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>

diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index dff633d..d95576d 100644 (file)
--- 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: