1 files changed, 14 insertions, 12 deletions

diff --git a/fs/netfs/read_collect.c b/fs/netfs/read_collect.c
index e70eb4ea21c0..eae415efae24 100644
--- a/fs/netfs/read_collect.c
+++ b/fs/netfs/read_collect.c
@@ -249,9 +249,9 @@ donation_changed:
 
 	/* Deal with the trickiest case: that this subreq is in the middle of a
 	 * folio, not touching either edge, but finishes first.  In such a
-	 * case, we donate to the previous subreq, if there is one, so that the
-	 * donation is only handled when that completes - and remove this
-	 * subreq from the list.
+	 * case, we donate to the previous subreq, if there is one and if it is
+	 * contiguous, so that the donation is only handled when that completes
+	 * - and remove this subreq from the list.
 	 *
 	 * If the previous subreq finished first, we will have acquired their
 	 * donation and should be able to unlock folios and/or donate nextwards.
@@ -260,14 +260,16 @@ donation_changed:
 	    !prev_donated &&
 	    !list_is_first(&subreq->rreq_link, &rreq->subrequests)) {
 		prev = list_prev_entry(subreq, rreq_link);
-		WRITE_ONCE(prev->next_donated, prev->next_donated + subreq->len);
-		subreq->start += subreq->len;
-		subreq->len = 0;
-		subreq->transferred = 0;
-		trace_netfs_donate(rreq, subreq, prev, subreq->len,
-				   netfs_trace_donate_to_prev);
-		trace_netfs_sreq(subreq, netfs_sreq_trace_donate_to_prev);
-		goto remove_subreq_locked;
+		if (subreq->start == prev->start + prev->len) {
+			WRITE_ONCE(prev->next_donated, prev->next_donated + subreq->len);
+			subreq->start += subreq->len;
+			subreq->len = 0;
+			subreq->transferred = 0;
+			trace_netfs_donate(rreq, subreq, prev, subreq->len,
+					   netfs_trace_donate_to_prev);
+			trace_netfs_sreq(subreq, netfs_sreq_trace_donate_to_prev);
+			goto remove_subreq_locked;
+		}
 	}
 
 	/* If we can't donate down the chain, donate up the chain instead. */
@@ -282,7 +284,7 @@ donation_changed:
 				   netfs_trace_donate_to_deferred_next);
 	} else {
 		next = list_next_entry(subreq, rreq_link);
-		WRITE_ONCE(next->prev_donated, excess);
+		WRITE_ONCE(next->prev_donated, next->prev_donated + excess);
 		trace_netfs_donate(rreq, subreq, next, excess,
 				   netfs_trace_donate_to_next);
 	}