This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / fs / dlm / midcomms.c

diff --git a/fs/dlm/midcomms.c b/fs/dlm/midcomms.c
new file mode 100644 (file)
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+++ b/fs/dlm/midcomms.c
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+/******************************************************************************
+*******************************************************************************
+**
+**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
+**  Copyright (C) 2004-2005 Red Hat, Inc.  All rights reserved.
+**
+**  This copyrighted material is made available to anyone wishing to use,
+**  modify, copy, or redistribute it subject to the terms and conditions
+**  of the GNU General Public License v.2.
+**
+*******************************************************************************
+******************************************************************************/
+
+/*
+ * midcomms.c
+ *
+ * This is the appallingly named "mid-level" comms layer.
+ *
+ * Its purpose is to take packets from the "real" comms layer,
+ * split them up into packets and pass them to the interested
+ * part of the locking mechanism.
+ *
+ * It also takes messages from the locking layer, formats them
+ * into packets and sends them to the comms layer.
+ */
+
+#include "dlm_internal.h"
+#include "lowcomms.h"
+#include "config.h"
+#include "rcom.h"
+#include "lock.h"
+#include "midcomms.h"
+
+
+static void copy_from_cb(void *dst, const void *base, unsigned offset,
+                        unsigned len, unsigned limit)
+{
+       unsigned copy = len;
+
+       if ((copy + offset) > limit)
+               copy = limit - offset;
+       memcpy(dst, base + offset, copy);
+       len -= copy;
+       if (len)
+               memcpy(dst + copy, base, len);
+}
+
+/*
+ * Called from the low-level comms layer to process a buffer of
+ * commands.
+ *
+ * Only complete messages are processed here, any "spare" bytes from
+ * the end of a buffer are saved and tacked onto the front of the next
+ * message that comes in. I doubt this will happen very often but we
+ * need to be able to cope with it and I don't want the task to be waiting
+ * for packets to come in when there is useful work to be done.
+ */
+
+int dlm_process_incoming_buffer(int nodeid, const void *base,
+                               unsigned offset, unsigned len, unsigned limit)
+{
+       unsigned char __tmp[DLM_INBUF_LEN];
+       struct dlm_header *msg = (struct dlm_header *) __tmp;
+       int ret = 0;
+       int err = 0;
+       uint16_t msglen;
+       uint32_t lockspace;
+
+       while (len > sizeof(struct dlm_header)) {
+
+               /* Copy just the header to check the total length.  The
+                  message may wrap around the end of the buffer back to the
+                  start, so we need to use a temp buffer and copy_from_cb. */
+
+               copy_from_cb(msg, base, offset, sizeof(struct dlm_header),
+                            limit);
+
+               msglen = le16_to_cpu(msg->h_length);
+               lockspace = msg->h_lockspace;
+
+               err = -EINVAL;
+               if (msglen < sizeof(struct dlm_header))
+                       break;
+               err = -E2BIG;
+               if (msglen > dlm_config.ci_buffer_size) {
+                       log_print("message size %d from %d too big, buf len %d",
+                                 msglen, nodeid, len);
+                       break;
+               }
+               err = 0;
+
+               /* If only part of the full message is contained in this
+                  buffer, then do nothing and wait for lowcomms to call
+                  us again later with more data.  We return 0 meaning
+                  we've consumed none of the input buffer. */
+
+               if (msglen > len)
+                       break;
+
+               /* Allocate a larger temp buffer if the full message won't fit
+                  in the buffer on the stack (which should work for most
+                  ordinary messages). */
+
+               if (msglen > sizeof(__tmp) &&
+                   msg == (struct dlm_header *) __tmp) {
+                       msg = kmalloc(dlm_config.ci_buffer_size, GFP_KERNEL);
+                       if (msg == NULL)
+                               return ret;
+               }
+
+               copy_from_cb(msg, base, offset, msglen, limit);
+
+               BUG_ON(lockspace != msg->h_lockspace);
+
+               ret += msglen;
+               offset += msglen;
+               offset &= (limit - 1);
+               len -= msglen;
+
+               switch (msg->h_cmd) {
+               case DLM_MSG:
+                       dlm_receive_message(msg, nodeid, 0);
+                       break;
+
+               case DLM_RCOM:
+                       dlm_receive_rcom(msg, nodeid);
+                       break;
+
+               default:
+                       log_print("unknown msg type %x from %u: %u %u %u %u",
+                                 msg->h_cmd, nodeid, msglen, len, offset, ret);
+               }
+       }
+
+       if (msg != (struct dlm_header *) __tmp)
+               kfree(msg);
+
+       return err ? err : ret;
+}
+