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1#include <linux/fs.h>
2#include <linux/random.h>
3#include <linux/buffer_head.h>
4#include <linux/utsname.h>
5#include <linux/kthread.h>
6
7#include "ext4.h"
8
9/* Checksumming functions */
10static __u32 ext4_mmp_csum(struct super_block *sb, struct mmp_struct *mmp)
11{
12 struct ext4_sb_info *sbi = EXT4_SB(sb);
13 int offset = offsetof(struct mmp_struct, mmp_checksum);
14 __u32 csum;
15
16 csum = ext4_chksum(sbi, sbi->s_csum_seed, (char *)mmp, offset);
17
18 return cpu_to_le32(csum);
19}
20
21int ext4_mmp_csum_verify(struct super_block *sb, struct mmp_struct *mmp)
22{
23 if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
24 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
25 return 1;
26
27 return mmp->mmp_checksum == ext4_mmp_csum(sb, mmp);
28}
29
30void ext4_mmp_csum_set(struct super_block *sb, struct mmp_struct *mmp)
31{
32 if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
33 EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
34 return;
35
36 mmp->mmp_checksum = ext4_mmp_csum(sb, mmp);
37}
38
39/*
40 * Write the MMP block using WRITE_SYNC to try to get the block on-disk
41 * faster.
42 */
43static int write_mmp_block(struct super_block *sb, struct buffer_head *bh)
44{
45 struct mmp_struct *mmp = (struct mmp_struct *)(bh->b_data);
46
47 ext4_mmp_csum_set(sb, mmp);
48 mark_buffer_dirty(bh);
49 lock_buffer(bh);
50 bh->b_end_io = end_buffer_write_sync;
51 get_bh(bh);
52 submit_bh(WRITE_SYNC, bh);
53 wait_on_buffer(bh);
54 if (unlikely(!buffer_uptodate(bh)))
55 return 1;
56
57 return 0;
58}
59
60/*
61 * Read the MMP block. It _must_ be read from disk and hence we clear the
62 * uptodate flag on the buffer.
63 */
64static int read_mmp_block(struct super_block *sb, struct buffer_head **bh,
65 ext4_fsblk_t mmp_block)
66{
67 struct mmp_struct *mmp;
68
69 if (*bh)
70 clear_buffer_uptodate(*bh);
71
72 /* This would be sb_bread(sb, mmp_block), except we need to be sure
73 * that the MD RAID device cache has been bypassed, and that the read
74 * is not blocked in the elevator. */
75 if (!*bh)
76 *bh = sb_getblk(sb, mmp_block);
77 if (*bh) {
78 get_bh(*bh);
79 lock_buffer(*bh);
80 (*bh)->b_end_io = end_buffer_read_sync;
81 submit_bh(READ_SYNC, *bh);
82 wait_on_buffer(*bh);
83 if (!buffer_uptodate(*bh)) {
84 brelse(*bh);
85 *bh = NULL;
86 }
87 }
88 if (!*bh) {
89 ext4_warning(sb, "Error while reading MMP block %llu",
90 mmp_block);
91 return -EIO;
92 }
93
94 mmp = (struct mmp_struct *)((*bh)->b_data);
95 if (le32_to_cpu(mmp->mmp_magic) != EXT4_MMP_MAGIC ||
96 !ext4_mmp_csum_verify(sb, mmp))
97 return -EINVAL;
98
99 return 0;
100}
101
102/*
103 * Dump as much information as possible to help the admin.
104 */
105void __dump_mmp_msg(struct super_block *sb, struct mmp_struct *mmp,
106 const char *function, unsigned int line, const char *msg)
107{
108 __ext4_warning(sb, function, line, msg);
109 __ext4_warning(sb, function, line,
110 "MMP failure info: last update time: %llu, last update "
111 "node: %s, last update device: %s\n",
112 (long long unsigned int) le64_to_cpu(mmp->mmp_time),
113 mmp->mmp_nodename, mmp->mmp_bdevname);
114}
115
116/*
117 * kmmpd will update the MMP sequence every s_mmp_update_interval seconds
118 */
119static int kmmpd(void *data)
120{
121 struct super_block *sb = ((struct mmpd_data *) data)->sb;
122 struct buffer_head *bh = ((struct mmpd_data *) data)->bh;
123 struct ext4_super_block *es = EXT4_SB(sb)->s_es;
124 struct mmp_struct *mmp;
125 ext4_fsblk_t mmp_block;
126 u32 seq = 0;
127 unsigned long failed_writes = 0;
128 int mmp_update_interval = le16_to_cpu(es->s_mmp_update_interval);
129 unsigned mmp_check_interval;
130 unsigned long last_update_time;
131 unsigned long diff;
132 int retval;
133
134 mmp_block = le64_to_cpu(es->s_mmp_block);
135 mmp = (struct mmp_struct *)(bh->b_data);
136 mmp->mmp_time = cpu_to_le64(get_seconds());
137 /*
138 * Start with the higher mmp_check_interval and reduce it if
139 * the MMP block is being updated on time.
140 */
141 mmp_check_interval = max(EXT4_MMP_CHECK_MULT * mmp_update_interval,
142 EXT4_MMP_MIN_CHECK_INTERVAL);
143 mmp->mmp_check_interval = cpu_to_le16(mmp_check_interval);
144 bdevname(bh->b_bdev, mmp->mmp_bdevname);
145
146 memcpy(mmp->mmp_nodename, init_utsname()->nodename,
147 sizeof(mmp->mmp_nodename));
148
149 while (!kthread_should_stop()) {
150 if (++seq > EXT4_MMP_SEQ_MAX)
151 seq = 1;
152
153 mmp->mmp_seq = cpu_to_le32(seq);
154 mmp->mmp_time = cpu_to_le64(get_seconds());
155 last_update_time = jiffies;
156
157 retval = write_mmp_block(sb, bh);
158 /*
159 * Don't spew too many error messages. Print one every
160 * (s_mmp_update_interval * 60) seconds.
161 */
162 if (retval) {
163 if ((failed_writes % 60) == 0)
164 ext4_error(sb, "Error writing to MMP block");
165 failed_writes++;
166 }
167
168 if (!(le32_to_cpu(es->s_feature_incompat) &
169 EXT4_FEATURE_INCOMPAT_MMP)) {
170 ext4_warning(sb, "kmmpd being stopped since MMP feature"
171 " has been disabled.");
172 EXT4_SB(sb)->s_mmp_tsk = NULL;
173 goto failed;
174 }
175
176 if (sb->s_flags & MS_RDONLY) {
177 ext4_warning(sb, "kmmpd being stopped since filesystem "
178 "has been remounted as readonly.");
179 EXT4_SB(sb)->s_mmp_tsk = NULL;
180 goto failed;
181 }
182
183 diff = jiffies - last_update_time;
184 if (diff < mmp_update_interval * HZ)
185 schedule_timeout_interruptible(mmp_update_interval *
186 HZ - diff);
187
188 /*
189 * We need to make sure that more than mmp_check_interval
190 * seconds have not passed since writing. If that has happened
191 * we need to check if the MMP block is as we left it.
192 */
193 diff = jiffies - last_update_time;
194 if (diff > mmp_check_interval * HZ) {
195 struct buffer_head *bh_check = NULL;
196 struct mmp_struct *mmp_check;
197
198 retval = read_mmp_block(sb, &bh_check, mmp_block);
199 if (retval) {
200 ext4_error(sb, "error reading MMP data: %d",
201 retval);
202
203 EXT4_SB(sb)->s_mmp_tsk = NULL;
204 goto failed;
205 }
206
207 mmp_check = (struct mmp_struct *)(bh_check->b_data);
208 if (mmp->mmp_seq != mmp_check->mmp_seq ||
209 memcmp(mmp->mmp_nodename, mmp_check->mmp_nodename,
210 sizeof(mmp->mmp_nodename))) {
211 dump_mmp_msg(sb, mmp_check,
212 "Error while updating MMP info. "
213 "The filesystem seems to have been"
214 " multiply mounted.");
215 ext4_error(sb, "abort");
216 goto failed;
217 }
218 put_bh(bh_check);
219 }
220
221 /*
222 * Adjust the mmp_check_interval depending on how much time
223 * it took for the MMP block to be written.
224 */
225 mmp_check_interval = max(min(EXT4_MMP_CHECK_MULT * diff / HZ,
226 EXT4_MMP_MAX_CHECK_INTERVAL),
227 EXT4_MMP_MIN_CHECK_INTERVAL);
228 mmp->mmp_check_interval = cpu_to_le16(mmp_check_interval);
229 }
230
231 /*
232 * Unmount seems to be clean.
233 */
234 mmp->mmp_seq = cpu_to_le32(EXT4_MMP_SEQ_CLEAN);
235 mmp->mmp_time = cpu_to_le64(get_seconds());
236
237 retval = write_mmp_block(sb, bh);
238
239failed:
240 kfree(data);
241 brelse(bh);
242 return retval;
243}
244
245/*
246 * Get a random new sequence number but make sure it is not greater than
247 * EXT4_MMP_SEQ_MAX.
248 */
249static unsigned int mmp_new_seq(void)
250{
251 u32 new_seq;
252
253 do {
254 get_random_bytes(&new_seq, sizeof(u32));
255 } while (new_seq > EXT4_MMP_SEQ_MAX);
256
257 return new_seq;
258}
259
260/*
261 * Protect the filesystem from being mounted more than once.
262 */
263int ext4_multi_mount_protect(struct super_block *sb,
264 ext4_fsblk_t mmp_block)
265{
266 struct ext4_super_block *es = EXT4_SB(sb)->s_es;
267 struct buffer_head *bh = NULL;
268 struct mmp_struct *mmp = NULL;
269 struct mmpd_data *mmpd_data;
270 u32 seq;
271 unsigned int mmp_check_interval = le16_to_cpu(es->s_mmp_update_interval);
272 unsigned int wait_time = 0;
273 int retval;
274
275 if (mmp_block < le32_to_cpu(es->s_first_data_block) ||
276 mmp_block >= ext4_blocks_count(es)) {
277 ext4_warning(sb, "Invalid MMP block in superblock");
278 goto failed;
279 }
280
281 retval = read_mmp_block(sb, &bh, mmp_block);
282 if (retval)
283 goto failed;
284
285 mmp = (struct mmp_struct *)(bh->b_data);
286
287 if (mmp_check_interval < EXT4_MMP_MIN_CHECK_INTERVAL)
288 mmp_check_interval = EXT4_MMP_MIN_CHECK_INTERVAL;
289
290 /*
291 * If check_interval in MMP block is larger, use that instead of
292 * update_interval from the superblock.
293 */
294 if (le16_to_cpu(mmp->mmp_check_interval) > mmp_check_interval)
295 mmp_check_interval = le16_to_cpu(mmp->mmp_check_interval);
296
297 seq = le32_to_cpu(mmp->mmp_seq);
298 if (seq == EXT4_MMP_SEQ_CLEAN)
299 goto skip;
300
301 if (seq == EXT4_MMP_SEQ_FSCK) {
302 dump_mmp_msg(sb, mmp, "fsck is running on the filesystem");
303 goto failed;
304 }
305
306 wait_time = min(mmp_check_interval * 2 + 1,
307 mmp_check_interval + 60);
308
309 /* Print MMP interval if more than 20 secs. */
310 if (wait_time > EXT4_MMP_MIN_CHECK_INTERVAL * 4)
311 ext4_warning(sb, "MMP interval %u higher than expected, please"
312 " wait.\n", wait_time * 2);
313
314 if (schedule_timeout_interruptible(HZ * wait_time) != 0) {
315 ext4_warning(sb, "MMP startup interrupted, failing mount\n");
316 goto failed;
317 }
318
319 retval = read_mmp_block(sb, &bh, mmp_block);
320 if (retval)
321 goto failed;
322 mmp = (struct mmp_struct *)(bh->b_data);
323 if (seq != le32_to_cpu(mmp->mmp_seq)) {
324 dump_mmp_msg(sb, mmp,
325 "Device is already active on another node.");
326 goto failed;
327 }
328
329skip:
330 /*
331 * write a new random sequence number.
