ocfs2: Add metaecc for ocfs2_refcount_block.
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / md / dm-log-userspace-transfer.c
blob0ca1ee768a1fcf4ac0f995813e69485dad4b6d0f
1 /*
2 * Copyright (C) 2006-2009 Red Hat, Inc.
4 * This file is released under the LGPL.
5 */
7 #include <linux/kernel.h>
8 #include <linux/module.h>
9 #include <net/sock.h>
10 #include <linux/workqueue.h>
11 #include <linux/connector.h>
12 #include <linux/device-mapper.h>
13 #include <linux/dm-log-userspace.h>
15 #include "dm-log-userspace-transfer.h"
17 static uint32_t dm_ulog_seq;
20 * Netlink/Connector is an unreliable protocol. How long should
21 * we wait for a response before assuming it was lost and retrying?
22 * (If we do receive a response after this time, it will be discarded
23 * and the response to the resent request will be waited for.
25 #define DM_ULOG_RETRY_TIMEOUT (15 * HZ)
28 * Pre-allocated space for speed
30 #define DM_ULOG_PREALLOCED_SIZE 512
31 static struct cn_msg *prealloced_cn_msg;
32 static struct dm_ulog_request *prealloced_ulog_tfr;
34 static struct cb_id ulog_cn_id = {
35 .idx = CN_IDX_DM,
36 .val = CN_VAL_DM_USERSPACE_LOG
39 static DEFINE_MUTEX(dm_ulog_lock);
41 struct receiving_pkg {
42 struct list_head list;
43 struct completion complete;
45 uint32_t seq;
47 int error;
48 size_t *data_size;
49 char *data;
52 static DEFINE_SPINLOCK(receiving_list_lock);
53 static struct list_head receiving_list;
55 static int dm_ulog_sendto_server(struct dm_ulog_request *tfr)
57 int r;
58 struct cn_msg *msg = prealloced_cn_msg;
60 memset(msg, 0, sizeof(struct cn_msg));
62 msg->id.idx = ulog_cn_id.idx;
63 msg->id.val = ulog_cn_id.val;
64 msg->ack = 0;
65 msg->seq = tfr->seq;
66 msg->len = sizeof(struct dm_ulog_request) + tfr->data_size;
68 r = cn_netlink_send(msg, 0, gfp_any());
70 return r;
74 * Parameters for this function can be either msg or tfr, but not
75 * both. This function fills in the reply for a waiting request.
76 * If just msg is given, then the reply is simply an ACK from userspace
77 * that the request was received.
79 * Returns: 0 on success, -ENOENT on failure
81 static int fill_pkg(struct cn_msg *msg, struct dm_ulog_request *tfr)
83 uint32_t rtn_seq = (msg) ? msg->seq : (tfr) ? tfr->seq : 0;
84 struct receiving_pkg *pkg;
87 * The 'receiving_pkg' entries in this list are statically
88 * allocated on the stack in 'dm_consult_userspace'.
89 * Each process that is waiting for a reply from the user
90 * space server will have an entry in this list.
92 * We are safe to do it this way because the stack space
93 * is unique to each process, but still addressable by
94 * other processes.
96 list_for_each_entry(pkg, &receiving_list, list) {
97 if (rtn_seq != pkg->seq)
98 continue;
100 if (msg) {
101 pkg->error = -msg->ack;
103 * If we are trying again, we will need to know our
104 * storage capacity. Otherwise, along with the
105 * error code, we make explicit that we have no data.
107 if (pkg->error != -EAGAIN)
108 *(pkg->data_size) = 0;
109 } else if (tfr->data_size > *(pkg->data_size)) {
110 DMERR("Insufficient space to receive package [%u] "
111 "(%u vs %lu)", tfr->request_type,
112 tfr->data_size, *(pkg->data_size));
114 *(pkg->data_size) = 0;
115 pkg->error = -ENOSPC;
116 } else {
117 pkg->error = tfr->error;
118 memcpy(pkg->data, tfr->data, tfr->data_size);
119 *(pkg->data_size) = tfr->data_size;
121 complete(&pkg->complete);
122 return 0;
125 return -ENOENT;
129 * This is the connector callback that delivers data
130 * that was sent from userspace.
