Commit | Line | Data |
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c5e06d10 JL |
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 | ||
5c359a47 | 9 | /* Checksumming functions */ |
171a7f21 | 10 | static __le32 ext4_mmp_csum(struct super_block *sb, struct mmp_struct *mmp) |
5c359a47 DW |
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 | ||
21 | int 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 | ||
30 | void 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 | ||
c5e06d10 JL |
39 | /* |
40 | * Write the MMP block using WRITE_SYNC to try to get the block on-disk | |
41 | * faster. | |
42 | */ | |
5c359a47 | 43 | static int write_mmp_block(struct super_block *sb, struct buffer_head *bh) |
c5e06d10 | 44 | { |
5c359a47 DW |
45 | struct mmp_struct *mmp = (struct mmp_struct *)(bh->b_data); |
46 | ||
8e8ad8a5 JK |
47 | /* |
48 | * We protect against freezing so that we don't create dirty buffers | |
49 | * on frozen filesystem. | |
50 | */ | |
51 | sb_start_write(sb); | |
5c359a47 | 52 | ext4_mmp_csum_set(sb, mmp); |
c5e06d10 JL |
53 | mark_buffer_dirty(bh); |
54 | lock_buffer(bh); | |
55 | bh->b_end_io = end_buffer_write_sync; | |
56 | get_bh(bh); | |
9f203507 | 57 | submit_bh(WRITE_SYNC | REQ_META | REQ_PRIO, bh); |
c5e06d10 | 58 | wait_on_buffer(bh); |
8e8ad8a5 | 59 | sb_end_write(sb); |
c5e06d10 JL |
60 | 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 | */ | |
70 | static 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); | |
860d21e2 TT |
83 | if (!*bh) |
84 | return -ENOMEM; | |
c5e06d10 JL |
85 | if (*bh) { |
86 | get_bh(*bh); | |
87 | lock_buffer(*bh); | |
88 | (*bh)->b_end_io = end_buffer_read_sync; | |
9f203507 | 89 | submit_bh(READ_SYNC | REQ_META | REQ_PRIO, *bh); |
c5e06d10 JL |
90 | wait_on_buffer(*bh); |
91 | if (!buffer_uptodate(*bh)) { | |
92 | brelse(*bh); | |
93 | *bh = NULL; | |
94 | } | |
95 | } | |
aebf0243 | 96 | if (unlikely(!*bh)) { |
c5e06d10 JL |
97 | ext4_warning(sb, "Error while reading MMP block %llu", |
98 | mmp_block); | |
99 | return -EIO; | |
100 | } | |
101 | ||
102 | mmp = (struct mmp_struct *)((*bh)->b_data); | |
5c359a47 DW |
103 | if (le32_to_cpu(mmp->mmp_magic) != EXT4_MMP_MAGIC || |
104 | !ext4_mmp_csum_verify(sb, mmp)) | |
c5e06d10 JL |
105 | return -EINVAL; |
106 | ||
107 | return 0; | |
108 | } | |
109 | ||
110 | /* | |
111 | * Dump as much information as possible to help the admin. | |
112 | */ | |
113 | void __dump_mmp_msg(struct super_block *sb, struct mmp_struct *mmp, | |
114 | const char *function, unsigned int line, const char *msg) | |
115 | { | |
116 | __ext4_warning(sb, function, line, msg); | |
117 | __ext4_warning(sb, function, line, | |
118 | "MMP failure info: last update time: %llu, last update " | |
119 | "node: %s, last update device: %s\n", | |
120 | (long long unsigned int) le64_to_cpu(mmp->mmp_time), | |
121 | mmp->mmp_nodename, mmp->mmp_bdevname); | |
122 | } | |
123 | ||
124 | /* | |
125 | * kmmpd will update the MMP sequence every s_mmp_update_interval seconds | |
126 | */ | |
127 | static int kmmpd(void *data) | |
128 | { | |
129 | struct super_block *sb = ((struct mmpd_data *) data)->sb; | |
130 | struct buffer_head *bh = ((struct mmpd_data *) data)->bh; | |
131 | struct ext4_super_block *es = EXT4_SB(sb)->s_es; | |
132 | struct mmp_struct *mmp; | |
133 | ext4_fsblk_t mmp_block; | |
134 | u32 seq = 0; | |
135 | unsigned long failed_writes = 0; | |
136 | int mmp_update_interval = le16_to_cpu(es->s_mmp_update_interval); | |
137 | unsigned mmp_check_interval; | |
138 | unsigned long last_update_time; | |
139 | unsigned long diff; | |
140 | int retval; | |
141 | ||
142 | mmp_block = le64_to_cpu(es->s_mmp_block); | |
143 | mmp = (struct mmp_struct *)(bh->b_data); | |
144 | mmp->mmp_time = cpu_to_le64(get_seconds()); | |
145 | /* | |
146 | * Start with the higher mmp_check_interval and reduce it if | |
147 | * the MMP block is being updated on time. | |
148 | */ | |
149 | mmp_check_interval = max(EXT4_MMP_CHECK_MULT * mmp_update_interval, | |
150 | EXT4_MMP_MIN_CHECK_INTERVAL); | |
151 | mmp->mmp_check_interval = cpu_to_le16(mmp_check_interval); | |
152 | bdevname(bh->b_bdev, mmp->mmp_bdevname); | |
153 | ||
215fc6af | 154 | memcpy(mmp->mmp_nodename, init_utsname()->nodename, |
c5e06d10 JL |
155 | sizeof(mmp->mmp_nodename)); |
156 | ||
157 | while (!kthread_should_stop()) { | |
158 | if (++seq > EXT4_MMP_SEQ_MAX) | |
159 | seq = 1; | |
160 | ||
161 | mmp->mmp_seq = cpu_to_le32(seq); | |
162 | mmp->mmp_time = cpu_to_le64(get_seconds()); | |
163 | last_update_time = jiffies; | |
164 | ||
5c359a47 | 165 | retval = write_mmp_block(sb, bh); |
c5e06d10 JL |
166 | /* |
167 | * Don't spew too many error messages. Print one every | |
168 | * (s_mmp_update_interval * 60) seconds. | |
169 | */ | |
bdfc230f NA |
170 | if (retval) { |
171 | if ((failed_writes % 60) == 0) | |
172 | ext4_error(sb, "Error writing to MMP block"); | |
c5e06d10 JL |
173 | failed_writes++; |
174 | } | |
175 | ||
176 | if (!(le32_to_cpu(es->s_feature_incompat) & | |
177 | EXT4_FEATURE_INCOMPAT_MMP)) { | |
178 | ext4_warning(sb, "kmmpd being stopped since MMP feature" | |
179 | " has been disabled."); | |
180 | EXT4_SB(sb)->s_mmp_tsk = NULL; | |
181 | goto failed; | |
182 | } | |
183 | ||
184 | if (sb->s_flags & MS_RDONLY) { | |
185 | ext4_warning(sb, "kmmpd being stopped since filesystem " | |
186 | "has been remounted as readonly."); | |
187 | EXT4_SB(sb)->s_mmp_tsk = NULL; | |
188 | goto failed; | |
189 | } | |
190 | ||
191 | diff = jiffies - last_update_time; | |
192 | if (diff < mmp_update_interval * HZ) | |
193 | schedule_timeout_interruptible(mmp_update_interval * | |
194 | HZ - diff); | |
195 | ||
196 | /* | |
197 | * We need to make sure that more than mmp_check_interval | |
198 | * seconds have not passed since writing. If that has happened | |
199 | * we need to check if the MMP block is as we left it. | |
200 | */ | |
201 | diff = jiffies - last_update_time; | |
202 | if (diff > mmp_check_interval * HZ) { | |
203 | struct buffer_head *bh_check = NULL; | |
204 | struct mmp_struct *mmp_check; | |
205 | ||
206 | retval = read_mmp_block(sb, &bh_check, mmp_block); | |
207 | if (retval) { | |
208 | ext4_error(sb, "error reading MMP data: %d", | |
209 | retval); | |
210 | ||
211 | EXT4_SB(sb)->s_mmp_tsk = NULL; | |
212 | goto failed; | |
213 | } | |
214 | ||
215 | mmp_check = (struct mmp_struct *)(bh_check->b_data); | |
216 | if (mmp->mmp_seq != mmp_check->mmp_seq || | |
217 | memcmp(mmp->mmp_nodename, mmp_check->mmp_nodename, | |
218 | sizeof(mmp->mmp_nodename))) { | |
219 | dump_mmp_msg(sb, mmp_check, | |
220 | "Error while updating MMP info. " | |
221 | "The filesystem seems to have been" | |
222 | " multiply mounted."); | |
223 | ext4_error(sb, "abort"); | |
224 | goto failed; | |
225 | } | |
226 | put_bh(bh_check); | |
227 | } | |
228 | ||
229 | /* | |
230 | * Adjust the mmp_check_interval depending on how much time | |
231 | * it took for the MMP block to be written. | |
232 | */ | |
233 | mmp_check_interval = max(min(EXT4_MMP_CHECK_MULT * diff / HZ, | |
234 | EXT4_MMP_MAX_CHECK_INTERVAL), | |
235 | EXT4_MMP_MIN_CHECK_INTERVAL); | |
236 | mmp->mmp_check_interval = cpu_to_le16(mmp_check_interval); | |
237 | } | |
238 | ||
239 | /* | |
240 | * Unmount seems to be clean. | |
241 | */ | |
242 | mmp->mmp_seq = cpu_to_le32(EXT4_MMP_SEQ_CLEAN); | |
243 | mmp->mmp_time = cpu_to_le64(get_seconds()); | |
244 | ||
5c359a47 | 245 | retval = write_mmp_block(sb, bh); |
c5e06d10 JL |
246 | |
247 | failed: | |
248 | kfree(data); | |
249 | brelse(bh); | |
250 | return retval; | |
251 | } | |
252 | ||
253 | /* | |
254 | * Get a random new sequence number but make sure it is not greater than | |
255 | * EXT4_MMP_SEQ_MAX. | |
256 | */ | |
257 | static unsigned int mmp_new_seq(void) | |
258 | { | |
259 | u32 new_seq; | |
260 | ||
261 | do { | |
dd1f723b | 262 | new_seq = prandom_u32(); |
c5e06d10 JL |
263 | } while (new_seq > EXT4_MMP_SEQ_MAX); |
264 | ||
265 | return new_seq; | |
266 | } | |
267 | ||
268 | /* | |
269 | * Protect the filesystem from being mounted more than once. | |
270 | */ | |
271 | int ext4_multi_mount_protect(struct super_block *sb, | |
272 | ext4_fsblk_t mmp_block) | |
273 | { | |
274 | struct ext4_super_block *es = EXT4_SB(sb)->s_es; | |
275 | struct buffer_head *bh = NULL; | |
276 | struct mmp_struct *mmp = NULL; | |
277 | struct mmpd_data *mmpd_data; | |
278 | u32 seq; | |
279 | unsigned int mmp_check_interval = le16_to_cpu(es->s_mmp_update_interval); | |
280 | unsigned int wait_time = 0; | |
281 | int retval; | |
282 | ||
283 | if (mmp_block < le32_to_cpu(es->s_first_data_block) || | |
284 | mmp_block >= ext4_blocks_count(es)) { | |
285 | ext4_warning(sb, "Invalid MMP block in superblock"); | |
286 | goto failed; | |
287 | } | |
288 | ||
289 | retval = read_mmp_block(sb, &bh, mmp_block); | |
290 | if (retval) | |
291 | goto failed; | |
292 | ||
293 | mmp = (struct mmp_struct *)(bh->b_data); | |
294 | ||
295 | if (mmp_check_interval < EXT4_MMP_MIN_CHECK_INTERVAL) | |
296 | mmp_check_interval = EXT4_MMP_MIN_CHECK_INTERVAL; | |
297 | ||
298 | /* | |
299 | * If check_interval in MMP block is larger, use that instead of | |
300 | * update_interval from the superblock. | |
301 | */ | |
