netfs: Don't use bh spinlock

All the accessing of the subrequest lists is now done in process context,
possibly in a workqueue, but not now in a BH context, so we don't need the
lock against BH interference when taking the netfs_io_request::lock
spinlock.

Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/20241216204124.3752367-11-dhowells@redhat.com
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs/netfs/buffered_read.c

@@ -200,12 +200,12 @@ static void netfs_read_to_pagecache(struct netfs_io_request *rreq)
 		subreq->len	= size;
 
 		atomic_inc(&rreq->nr_outstanding);
-		spin_lock_bh(&rreq->lock);
+		spin_lock(&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_added);
-		spin_unlock_bh(&rreq->lock);
+		spin_unlock(&rreq->lock);
 
 		source = netfs_cache_prepare_read(rreq, subreq, rreq->i_size);
 		subreq->source = source;

fs/netfs/direct_read.c

@@ -68,12 +68,12 @@ static int netfs_dispatch_unbuffered_reads(struct netfs_io_request *rreq)
 		subreq->len	= size;
 
 		atomic_inc(&rreq->nr_outstanding);
-		spin_lock_bh(&rreq->lock);
+		spin_lock(&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_added);
-		spin_unlock_bh(&rreq->lock);
+		spin_unlock(&rreq->lock);
 
 		netfs_stat(&netfs_n_rh_download);
 		if (rreq->netfs_ops->prepare_read) {

fs/netfs/read_collect.c

@@ -144,7 +144,7 @@ donation_changed:
 	prev_donated = READ_ONCE(subreq->prev_donated);
 	next_donated =  READ_ONCE(subreq->next_donated);
 	if (prev_donated || next_donated) {
-		spin_lock_bh(&rreq->lock);
+		spin_lock(&rreq->lock);
 		prev_donated = subreq->prev_donated;
 		next_donated =  subreq->next_donated;
 		subreq->start -= prev_donated;
@@ -157,7 +157,7 @@ donation_changed:
 			next_donated = subreq->next_donated = 0;
 		}
 		trace_netfs_sreq(subreq, netfs_sreq_trace_add_donations);
-		spin_unlock_bh(&rreq->lock);
+		spin_unlock(&rreq->lock);
 	}
 
 	avail = subreq->transferred;
@@ -186,18 +186,18 @@ donation_changed:
 		} else if (fpos < start) {
 			excess = fend - subreq->start;
 
-			spin_lock_bh(&rreq->lock);
+			spin_lock(&rreq->lock);
 			/* If we complete first on a folio split with the
 			 * preceding subreq, donate to that subreq - otherwise
 			 * we get the responsibility.
 			 */
 			if (subreq->prev_donated != prev_donated) {
-				spin_unlock_bh(&rreq->lock);
+				spin_unlock(&rreq->lock);
 				goto donation_changed;
 			}
 
 			if (list_is_first(&subreq->rreq_link, &rreq->subrequests)) {
-				spin_unlock_bh(&rreq->lock);
+				spin_unlock(&rreq->lock);
 				pr_err("Can't donate prior to front\n");
 				goto bad;
 			}
@@ -213,7 +213,7 @@ donation_changed:
 
 			if (subreq->consumed >= subreq->len)
 				goto remove_subreq_locked;
-			spin_unlock_bh(&rreq->lock);
+			spin_unlock(&rreq->lock);
 		} else {
 			pr_err("fpos > start\n");
 			goto bad;
@@ -241,11 +241,11 @@ donation_changed:
 	/* Donate the remaining downloaded data to one of the neighbouring
 	 * subrequests.  Note that we may race with them doing the same thing.
 	 */
-	spin_lock_bh(&rreq->lock);
+	spin_lock(&rreq->lock);
 
 	if (subreq->prev_donated != prev_donated ||
 	    subreq->next_donated != next_donated) {
-		spin_unlock_bh(&rreq->lock);
+		spin_unlock(&rreq->lock);
 		cond_resched();
 		goto donation_changed;
 	}
@@ -296,11 +296,11 @@ donation_changed:
 	goto remove_subreq_locked;
 
 remove_subreq:
-	spin_lock_bh(&rreq->lock);
+	spin_lock(&rreq->lock);
 remove_subreq_locked:
 	subreq->consumed = subreq->len;
 	list_del(&subreq->rreq_link);
-	spin_unlock_bh(&rreq->lock);
+	spin_unlock(&rreq->lock);
 	netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_consumed);
 	return true;
 

fs/netfs/read_retry.c

@@ -142,12 +142,12 @@ static void netfs_retry_read_subrequests(struct netfs_io_request *rreq)
 			__clear_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
 			subreq->retry_count++;
 
-			spin_lock_bh(&rreq->lock);
+			spin_lock(&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);
+			spin_unlock(&rreq->lock);
 
 			BUG_ON(!len);
 
@@ -217,9 +217,9 @@ abandon:
 		__clear_bit(NETFS_SREQ_FAILED, &subreq->flags);
 		__clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
 	}
-	spin_lock_bh(&rreq->lock);
+	spin_lock(&rreq->lock);
 	list_splice_tail_init(&queue, &rreq->subrequests);
-	spin_unlock_bh(&rreq->lock);
+	spin_unlock(&rreq->lock);
 }
 
 /*

fs/netfs/write_collect.c

@@ -238,14 +238,14 @@ reassess_streams:
 
 		cancel:
 			/* Remove if completely consumed. */
-			spin_lock_bh(&wreq->lock);
+			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);
 			stream->front = front;
-			spin_unlock_bh(&wreq->lock);
+			spin_unlock(&wreq->lock);
 			netfs_put_subrequest(remove, false,
 					     notes & SAW_FAILURE ?
 					     netfs_sreq_trace_put_cancel :

fs/netfs/write_issue.c

@@ -203,7 +203,7 @@ static void netfs_prepare_write(struct netfs_io_request *wreq,
 	 * the list.  The collector only goes nextwards and uses the lock to
 	 * remove entries off of the front.
 	 */
-	spin_lock_bh(&wreq->lock);
+	spin_lock(&wreq->lock);
 	list_add_tail(&subreq->rreq_link, &stream->subrequests);
 	if (list_is_first(&subreq->rreq_link, &stream->subrequests)) {
 		stream->front = subreq;
@@ -214,7 +214,7 @@ static void netfs_prepare_write(struct netfs_io_request *wreq,
 		}
 	}
 
-	spin_unlock_bh(&wreq->lock);
+	spin_unlock(&wreq->lock);
 
 	stream->construct = subreq;
 }