132 static void cn_ulog_callback(void *data)
134 struct cn_msg *msg = (struct cn_msg *)data;
135 struct dm_ulog_request *tfr = (struct dm_ulog_request *)(msg + 1);
137 spin_lock(&receiving_list_lock);
138 if (msg->len == 0)
139 fill_pkg(msg, NULL);
140 else if (msg->len < sizeof(*tfr))
141 DMERR("Incomplete message received (expected %u, got %u): [%u]",
142 (unsigned)sizeof(*tfr), msg->len, msg->seq);
143 else
144 fill_pkg(NULL, tfr);
145 spin_unlock(&receiving_list_lock);
149 * dm_consult_userspace
150 * @uuid: log's uuid (must be DM_UUID_LEN in size)
151 * @request_type: found in include/linux/dm-log-userspace.h
152 * @data: data to tx to the server
153 * @data_size: size of data in bytes
154 * @rdata: place to put return data from server
155 * @rdata_size: value-result (amount of space given/amount of space used)
157 * rdata_size is undefined on failure.
159 * Memory used to communicate with userspace is zero'ed
160 * before populating to ensure that no unwanted bits leak
161 * from kernel space to user-space. All userspace log communications
162 * between kernel and user space go through this function.
164 * Returns: 0 on success, -EXXX on failure
166 int dm_consult_userspace(const char *uuid, int request_type,
167 char *data, size_t data_size,
168 char *rdata, size_t *rdata_size)
170 int r = 0;
171 size_t dummy = 0;
172 int overhead_size =
173 sizeof(struct dm_ulog_request *) + sizeof(struct cn_msg);
174 struct dm_ulog_request *tfr = prealloced_ulog_tfr;
175 struct receiving_pkg pkg;
177 if (data_size > (DM_ULOG_PREALLOCED_SIZE - overhead_size)) {
178 DMINFO("Size of tfr exceeds preallocated size");
179 return -EINVAL;
182 if (!rdata_size)
183 rdata_size = &dummy;
184 resend:
186 * We serialize the sending of requests so we can
187 * use the preallocated space.
189 mutex_lock(&dm_ulog_lock);
191 memset(tfr, 0, DM_ULOG_PREALLOCED_SIZE - overhead_size);
192 memcpy(tfr->uuid, uuid, DM_UUID_LEN);
193 tfr->seq = dm_ulog_seq++;
196 * Must be valid request type (all other bits set to
197 * zero). This reserves other bits for possible future
198 * use.
200 tfr->request_type = request_type & DM_ULOG_REQUEST_MASK;
202 tfr->data_size = data_size;
203 if (data && data_size)
204 memcpy(tfr->data, data, data_size);
206 memset(&pkg, 0, sizeof(pkg));
207 init_completion(&pkg.complete);
208 pkg.seq = tfr->seq;
209 pkg.data_size = rdata_size;
210 pkg.data = rdata;
211 spin_lock(&receiving_list_lock);
212 list_add(&(pkg.list), &receiving_list);
213 spin_unlock(&receiving_list_lock);
215 r = dm_ulog_sendto_server(tfr);
217 mutex_unlock(&dm_ulog_lock);
219 if (r) {
220 DMERR("Unable to send log request [%u] to userspace: %d",
221 request_type, r);
222 spin_lock(&receiving_list_lock);
223 list_del_init(&(pkg.list));
224 spin_unlock(&receiving_list_lock);
226 goto out;
229 r = wait_for_completion_timeout(&(pkg.complete), DM_ULOG_RETRY_TIMEOUT);
230 spin_lock(&receiving_list_lock);
231 list_del_init(&(pkg.list));
232 spin_unlock(&receiving_list_lock);
233 if (!r) {
234 DMWARN("[%s] Request timed out: [%u/%u] - retrying",
235 (strlen(uuid) > 8) ?
236 (uuid + (strlen(uuid) - 8)) : (uuid),
237 request_type, pkg.seq);
238 goto resend;
241 r = pkg.error;
242 if (r == -EAGAIN)
243 goto resend;
245 out:
246 return r;
249 int dm_ulog_tfr_init(void)
251 int r;
252 void *prealloced;
254 INIT_LIST_HEAD(&receiving_list);
256 prealloced = kmalloc(DM_ULOG_PREALLOCED_SIZE, GFP_KERNEL);
257 if (!prealloced)
258 return -ENOMEM;
260 prealloced_cn_msg = prealloced;
261 prealloced_ulog_tfr = prealloced + sizeof(struct cn_msg);
263 r = cn_add_callback(&ulog_cn_id, "dmlogusr", cn_ulog_callback);
264 if (r) {
265 cn_del_callback(&ulog_cn_id);
266 return r;
269 return 0;
272 void dm_ulog_tfr_exit(void)
274 cn_del_callback(&ulog_cn_id);
275 kfree(prealloced_cn_msg);