332 */
333 seq = mmp_new_seq();
334 mmp->mmp_seq = cpu_to_le32(seq);
335
336 retval = write_mmp_block(sb, bh);
337 if (retval)
338 goto failed;
339
340 /*
341 * wait for MMP interval and check mmp_seq.
342 */
343 if (schedule_timeout_interruptible(HZ * wait_time) != 0) {
344 ext4_warning(sb, "MMP startup interrupted, failing mount\n");
345 goto failed;
346 }
347
348 retval = read_mmp_block(sb, &bh, mmp_block);
349 if (retval)
350 goto failed;
351 mmp = (struct mmp_struct *)(bh->b_data);
352 if (seq != le32_to_cpu(mmp->mmp_seq)) {
353 dump_mmp_msg(sb, mmp,
354 "Device is already active on another node.");
355 goto failed;
356 }
357
358 mmpd_data = kmalloc(sizeof(struct mmpd_data), GFP_KERNEL);
359 if (!mmpd_data) {
360 ext4_warning(sb, "not enough memory for mmpd_data");
361 goto failed;
362 }
363 mmpd_data->sb = sb;
364 mmpd_data->bh = bh;
365
366 /*
367 * Start a kernel thread to update the MMP block periodically.
368 */
369 EXT4_SB(sb)->s_mmp_tsk = kthread_run(kmmpd, mmpd_data, "kmmpd-%s",
370 bdevname(bh->b_bdev,
371 mmp->mmp_bdevname));
372 if (IS_ERR(EXT4_SB(sb)->s_mmp_tsk)) {
373 EXT4_SB(sb)->s_mmp_tsk = NULL;
374 kfree(mmpd_data);
375 ext4_warning(sb, "Unable to create kmmpd thread for %s.",
376 sb->s_id);
377 goto failed;
378 }
379
380 return 0;
381
382failed:
383 brelse(bh);
384 return 1;
385}
386
387
1#include <linux/fs.h>
2#include <linux/random.h>
3#include <linux/buffer_head.h>
4#include <linux/utsname.h>
5#include <linux/kthread.h>
6
7#include "ext4.h"
8
9/*
10 * Write the MMP block using WRITE_SYNC to try to get the block on-disk
11 * faster.
12 */
13static int write_mmp_block(struct buffer_head *bh)
14{
15 mark_buffer_dirty(bh);
16 lock_buffer(bh);
17 bh->b_end_io = end_buffer_write_sync;
18 get_bh(bh);
19 submit_bh(WRITE_SYNC, bh);
20 wait_on_buffer(bh);
21 if (unlikely(!buffer_uptodate(bh)))
22 return 1;
23
24 return 0;
25}
26
27/*
28 * Read the MMP block. It _must_ be read from disk and hence we clear the
29 * uptodate flag on the buffer.
