splice: fix sendfile() issue with relay

Splice isn't always incrementing the ppos correctly, which broke
relay splice.

Signed-off-by: Tom Zanussi <zanussi@comcast.net>
Tested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

2 files changed, 9 insertions, 5 deletions

diff --git a/fs/splice.c b/fs/splice.c
index 78150038b584..a048ad2130c3 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -983,7 +983,7 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
 
         while (len) {
                 size_t read_len;
-                loff_t pos = sd->pos;
+                loff_t pos = sd->pos, prev_pos = pos;
 
                 ret = do_splice_to(in, &pos, pipe, len, flags);
                 if (unlikely(ret <= 0))
@@ -998,15 +998,19 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
                  * could get stuck data in the internal pipe:
                  */
                 ret = actor(pipe, sd);
-                if (unlikely(ret <= 0))
+                if (unlikely(ret <= 0)) {
+                        sd->pos = prev_pos;
                         goto out_release;
+                }
 
                 bytes += ret;
                 len -= ret;
                 sd->pos = pos;
 
-                if (ret < read_len)
+                if (ret < read_len) {
+                        sd->pos = prev_pos + ret;
                         goto out_release;
+                }
         }
 
 done:
@@ -1072,7 +1076,7 @@ long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
 
         ret = splice_direct_to_actor(in, &sd, direct_splice_actor);
         if (ret > 0)
-                *ppos += ret;
+                *ppos = sd.pos;
 
         return ret;
 }
diff --git a/kernel/relay.c b/kernel/relay.c
index bc24dcdc570f..7de644cdec43 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -1191,7 +1191,7 @@ static ssize_t relay_file_splice_read(struct file *in,
         ret = 0;
         spliced = 0;
 
-        while (len) {
+        while (len && !spliced) {
                 ret = subbuf_splice_actor(in, ppos, pipe, len, flags, &nonpad_ret);
                 if (ret < 0)
                         break;