relay file read: start-pos fix

Fix a bug in the relay read interface causing the number of consumed bytes
to be set incorrectly.

Signed-off-by: Tom Zanussi <zanussi@us.ibm.com>
Signed-off-by: David Wilder <dwilder@us.ibm.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/kernel/relay.c b/kernel/relay.c
index 4311101b0ca7..e61156ea4e25 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -899,7 +899,10 @@ static size_t relay_file_read_start_pos(size_t read_pos,
         size_t read_subbuf, padding, padding_start, padding_end;
         size_t subbuf_size = buf->chan->subbuf_size;
         size_t n_subbufs = buf->chan->n_subbufs;
+        size_t consumed = buf->subbufs_consumed % n_subbufs;
 
+        if (!read_pos)
+                read_pos = consumed * subbuf_size + buf->bytes_consumed;
         read_subbuf = read_pos / subbuf_size;
         padding = buf->padding[read_subbuf];
         padding_start = (read_subbuf + 1) * subbuf_size - padding;