netfs: Drop the was_async arg from netfs_read_subreq_terminated()

Drop the was_async argument from netfs_read_subreq_terminated().  Almost
every caller is either in process context and passes false.  Some
filesystems delegate the call to a workqueue to avoid doing the work in
their network message queue parsing thread.

The only exception is netfs_cache_read_terminated() which handles
completion in the cache - which is usually a callback from the backing
filesystem in softirq context, though it can be from process context if an
error occurred.  In this case, delegate to a workqueue.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/CAHk-=wiVC5Cgyz6QKXFu6fTaA6h4CjexDR-OV9kL6Vo5x9v8=A@mail.gmail.com/
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20241216204124.3752367-10-dhowells@redhat.com
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs/netfs/buffered_read.c

@@ -154,7 +154,7 @@ static void netfs_cache_read_terminated(void *priv, ssize_t transferred_or_error
 	} else {
 		subreq->error = transferred_or_error;
 	}
-	netfs_read_subreq_terminated(subreq, was_async);
+	schedule_work(&subreq->work);
 }
 
 /*
@@ -255,7 +255,7 @@ static void netfs_read_to_pagecache(struct netfs_io_request *rreq)
 				goto prep_iter_failed;
 			__set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
 			subreq->error = 0;
-			netfs_read_subreq_terminated(subreq, false);
+			netfs_read_subreq_terminated(subreq);
 			goto done;
 		}
 
@@ -287,7 +287,7 @@ static void netfs_read_to_pagecache(struct netfs_io_request *rreq)
 	} while (size > 0);
 
 	if (atomic_dec_and_test(&rreq->nr_outstanding))
-		netfs_rreq_terminated(rreq, false);
+		netfs_rreq_terminated(rreq);
 
 	/* Defer error return as we may need to wait for outstanding I/O. */
 	cmpxchg(&rreq->error, 0, ret);

fs/netfs/direct_read.c

@@ -100,7 +100,7 @@ static int netfs_dispatch_unbuffered_reads(struct netfs_io_request *rreq)
 	} while (size > 0);
 
 	if (atomic_dec_and_test(&rreq->nr_outstanding))
-		netfs_rreq_terminated(rreq, false);
+		netfs_rreq_terminated(rreq);
 	return ret;
 }
 

fs/netfs/internal.h

@@ -85,7 +85,7 @@ static inline void netfs_see_request(struct netfs_io_request *rreq,
  * read_collect.c
  */
 void netfs_read_termination_worker(struct work_struct *work);
-void netfs_rreq_terminated(struct netfs_io_request *rreq, bool was_async);
+void netfs_rreq_terminated(struct netfs_io_request *rreq);
 
 /*
  * read_pgpriv2.c

fs/netfs/objects.c

@@ -56,7 +56,7 @@ struct netfs_io_request *netfs_alloc_request(struct address_space *mapping,
 	    origin == NETFS_READ_GAPS ||
 	    origin == NETFS_READ_FOR_WRITE ||
 	    origin == NETFS_DIO_READ)
-		INIT_WORK(&rreq->work, netfs_read_termination_worker);
+		INIT_WORK(&rreq->work, NULL);
 	else
 		INIT_WORK(&rreq->work, netfs_write_collection_worker);
 

fs/netfs/read_collect.c

@@ -87,7 +87,7 @@ static void netfs_unlock_read_folio(struct netfs_io_subrequest *subreq,
  * Unlock any folios that are now completely read.  Returns true if the
  * subrequest is removed from the list.
  */
-static bool netfs_consume_read_data(struct netfs_io_subrequest *subreq, bool was_async)
+static bool netfs_consume_read_data(struct netfs_io_subrequest *subreq)
 {
 	struct netfs_io_subrequest *prev, *next;
 	struct netfs_io_request *rreq = subreq->rreq;
@@ -230,8 +230,7 @@ donation_changed:
 		subreq->curr_folioq_slot = slot;
 		if (folioq && folioq_folio(folioq, slot))
 			subreq->curr_folio_order = folioq->orders[slot];
-		if (!was_async)
-			cond_resched();
+		cond_resched();
 		goto next_folio;
 	}
 
@@ -368,7 +367,7 @@ static void netfs_rreq_assess_dio(struct netfs_io_request *rreq)
  * Note that we're in normal kernel thread context at this point, possibly
  * running on a workqueue.
  */
-static void netfs_rreq_assess(struct netfs_io_request *rreq)
+void netfs_rreq_terminated(struct netfs_io_request *rreq)
 {
 	trace_netfs_rreq(rreq, netfs_rreq_trace_assess);
 
@@ -394,56 +393,29 @@ static void netfs_rreq_assess(struct netfs_io_request *rreq)
 		netfs_pgpriv2_write_to_the_cache(rreq);
 }
 