30 */
31static int read_mmp_block(struct super_block *sb, struct buffer_head **bh,
32 ext4_fsblk_t mmp_block)
33{
34 struct mmp_struct *mmp;
35
36 if (*bh)
37 clear_buffer_uptodate(*bh);
38
39 /* This would be sb_bread(sb, mmp_block), except we need to be sure
40 * that the MD RAID device cache has been bypassed, and that the read
41 * is not blocked in the elevator. */
42 if (!*bh)
43 *bh = sb_getblk(sb, mmp_block);
44 if (*bh) {
45 get_bh(*bh);
46 lock_buffer(*bh);
47 (*bh)->b_end_io = end_buffer_read_sync;
48 submit_bh(READ_SYNC, *bh);
49 wait_on_buffer(*bh);
50 if (!buffer_uptodate(*bh)) {
51 brelse(*bh);
52 *bh = NULL;
53 }
54 }
55 if (!*bh) {
56 ext4_warning(sb, "Error while reading MMP block %llu",
57 mmp_block);
58 return -EIO;
59 }
60
61 mmp = (struct mmp_struct *)((*bh)->b_data);
62 if (le32_to_cpu(mmp->mmp_magic) != EXT4_MMP_MAGIC)
63 return -EINVAL;
64
65 return 0;
66}
67
68/*
69 * Dump as much information as possible to help the admin.
70 */
71void __dump_mmp_msg(struct super_block *sb, struct mmp_struct *mmp,
72 const char *function, unsigned int line, const char *msg)
73{
74 __ext4_warning(sb, function, line, msg);
75 __ext4_warning(sb, function, line,
76 "MMP failure info: last update time: %llu, last update "
77 "node: %s, last update device: %s\n",
78 (long long unsigned int) le64_to_cpu(mmp->mmp_time),
79 mmp->mmp_nodename, mmp->mmp_bdevname);
80}
81
82/*
83 * kmmpd will update the MMP sequence every s_mmp_update_interval seconds
84 */
85static int kmmpd(void *data)
86{
87 struct super_block *sb = ((struct mmpd_data *) data)->sb;
88 struct buffer_head *bh = ((struct mmpd_data *) data)->bh;
89 struct ext4_super_block *es = EXT4_SB(sb)->s_es;
90 struct mmp_struct *mmp;
91 ext4_fsblk_t mmp_block;
92 u32 seq = 0;
93 unsigned long failed_writes = 0;
94 int mmp_update_interval = le16_to_cpu(es->s_mmp_update_interval);
95 unsigned mmp_check_interval;
96 unsigned long last_update_time;
97 unsigned long diff;
98 int retval;
99
100 mmp_block = le64_to_cpu(es->s_mmp_block);
101 mmp = (struct mmp_struct *)(bh->b_data);
102 mmp->mmp_time = cpu_to_le64(get_seconds());
103 /*
104 * Start with the higher mmp_check_interval and reduce it if
105 * the MMP block is being updated on time.
106 */
107 mmp_check_interval = max(EXT4_MMP_CHECK_MULT * mmp_update_interval,
108 EXT4_MMP_MIN_CHECK_INTERVAL);
109 mmp->mmp_check_interval = cpu_to_le16(mmp_check_interval);
110 bdevname(bh->b_bdev, mmp->mmp_bdevname);
111
112 memcpy(mmp->mmp_nodename, init_utsname()->sysname,
113 sizeof(mmp->mmp_nodename));
114
115 while (!kthread_should_stop()) {
116 if (++seq > EXT4_MMP_SEQ_MAX)
117 seq = 1;
118
119 mmp->mmp_seq = cpu_to_le32(seq);
120 mmp->mmp_time = cpu_to_le64(get_seconds());
121 last_update_time = jiffies;
122
123 retval = write_mmp_block(bh);
124 /*
125 * Don't spew too many error messages. Print one every
126 * (s_mmp_update_interval * 60) seconds.
