Branch data Line data Source code
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 */
10 : 0 : static __le32 ext4_mmp_csum(struct super_block *sb, struct mmp_struct *mmp)
11 : : {
12 : 0 : struct ext4_sb_info *sbi = EXT4_SB(sb);
13 : : int offset = offsetof(struct mmp_struct, mmp_checksum);
14 : : __u32 csum;
15 : :
16 : 0 : csum = ext4_chksum(sbi, sbi->s_csum_seed, (char *)mmp, offset);
17 : :
18 : 0 : return cpu_to_le32(csum);
19 : : }
20 : :
21 : 0 : int ext4_mmp_csum_verify(struct super_block *sb, struct mmp_struct *mmp)
22 : : {
23 [ # # ]: 0 : if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
24 : : EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
25 : : return 1;
26 : :
27 : 0 : return mmp->mmp_checksum == ext4_mmp_csum(sb, mmp);
28 : : }
29 : :
30 : 0 : void ext4_mmp_csum_set(struct super_block *sb, struct mmp_struct *mmp)
31 : : {
32 [ # # ]: 0 : if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
33 : : EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
34 : 0 : return;
35 : :
36 : 0 : 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 : : */
43 : 0 : static int write_mmp_block(struct super_block *sb, struct buffer_head *bh)
44 : : {
45 : 0 : struct mmp_struct *mmp = (struct mmp_struct *)(bh->b_data);
46 : :
47 : : /*
48 : : * We protect against freezing so that we don't create dirty buffers
49 : : * on frozen filesystem.
50 : : */
51 : : sb_start_write(sb);
52 : 0 : ext4_mmp_csum_set(sb, mmp);
53 : 0 : mark_buffer_dirty(bh);
54 : : lock_buffer(bh);
55 : 0 : bh->b_end_io = end_buffer_write_sync;
56 : : get_bh(bh);
57 : 0 : submit_bh(WRITE_SYNC | REQ_META | REQ_PRIO, bh);
58 : : wait_on_buffer(bh);
59 : : sb_end_write(sb);
60 [ # # ]: 0 : if (unlikely(!buffer_uptodate(bh)))
61 : : return 1;
62 : :
63 : 0 : 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 : 0 : 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 [ # # ]: 0 : 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 [ # # ]: 0 : if (!*bh)
82 : 0 : *bh = sb_getblk(sb, mmp_block);
83 [ # # ]: 0 : if (!*bh)
84 : : return -ENOMEM;
85 [ # # ]: 0 : if (*bh) {
86 : : get_bh(*bh);
87 : 0 : lock_buffer(*bh);
88 : 0 : (*bh)->b_end_io = end_buffer_read_sync;
89 : 0 : submit_bh(READ_SYNC | REQ_META | REQ_PRIO, *bh);
90 : 0 : wait_on_buffer(*bh);
91 [ # # ]: 0 : if (!buffer_uptodate(*bh)) {
92 : : brelse(*bh);
93 : 0 : *bh = NULL;
94 : : }
95 : : }
96 [ # # ]: 0 : if (unlikely(!*bh)) {
97 : 0 : ext4_warning(sb, "Error while reading MMP block %llu",
98 : : mmp_block);
99 : 0 : return -EIO;
100 : : }
101 : :
102 : 0 : mmp = (struct mmp_struct *)((*bh)->b_data);
103 [ # # # # ]: 0 : if (le32_to_cpu(mmp->mmp_magic) != EXT4_MMP_MAGIC ||
104 : 0 : !ext4_mmp_csum_verify(sb, mmp))
105 : : return -EINVAL;
106 : :
107 : : return 0;
108 : : }
109 : :
110 : : /*
111 : : * Dump as much information as possible to help the admin.
112 : : */
113 : 0 : void __dump_mmp_msg(struct super_block *sb, struct mmp_struct *mmp,
114 : : const char *function, unsigned int line, const char *msg)
115 : : {
116 : 0 : __ext4_warning(sb, function, line, msg);
117 : 0 : __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 : 0 : mmp->mmp_nodename, mmp->mmp_bdevname);
122 : 0 : }
123 : :
124 : : /*
125 : : * kmmpd will update the MMP sequence every s_mmp_update_interval seconds
126 : : */
127 : 0 : static int kmmpd(void *data)
128 : : {
129 : 0 : struct super_block *sb = ((struct mmpd_data *) data)->sb;
130 : 0 : struct buffer_head *bh = ((struct mmpd_data *) data)->bh;
131 : 0 : 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 : 0 : 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 : 0 : mmp_block = le64_to_cpu(es->s_mmp_block);
143 : 0 : mmp = (struct mmp_struct *)(bh->b_data);
144 : 0 : 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 : 0 : mmp_check_interval = max(EXT4_MMP_CHECK_MULT * mmp_update_interval,
150 : : EXT4_MMP_MIN_CHECK_INTERVAL);
151 : 0 : mmp->mmp_check_interval = cpu_to_le16(mmp_check_interval);
152 : 0 : bdevname(bh->b_bdev, mmp->mmp_bdevname);
153 : :
154 : 0 : memcpy(mmp->mmp_nodename, init_utsname()->nodename,
155 : : sizeof(mmp->mmp_nodename));
156 : :
157 [ # # ]: 0 : while (!kthread_should_stop()) {
158 [ # # ]: 0 : if (++seq > EXT4_MMP_SEQ_MAX)
159 : : seq = 1;
160 : :
161 : 0 : mmp->mmp_seq = cpu_to_le32(seq);
162 : 0 : mmp->mmp_time = cpu_to_le64(get_seconds());
163 : 0 : last_update_time = jiffies;
164 : :
165 : 0 : retval = write_mmp_block(sb, bh);
166 : : /*
167 : : * Don't spew too many error messages. Print one every
168 : : * (s_mmp_update_interval * 60) seconds.
