Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 525 insertions, 0 deletions

diff --git a/fs/netfs/write_collect.c b/fs/netfs/write_collect.c
new file mode 100644
index 000000000..210eb8f39
--- /dev/null
+++ b/fs/netfs/write_collect.c
@@ -0,0 +1,525 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Network filesystem write subrequest result collection, assessment
+ * and retrying.
+ *
+ * Copyright (C) 2024 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/export.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/pagemap.h>
+#include <linux/slab.h>
+#include "internal.h"
+
+/* Notes made in the collector */
+#define HIT_PENDING		0x01	/* A front op was still pending */
+#define NEED_REASSESS		0x02	/* Need to loop round and reassess */
+#define MADE_PROGRESS		0x04	/* Made progress cleaning up a stream or the folio set */
+#define NEED_UNLOCK		0x08	/* The pagecache needs unlocking */
+#define NEED_RETRY		0x10	/* A front op requests retrying */
+#define SAW_FAILURE		0x20	/* One stream or hit a permanent failure */
+
+static void netfs_dump_request(const struct netfs_io_request *rreq)
+{
+	pr_err("Request R=%08x r=%d fl=%lx or=%x e=%ld\n",
+	       rreq->debug_id, refcount_read(&rreq->ref), rreq->flags,
+	       rreq->origin, rreq->error);
+	pr_err("  st=%llx tsl=%zx/%llx/%llx\n",
+	       rreq->start, rreq->transferred, rreq->submitted, rreq->len);
+	pr_err("  cci=%llx/%llx/%llx\n",
+	       rreq->cleaned_to, rreq->collected_to, atomic64_read(&rreq->issued_to));
+	pr_err("  iw=%pSR\n", rreq->netfs_ops->issue_write);
+	for (int i = 0; i < NR_IO_STREAMS; i++) {
+		const struct netfs_io_subrequest *sreq;
+		const struct netfs_io_stream *s = &rreq->io_streams[i];
+
+		pr_err("  str[%x] s=%x e=%d acnf=%u,%u,%u,%u\n",
+		       s->stream_nr, s->source, s->error,
+		       s->avail, s->active, s->need_retry, s->failed);
+		pr_err("  str[%x] ct=%llx t=%zx\n",
+		       s->stream_nr, s->collected_to, s->transferred);
+		list_for_each_entry(sreq, &s->subrequests, rreq_link) {
+			pr_err("  sreq[%x:%x] sc=%u s=%llx t=%zx/%zx r=%d f=%lx\n",
+			       sreq->stream_nr, sreq->debug_index, sreq->source,
+			       sreq->start, sreq->transferred, sreq->len,
+			       refcount_read(&sreq->ref), sreq->flags);
+		}
+	}
+}
+
+/*
+ * Successful completion of write of a folio to the server and/or cache.  Note
+ * that we are not allowed to lock the folio here on pain of deadlocking with
+ * truncate.
+ */
+int netfs_folio_written_back(struct folio *folio)
+{
+	enum netfs_folio_trace why = netfs_folio_trace_clear;
+	struct inode *inode = folio_inode(folio);
+	struct netfs_inode *ictx = netfs_inode(inode);
+	struct netfs_folio *finfo;
+	struct netfs_group *group = NULL;
+	int gcount = 0;
+
+	if ((finfo = netfs_folio_info(folio))) {
+		/* Streaming writes cannot be redirtied whilst under writeback,
+		 * so discard the streaming record.
+		 */
+		unsigned long long fend;
+
+		fend = folio_pos(folio) + finfo->dirty_offset + finfo->dirty_len;
+		spin_lock(&ictx->inode.i_lock);
+		if (fend > ictx->_zero_point)
+			netfs_write_zero_point(inode, fend);
+		spin_unlock(&ictx->inode.i_lock);
+
+		folio_detach_private(folio);
+		group = finfo->netfs_group;
+		gcount++;
+		kfree(finfo);
+		why = netfs_folio_trace_clear_s;
+		goto end_wb;
+	}
+
+	if ((group = netfs_folio_group(folio))) {
+		if (group == NETFS_FOLIO_COPY_TO_CACHE) {
+			why = netfs_folio_trace_clear_cc;
+			folio_detach_private(folio);
+			goto end_wb;
+		}
+
+		/* Need to detach the group pointer if the page didn't get
+		 * redirtied.  If it has been redirtied, then it must be within
+		 * the same group.
+		 */
+		why = netfs_folio_trace_redirtied;
+		if (!folio_test_dirty(folio)) {
+			folio_detach_private(folio);
+			gcount++;
+			why = netfs_folio_trace_clear_g;
+		}
+	}
+
+end_wb:
+	trace_netfs_folio(folio, why);
+	folio_end_writeback(folio);
+	return gcount;
+}
+
+/*
+ * Unlock any folios we've finished with.
+ */
+static void netfs_writeback_unlock_folios(struct netfs_io_request *wreq,
+					  unsigned int *notes)
+{
+	struct folio_queue *folioq = wreq->buffer.tail;
+	unsigned long long collected_to = wreq->collected_to;
+	unsigned int slot = wreq->buffer.first_tail_slot;
+
+	if (WARN_ON_ONCE(!folioq)) {
+		pr_err("[!] Writeback unlock found empty rolling buffer!\n");
+		netfs_dump_request(wreq);
+		return;
+	}
+
+	if (wreq->origin == NETFS_PGPRIV2_COPY_TO_CACHE) {
+		if (netfs_pgpriv2_unlock_copied_folios(wreq))
+			*notes |= MADE_PROGRESS;
+		return;
+	}
+
+	if (slot >= folioq_nr_slots(folioq)) {
+		folioq = rolling_buffer_delete_spent(&wreq->buffer);
+		if (!folioq)
+			return;
+		slot = 0;
+	}
+
+	for (;;) {
+		struct folio *folio;
+		struct netfs_folio *finfo;
+		unsigned long long fpos, fend;
+		size_t fsize, flen;
+
+		folio = folioq_folio(folioq, slot);
+		if (WARN_ONCE(!folio_test_writeback(folio),
+			      "R=%08x: folio %lx is not under writeback\n",
+			      wreq->debug_id, folio->index))
+			trace_netfs_folio(folio, netfs_folio_trace_not_under_wback);
+
+		fpos = folio_pos(folio);
+		fsize = folio_size(folio);
+		finfo = netfs_folio_info(folio);
+		flen = finfo ? finfo->dirty_offset + finfo->dirty_len : fsize;
+
+		fend = min_t(unsigned long long, fpos + flen, wreq->i_size);
+
+		trace_netfs_collect_folio(wreq, folio, fend, collected_to);
+
+		/* Unlock any folio we've transferred all of. */
+		if (collected_to < fend)
+			break;
+
+		wreq->nr_group_rel += netfs_folio_written_back(folio);
+		wreq->cleaned_to = fpos + fsize;
+		*notes |= MADE_PROGRESS;
+
+		/* Clean up the head folioq.  If we clear an entire folioq, then
+		 * we can get rid of it provided it's not also the tail folioq
+		 * being filled by the issuer.
+		 */
+		folioq_clear(folioq, slot);
+		slot++;
+		if (slot >= folioq_nr_slots(folioq)) {
+			folioq = rolling_buffer_delete_spent(&wreq->buffer);
+			if (!folioq)
+				goto done;
+			slot = 0;
+		}
+
+		if (fpos + fsize >= collected_to)
+			break;
+	}
+
+	wreq->buffer.tail = folioq;
+done:
+	wreq->buffer.first_tail_slot = slot;
+}
+
+/*
+ * Collect and assess the results of various write subrequests.  We may need to
+ * retry some of the results - or even do an RMW cycle for content crypto.
+ *
+ * Note that we have a number of parallel, overlapping lists of subrequests,
+ * one to the server and one to the local cache for example, which may not be
+ * the same size or starting position and may not even correspond in boundary
+ * alignment.
+ */
+static void netfs_collect_write_results(struct netfs_io_request *wreq)
+{
+	struct netfs_io_subrequest *front, *remove;
+	struct netfs_io_stream *stream;
+	unsigned long long collected_to, issued_to;
+	unsigned int notes;
+	int s;
+
+	_enter("%llx-%llx", wreq->start, wreq->start + wreq->len);
+	trace_netfs_collect(wreq);
+	trace_netfs_rreq(wreq, netfs_rreq_trace_collect);
+
+reassess_streams:
+	issued_to = atomic64_read(&wreq->issued_to);
+	smp_rmb();
+	collected_to = ULLONG_MAX;
+	if (wreq->origin == NETFS_WRITEBACK ||
+	    wreq->origin == NETFS_WRITETHROUGH ||
+	    wreq->origin == NETFS_PGPRIV2_COPY_TO_CACHE)
+		notes = NEED_UNLOCK;
+	else
+		notes = 0;
+
+	/* Remove completed subrequests from the front of the streams and
+	 * advance the completion point on each stream.  We stop when we hit
+	 * something that's in progress.  The issuer thread may be adding stuff
+	 * to the tail whilst we're doing this.
+	 */
+	for (s = 0; s < NR_IO_STREAMS; s++) {
+		stream = &wreq->io_streams[s];
+		/* Read active flag before list pointers */
+		if (!smp_load_acquire(&stream->active))
+			continue;
+
+		front = list_first_entry_or_null_acquire(&stream->subrequests,
+							 struct netfs_io_subrequest, rreq_link);
+		/* Read first subreq pointer before IN_PROGRESS flag. */
+
+		while (front) {
+			trace_netfs_collect_sreq(wreq, front);
+			//_debug("sreq [%x] %llx %zx/%zx",
+			//       front->debug_index, front->start, front->transferred, front->len);
+
+			if (stream->collected_to < front->start) {
+				trace_netfs_collect_gap(wreq, stream, issued_to, 'F');
+				stream->collected_to = front->start;
+			}
+
+			/* Stall if the front is still undergoing I/O. */
+			if (netfs_check_subreq_in_progress(front)) {
+				notes |= HIT_PENDING;
+				break;
+			}
+			smp_rmb(); /* Read counters after I-P flag. */
+
+			if (stream->failed) {
+				stream->collected_to = front->start + front->len;
+				notes |= MADE_PROGRESS | SAW_FAILURE;
+				goto cancel;
+			}
+			if (front->start + front->transferred > stream->collected_to) {
+				stream->collected_to = front->start + front->transferred;
+				stream->transferred = stream->collected_to - wreq->start;
+				stream->transferred_valid = true;
+				notes |= MADE_PROGRESS;
+			}
+			if (test_bit(NETFS_SREQ_FAILED, &front->flags)) {
+				stream->failed = true;
+				stream->error = front->error;
+				if (stream->source == NETFS_UPLOAD_TO_SERVER)
+					mapping_set_error(wreq->mapping, front->error);
+				notes |= NEED_REASSESS | SAW_FAILURE;
+				break;
+			}
+			if (front->transferred < front->len) {
+				stream->need_retry = true;
+				notes |= NEED_RETRY | MADE_PROGRESS;
+				break;
+			}
+
+		cancel:
+			/* Remove if completely consumed. */
+			spin_lock(&wreq->lock);
+
+			remove = front;
+			list_del_init(&front->rreq_link);
+			front = list_first_entry_or_null(&stream->subrequests,
+							 struct netfs_io_subrequest, rreq_link);
+			spin_unlock(&wreq->lock);
+			netfs_put_subrequest(remove,
+					     notes & SAW_FAILURE ?
+					     netfs_sreq_trace_put_cancel :
+					     netfs_sreq_trace_put_done);
+		}
+
+		/* If we have an empty stream, we need to jump it forward
+		 * otherwise the collection point will never advance.
