blob: 6eb1a619890c580786f92a71c342a2eed41be973 [file] [log] [blame]
Johann Lombardic5e06d12011-05-24 18:31:25 -04001#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
Darrick J. Wong5c359a42012-04-29 18:47:10 -04009/* Checksumming functions */
Dmitry Monakhov171a7f22013-04-09 23:56:48 -040010static __le32 ext4_mmp_csum(struct super_block *sb, struct mmp_struct *mmp)
Darrick J. Wong5c359a42012-04-29 18:47:10 -040011{
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
Stephen Hemmingerc1978552014-05-12 10:50:23 -040021static int ext4_mmp_csum_verify(struct super_block *sb, struct mmp_struct *mmp)
Darrick J. Wong5c359a42012-04-29 18:47:10 -040022{
Dmitry Monakhov9aa5d322014-10-13 03:36:16 -040023 if (!ext4_has_metadata_csum(sb))
Darrick J. Wong5c359a42012-04-29 18:47:10 -040024 return 1;
25
26 return mmp->mmp_checksum == ext4_mmp_csum(sb, mmp);
27}
28
Stephen Hemmingerc1978552014-05-12 10:50:23 -040029static void ext4_mmp_csum_set(struct super_block *sb, struct mmp_struct *mmp)
Darrick J. Wong5c359a42012-04-29 18:47:10 -040030{
Dmitry Monakhov9aa5d322014-10-13 03:36:16 -040031 if (!ext4_has_metadata_csum(sb))
Darrick J. Wong5c359a42012-04-29 18:47:10 -040032 return;
33
34 mmp->mmp_checksum = ext4_mmp_csum(sb, mmp);
35}
36
Johann Lombardic5e06d12011-05-24 18:31:25 -040037/*
38 * Write the MMP block using WRITE_SYNC to try to get the block on-disk
39 * faster.
40 */
Darrick J. Wong5c359a42012-04-29 18:47:10 -040041static int write_mmp_block(struct super_block *sb, struct buffer_head *bh)
Johann Lombardic5e06d12011-05-24 18:31:25 -040042{
Darrick J. Wong5c359a42012-04-29 18:47:10 -040043 struct mmp_struct *mmp = (struct mmp_struct *)(bh->b_data);
44
Jan Kara8e8ad8a2012-06-12 16:20:38 +020045 /*
46 * We protect against freezing so that we don't create dirty buffers
47 * on frozen filesystem.
48 */
49 sb_start_write(sb);
Darrick J. Wong5c359a42012-04-29 18:47:10 -040050 ext4_mmp_csum_set(sb, mmp);
Johann Lombardic5e06d12011-05-24 18:31:25 -040051 mark_buffer_dirty(bh);
52 lock_buffer(bh);
53 bh->b_end_io = end_buffer_write_sync;
54 get_bh(bh);
Theodore Ts'o9f203502013-04-20 15:46:17 -040055 submit_bh(WRITE_SYNC | REQ_META | REQ_PRIO, bh);
Johann Lombardic5e06d12011-05-24 18:31:25 -040056 wait_on_buffer(bh);
Jan Kara8e8ad8a2012-06-12 16:20:38 +020057 sb_end_write(sb);
Johann Lombardic5e06d12011-05-24 18:31:25 -040058 if (unlikely(!buffer_uptodate(bh)))
59 return 1;
60
61 return 0;
62}
63
64/*
65 * Read the MMP block. It _must_ be read from disk and hence we clear the
66 * uptodate flag on the buffer.
67 */
68static int read_mmp_block(struct super_block *sb, struct buffer_head **bh,
69 ext4_fsblk_t mmp_block)
70{
71 struct mmp_struct *mmp;
Dan Carpenter98104462015-08-15 11:30:31 -040072 int ret;
Johann Lombardic5e06d12011-05-24 18:31:25 -040073
74 if (*bh)
75 clear_buffer_uptodate(*bh);
76
77 /* This would be sb_bread(sb, mmp_block), except we need to be sure
78 * that the MD RAID device cache has been bypassed, and that the read
79 * is not blocked in the elevator. */
Dan Carpenter98104462015-08-15 11:30:31 -040080 if (!*bh) {
Johann Lombardic5e06d12011-05-24 18:31:25 -040081 *bh = sb_getblk(sb, mmp_block);
Dan Carpenter98104462015-08-15 11:30:31 -040082 if (!*bh) {
83 ret = -ENOMEM;
84 goto warn_exit;
Johann Lombardic5e06d12011-05-24 18:31:25 -040085 }
86 }
Dan Carpenter98104462015-08-15 11:30:31 -040087
88 get_bh(*bh);
89 lock_buffer(*bh);
90 (*bh)->b_end_io = end_buffer_read_sync;
91 submit_bh(READ_SYNC | REQ_META | REQ_PRIO, *bh);
92 wait_on_buffer(*bh);
93 if (!buffer_uptodate(*bh)) {
94 brelse(*bh);
95 *bh = NULL;
96 ret = -EIO;
97 goto warn_exit;
Johann Lombardic5e06d12011-05-24 18:31:25 -040098 }
99
100 mmp = (struct mmp_struct *)((*bh)->b_data);
Dan Carpenter98104462015-08-15 11:30:31 -0400101 if (le32_to_cpu(mmp->mmp_magic) == EXT4_MMP_MAGIC &&
102 ext4_mmp_csum_verify(sb, mmp))
103 return 0;
104 ret = -EINVAL;
Johann Lombardic5e06d12011-05-24 18:31:25 -0400105
Dan Carpenter98104462015-08-15 11:30:31 -0400106warn_exit:
107 ext4_warning(sb, "Error %d while reading MMP block %llu",
108 ret, mmp_block);
109 return ret;
Johann Lombardic5e06d12011-05-24 18:31:25 -0400110}
111
112/*
113 * Dump as much information as possible to help the admin.
114 */
115void __dump_mmp_msg(struct super_block *sb, struct mmp_struct *mmp,
116 const char *function, unsigned int line, const char *msg)
117{
Dan Carpenterda0b5e42015-08-15 11:38:13 -0400118 __ext4_warning(sb, function, line, "%s", msg);
Johann Lombardic5e06d12011-05-24 18:31:25 -0400119 __ext4_warning(sb, function, line,
120 "MMP failure info: last update time: %llu, last update "
121 "node: %s, last update device: %s\n",
122 (long long unsigned int) le64_to_cpu(mmp->mmp_time),
123 mmp->mmp_nodename, mmp->mmp_bdevname);
124}
125
126/*
127 * kmmpd will update the MMP sequence every s_mmp_update_interval seconds
128 */
129static int kmmpd(void *data)
130{
131 struct super_block *sb = ((struct mmpd_data *) data)->sb;
132 struct buffer_head *bh = ((struct mmpd_data *) data)->bh;
133 struct ext4_super_block *es = EXT4_SB(sb)->s_es;
134 struct mmp_struct *mmp;
135 ext4_fsblk_t mmp_block;
136 u32 seq = 0;
137 unsigned long failed_writes = 0;
138 int mmp_update_interval = le16_to_cpu(es->s_mmp_update_interval);
139 unsigned mmp_check_interval;
140 unsigned long last_update_time;
141 unsigned long diff;
142 int retval;
143
144 mmp_block = le64_to_cpu(es->s_mmp_block);
145 mmp = (struct mmp_struct *)(bh->b_data);
146 mmp->mmp_time = cpu_to_le64(get_seconds());
147 /*
148 * Start with the higher mmp_check_interval and reduce it if
149 * the MMP block is being updated on time.
150 */
151 mmp_check_interval = max(EXT4_MMP_CHECK_MULT * mmp_update_interval,
152 EXT4_MMP_MIN_CHECK_INTERVAL);
153 mmp->mmp_check_interval = cpu_to_le16(mmp_check_interval);
154 bdevname(bh->b_bdev, mmp->mmp_bdevname);
155
Nikitas Angelinas215fc6a2011-10-18 10:49:51 -0400156 memcpy(mmp->mmp_nodename, init_utsname()->nodename,
Johann Lombardic5e06d12011-05-24 18:31:25 -0400157 sizeof(mmp->mmp_nodename));
158
159 while (!kthread_should_stop()) {
160 if (++seq > EXT4_MMP_SEQ_MAX)
161 seq = 1;
162
163 mmp->mmp_seq = cpu_to_le32(seq);
164 mmp->mmp_time = cpu_to_le64(get_seconds());
165 last_update_time = jiffies;
166
Darrick J. Wong5c359a42012-04-29 18:47:10 -0400167 retval = write_mmp_block(sb, bh);
Johann Lombardic5e06d12011-05-24 18:31:25 -0400168 /*
169 * Don't spew too many error messages. Print one every
170 * (s_mmp_update_interval * 60) seconds.
