v_break(volume->vid, snap, afs_cb_break_for_vos_release);
+	volume->creation_time = new;
+	return 0;
+
+regressed:
+	atomic_inc(&volume->cb_scrub);
+	trace_afs_cb_v_break(volume->vid, 0, afs_cb_break_for_creation_regress);
+	volume->creation_time = new;
+	return 0;
+}
+
+/*
+ * Handle a change to the volume update time in the VolSync record.
+ */
+static void afs_update_volume_update_time(struct afs_operation *op, struct afs_volume *volume)
+{
+	enum afs_cb_break_reason reason = afs_cb_break_no_break;
+	time64_t cur = volume->update_time;
+	time64_t old = op->pre_volsync.update;
+	time64_t new = op->volsync.update;
+
+	_enter("%llx,%llx,%llx->%llx", volume->vid, cur, old, new);
+
+	if (cur == TIME64_MIN) {
+		volume->update_time = new;
+		return;
+	}
+
+	if (new == cur)
+		return;
+
+	/* If the volume update time changes in an unexpected way, we need to
+	 * scrub our caches.  For a RW vol, this will advance on every
+	 * modification op; for a RO/Backup vol, this will advance when the
+	 * volume is updated to a new snapshot (eg. "vos release").
+	 */
+	if (new < old)
+		reason = afs_cb_break_for_update_regress;
+
+	/* Try to advance the update timestamp from what we had before the
+	 * operation to what we got back from the server.  This should
+	 * hopefully ensure that in a race between multiple operations only one
+	 * of them will do this.
+	 */
+	if (cur == old) {
+		if (reason == afs_cb_break_for_update_regress) {
+			atomic_inc(&volume->cb_scrub);
+			trace_afs_cb_v_break(volume->vid, 0, reason);
+		}
+		volume->update_time = new;
+	}
+}
+
+static int afs_update_volume_times(struct afs_operation *op, struct afs_volume *volume)
+{
+	int ret = 0;
+
+	if (likely(op->volsync.creation == volume->creation_time &&
+		   op->volsync.update == volume->update_time))
+		return 0;
+
+	mutex_lock(&volume->volsync_lock);
+	if (op->volsync.creation != volume->creation_time) {
+		ret = afs_update_volume_creation_time(op, volume);
+		if (ret < 0)
+			goto out;
+	}
+	if (op->volsync.update != volume->update_time)
+		afs_update_volume_update_time(op, volume);
+out:
+	mutex_unlock(&volume->volsync_lock);
+	return ret;
+}
+
+/*
+ * Update the state of a volume, including recording the expiration time of the
+ * callback promise.  Returns 1 to redo the operation from the start.
+ */
+int afs_update_volume_state(struct afs_operation *op)
+{
+	struct afs_server_list *slist = op->server_list;
+	struct afs_server_entry *se = &slist->servers[op->server_index];
+	struct afs_callback *cb = &op->file[0].scb.callback;
+	struct afs_volume *volume = op->volume;
+	unsigned int cb_v_break = atomic_read(&volume->cb_v_break);
+	unsigned int cb_v_check = atomic_read(&volume->cb_v_check);
+	int ret;
+
+	_enter("%llx", op->volume->vid);
+
+	if (op->volsync.creation != TIME64_MIN || op->volsync.update != TIME64_MIN) {
+		ret = afs_update_volume_times(op, volume);
+		if (ret != 0) {
+			_leave(" = %d", ret);
+			return ret;
+		}
+	}
+
+	if (op->cb_v_break == cb_v_break &&
+	    (op->file[0].scb.have_cb || op->file[1].scb.have_cb)) {
+		time64_t expires_at = cb->expires_at;
+
+		if (!op->file[0].scb.have_cb)
+			expires_at = op->file[1].scb.callback.expires_at;
+
+		se->cb_expires_at = expires_at;