-void netfs_read_termination_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);
-	netfs_rreq_assess(rreq);
-	netfs_put_request(rreq, false, netfs_rreq_trace_put_work_complete);
-}
-
-/*
- * Handle the completion of all outstanding I/O operations on a read request.
- * We inherit a ref from the caller.
- */
-void netfs_rreq_terminated(struct netfs_io_request *rreq, bool was_async)
-{
-	if (!was_async)
-		return netfs_rreq_assess(rreq);
-	if (!work_pending(&rreq->work)) {
-		netfs_get_request(rreq, netfs_rreq_trace_get_work);
-		if (!queue_work(system_unbound_wq, &rreq->work))
-			netfs_put_request(rreq, was_async, netfs_rreq_trace_put_work_nq);
-	}
-}
-
 /**
  * netfs_read_subreq_progress - Note progress of a read operation.
  * @subreq: The read request that has terminated.
- * @was_async: True if we're in an asynchronous context.
  *
  * This tells the read side of netfs lib that a contributory I/O operation has
  * made some progress and that it may be possible to unlock some folios.
  *
  * Before calling, the filesystem should update subreq->transferred to track
  * the amount of data copied into the output buffer.
- *
- * If @was_async is true, the caller might be running in softirq or interrupt
- * context and we can't sleep.
  */
-void netfs_read_subreq_progress(struct netfs_io_subrequest *subreq,
-				bool was_async)
+void netfs_read_subreq_progress(struct netfs_io_subrequest *subreq)
 {
 	struct netfs_io_request *rreq = subreq->rreq;
 
+	might_sleep();
+
 	trace_netfs_sreq(subreq, netfs_sreq_trace_progress);
 
 	if (subreq->transferred > subreq->consumed &&
 	    (rreq->origin == NETFS_READAHEAD ||
 	     rreq->origin == NETFS_READPAGE ||
 	     rreq->origin == NETFS_READ_FOR_WRITE)) {
-		netfs_consume_read_data(subreq, was_async);
+		netfs_consume_read_data(subreq);
 		__set_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
 	}
 }
@@ -452,7 +424,6 @@ EXPORT_SYMBOL(netfs_read_subreq_progress);
 /**
  * netfs_read_subreq_terminated - Note the termination of an I/O operation.
  * @subreq: The I/O request that has terminated.
- * @was_async: True if we're in an asynchronous context.
  *
  * This tells the read helper that a contributory I/O operation has terminated,
  * one way or another, and that it should integrate the results.
@@ -466,7 +437,7 @@ EXPORT_SYMBOL(netfs_read_subreq_progress);
  * Before calling, the filesystem should update subreq->transferred to track
  * the amount of data copied into the output buffer.
  */
-void netfs_read_subreq_terminated(struct netfs_io_subrequest *subreq, bool was_async)
+void netfs_read_subreq_terminated(struct netfs_io_subrequest *subreq)
 {
 	struct netfs_io_request *rreq = subreq->rreq;
 
@@ -500,7 +471,7 @@ void netfs_read_subreq_terminated(struct netfs_io_subrequest *subreq, bool was_a
 		    (rreq->origin == NETFS_READAHEAD ||
 		     rreq->origin == NETFS_READPAGE ||
 		     rreq->origin == NETFS_READ_FOR_WRITE)) {
-			netfs_consume_read_data(subreq, was_async);
+			netfs_consume_read_data(subreq);
 			__set_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
 		}
 		rreq->transferred += subreq->transferred;
@@ -545,9 +516,9 @@ void netfs_read_subreq_terminated(struct netfs_io_subrequest *subreq, bool was_a
 	}
 
 	if (atomic_dec_and_test(&rreq->nr_outstanding))
-		netfs_rreq_terminated(rreq, was_async);
+		netfs_rreq_terminated(rreq);
 
-	netfs_put_subrequest(subreq, was_async, netfs_sreq_trace_put_terminated);
+	netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_terminated);
 }
 EXPORT_SYMBOL(netfs_read_subreq_terminated);
 
@@ -563,6 +534,6 @@ void netfs_read_subreq_termination_worker(struct work_struct *work)
 	struct netfs_io_subrequest *subreq =
 		container_of(work, struct netfs_io_subrequest, work);
 
-	netfs_read_subreq_terminated(subreq, false);
+	netfs_read_subreq_terminated(subreq);
 }
 EXPORT_SYMBOL(netfs_read_subreq_termination_worker);

fs/netfs/read_retry.c

@@ -234,7 +234,7 @@ void netfs_retry_reads(struct netfs_io_request *rreq)
 	netfs_retry_read_subrequests(rreq);
 
 	if (atomic_dec_and_test(&rreq->nr_outstanding))
-		netfs_rreq_terminated(rreq, false);
+		netfs_rreq_terminated(rreq);
 }
 
 /*