[RFC PATCH 16/17] netfs: Check for too much data being read

David Howells
2026-03-04T14:05:37Z

Put in a check in read subreq termination to detect more data being read
for a subrequest than was requested.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Paulo Alcantara <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
---
fs/netfs/read_collect.c | 8 ++++++++
include/trace/events/netfs.h | 1 +
2 files changed, 9 insertions(+)

diff --git a/fs/netfs/read_collect.c b/fs/netfs/read_collect.c
index 3b5978832369..20c80df8914f 100644
--- a/fs/netfs/read_collect.c
+++ b/fs/netfs/read_collect.c
@@ -545,6 +545,14 @@ void netfs_read_subreq_terminated(struct netfs_io_subrequest *subreq)
break;
}

+ if (subreq->transferred > subreq->len) {
+ subreq->transferred = 0;
+ __set_bit(NETFS_SREQ_FAILED, &subreq->flags);
+ __clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
+ trace_netfs_sreq(subreq, netfs_sreq_trace_too_much);
+ subreq->error = -EIO;
+ }
+
/* Deal with retry requests, short reads and errors. If we retry
* but don't make progress, we abandon the attempt.
*/
diff --git a/include/trace/events/netfs.h b/include/trace/events/netfs.h
index 861dc7849067..899b85d7ef92 100644
--- a/include/trace/events/netfs.h
+++ b/include/trace/events/netfs.h
@@ -124,6 +124,7 @@
EM(netfs_sreq_trace_submit, "SUBMT") \
EM(netfs_sreq_trace_superfluous, "SPRFL") \
EM(netfs_sreq_trace_terminated, "TERM ") \
+ EM(netfs_sreq_trace_too_much, "!TOOM") \
EM(netfs_sreq_trace_wait_for, "_WAIT") \
EM(netfs_sreq_trace_write, "WRITE") \
EM(netfs_sreq_trace_write_skip, "SKIP ") \