netfs: zero the tail of a short DIO/unbuffered readgrafted

The buffered read collector zero-fills the tail of a short read that
stops below the inode's i_size (netfs_clear_unread()), so a read that
races an extending write still returns the expected number of bytes.
The non-buffered collector path does no such thing: it just records
how much was transferred.

Add the same zero-fill for the non-buffered case, gated on
NETFS_SREQ_CLEAR_TAIL: a subreq's source sets that flag when a short
result from it is known to be safe to treat as a hole, as opposed to
NETFS_SREQ_HIT_EOF, which means the read genuinely ran off the end of
the file and should be reported short as-is. Only CLEAR_TAIL should
zero-fill here; a real EOF must stay a real short read.

No source currently sets CLEAR_TAIL on an unbuffered/DIO subrequest,
so this is inert on its own -- a following change teaches cifs to set
it in the one case that needs it.

Fixes: e2d46f2ec332 ("netfs: Change the read result collector to only use one work item")
Reviewed-by: David Howells <dhowells@redhat.com>
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Paulo Alcantara <pc@manguebit.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Cc: Shyam Prasad N <sprasad@microsoft.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Bharath SM <bharathsm@microsoft.com>
Cc: stable@vger.kernel.org

1 files changed, 92 insertions, 0 deletions

diff --git a/drivers/usb/chipidea/trace.h b/drivers/usb/chipidea/trace.h
new file mode 100644
index 000000000..1875419cd
--- /dev/null
+++ b/drivers/usb/chipidea/trace.h
@@ -0,0 +1,92 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Trace support header file for device mode
+ *
+ * Copyright (C) 2020 NXP
+ *
+ * Author: Peter Chen <peter.chen@nxp.com>
+ */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM chipidea
+
+#if !defined(__LINUX_CHIPIDEA_TRACE) || defined(TRACE_HEADER_MULTI_READ)
+#define __LINUX_CHIPIDEA_TRACE
+
+#include <linux/types.h>
+#include <linux/tracepoint.h>
+#include <linux/usb/chipidea.h>
+#include "ci.h"
+#include "udc.h"
+
+#define CHIPIDEA_MSG_MAX	500
+
+void ci_log(struct ci_hdrc *ci, const char *fmt, ...);
+
+TRACE_EVENT(ci_log,
+	TP_PROTO(struct ci_hdrc *ci, struct va_format *vaf),
+	TP_ARGS(ci, vaf),
+	TP_STRUCT__entry(
+		__string(name, dev_name(ci->dev))
+		__vstring(msg, vaf->fmt, vaf->va)
+	),
+	TP_fast_assign(
+		__assign_str(name);
+		__assign_vstr(msg, vaf->fmt, vaf->va);
+	),
+	TP_printk("%s: %s", __get_str(name), __get_str(msg))
+);
+
+DECLARE_EVENT_CLASS(ci_log_trb,
+	TP_PROTO(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq, struct td_node *td),
+	TP_ARGS(hwep, hwreq, td),
+	TP_STRUCT__entry(
+		__string(name, hwep->name)
+		__field(struct td_node *, td)
+		__field(struct usb_request *, req)
+		__field(dma_addr_t, dma)
+		__field(s32, td_remaining_size)
+		__field(u32, next)
+		__field(u32, token)
+		__field(u32, type)
+	),
+	TP_fast_assign(
+		__assign_str(name);
+		__entry->req = &hwreq->req;
+		__entry->td = td;
+		__entry->dma = td->dma;
+		__entry->td_remaining_size = td->td_remaining_size;
+		__entry->next = le32_to_cpu(td->ptr->next);
+		__entry->token = le32_to_cpu(td->ptr->token);
+		__entry->type = usb_endpoint_type(hwep->ep.desc);
+	),
+	TP_printk("%s: req: %p, td: %p, td_dma_address: %pad, remaining_size: %d, "
+	       "next: %x, total bytes: %d, status: %lx",
+		__get_str(name), __entry->req, __entry->td, &__entry->dma,
+		__entry->td_remaining_size, __entry->next,
+		(int)((__entry->token & TD_TOTAL_BYTES) >> __ffs(TD_TOTAL_BYTES)),
+		__entry->token & TD_STATUS
+	)
+);
+
+DEFINE_EVENT(ci_log_trb, ci_prepare_td,
+	TP_PROTO(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq, struct td_node *td),
+	TP_ARGS(hwep, hwreq, td)
+);
+
+DEFINE_EVENT(ci_log_trb, ci_complete_td,
+	TP_PROTO(struct ci_hw_ep *hwep, struct ci_hw_req *hwreq, struct td_node *td),
+	TP_ARGS(hwep, hwreq, td)
+);
+
+#endif /* __LINUX_CHIPIDEA_TRACE */
+
+/* this part must be outside header guard */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE trace
+
+#include <trace/define_trace.h>