1 files changed, 144 insertions, 90 deletions

diff --git a/fs/netfs/read_retry.c b/fs/netfs/read_retry.c
index 16b676c68dcd..0f294b26e08c 100644
--- a/fs/netfs/read_retry.c
+++ b/fs/netfs/read_retry.c
@@ -12,17 +12,9 @@
 static void netfs_reissue_read(struct netfs_io_request *rreq,
 			       struct netfs_io_subrequest *subreq)
 {
-	struct iov_iter *io_iter = &subreq->io_iter;
-
-	if (iov_iter_is_folioq(io_iter)) {
-		subreq->curr_folioq = (struct folio_queue *)io_iter->folioq;
-		subreq->curr_folioq_slot = io_iter->folioq_slot;
-		subreq->curr_folio_order = subreq->curr_folioq->orders[subreq->curr_folioq_slot];
-	}
-
-	atomic_inc(&rreq->nr_outstanding);
+	__clear_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
 	__set_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags);
-	netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit);
+	netfs_stat(&netfs_n_rh_retry_read_subreq);
 	subreq->rreq->netfs_ops->issue_read(subreq);
 }
 
@@ -33,13 +25,12 @@ static void netfs_reissue_read(struct netfs_io_request *rreq,
 static void netfs_retry_read_subrequests(struct netfs_io_request *rreq)
 {
 	struct netfs_io_subrequest *subreq;
-	struct netfs_io_stream *stream0 = &rreq->io_streams[0];
-	LIST_HEAD(sublist);
-	LIST_HEAD(queue);
+	struct netfs_io_stream *stream = &rreq->io_streams[0];
+	struct list_head *next;
 
 	_enter("R=%x", rreq->debug_id);
 
-	if (list_empty(&rreq->subrequests))
+	if (list_empty(&stream->subrequests))
 		return;
 
 	if (rreq->netfs_ops->retry_request)
@@ -50,15 +41,14 @@ static void netfs_retry_read_subrequests(struct netfs_io_request *rreq)
 	 */
 	if (!rreq->netfs_ops->prepare_read &&
 	    !rreq->cache_resources.ops) {
-		struct netfs_io_subrequest *subreq;
-
-		list_for_each_entry(subreq, &rreq->subrequests, rreq_link) {
+		list_for_each_entry(subreq, &stream->subrequests, rreq_link) {
 			if (test_bit(NETFS_SREQ_FAILED, &subreq->flags))
 				break;
 			if (__test_and_clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags)) {
 				__clear_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
 				subreq->retry_count++;
 				netfs_reset_iter(subreq);
+				netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit);
 				netfs_reissue_read(rreq, subreq);
 			}
 		}
@@ -75,48 +65,44 @@ static void netfs_retry_read_subrequests(struct netfs_io_request *rreq)
 	 * populating with smaller subrequests.  In the event that the subreq
 	 * we just launched finishes before we insert the next subreq, it'll
 	 * fill in rreq->prev_donated instead.
-
+	 *
 	 * Note: Alternatively, we could split the tail subrequest right before
 	 * we reissue it and fix up the donations under lock.
 	 */
-	list_splice_init(&rreq->subrequests, &queue);
+	next = stream->subrequests.next;
 
 	do {
-		struct netfs_io_subrequest *from;
+		struct netfs_io_subrequest *from, *to, *tmp;
 		struct iov_iter source;
 		unsigned long long start, len;
-		size_t part, deferred_next_donated = 0;
-		bool boundary = false;
+		size_t part;
+		bool boundary = false, subreq_superfluous = false;
 
 		/* Go through the subreqs and find the next span of contiguous
 		 * buffer that we then rejig (cifs, for example, needs the
 		 * rsize renegotiating) and reissue.
 		 */
-		from = list_first_entry(&queue, struct netfs_io_subrequest, rreq_link);
-		list_move_tail(&from->rreq_link, &sublist);
+		from = list_entry(next, struct netfs_io_subrequest, rreq_link);
+		to = from;
 		start = from->start + from->transferred;
 		len   = from->len   - from->transferred;
 
-		_debug("from R=%08x[%x] s=%llx ctl=%zx/%zx/%zx",
+		_debug("from R=%08x[%x] s=%llx ctl=%zx/%zx",
 		       rreq->debug_id, from->debug_index,
-		       from->start, from->consumed, from->transferred, from->len);
+		       from->start, from->transferred, from->len);
 
 		if (test_bit(NETFS_SREQ_FAILED, &from->flags) ||
 		    !test_bit(NETFS_SREQ_NEED_RETRY, &from->flags))
 			goto abandon;
 
-		deferred_next_donated = from->next_donated;
-		while ((subreq = list_first_entry_or_null(
-				&queue, struct netfs_io_subrequest, rreq_link))) {
-			if (subreq->start != start + len ||
-			    subreq->transferred > 0 ||
+		list_for_each_continue(next, &stream->subrequests) {
+			subreq = list_entry(next, struct netfs_io_subrequest, rreq_link);
+			if (subreq->start + subreq->transferred != start + len ||
+			    test_bit(NETFS_SREQ_BOUNDARY, &subreq->flags) ||
 			    !test_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags))
 				break;
-			list_move_tail(&subreq->rreq_link, &sublist);
-			len += subreq->len;
-			deferred_next_donated = subreq->next_donated;
-			if (test_bit(NETFS_SREQ_BOUNDARY, &subreq->flags))
-				break;
+			to = subreq;
+			len += to->len;
 		}
 
 		_debug(" - range: %llx-%llx %llx", start, start + len - 1, len);
@@ -129,38 +115,33 @@ static void netfs_retry_read_subrequests(struct netfs_io_request *rreq)
 		source.count = len;
 
 		/* Work through the sublist. */
-		while ((subreq = list_first_entry_or_null(
-				&sublist, struct netfs_io_subrequest, rreq_link))) {
-			list_del(&subreq->rreq_link);
-
+		subreq = from;
+		list_for_each_entry_from(subreq, &stream->subrequests, rreq_link) {
+			if (!len) {
+				subreq_superfluous = true;
+				break;
+			}
 			subreq->source	= NETFS_DOWNLOAD_FROM_SERVER;
 			subreq->start	= start - subreq->transferred;
 			subreq->len	= len   + subreq->transferred;
-			stream0->sreq_max_len = subreq->len;
-
 			__clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
 			__clear_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
 			subreq->retry_count++;
 
-			spin_lock_bh(&rreq->lock);
-			list_add_tail(&subreq->rreq_link, &rreq->subrequests);
-			subreq->prev_donated += rreq->prev_donated;
-			rreq->prev_donated = 0;
 			trace_netfs_sreq(subreq, netfs_sreq_trace_retry);
-			spin_unlock_bh(&rreq->lock);
-
-			BUG_ON(!len);
 
 			/* Renegotiate max_len (rsize) */
+			stream->sreq_max_len = subreq->len;
 			if (rreq->netfs_ops->prepare_read &&
 			    rreq->netfs_ops->prepare_read(subreq) < 0) {
 				trace_netfs_sreq(subreq, netfs_sreq_trace_reprep_failed);
 				__set_bit(NETFS_SREQ_FAILED, &subreq->flags);
+				goto abandon;
 			}
 
-			part = umin(len, stream0->sreq_max_len);
-			if (unlikely(rreq->io_streams[0].sreq_max_segs))
-				part = netfs_limit_iter(&source, 0, part, stream0->sreq_max_segs);
+			part = umin(len, stream->sreq_max_len);
+			if (unlikely(stream->sreq_max_segs))
+				part = netfs_limit_iter(&source, 0, part, stream->sreq_max_segs);
 			subreq->len = subreq->transferred + part;
 			subreq->io_iter = source;
 			iov_iter_truncate(&subreq->io_iter, part);
@@ -170,57 +151,105 @@ static void netfs_retry_read_subrequests(struct netfs_io_request *rreq)
 			if (!len) {
 				if (boundary)
 					__set_bit(NETFS_SREQ_BOUNDARY, &subreq->flags);
-				subreq->next_donated = deferred_next_donated;
 			} else {
 				__clear_bit(NETFS_SREQ_BOUNDARY, &subreq->flags);
-				subreq->next_donated = 0;
 			}
 
+			netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit);
 			netfs_reissue_read(rreq, subreq);
-			if (!len)
+			if (subreq == to) {
+				subreq_superfluous = false;
 				break;
-
-			/* If we ran out of subrequests, allocate another. */
-			if (list_empty(&sublist)) {
-				subreq = netfs_alloc_subrequest(rreq);
-				if (!subreq)
-					goto abandon;
-				subreq->source = NETFS_DOWNLOAD_FROM_SERVER;
-				subreq->start = start;
-
-				/* We get two refs, but need just one. */
-				netfs_put_subrequest(subreq, false, netfs_sreq_trace_new);
-				trace_netfs_sreq(subreq, netfs_sreq_trace_split);
-				list_add_tail(&subreq->rreq_link, &sublist);
 			}
 		}
 
 		/* If we managed to use fewer subreqs, we can discard the
-		 * excess.
+		 * excess; if we used the same number, then we're done.
 		 */
-		while ((subreq = list_first_entry_or_null(
-				&sublist, struct netfs_io_subrequest, rreq_link))) {
-			trace_netfs_sreq(subreq, netfs_sreq_trace_discard);
-			list_del(&subreq->rreq_link);
-			netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_done);
+		if (!len) {
+			if (!subreq_superfluous)
+				continue;
+			list_for_each_entry_safe_from(subreq, tmp,
+						      &stream->subrequests, rreq_link) {
+				trace_netfs_sreq(subreq, netfs_sreq_trace_superfluous);
+				list_del(&subreq->rreq_link);
+				netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_done);
+				if (subreq == to)
+					break;
+			}
+			continue;
 		}
 
-	} while (!list_empty(&queue));
+		/* We ran out of subrequests, so we need to allocate some more
+		 * and insert them after.
+		 */
+		do {
+			subreq = netfs_alloc_subrequest(rreq);
+			if (!subreq) {
+				subreq = to;
+				goto abandon_after;
+			}
+			subreq->source		= NETFS_DOWNLOAD_FROM_SERVER;
+			subreq->start		= start;
+			subreq->len		= len;
+			subreq->stream_nr	= stream->stream_nr;
+			subreq->retry_count	= 1;
+
+			trace_netfs_sreq_ref(rreq->debug_id, subreq->debug_index,
+					     refcount_read(&subreq->ref),
+					     netfs_sreq_trace_new);
+
+			list_add(&subreq->rreq_link, &to->rreq_link);
+			to = list_next_entry(to, rreq_link);
+			trace_netfs_sreq(subreq, netfs_sreq_trace_retry);
+
+			stream->sreq_max_len	= umin(len, rreq->rsize);
+			stream->sreq_max_segs	= 0;
+			if (unlikely(stream->sreq_max_segs))
+				part = netfs_limit_iter(&source, 0, part, stream->sreq_max_segs);
+
+			netfs_stat(&netfs_n_rh_download);
+			if (rreq->netfs_ops->prepare_read(subreq) < 0) {
+				trace_netfs_sreq(subreq, netfs_sreq_trace_reprep_failed);
+				__set_bit(NETFS_SREQ_FAILED, &subreq->flags);
+				goto abandon;
+			}
+
+			part = umin(len, stream->sreq_max_len);
+			subreq->len = subreq->transferred + part;
+			subreq->io_iter = source;
+			iov_iter_truncate(&subreq->io_iter, part);
+			iov_iter_advance(&source, part);
+
+			len -= part;
+			start += part;
+			if (!len && boundary) {
+				__set_bit(NETFS_SREQ_BOUNDARY, &to->flags);
+				boundary = false;
+			}
+
+			netfs_reissue_read(rreq, subreq);
+		} while (len);
+
+	} while (!list_is_head(next, &stream->subrequests));
 
 	return;
 
