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

[David Howells <dhowells@redhat.com>]

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 ")	\