[SCSI] iscsi: add high mem support

From Mike Christie <michaelc@cs.wisc.edu> and FUJITA Tomonori <tomof@acm.org>:

We cannot use page_address becuase some pages could be highmem.
Instead, we can use sock_no_sendpage which does kmap for us.

Signed-off-by: Alex Aizman <itn780@yahoo.com>
Signed-off-by: Dmitry Yusupov <dmitry_yus@yahoo.com>
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

2 files changed, 31 insertions, 55 deletions

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index 5e8b3135574c..0acc4b235d9b 100644
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -87,35 +87,32 @@ iscsi_buf_init_virt(struct iscsi_buf *ibuf, char *vbuf, int size)
 {
         sg_init_one(&ibuf->sg, (u8 *)vbuf, size);
         ibuf->sent = 0;
+        ibuf->use_sendmsg = 0;
 }
 
 static inline void
 iscsi_buf_init_iov(struct iscsi_buf *ibuf, char *vbuf, int size)
 {
-        ibuf->sg.page = (void*)vbuf;
-        ibuf->sg.offset = (unsigned int)-1;
+        ibuf->sg.page = virt_to_page(vbuf);
+        ibuf->sg.offset = offset_in_page(vbuf);
         ibuf->sg.length = size;
         ibuf->sent = 0;
-}
-
-static inline void*
-iscsi_buf_iov_base(struct iscsi_buf *ibuf)
-{
-        return (char*)ibuf->sg.page + ibuf->sent;
+        ibuf->use_sendmsg = 1;
 }
 
 static inline void
 iscsi_buf_init_sg(struct iscsi_buf *ibuf, struct scatterlist *sg)
 {
+        ibuf->sg.page = sg->page;
+        ibuf->sg.offset = sg->offset;
+        ibuf->sg.length = sg->length;
         /*
          * Fastpath: sg element fits into single page
          */
-        if (sg->length + sg->offset <= PAGE_SIZE && page_count(sg->page) >= 2) {
-                ibuf->sg.page = sg->page;
-                ibuf->sg.offset = sg->offset;
-                ibuf->sg.length = sg->length;
-        } else
-                iscsi_buf_init_iov(ibuf, page_address(sg->page), sg->length);
+        if (sg->length + sg->offset <= PAGE_SIZE && page_count(sg->page) >= 2)
+                ibuf->use_sendmsg = 0;
+        else
+                ibuf->use_sendmsg = 1;
         ibuf->sent = 0;
 }
 
@@ -1311,35 +1308,25 @@ iscsi_conn_restore_callbacks(struct iscsi_conn *conn)
  * @buf: buffer to write from
  * @size: actual size to write
  * @flags: socket's flags
- *
- * Notes:
- *      depending on buffer will use tcp_sendpage() or tcp_sendmsg().
- *      buf->sg.offset == -1 tells us that buffer is non S/G and forces
- *      to use tcp_sendmsg().
  */
 static inline int
 iscsi_send(struct iscsi_conn *conn, struct iscsi_buf *buf, int size, int flags)
 {
         struct socket *sk = conn->sock;
-        int res;
-
-        if ((int)buf->sg.offset >= 0) {
-                int offset = buf->sg.offset + buf->sent;
-
-                res = conn->sendpage(sk, buf->sg.page, offset, size, flags);
-        } else {
-                struct msghdr msg;
-
-                buf->iov.iov_base = iscsi_buf_iov_base(buf);
-                buf->iov.iov_len = size;
-
-                memset(&msg, 0, sizeof(struct msghdr));
-
-                /* tcp_sendmsg */
-                res = kernel_sendmsg(sk, &msg, &buf->iov, 1, size);
-        }
+        int offset = buf->sg.offset + buf->sent;
 
-        return res;
+        /*
+         * if we got use_sg=0 or are sending something we kmallocd
+         * then we did not have to do kmap (kmap returns page_address)
+         *
+         * if we got use_sg > 0, but had to drop down, we do not
+         * set clustering so this should only happen for that
+         * slab case.
+         */
+        if (buf->use_sendmsg)
+                return sock_no_sendpage(sk, buf->sg.page, offset, size, flags);
+        else
+                return conn->sendpage(sk, buf->sg.page, offset, size, flags);
 }
 
 /**
@@ -1431,19 +1418,6 @@ iscsi_data_digest_init(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
         ctask->digest_count = 4;
 }
 
-static inline void
-iscsi_buf_data_digest_update(struct iscsi_conn *conn, struct iscsi_buf *buf)
-{
-        struct scatterlist sg;
-
-        if (buf->sg.offset != -1)
-                crypto_digest_update(conn->data_tx_tfm, &buf->sg, 1);
-        else {
-                sg_init_one(&sg, (char *)buf->sg.page, buf->sg.length);
-                crypto_digest_update(conn->data_tx_tfm, &sg, 1);
-        }
-}
-
 static inline int
 iscsi_digest_final_send(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask,
                         struct iscsi_buf *buf, uint32_t *digest, int final)
@@ -1806,7 +1780,8 @@ handle_xmstate_imm_data(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
                         return -EAGAIN;
                 }
                 if (conn->datadgst_en)
-                        iscsi_buf_data_digest_update(conn, &ctask->sendbuf);
+                        crypto_digest_update(conn->data_tx_tfm,
+                                             &ctask->sendbuf.sg, 1);
 
                 if (!ctask->imm_count)
                         break;
@@ -1891,7 +1866,8 @@ handle_xmstate_uns_data(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
                  * so pass it
                  */
                 if (conn->datadgst_en && ctask->sent - start > 0)
-                        iscsi_buf_data_digest_update(conn, &ctask->sendbuf);
+                        crypto_digest_update(conn->data_tx_tfm,
+                                             &ctask->sendbuf.sg, 1);
 
                 if (!ctask->data_count)
                         break;
@@ -1969,7 +1945,7 @@ solicit_again:
 
         BUG_ON(r2t->data_count < 0);
         if (conn->datadgst_en)
-                iscsi_buf_data_digest_update(conn, &r2t->sendbuf);
+                crypto_digest_update(conn->data_tx_tfm, &r2t->sendbuf.sg, 1);
 
         if (r2t->data_count) {
                 BUG_ON(ctask->sc->use_sg == 0);
@@ -2051,7 +2027,7 @@ handle_xmstate_w_pad(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
         }
 
         if (conn->datadgst_en) {
-                iscsi_buf_data_digest_update(conn, &ctask->sendbuf);
+                crypto_digest_update(conn->data_tx_tfm, &ctask->sendbuf.sg, 1);
                 /* imm data? */
                 if (!dtask) {
                         if (iscsi_digest_final_send(conn, ctask, &ctask->immbuf,
diff --git a/drivers/scsi/iscsi_tcp.h b/drivers/scsi/iscsi_tcp.h
index c8bb5b0bcb4b..f95e61b76f70 100644
--- a/drivers/scsi/iscsi_tcp.h
+++ b/drivers/scsi/iscsi_tcp.h
@@ -242,8 +242,8 @@ struct iscsi_session {
 
 struct iscsi_buf {
         struct scatterlist      sg;
-        struct kvec             iov;
         unsigned int            sent;
+        char                    use_sendmsg;
 };
 
 struct iscsi_data_task {