netfs: Fix double put of request

If a netfs request finishes during the pause loop, it will have the ref
that belongs to the IN_PROGRESS flag removed at that point - however, if it
then goes to the final wait loop, that will *also* put the ref because it
sees that the IN_PROGRESS flag is clear and incorrectly assumes that this
happened when it called the collector.

In fact, since IN_PROGRESS is clear, we shouldn't call the collector again
since it's done all the cleanup, such as calling ->ki_complete().

Fix this by making netfs_collect_in_app() just return, indicating that
we're done if IN_PROGRESS is removed.

Fixes: 2b1424c ("netfs: Fix wait/wake to be consistent about the waitqueue used")
Signed-off-by: David Howells <[email protected]>
Link: https://lore.kernel.org/[email protected]
Tested-by: Steve French <[email protected]>
Reviewed-by: Paulo Alcantara <[email protected]>
cc: Steve French <[email protected]>
cc: [email protected]
cc: [email protected]
cc: [email protected]
Signed-off-by: Christian Brauner <[email protected]>

Author: dhowells

fs/netfs/misc.c

@@ -383,6 +383,11 @@ static int netfs_collect_in_app(struct netfs_io_request *rreq,
 {
 	bool need_collect = false, inactive = true, done = true;
 
+	if (!netfs_check_rreq_in_progress(rreq)) {
+		trace_netfs_rreq(rreq, netfs_rreq_trace_recollect);
+		return 1; /* Done */
+	}
+
 	for (int i = 0; i < NR_IO_STREAMS; i++) {
 		struct netfs_io_subrequest *subreq;
 		struct netfs_io_stream *stream = &rreq->io_streams[i];

include/trace/events/netfs.h

@@ -56,6 +56,7 @@
 	EM(netfs_rreq_trace_dirty,		"DIRTY  ")	\
 	EM(netfs_rreq_trace_done,		"DONE   ")	\
 	EM(netfs_rreq_trace_free,		"FREE   ")	\
+	EM(netfs_rreq_trace_recollect,		"RECLLCT")	\
 	EM(netfs_rreq_trace_redirty,		"REDIRTY")	\
 	EM(netfs_rreq_trace_resubmit,		"RESUBMT")	\
 	EM(netfs_rreq_trace_set_abandon,	"S-ABNDN")	\