+		 */
+		if (!front && issued_to > stream->collected_to) {
+			trace_netfs_collect_gap(wreq, stream, issued_to, 'E');
+			stream->collected_to = issued_to;
+		}
+
+		if (stream->collected_to < collected_to)
+			collected_to = stream->collected_to;
+	}
+
+	if (collected_to != ULLONG_MAX && collected_to > wreq->collected_to)
+		wreq->collected_to = collected_to;
+
+	for (s = 0; s < NR_IO_STREAMS; s++) {
+		stream = &wreq->io_streams[s];
+		if (stream->active)
+			trace_netfs_collect_stream(wreq, stream);
+	}
+
+	trace_netfs_collect_state(wreq, wreq->collected_to, notes);
+
+	/* Unlock any folios that we have now finished with. */
+	if (notes & NEED_UNLOCK) {
+		if (wreq->cleaned_to < wreq->collected_to)
+			netfs_writeback_unlock_folios(wreq, &notes);
+	} else {
+		wreq->cleaned_to = wreq->collected_to;
+	}
+
+	// TODO: Discard encryption buffers
+
+	if (notes & NEED_RETRY)
+		goto need_retry;
+
+	if (notes & MADE_PROGRESS) {
+		netfs_wake_rreq_flag(wreq, NETFS_RREQ_PAUSE, netfs_rreq_trace_unpause);
+		//cond_resched();
+		goto reassess_streams;
+	}
+
+	if (notes & NEED_REASSESS) {
+		//cond_resched();
+		goto reassess_streams;
+	}
+
+out:
+	netfs_put_group_many(wreq->group, wreq->nr_group_rel);
+	wreq->nr_group_rel = 0;
+	_leave(" = %x", notes);
+	return;
+
+need_retry:
+	/* Okay...  We're going to have to retry one or both streams.  Note
+	 * that any partially completed op will have had any wholly transferred
+	 * folios removed from it.
+	 */
+	_debug("retry");
+	netfs_retry_writes(wreq);
+	goto out;
+}
+
+/*
+ * Perform the collection of subrequests, folios and encryption buffers.
+ */
+bool netfs_write_collection(struct netfs_io_request *wreq)
+{
+	struct netfs_inode *ictx = netfs_inode(wreq->inode);
+	size_t transferred;
+	bool transferred_valid = false;
+	int s;
+
+	_enter("R=%x", wreq->debug_id);
+
+	netfs_collect_write_results(wreq);
+
+	/* We're done when the app thread has finished posting subreqs and all
+	 * the queues in all the streams are empty.
+	 */
+	if (!test_bit(NETFS_RREQ_ALL_QUEUED, &wreq->flags))
+		return false;
+	smp_rmb(); /* Read ALL_QUEUED before lists. */
+
+	transferred = LONG_MAX;
+	for (s = 0; s < NR_IO_STREAMS; s++) {
+		struct netfs_io_stream *stream = &wreq->io_streams[s];
+		if (!stream->active)
+			continue;
+		if (!list_empty(&stream->subrequests))
+			return false;
+		if (stream->transferred_valid &&
+		    stream->transferred < transferred) {
+			transferred = stream->transferred;
+			transferred_valid = true;
+		}
+	}
+
+	/* Okay, declare that all I/O is complete. */
+	if (transferred_valid)
+		wreq->transferred = transferred;
+	trace_netfs_rreq(wreq, netfs_rreq_trace_write_done);
+
+	if (wreq->io_streams[1].active &&
+	    wreq->io_streams[1].failed &&
+	    ictx->ops->invalidate_cache) {
+		/* Cache write failure doesn't prevent writeback completion
+		 * unless we're in disconnected mode.