85d21650 SN |
302 | if (le16_to_cpu(mmp->mmp_check_interval) > mmp_check_interval) |
303 | mmp_check_interval = le16_to_cpu(mmp->mmp_check_interval); | |
c5e06d10 JL |
304 | |
305 | seq = le32_to_cpu(mmp->mmp_seq); | |
306 | if (seq == EXT4_MMP_SEQ_CLEAN) | |
307 | goto skip; | |
308 | ||
309 | if (seq == EXT4_MMP_SEQ_FSCK) { | |
310 | dump_mmp_msg(sb, mmp, "fsck is running on the filesystem"); | |
311 | goto failed; | |
312 | } | |
313 | ||
314 | wait_time = min(mmp_check_interval * 2 + 1, | |
315 | mmp_check_interval + 60); | |
316 | ||
317 | /* Print MMP interval if more than 20 secs. */ | |
318 | if (wait_time > EXT4_MMP_MIN_CHECK_INTERVAL * 4) | |
319 | ext4_warning(sb, "MMP interval %u higher than expected, please" | |
320 | " wait.\n", wait_time * 2); | |
321 | ||
322 | if (schedule_timeout_interruptible(HZ * wait_time) != 0) { | |
323 | ext4_warning(sb, "MMP startup interrupted, failing mount\n"); | |
324 | goto failed; | |
325 | } | |
326 | ||
327 | retval = read_mmp_block(sb, &bh, mmp_block); | |
328 | if (retval) | |
329 | goto failed; | |
330 | mmp = (struct mmp_struct *)(bh->b_data); | |
331 | if (seq != le32_to_cpu(mmp->mmp_seq)) { | |
332 | dump_mmp_msg(sb, mmp, | |
333 | "Device is already active on another node."); | |
334 | goto failed; | |
335 | } | |
336 | ||
337 | skip: | |
338 | /* | |
339 | * write a new random sequence number. | |
340 | */ | |
f6f96fdb DW |
341 | seq = mmp_new_seq(); |
342 | mmp->mmp_seq = cpu_to_le32(seq); | |
c5e06d10 | 343 | |
5c359a47 | 344 | retval = write_mmp_block(sb, bh); |
c5e06d10 JL |
345 | if (retval) |
346 | goto failed; | |
347 | ||
348 | /* | |
349 | * wait for MMP interval and check mmp_seq. | |
350 | */ | |
351 | if (schedule_timeout_interruptible(HZ * wait_time) != 0) { | |
352 | ext4_warning(sb, "MMP startup interrupted, failing mount\n"); | |
353 | goto failed; | |
354 | } | |
355 | ||
356 | retval = read_mmp_block(sb, &bh, mmp_block); | |
357 | if (retval) | |
358 | goto failed; | |
359 | mmp = (struct mmp_struct *)(bh->b_data); | |
360 | if (seq != le32_to_cpu(mmp->mmp_seq)) { | |
361 | dump_mmp_msg(sb, mmp, | |
362 | "Device is already active on another node."); | |
363 | goto failed; | |
364 | } | |
365 | ||
366 | mmpd_data = kmalloc(sizeof(struct mmpd_data), GFP_KERNEL); | |
367 | if (!mmpd_data) { | |
368 | ext4_warning(sb, "not enough memory for mmpd_data"); | |
369 | goto failed; | |
370 | } | |
371 | mmpd_data->sb = sb; | |
372 | mmpd_data->bh = bh; | |
373 | ||
374 | /* | |
375 | * Start a kernel thread to update the MMP block periodically. | |
376 | */ | |
377 | EXT4_SB(sb)->s_mmp_tsk = kthread_run(kmmpd, mmpd_data, "kmmpd-%s", | |
378 | bdevname(bh->b_bdev, | |
379 | mmp->mmp_bdevname)); | |
380 | if (IS_ERR(EXT4_SB(sb)->s_mmp_tsk)) { | |
381 | EXT4_SB(sb)->s_mmp_tsk = NULL; | |
382 | kfree(mmpd_data); | |
383 | ext4_warning(sb, "Unable to create kmmpd thread for %s.", | |
384 | sb->s_id); | |
385 | goto failed; | |
386 | } | |
387 | ||
388 | return 0; | |
389 | ||
390 | failed: | |
391 | brelse(bh); | |
392 | return 1; | |
393 | } | |
394 | ||
395 |