-	/* If we hit ENOMEM, fail all remaining subrequests */
+	/* If we hit an error, fail all remaining incomplete subrequests */
+abandon_after:
+	if (list_is_last(&subreq->rreq_link, &stream->subrequests))
+		return;
+	subreq = list_next_entry(subreq, rreq_link);
 abandon:
-	list_splice_init(&sublist, &queue);
-	list_for_each_entry(subreq, &queue, rreq_link) {
-		if (!subreq->error)
-			subreq->error = -ENOMEM;
-		__clear_bit(NETFS_SREQ_FAILED, &subreq->flags);
+	list_for_each_entry_from(subreq, &stream->subrequests, rreq_link) {
+		if (!subreq->error &&
+		    !test_bit(NETFS_SREQ_FAILED, &subreq->flags) &&
+		    !test_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags))
+			continue;
+		subreq->error = -ENOMEM;
+		__set_bit(NETFS_SREQ_FAILED, &subreq->flags);
 		__clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
 	}
-	spin_lock_bh(&rreq->lock);
-	list_splice_tail_init(&queue, &rreq->subrequests);
-	spin_unlock_bh(&rreq->lock);
 }
 
 /*
@@ -228,14 +257,39 @@ abandon:
  */
 void netfs_retry_reads(struct netfs_io_request *rreq)
 {
-	trace_netfs_rreq(rreq, netfs_rreq_trace_resubmit);
+	struct netfs_io_subrequest *subreq;
+	struct netfs_io_stream *stream = &rreq->io_streams[0];
+	DEFINE_WAIT(myself);
 
-	atomic_inc(&rreq->nr_outstanding);
+	netfs_stat(&netfs_n_rh_retry_read_req);
 
-	netfs_retry_read_subrequests(rreq);
+	set_bit(NETFS_RREQ_RETRYING, &rreq->flags);
+
+	/* Wait for all outstanding I/O to quiesce before performing retries as
+	 * we may need to renegotiate the I/O sizes.
+	 */
+	list_for_each_entry(subreq, &stream->subrequests, rreq_link) {
+		if (!test_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags))
+			continue;
+
+		trace_netfs_rreq(rreq, netfs_rreq_trace_wait_queue);
+		for (;;) {
+			prepare_to_wait(&rreq->waitq, &myself, TASK_UNINTERRUPTIBLE);
+
+			if (!test_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags))
+				break;
 
-	if (atomic_dec_and_test(&rreq->nr_outstanding))
-		netfs_rreq_terminated(rreq, false);
+			trace_netfs_sreq(subreq, netfs_sreq_trace_wait_for);
+			schedule();
+			trace_netfs_rreq(rreq, netfs_rreq_trace_woke_queue);
+		}
+
+		finish_wait(&rreq->waitq, &myself);
+	}
+	clear_bit(NETFS_RREQ_RETRYING, &rreq->flags);
+
+	trace_netfs_rreq(rreq, netfs_rreq_trace_resubmit);
+	netfs_retry_read_subrequests(rreq);
 }
 
 /*
@@ -246,7 +300,7 @@ void netfs_unlock_abandoned_read_pages(struct netfs_io_request *rreq)
 {
 	struct folio_queue *p;
 
-	for (p = rreq->buffer; p; p = p->next) {
+	for (p = rreq->buffer.tail; p; p = p->next) {
 		for (int slot = 0; slot < folioq_count(p); slot++) {
 			struct folio *folio = folioq_folio(p, slot);