diff options
Diffstat (limited to 'fs/dlm/midcomms.c')
| -rw-r--r-- | fs/dlm/midcomms.c | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/fs/dlm/midcomms.c b/fs/dlm/midcomms.c new file mode 100644 index 000000000..f3396c622 --- /dev/null +++ b/fs/dlm/midcomms.c @@ -0,0 +1,137 @@ +/****************************************************************************** +******************************************************************************* +** +** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved. +** Copyright (C) 2004-2008 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 "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) +{ + union { + unsigned char __buf[DLM_INBUF_LEN]; + /* this is to force proper alignment on some arches */ + union dlm_packet p; + } __tmp; + union dlm_packet *p = &__tmp.p; + 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(p, base, offset, sizeof(struct dlm_header), + limit); + + msglen = le16_to_cpu(p->header.h_length); + lockspace = p->header.h_lockspace; + + err = -EINVAL; + if (msglen < sizeof(struct dlm_header)) + break; + if (p->header.h_cmd == DLM_MSG) { + if (msglen < sizeof(struct dlm_message)) + break; + } else { + if (msglen < sizeof(struct dlm_rcom)) + 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) && p == &__tmp.p) { + p = kmalloc(dlm_config.ci_buffer_size, GFP_NOFS); + if (p == NULL) + return ret; + } + + copy_from_cb(p, base, offset, msglen, limit); + + BUG_ON(lockspace != p->header.h_lockspace); + + ret += msglen; + offset += msglen; + offset &= (limit - 1); + len -= msglen; + + dlm_receive_buffer(p, nodeid); + } + + if (p != &__tmp.p) + kfree(p); + + return err ? err : ret; +} + |