+		 */
+		ictx->ops->invalidate_cache(wreq);
+	}
+
+	_debug("finished");
+	netfs_wake_rreq_flag(wreq, NETFS_RREQ_IN_PROGRESS, netfs_rreq_trace_wake_ip);
+	/* As we cleared NETFS_RREQ_IN_PROGRESS, we acquired its ref. */
+
+	switch (wreq->origin) {
+	case NETFS_WRITEBACK:
+	case NETFS_WRITEBACK_SINGLE:
+	case NETFS_WRITETHROUGH:
+		netfs_wb_end(ictx);
+		break;
+	default:
+		break;
+	}
+
+	if (wreq->iocb) {
+		size_t written = min(wreq->transferred, wreq->len);
+		wreq->iocb->ki_pos += written;
+		if (wreq->iocb->ki_complete) {
+			trace_netfs_rreq(wreq, netfs_rreq_trace_ki_complete);
+			wreq->iocb->ki_complete(
+				wreq->iocb, wreq->error ? wreq->error : written);
+		}
+		wreq->iocb = VFS_PTR_POISON;
+	}
+
+	netfs_clear_subrequests(wreq);
+	return true;
+}
+
+void netfs_write_collection_worker(struct work_struct *work)
+{
+	struct netfs_io_request *rreq = container_of(work, struct netfs_io_request, work);
+
+	netfs_see_request(rreq, netfs_rreq_trace_see_work);
+	if (netfs_check_rreq_in_progress(rreq)) {
+		if (netfs_write_collection(rreq))
+			/* Drop the ref from the IN_PROGRESS flag. */
+			netfs_put_request(rreq, netfs_rreq_trace_put_work_ip);
+		else
+			netfs_see_request(rreq, netfs_rreq_trace_see_work_complete);
+	}
+}
+
+/**
+ * netfs_write_subrequest_terminated - Note the termination of a write operation.
+ * @_op: The I/O request that has terminated.
+ * @transferred_or_error: The amount of data transferred or an error code.
+ *
+ * This tells the library that a contributory write I/O operation has
+ * terminated, one way or another, and that it should collect the results.
+ *
+ * The caller indicates in @transferred_or_error the outcome of the operation,
+ * supplying a positive value to indicate the number of bytes transferred or a
+ * negative error code.  The library will look after reissuing I/O operations
+ * as appropriate and writing downloaded data to the cache.
+ *
+ * When this is called, ownership of the subrequest is transferred back to the
+ * library, along with a ref.
+ *
+ * Note that %_op is a void* so that the function can be passed to
+ * kiocb::term_func without the need for a casting wrapper.
+ */
+void netfs_write_subrequest_terminated(void *_op, ssize_t transferred_or_error)
+{
+	struct netfs_io_subrequest *subreq = _op;
+	struct netfs_io_request *wreq = subreq->rreq;
+
+	_enter("%x[%x] %zd", wreq->debug_id, subreq->debug_index, transferred_or_error);
+
+	switch (subreq->source) {
+	case NETFS_UPLOAD_TO_SERVER:
+		netfs_stat(&netfs_n_wh_upload_done);
+		break;
+	case NETFS_WRITE_TO_CACHE:
+		netfs_stat(&netfs_n_wh_write_done);
+		break;
+	default:
+		BUG();
+	}
+
+	if (IS_ERR_VALUE(transferred_or_error)) {
+		subreq->error = transferred_or_error;
+		/* if need retry is set, error should not matter */
+		if (!test_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags)) {
+			set_bit(NETFS_SREQ_FAILED, &subreq->flags);
+			trace_netfs_failure(wreq, subreq, transferred_or_error, netfs_fail_write);
+		}
+
+		switch (subreq->source) {
+		case NETFS_WRITE_TO_CACHE:
+			netfs_stat(&netfs_n_wh_write_failed);
+			break;
+		case NETFS_UPLOAD_TO_SERVER:
+			netfs_stat(&netfs_n_wh_upload_failed);
+			break;
+		default:
+			break;
+		}
+		trace_netfs_rreq(wreq, netfs_rreq_trace_set_pause);
+		set_bit(NETFS_RREQ_PAUSE, &wreq->flags);
+	} else {
+		if (WARN(transferred_or_error > subreq->len - subreq->transferred,
+			 "Subreq excess write: R=%x[%x] %zd > %zu - %zu",
+			 wreq->debug_id, subreq->debug_index,
+			 transferred_or_error, subreq->len, subreq->transferred))
+			transferred_or_error = subreq->len - subreq->transferred;
+
+		subreq->error = 0;
+		subreq->transferred += transferred_or_error;
+
+		if (subreq->transferred < subreq->len)
+			set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
+	}
+
+	trace_netfs_sreq(subreq, netfs_sreq_trace_terminated);
+	netfs_subreq_clear_in_progress(subreq);
+	netfs_put_subrequest(subreq, netfs_sreq_trace_put_terminated);
+}
+EXPORT_SYMBOL(netfs_write_subrequest_terminated);