[PATCH v7 13/15] io_uring: Add tracepoint for short writes

Stefan Roesch
2022-06-01T21:04:53Z

This adds the io_uring_short_write tracepoint to io_uring. A short write
is issued if not all pages that are required for a write are in the page
cache and the async buffered writes have to return EAGAIN.

Signed-off-by: Stefan Roesch <shr@fb.com>
---
fs/io_uring.c | 3 +++
include/trace/events/io_uring.h | 25 +++++++++++++++++++++++++
2 files changed, 28 insertions(+)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index c0771e215669..9ab68138f442 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4543,6 +4543,9 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags)
if (ret2 != req->cqe.res && ret2 >= 0 && need_complete_io(req)) {
struct io_async_rw *rw;

+ trace_io_uring_short_write(req->ctx, kiocb->ki_pos - ret2,
+ req->cqe.res, ret2);
+
/* This is a partial write. The file pos has already been
* updated, setup the async struct to complete the request
* in the worker. Also update bytes_done to account for
diff --git a/include/trace/events/io_uring.h b/include/trace/events/io_uring.h
index 66fcc5a1a5b1..25df513660cc 100644
--- a/include/trace/events/io_uring.h
+++ b/include/trace/events/io_uring.h
@@ -600,6 +600,31 @@ TRACE_EVENT(io_uring_cqe_overflow,
__entry->cflags, __entry->ocqe)
);

+TRACE_EVENT(io_uring_short_write,
+
+ TP_PROTO(void *ctx, u64 fpos, u64 wanted, u64 got),
+
+ TP_ARGS(ctx, fpos, wanted, got),
+
+ TP_STRUCT__entry(
+ __field(void *, ctx)
+ __field(u64, fpos)
+ __field(u64, wanted)
+ __field(u64, got)
+ ),
+
+ TP_fast_assign(
+ __entry->ctx = ctx;
+ __entry->fpos = fpos;
+ __entry->wanted = wanted;
+ __entry->got = got;
+ ),
+
+ TP_printk("ring %p, fpos %lld, wanted %lld, got %lld",
+ __entry->ctx, __entry->fpos,
+ __entry->wanted, __entry->got)
+);
+
#endif /* _TRACE_IO_URING_H */

/* This part must be outside protection */
--
2.30.2