171 */
Nikitas Angelinasbdfc2302011-10-18 10:51:51 -0400172 if (retval) {
173 if ((failed_writes % 60) == 0)
174 ext4_error(sb, "Error writing to MMP block");
Johann Lombardic5e06d12011-05-24 18:31:25 -0400175 failed_writes++;
176 }
177
178 if (!(le32_to_cpu(es->s_feature_incompat) &
179 EXT4_FEATURE_INCOMPAT_MMP)) {
180 ext4_warning(sb, "kmmpd being stopped since MMP feature"
181 " has been disabled.");
182 EXT4_SB(sb)->s_mmp_tsk = NULL;
183 goto failed;
184 }
185
186 if (sb->s_flags & MS_RDONLY) {
187 ext4_warning(sb, "kmmpd being stopped since filesystem "
188 "has been remounted as readonly.");
189 EXT4_SB(sb)->s_mmp_tsk = NULL;
190 goto failed;
191 }
192
193 diff = jiffies - last_update_time;
194 if (diff < mmp_update_interval * HZ)
195 schedule_timeout_interruptible(mmp_update_interval *
196 HZ - diff);
197
198 /*
199 * We need to make sure that more than mmp_check_interval
200 * seconds have not passed since writing. If that has happened
201 * we need to check if the MMP block is as we left it.
202 */
203 diff = jiffies - last_update_time;
204 if (diff > mmp_check_interval * HZ) {
205 struct buffer_head *bh_check = NULL;
206 struct mmp_struct *mmp_check;
207
208 retval = read_mmp_block(sb, &bh_check, mmp_block);
209 if (retval) {
210 ext4_error(sb, "error reading MMP data: %d",
211 retval);
212
213 EXT4_SB(sb)->s_mmp_tsk = NULL;
214 goto failed;
215 }
216
217 mmp_check = (struct mmp_struct *)(bh_check->b_data);
218 if (mmp->mmp_seq != mmp_check->mmp_seq ||
219 memcmp(mmp->mmp_nodename, mmp_check->mmp_nodename,
220 sizeof(mmp->mmp_nodename))) {
221 dump_mmp_msg(sb, mmp_check,
222 "Error while updating MMP info. "
223 "The filesystem seems to have been"
224 " multiply mounted.");
225 ext4_error(sb, "abort");
226 goto failed;
227 }
228 put_bh(bh_check);
229 }
230
231 /*
232 * Adjust the mmp_check_interval depending on how much time
233 * it took for the MMP block to be written.
234 */
235 mmp_check_interval = max(min(EXT4_MMP_CHECK_MULT * diff / HZ,
236 EXT4_MMP_MAX_CHECK_INTERVAL),
237 EXT4_MMP_MIN_CHECK_INTERVAL);
238 mmp->mmp_check_interval = cpu_to_le16(mmp_check_interval);
239 }
240
241 /*
242 * Unmount seems to be clean.
243 */
244 mmp->mmp_seq = cpu_to_le32(EXT4_MMP_SEQ_CLEAN);
245 mmp->mmp_time = cpu_to_le64(get_seconds());
246
Darrick J. Wong5c359a42012-04-29 18:47:10 -0400247 retval = write_mmp_block(sb, bh);
Johann Lombardic5e06d12011-05-24 18:31:25 -0400248
249failed:
250 kfree(data);
251 brelse(bh);
252 return retval;
253}
254
255/*
256 * Get a random new sequence number but make sure it is not greater than
257 * EXT4_MMP_SEQ_MAX.
258 */
259static unsigned int mmp_new_seq(void)
260{
261 u32 new_seq;
262
263 do {
Theodore Ts'odd1f7232013-11-08 00:14:53 -0500264 new_seq = prandom_u32();
Johann Lombardic5e06d12011-05-24 18:31:25 -0400265 } while (new_seq > EXT4_MMP_SEQ_MAX);
266
267 return new_seq;
268}
269
270/*
271 * Protect the filesystem from being mounted more than once.
272 */
273int ext4_multi_mount_protect(struct super_block *sb,
274 ext4_fsblk_t mmp_block)
275{
276 struct ext4_super_block *es = EXT4_SB(sb)->s_es;
277 struct buffer_head *bh = NULL;
278 struct mmp_struct *mmp = NULL;
279 struct mmpd_data *mmpd_data;
280 u32 seq;
281 unsigned int mmp_check_interval = le16_to_cpu(es->s_mmp_update_interval);
282 unsigned int wait_time = 0;
283 int retval;
284
285 if (mmp_block < le32_to_cpu(es->s_first_data_block) ||
286 mmp_block >= ext4_blocks_count(es)) {
287 ext4_warning(sb, "Invalid MMP block in superblock");
288 goto failed;
289 }
290
291 retval = read_mmp_block(sb, &bh, mmp_block);
292 if (retval)
293 goto failed;
294
295 mmp = (struct mmp_struct *)(bh->b_data);
296
297 if (mmp_check_interval < EXT4_MMP_MIN_CHECK_INTERVAL)
298 mmp_check_interval = EXT4_MMP_MIN_CHECK_INTERVAL;
299
300 /*
301 * If check_interval in MMP block is larger, use that instead of
302 * update_interval from the superblock.
303 */
Santosh Nayak85d21652012-02-27 01:09:03 -0500304 if (le16_to_cpu(mmp->mmp_check_interval) > mmp_check_interval)
305 mmp_check_interval = le16_to_cpu(mmp->mmp_check_interval);
Johann Lombardic5e06d12011-05-24 18:31:25 -0400306
307 seq = le32_to_cpu(mmp->mmp_seq);
308 if (seq == EXT4_MMP_SEQ_CLEAN)
309 goto skip;
310
311 if (seq == EXT4_MMP_SEQ_FSCK) {
312 dump_mmp_msg(sb, mmp, "fsck is running on the filesystem");
313 goto failed;
314 }
315
316 wait_time = min(mmp_check_interval * 2 + 1,
317 mmp_check_interval + 60);
318
319 /* Print MMP interval if more than 20 secs. */
320 if (wait_time > EXT4_MMP_MIN_CHECK_INTERVAL * 4)
321 ext4_warning(sb, "MMP interval %u higher than expected, please"
322 " wait.\n", wait_time * 2);
323
324 if (schedule_timeout_interruptible(HZ * wait_time) != 0) {
325 ext4_warning(sb, "MMP startup interrupted, failing mount\n");
326 goto failed;
327 }
328
329 retval = read_mmp_block(sb, &bh, mmp_block);
330 if (retval)
331 goto failed;
332 mmp = (struct mmp_struct *)(bh->b_data);
333 if (seq != le32_to_cpu(mmp->mmp_seq)) {
334 dump_mmp_msg(sb, mmp,
335 "Device is already active on another node.");
336 goto failed;
337 }
338
339skip:
340 /*
341 * write a new random sequence number.
342 */
Darrick J. Wongf6f96fd2011-10-18 10:53:51 -0400343 seq = mmp_new_seq();
344 mmp->mmp_seq = cpu_to_le32(seq);
Johann Lombardic5e06d12011-05-24 18:31:25 -0400345
Darrick J. Wong5c359a42012-04-29 18:47:10 -0400346 retval = write_mmp_block(sb, bh);
Johann Lombardic5e06d12011-05-24 18:31:25 -0400347 if (retval)
348 goto failed;
349
350 /*
351 * wait for MMP interval and check mmp_seq.
352 */
353 if (schedule_timeout_interruptible(HZ * wait_time) != 0) {
354 ext4_warning(sb, "MMP startup interrupted, failing mount\n");
355 goto failed;
356 }
357
358 retval = read_mmp_block(sb, &bh, mmp_block);
359 if (retval)
360 goto failed;
361 mmp = (struct mmp_struct *)(bh->b_data);
362 if (seq != le32_to_cpu(mmp->mmp_seq)) {
363 dump_mmp_msg(sb, mmp,
364 "Device is already active on another node.");
365 goto failed;
366 }
367
368 mmpd_data = kmalloc(sizeof(struct mmpd_data), GFP_KERNEL);
369 if (!mmpd_data) {
370 ext4_warning(sb, "not enough memory for mmpd_data");
371 goto failed;
372 }
373 mmpd_data->sb = sb;
374 mmpd_data->bh = bh;
375
376 /*
377 * Start a kernel thread to update the MMP block periodically.
378 */
379 EXT4_SB(sb)->s_mmp_tsk = kthread_run(kmmpd, mmpd_data, "kmmpd-%s",
380 bdevname(bh->b_bdev,
381 mmp->mmp_bdevname));
382 if (IS_ERR(EXT4_SB(sb)->s_mmp_tsk)) {
383 EXT4_SB(sb)->s_mmp_tsk = NULL;
384 kfree(mmpd_data);
385 ext4_warning(sb, "Unable to create kmmpd thread for %s.",
386 sb->s_id);
387 goto failed;
388 }
389
390 return 0;
391
392failed:
393 brelse(bh);
394 return 1;
395}
396
397