127 */
128 if (retval && (failed_writes % 60) == 0) {
129 ext4_error(sb, "Error writing to MMP block");
130 failed_writes++;
131 }
132
133 if (!(le32_to_cpu(es->s_feature_incompat) &
134 EXT4_FEATURE_INCOMPAT_MMP)) {
135 ext4_warning(sb, "kmmpd being stopped since MMP feature"
136 " has been disabled.");
137 EXT4_SB(sb)->s_mmp_tsk = NULL;
138 goto failed;
139 }
140
141 if (sb->s_flags & MS_RDONLY) {
142 ext4_warning(sb, "kmmpd being stopped since filesystem "
143 "has been remounted as readonly.");
144 EXT4_SB(sb)->s_mmp_tsk = NULL;
145 goto failed;
146 }
147
148 diff = jiffies - last_update_time;
149 if (diff < mmp_update_interval * HZ)
150 schedule_timeout_interruptible(mmp_update_interval *
151 HZ - diff);
152
153 /*
154 * We need to make sure that more than mmp_check_interval
155 * seconds have not passed since writing. If that has happened
156 * we need to check if the MMP block is as we left it.
157 */
158 diff = jiffies - last_update_time;
159 if (diff > mmp_check_interval * HZ) {
160 struct buffer_head *bh_check = NULL;
161 struct mmp_struct *mmp_check;
162
163 retval = read_mmp_block(sb, &bh_check, mmp_block);
164 if (retval) {
165 ext4_error(sb, "error reading MMP data: %d",
166 retval);
167
168 EXT4_SB(sb)->s_mmp_tsk = NULL;
169 goto failed;
170 }
171
172 mmp_check = (struct mmp_struct *)(bh_check->b_data);
173 if (mmp->mmp_seq != mmp_check->mmp_seq ||
174 memcmp(mmp->mmp_nodename, mmp_check->mmp_nodename,
175 sizeof(mmp->mmp_nodename))) {
176 dump_mmp_msg(sb, mmp_check,
177 "Error while updating MMP info. "
178 "The filesystem seems to have been"
179 " multiply mounted.");
180 ext4_error(sb, "abort");
181 goto failed;
182 }
183 put_bh(bh_check);
184 }
185
186 /*
187 * Adjust the mmp_check_interval depending on how much time
188 * it took for the MMP block to be written.
189 */
190 mmp_check_interval = max(min(EXT4_MMP_CHECK_MULT * diff / HZ,
191 EXT4_MMP_MAX_CHECK_INTERVAL),
192 EXT4_MMP_MIN_CHECK_INTERVAL);
193 mmp->mmp_check_interval = cpu_to_le16(mmp_check_interval);
194 }
195
196 /*
197 * Unmount seems to be clean.
198 */
199 mmp->mmp_seq = cpu_to_le32(EXT4_MMP_SEQ_CLEAN);
200 mmp->mmp_time = cpu_to_le64(get_seconds());
201
202 retval = write_mmp_block(bh);
203
204failed:
205 kfree(data);
206 brelse(bh);
207 return retval;
208}
209
210/*
211 * Get a random new sequence number but make sure it is not greater than
212 * EXT4_MMP_SEQ_MAX.
213 */
214static unsigned int mmp_new_seq(void)
215{
216 u32 new_seq;
217
218 do {
219 get_random_bytes(&new_seq, sizeof(u32));
220 } while (new_seq > EXT4_MMP_SEQ_MAX);
221
222 return new_seq;
223}
224
225/*
226 * Protect the filesystem from being mounted more than once.
227 */
228int ext4_multi_mount_protect(struct super_block *sb,
229 ext4_fsblk_t mmp_block)
230{
231 struct ext4_super_block *es = EXT4_SB(sb)->s_es;
232 struct buffer_head *bh = NULL;
233 struct mmp_struct *mmp = NULL;
234 struct mmpd_data *mmpd_data;
235 u32 seq;
236 unsigned int mmp_check_interval = le16_to_cpu(es->s_mmp_update_interval);
237 unsigned int wait_time = 0;
238 int retval;
239
240 if (mmp_block < le32_to_cpu(es->s_first_data_block) ||
241 mmp_block >= ext4_blocks_count(es)) {
242 ext4_warning(sb, "Invalid MMP block in superblock");
243 goto failed;
244 }
245
246 retval = read_mmp_block(sb, &bh, mmp_block);
247 if (retval)
248 goto failed;
249
250 mmp = (struct mmp_struct *)(bh->b_data);
251
252 if (mmp_check_interval < EXT4_MMP_MIN_CHECK_INTERVAL)
253 mmp_check_interval = EXT4_MMP_MIN_CHECK_INTERVAL;
254
255 /*
256 * If check_interval in MMP block is larger, use that instead of
257 * update_interval from the superblock.
