libceph: fix socket read error handling

If we get EAGAIN when trying to read from the socket, it is not an error.
Return 0 from the helper in this case to simplify the error handling cases
in the caller (indirectly, try_read).

Fix try_read to pass any error to it's caller (con_work) instead of almost
always returning 0.  This let's us respond to things like socket
disconnects.

Signed-off-by: Sage Weil <sage@newdream.net>

1 files changed, 19 insertions, 20 deletions

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index dff633d62e5b..d95576d40c98 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -252,8 +252,12 @@ static int ceph_tcp_recvmsg(struct socket *sock, void *buf, size_t len)
 {
         struct kvec iov = {buf, len};
         struct msghdr msg = { .msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL };
+        int r;
 
-        return kernel_recvmsg(sock, &msg, &iov, 1, len, msg.msg_flags);
+        r = kernel_recvmsg(sock, &msg, &iov, 1, len, msg.msg_flags);
+        if (r == -EAGAIN)
+                r = 0;
+        return r;
 }
 
 /*
@@ -1821,19 +1825,17 @@ more:
                         dout("try_read connecting\n");
                         ret = read_partial_banner(con);
                         if (ret <= 0)
-                                goto done;
-                        if (process_banner(con) < 0) {
-                                ret = -1;
                                 goto out;
-                        }
+                        ret = process_banner(con);
+                        if (ret < 0)
+                                goto out;
                 }
                 ret = read_partial_connect(con);
                 if (ret <= 0)
-                        goto done;
-                if (process_connect(con) < 0) {
-                        ret = -1;
                         goto out;
-                }
+                ret = process_connect(con);
+                if (ret < 0)
+                        goto out;
                 goto more;
         }
 
@@ -1848,7 +1850,7 @@ more:
                 dout("skipping %d / %d bytes\n", skip, -con->in_base_pos);
                 ret = ceph_tcp_recvmsg(con->sock, buf, skip);
                 if (ret <= 0)
-                        goto done;
+                        goto out;
                 con->in_base_pos += ret;
                 if (con->in_base_pos)
                         goto more;
@@ -1859,7 +1861,7 @@ more:
                  */
                 ret = ceph_tcp_recvmsg(con->sock, &con->in_tag, 1);
                 if (ret <= 0)
-                        goto done;
+                        goto out;
                 dout("try_read got tag %d\n", (int)con->in_tag);
                 switch (con->in_tag) {
                 case CEPH_MSGR_TAG_MSG:
@@ -1870,7 +1872,7 @@ more:
                         break;
                 case CEPH_MSGR_TAG_CLOSE:
                         set_bit(CLOSED, &con->state);   /* fixme */
-                        goto done;
+                        goto out;
                 default:
                         goto bad_tag;
                 }
@@ -1882,13 +1884,12 @@ more:
                         case -EBADMSG:
                                 con->error_msg = "bad crc";
                                 ret = -EIO;
-                                goto out;
+                                break;
                         case -EIO:
                                 con->error_msg = "io error";
-                                goto out;
-                        default:
-                                goto done;
+                                break;
                         }
+                        goto out;
                 }
                 if (con->in_tag == CEPH_MSGR_TAG_READY)
                         goto more;
@@ -1898,15 +1899,13 @@ more:
         if (con->in_tag == CEPH_MSGR_TAG_ACK) {
                 ret = read_partial_ack(con);
                 if (ret <= 0)
-                        goto done;
+                        goto out;
                 process_ack(con);
                 goto more;
         }
 
-done:
-        ret = 0;
 out:
-        dout("try_read done on %p\n", con);
+        dout("try_read done on %p ret %d\n", con, ret);
         return ret;
 
 bad_tag: