blob: fe7c63f4717e09616b92f7d3b4850ab99671cff6 [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 */
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
Johann Lombardic5e06d12011-05-24 18:31:25 -040039/*
40 * Write the MMP block using WRITE_SYNC to try to get the block on-disk
41 * faster.
42 */
Darrick J. Wong5c359a42012-04-29 18:47:10 -040043static int write_mmp_block(struct super_block *sb, struct buffer_head *bh)
Johann Lombardic5e06d12011-05-24 18:31:25 -040044{
Darrick J. Wong5c359a42012-04-29 18:47:10 -040045 struct mmp_struct *mmp = (struct mmp_struct *)(bh->b_data);
46
Jan Kara8e8ad8a2012-06-12 16:20:38 +020047 /*
48 * We protect against freezing so that we don't create dirty buffers
49 * on frozen filesystem.
50 */
51 sb_start_write(sb);
Darrick J. Wong5c359a42012-04-29 18:47:10 -040052 ext4_mmp_csum_set(sb, mmp);
Johann Lombardic5e06d12011-05-24 18:31:25 -040053 mark_buffer_dirty(bh);
54 lock_buffer(bh);
55 bh->b_end_io = end_buffer_write_sync;
56 get_bh(bh);
57 submit_bh(WRITE_SYNC, bh);
58 wait_on_buffer(bh);
Jan Kara8e8ad8a2012-06-12 16:20:38 +020059 sb_end_write(sb);
Johann Lombardic5e06d12011-05-24 18:31:25 -040060 if (unlikely(!buffer_uptodate(bh)))
61 return 1;
62
63 return 0;
64}
65
66/*
67 * Read the MMP block. It _must_ be read from disk and hence we clear the
68 * uptodate flag on the buffer.
69 */
70static int read_mmp_block(struct super_block *sb, struct buffer_head **bh,
71 ext4_fsblk_t mmp_block)
72{
73 struct mmp_struct *mmp;
74
75 if (*bh)
76 clear_buffer_uptodate(*bh);
77
78 /* This would be sb_bread(sb, mmp_block), except we need to be sure
79 * that the MD RAID device cache has been bypassed, and that the read
80 * is not blocked in the elevator. */
81 if (!*bh)
82 *bh = sb_getblk(sb, mmp_block);
83 if (*bh) {
84 get_bh(*bh);
85 lock_buffer(*bh);
86 (*bh)->b_end_io = end_buffer_read_sync;
87 submit_bh(READ_SYNC, *bh);
88 wait_on_buffer(*bh);
89 if (!buffer_uptodate(*bh)) {
90 brelse(*bh);
91 *bh = NULL;
92 }
93 }
94 if (!*bh) {
95 ext4_warning(sb, "Error while reading MMP block %llu",
96 mmp_block);
97 return -EIO;
98 }
99
100 mmp = (struct mmp_struct *)((*bh)->b_data);
Darrick J. Wong5c359a42012-04-29 18:47:10 -0400101 if (le32_to_cpu(mmp->mmp_magic) != EXT4_MMP_MAGIC ||
102 !ext4_mmp_csum_verify(sb, mmp))
Johann Lombardic5e06d12011-05-24 18:31:25 -0400103 return -EINVAL;
104
105 return 0;
106}
107
108/*
109 * Dump as much information as possible to help the admin.
110 */
111void __dump_mmp_msg(struct super_block *sb, struct mmp_struct *mmp,
112 const char *function, unsigned int line, const char *msg)
113{
114 __ext4_warning(sb, function, line, msg);
115 __ext4_warning(sb, function, line,
116 "MMP failure info: last update time: %llu, last update "
117 "node: %s, last update device: %s\n",
118 (long long unsigned int) le64_to_cpu(mmp->mmp_time),
119 mmp->mmp_nodename, mmp->mmp_bdevname);
120}
121
122/*
123 * kmmpd will update the MMP sequence every s_mmp_update_interval seconds
124 */
125static int kmmpd(void *data)
126{
127 struct super_block *sb = ((struct mmpd_data *) data)->sb;
128 struct buffer_head *bh = ((struct mmpd_data *) data)->bh;
129 struct ext4_super_block *es = EXT4_SB(sb)->s_es;
130 struct mmp_struct *mmp;
131 ext4_fsblk_t mmp_block;
132 u32 seq = 0;
133 unsigned long failed_writes = 0;
134 int mmp_update_interval = le16_to_cpu(es->s_mmp_update_interval);
135 unsigned mmp_check_interval;
136 unsigned long last_update_time;
137 unsigned long diff;
138 int retval;
139
140 mmp_block = le64_to_cpu(es->s_mmp_block);
141 mmp = (struct mmp_struct *)(bh->b_data);
142 mmp->mmp_time = cpu_to_le64(get_seconds());
143 /*
144 * Start with the higher mmp_check_interval and reduce it if
145 * the MMP block is being updated on time.
146 */
147 mmp_check_interval = max(EXT4_MMP_CHECK_MULT * mmp_update_interval,
148 EXT4_MMP_MIN_CHECK_INTERVAL);
149 mmp->mmp_check_interval = cpu_to_le16(mmp_check_interval);
150 bdevname(bh->b_bdev, mmp->mmp_bdevname);
151
Nikitas Angelinas215fc6a2011-10-18 10:49:51 -0400152 memcpy(mmp->mmp_nodename, init_utsname()->nodename,
Johann Lombardic5e06d12011-05-24 18:31:25 -0400153 sizeof(mmp->mmp_nodename));
154
155 while (!kthread_should_stop()) {
156 if (++seq > EXT4_MMP_SEQ_MAX)
157 seq = 1;
158
159 mmp->mmp_seq = cpu_to_le32(seq);
160 mmp->mmp_time = cpu_to_le64(get_seconds());
161 last_update_time = jiffies;
162
Darrick J. Wong5c359a42012-04-29 18:47:10 -0400163 retval = write_mmp_block(sb, bh);
Johann Lombardic5e06d12011-05-24 18:31:25 -0400164 /*
165 * Don't spew too many error messages. Print one every
166 * (s_mmp_update_interval * 60) seconds.
167 */
Nikitas Angelinasbdfc2302011-10-18 10:51:51 -0400168 if (retval) {
169 if ((failed_writes % 60) == 0)
170 ext4_error(sb, "Error writing to MMP block");
Johann Lombardic5e06d12011-05-24 18:31:25 -0400171 failed_writes++;
172 }
173
174 if (!(le32_to_cpu(es->s_feature_incompat) &
175 EXT4_FEATURE_INCOMPAT_MMP)) {
176 ext4_warning(sb, "kmmpd being stopped since MMP feature"
177 " has been disabled.");
178 EXT4_SB(sb)->s_mmp_tsk = NULL;
179 goto failed;
180 }
181
182 if (sb->s_flags & MS_RDONLY) {
183 ext4_warning(sb, "kmmpd being stopped since filesystem "
184 "has been remounted as readonly.");
185 EXT4_SB(sb)->s_mmp_tsk = NULL;
186 goto failed;
187 }
188
189 diff = jiffies - last_update_time;
190 if (diff < mmp_update_interval * HZ)
191 schedule_timeout_interruptible(mmp_update_interval *
192 HZ - diff);
193
194 /*
195 * We need to make sure that more than mmp_check_interval
196 * seconds have not passed since writing. If that has happened
197 * we need to check if the MMP block is as we left it.
198 */
199 diff = jiffies - last_update_time;
200 if (diff > mmp_check_interval * HZ) {
201 struct buffer_head *bh_check = NULL;
202 struct mmp_struct *mmp_check;
203
204 retval = read_mmp_block(sb, &bh_check, mmp_block);
205 if (retval) {
206 ext4_error(sb, "error reading MMP data: %d",
207 retval);
208
209 EXT4_SB(sb)->s_mmp_tsk = NULL;
210 goto failed;
211 }
212
213 mmp_check = (struct mmp_struct *)(bh_check->b_data);
214 if (mmp->mmp_seq != mmp_check->mmp_seq ||
215 memcmp(mmp->mmp_nodename, mmp_check->mmp_nodename,
216 sizeof(mmp->mmp_nodename))) {
217 dump_mmp_msg(sb, mmp_check,
218 "Error while updating MMP info. "
219 "The filesystem seems to have been"
220 " multiply mounted.");
221 ext4_error(sb, "abort");
222 goto failed;
223 }
224 put_bh(bh_check);
225 }
226
227 /*
228 * Adjust the mmp_check_interval depending on how much time
229 * it took for the MMP block to be written.
230 */
231 mmp_check_interval = max(min(EXT4_MMP_CHECK_MULT * diff / HZ,
232 EXT4_MMP_MAX_CHECK_INTERVAL),
233 EXT4_MMP_MIN_CHECK_INTERVAL);
234 mmp->mmp_check_interval = cpu_to_le16(mmp_check_interval);
235 }
236
237 /*
238 * Unmount seems to be clean.
239 */
240 mmp->mmp_seq = cpu_to_le32(EXT4_MMP_SEQ_CLEAN);
241 mmp->mmp_time = cpu_to_le64(get_seconds());
242
Darrick J. Wong5c359a42012-04-29 18:47:10 -0400243 retval = write_mmp_block(sb, bh);
Johann Lombardic5e06d12011-05-24 18:31:25 -0400244
245failed:
246 kfree(data);
247 brelse(bh);
248 return retval;
249}
250
251/*
252 * Get a random new sequence number but make sure it is not greater than
253 * EXT4_MMP_SEQ_MAX.
254 */
255static unsigned int mmp_new_seq(void)
256{
257 u32 new_seq;
258
259 do {
260 get_random_bytes(&new_seq, sizeof(u32));
261 } while (new_seq > EXT4_MMP_SEQ_MAX);
262
263 return new_seq;
264}
265
266/*
267 * Protect the filesystem from being mounted more than once.