+		volume->cb_expires_at = expires_at;
+	}
+	if (cb_v_check < op->cb_v_break)
+		atomic_cmpxchg(&volume->cb_v_check, cb_v_check, op->cb_v_break);
+	return 0;
+}
+
+/*
+ * 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))
+		filemap_invalidate_inode(&vnode->netfs.inode, true, 0, LLONG_MAX);
+	else
+		filemap_invalidate_inode(&vnode->netfs.inode, false, 0, LLONG_MAX);
+}
+
+/*
+ * 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)
+{
+	struct afs_volume *volume = vnode->volume;
+	unsigned int cb_ro_snapshot, cb_scrub;
+	time64_t deadline = ktime_get_real_seconds() + 10;
+	bool zap = false, locked_vol = false;
+	int ret;
+
+	_enter("{v={%llx:%llu} fl=%lx},%x",
+	       vnode->fid.vid, vnode->fid.vnode, vnode->flags,
+	       key_serial(key));
+
+	if (afs_check_validity(vnode))
+		return test_bit(AFS_VNODE_DELETED, &vnode->flags) ? -ESTALE : 0;
+
+	ret = down_write_killable(&vnode->validate_lock);
+	if (ret < 0)
+		goto error;
+
+	if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
+		ret = -ESTALE;
+		goto error_unlock;
+	}
+
+	/* Validate a volume after the v_break has changed or the volume
+	 * callback expired.  We only want to do this once per volume per
+	 * v_break change.  The actual work will be done when parsing the
+	 * status fetch reply.
+	 */
+	if (volume->cb_expires_at <= deadline ||
+	    atomic_read(&volume->cb_v_check) != atomic_read(&volume->cb_v_break)) {
+		ret = mutex_lock_interruptible(&volume->cb_check_lock);
+		if (ret < 0)
+			goto error_unlock;
+		locked_vol = true;
+	}
+
+	cb_ro_snapshot = atomic_read(&volume->cb_ro_snapshot);
+	cb_scrub = atomic_read(&volume->cb_scrub);
+	if (vnode->cb_ro_snapshot != cb_ro_snapshot ||
+	    vnode->cb_scrub	  != cb_scrub)
+		unmap_mapping_pages(vnode->netfs.inode.i_mapping, 0, 0, false);
+
+	if (vnode->cb_ro_snapshot != cb_ro_snapshot ||
+	    vnode->cb_scrub	  != cb_scrub ||
+	    volume->cb_expires_at <= deadline ||
+	    atomic_read(&volume->cb_v_check) != atomic_read(&volume->cb_v_break) ||
+	    atomic64_read(&vnode->cb_expires_at) <= deadline
+	    ) {
+		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);
+	}
+
+	/* We can drop the volume lock now as. */
+	if (locked_vol) {
+		mutex_unlock(&volume->cb_check_lock);
+		locked_vol = false;
+	}
+
+	cb_ro_snapshot = atomic_read(&volume->cb_ro_snapshot);
+	cb_scrub = atomic_read(&volume->cb_scrub);
+	_debug("vnode inval %x==%x %x==%x",
+	       vnode->cb_ro_snapshot, cb_ro_snapshot,
+	       vnode->cb_scrub, cb_scrub);
+	if (vnode->cb_scrub != cb_scrub)
+		zap = true;
+	vnode->cb_ro_snapshot = cb_ro_snapshot;
+	vnode->cb_scrub = cb_scrub;
+
+	/* If the vnode's data version number changed then its contents are
+	 * different.  Note that afs_apply_status() doesn't set ZAP_DATA on
+	 * directories.
+	 */
+	zap |= test_and_clear_bit(AFS_VNODE_ZAP_DATA, &vnode->flags);
+	if (zap) {
+		if (S_ISREG(vnode->netfs.inode.i_mode))
+			afs_zap_data(vnode);
+		else if (S_ISLNK(vnode->netfs.inode.i_mode))
+			afs_invalidate_symlink(vnode);
+	}
+	up_write(&vnode->validate_lock);
+	_leave(" = 0");
+	return 0;
+
+error_unlock:
+	if (locked_vol)
+		mutex_unlock(&volume->cb_check_lock);
+	up_write(&vnode->validate_lock);
+error:
+	_leave(" = %d", ret);
+	return ret;
+}