tracing: update file->f_pos when splice(2) it

Impact: Cleanup

These two lines:

	if (unlikely(*ppos))
		return -ESPIPE;

in tracing_buffers_splice_read() are not needed, VFS layer
has disabled seek(2).

We remove these two lines, and then we can update file->f_pos.

And tracing_buffers_read() updates file->f_pos, this fix
make tracing_buffers_splice_read() updates file->f_pos too.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <49D46670.4010503@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 1 insertions, 7 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8e189ffb899a..94629760dabf 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3428,13 +3428,6 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
         int size, i;
         size_t ret;
 
-        /*
-         * We can't seek on a buffer input
-         */
-        if (unlikely(*ppos))
-                return -ESPIPE;
-
-
         for (i = 0; i < PIPE_BUFFERS && len; i++, len -= size) {
                 struct page *page;
                 int r;
@@ -3474,6 +3467,7 @@ tracing_buffers_splice_read(struct file *file, loff_t *ppos,
                 spd.partial[i].offset = 0;
                 spd.partial[i].private = (unsigned long)ref;
                 spd.nr_pages++;
+                *ppos += size;
         }
 
         spd.nr_pages = i;