268 */
269int ext4_multi_mount_protect(struct super_block *sb,
270 ext4_fsblk_t mmp_block)
271{
272 struct ext4_super_block *es = EXT4_SB(sb)->s_es;
273 struct buffer_head *bh = NULL;
274 struct mmp_struct *mmp = NULL;
275 struct mmpd_data *mmpd_data;
276 u32 seq;
277 unsigned int mmp_check_interval = le16_to_cpu(es->s_mmp_update_interval);
278 unsigned int wait_time = 0;
279 int retval;
280
281 if (mmp_block < le32_to_cpu(es->s_first_data_block) ||
282 mmp_block >= ext4_blocks_count(es)) {
283 ext4_warning(sb, "Invalid MMP block in superblock");
284 goto failed;
285 }
286
287 retval = read_mmp_block(sb, &bh, mmp_block);
288 if (retval)
289 goto failed;
290
291 mmp = (struct mmp_struct *)(bh->b_data);
292
293 if (mmp_check_interval < EXT4_MMP_MIN_CHECK_INTERVAL)
294 mmp_check_interval = EXT4_MMP_MIN_CHECK_INTERVAL;
295
296 /*
297 * If check_interval in MMP block is larger, use that instead of
298 * update_interval from the superblock.
299 */
Santosh Nayak85d21652012-02-27 01:09:03 -0500300 if (le16_to_cpu(mmp->mmp_check_interval) > mmp_check_interval)
301 mmp_check_interval = le16_to_cpu(mmp->mmp_check_interval);
Johann Lombardic5e06d12011-05-24 18:31:25 -0400302
303 seq = le32_to_cpu(mmp->mmp_seq);
304 if (seq == EXT4_MMP_SEQ_CLEAN)
305 goto skip;
306
307 if (seq == EXT4_MMP_SEQ_FSCK) {
308 dump_mmp_msg(sb, mmp, "fsck is running on the filesystem");
309 goto failed;
310 }
311
312 wait_time = min(mmp_check_interval * 2 + 1,
313 mmp_check_interval + 60);
314
315 /* Print MMP interval if more than 20 secs. */
316 if (wait_time > EXT4_MMP_MIN_CHECK_INTERVAL * 4)
317 ext4_warning(sb, "MMP interval %u higher than expected, please"
318 " wait.\n", wait_time * 2);
319
320 if (schedule_timeout_interruptible(HZ * wait_time) != 0) {
321 ext4_warning(sb, "MMP startup interrupted, failing mount\n");
322 goto failed;
323 }
324
325 retval = read_mmp_block(sb, &bh, mmp_block);
326 if (retval)
327 goto failed;
328 mmp = (struct mmp_struct *)(bh->b_data);
329 if (seq != le32_to_cpu(mmp->mmp_seq)) {
330 dump_mmp_msg(sb, mmp,
331 "Device is already active on another node.");
332 goto failed;
333 }
334
335skip:
336 /*
337 * write a new random sequence number.
338 */
Darrick J. Wongf6f96fd2011-10-18 10:53:51 -0400339 seq = mmp_new_seq();
340 mmp->mmp_seq = cpu_to_le32(seq);
Johann Lombardic5e06d12011-05-24 18:31:25 -0400341
Darrick J. Wong5c359a42012-04-29 18:47:10 -0400342 retval = write_mmp_block(sb, bh);
Johann Lombardic5e06d12011-05-24 18:31:25 -0400343 if (retval)
344 goto failed;
345
346 /*
347 * wait for MMP interval and check mmp_seq.
348 */
349 if (schedule_timeout_interruptible(HZ * wait_time) != 0) {
350 ext4_warning(sb, "MMP startup interrupted, failing mount\n");
351 goto failed;
352 }
353
354 retval = read_mmp_block(sb, &bh, mmp_block);
355 if (retval)
356 goto failed;
357 mmp = (struct mmp_struct *)(bh->b_data);
358 if (seq != le32_to_cpu(mmp->mmp_seq)) {
359 dump_mmp_msg(sb, mmp,
360 "Device is already active on another node.");
361 goto failed;
362 }
363
364 mmpd_data = kmalloc(sizeof(struct mmpd_data), GFP_KERNEL);
365 if (!mmpd_data) {
366 ext4_warning(sb, "not enough memory for mmpd_data");
367 goto failed;
368 }
369 mmpd_data->sb = sb;
370 mmpd_data->bh = bh;
371
372 /*
373 * Start a kernel thread to update the MMP block periodically.
374 */
375 EXT4_SB(sb)->s_mmp_tsk = kthread_run(kmmpd, mmpd_data, "kmmpd-%s",
376 bdevname(bh->b_bdev,
377 mmp->mmp_bdevname));
378 if (IS_ERR(EXT4_SB(sb)->s_mmp_tsk)) {
379 EXT4_SB(sb)->s_mmp_tsk = NULL;
380 kfree(mmpd_data);
381 ext4_warning(sb, "Unable to create kmmpd thread for %s.",
382 sb->s_id);
383 goto failed;
384 }
385
386 return 0;
387
388failed:
389 brelse(bh);
390 return 1;
391}
392
393