258 */
259 if (mmp->mmp_check_interval > mmp_check_interval)
260 mmp_check_interval = mmp->mmp_check_interval;
261
262 seq = le32_to_cpu(mmp->mmp_seq);
263 if (seq == EXT4_MMP_SEQ_CLEAN)
264 goto skip;
265
266 if (seq == EXT4_MMP_SEQ_FSCK) {
267 dump_mmp_msg(sb, mmp, "fsck is running on the filesystem");
268 goto failed;
269 }
270
271 wait_time = min(mmp_check_interval * 2 + 1,
272 mmp_check_interval + 60);
273
274 /* Print MMP interval if more than 20 secs. */
275 if (wait_time > EXT4_MMP_MIN_CHECK_INTERVAL * 4)
276 ext4_warning(sb, "MMP interval %u higher than expected, please"
277 " wait.\n", wait_time * 2);
278
279 if (schedule_timeout_interruptible(HZ * wait_time) != 0) {
280 ext4_warning(sb, "MMP startup interrupted, failing mount\n");
281 goto failed;
282 }
283
284 retval = read_mmp_block(sb, &bh, mmp_block);
285 if (retval)
286 goto failed;
287 mmp = (struct mmp_struct *)(bh->b_data);
288 if (seq != le32_to_cpu(mmp->mmp_seq)) {
289 dump_mmp_msg(sb, mmp,
290 "Device is already active on another node.");
291 goto failed;
292 }
293
294skip:
295 /*
296 * write a new random sequence number.
297 */
298 mmp->mmp_seq = seq = cpu_to_le32(mmp_new_seq());
299
300 retval = write_mmp_block(bh);
301 if (retval)
302 goto failed;
303
304 /*
305 * wait for MMP interval and check mmp_seq.
306 */
307 if (schedule_timeout_interruptible(HZ * wait_time) != 0) {
308 ext4_warning(sb, "MMP startup interrupted, failing mount\n");
309 goto failed;
310 }
311
312 retval = read_mmp_block(sb, &bh, mmp_block);
313 if (retval)
314 goto failed;
315 mmp = (struct mmp_struct *)(bh->b_data);
316 if (seq != le32_to_cpu(mmp->mmp_seq)) {
317 dump_mmp_msg(sb, mmp,
318 "Device is already active on another node.");
319 goto failed;
320 }
321
322 mmpd_data = kmalloc(sizeof(struct mmpd_data), GFP_KERNEL);
323 if (!mmpd_data) {
324 ext4_warning(sb, "not enough memory for mmpd_data");
325 goto failed;
326 }
327 mmpd_data->sb = sb;
328 mmpd_data->bh = bh;
329
330 /*
331 * Start a kernel thread to update the MMP block periodically.
332 */
333 EXT4_SB(sb)->s_mmp_tsk = kthread_run(kmmpd, mmpd_data, "kmmpd-%s",
334 bdevname(bh->b_bdev,
335 mmp->mmp_bdevname));
336 if (IS_ERR(EXT4_SB(sb)->s_mmp_tsk)) {
337 EXT4_SB(sb)->s_mmp_tsk = NULL;
338 kfree(mmpd_data);
339 ext4_warning(sb, "Unable to create kmmpd thread for %s.",
340 sb->s_id);
341 goto failed;
342 }
343
344 return 0;
345
346failed:
347 brelse(bh);
348 return 1;
349}
350
351