169 : : */
170 [ # # ]: 0 : if (retval) {
171 [ # # ]: 0 : if ((failed_writes % 60) == 0)
172 : 0 : ext4_error(sb, "Error writing to MMP block");
173 : 0 : failed_writes++;
174 : : }
175 : :
176 [ # # ]: 0 : if (!(le32_to_cpu(es->s_feature_incompat) &
177 : : EXT4_FEATURE_INCOMPAT_MMP)) {
178 : 0 : ext4_warning(sb, "kmmpd being stopped since MMP feature"
179 : : " has been disabled.");
180 : 0 : EXT4_SB(sb)->s_mmp_tsk = NULL;
181 : 0 : goto failed;
182 : : }
183 : :
184 [ # # ]: 0 : if (sb->s_flags & MS_RDONLY) {
185 : 0 : ext4_warning(sb, "kmmpd being stopped since filesystem "
186 : : "has been remounted as readonly.");
187 : 0 : EXT4_SB(sb)->s_mmp_tsk = NULL;
188 : 0 : goto failed;
189 : : }
190 : :
191 : 0 : diff = jiffies - last_update_time;
192 [ # # ]: 0 : if (diff < mmp_update_interval * HZ)
193 : 0 : schedule_timeout_interruptible(mmp_update_interval *
194 : 0 : 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 : 0 : diff = jiffies - last_update_time;
202 [ # # ]: 0 : if (diff > mmp_check_interval * HZ) {
203 : 0 : struct buffer_head *bh_check = NULL;
204 : : struct mmp_struct *mmp_check;
205 : :
206 : 0 : retval = read_mmp_block(sb, &bh_check, mmp_block);
207 [ # # ]: 0 : if (retval) {
208 : 0 : ext4_error(sb, "error reading MMP data: %d",
209 : : retval);
210 : :
211 : 0 : EXT4_SB(sb)->s_mmp_tsk = NULL;
212 : 0 : goto failed;
213 : : }
214 : :
215 : 0 : mmp_check = (struct mmp_struct *)(bh_check->b_data);
216 [ # # ][ # # ]: 0 : if (mmp->mmp_seq != mmp_check->mmp_seq ||
217 : 0 : memcmp(mmp->mmp_nodename, mmp_check->mmp_nodename,
218 : : sizeof(mmp->mmp_nodename))) {
219 : 0 : dump_mmp_msg(sb, mmp_check,
220 : : "Error while updating MMP info. "
221 : : "The filesystem seems to have been"
222 : : " multiply mounted.");
223 : 0 : ext4_error(sb, "abort");
224 : 0 : 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 : 0 : mmp_check_interval = max(min(EXT4_MMP_CHECK_MULT * diff / HZ,
234 : : EXT4_MMP_MAX_CHECK_INTERVAL),
235 : : EXT4_MMP_MIN_CHECK_INTERVAL);
236 : 0 : mmp->mmp_check_interval = cpu_to_le16(mmp_check_interval);
237 : : }
238 : :
239 : : /*
240 : : * Unmount seems to be clean.
241 : : */
242 : 0 : mmp->mmp_seq = cpu_to_le32(EXT4_MMP_SEQ_CLEAN);
243 : 0 : mmp->mmp_time = cpu_to_le64(get_seconds());
244 : :
245 : 0 : retval = write_mmp_block(sb, bh);
246 : :
247 : : failed:
248 : 0 : kfree(data);
249 : : brelse(bh);
250 : 0 : 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 {
262 : 0 : new_seq = prandom_u32();
263 [ # # ]: 0 : } 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 : 0 : int ext4_multi_mount_protect(struct super_block *sb,
272 : : ext4_fsblk_t mmp_block)
273 : : {
274 : 0 : struct ext4_super_block *es = EXT4_SB(sb)->s_es;
275 : 0 : struct buffer_head *bh = NULL;
276 : : struct mmp_struct *mmp = NULL;
277 : : struct mmpd_data *mmpd_data;
278 : : u32 seq;
279 : 0 : unsigned int mmp_check_interval = le16_to_cpu(es->s_mmp_update_interval);
280 : : unsigned int wait_time = 0;
281 : : int retval;
282 : :
283 [ # # ][ # # ]: 0 : if (mmp_block < le32_to_cpu(es->s_first_data_block) ||
284 : : mmp_block >= ext4_blocks_count(es)) {
285 : 0 : ext4_warning(sb, "Invalid MMP block in superblock");
286 : 0 : goto failed;
287 : : }
288 : :
289 : 0 : retval = read_mmp_block(sb, &bh, mmp_block);
290 [ # # ]: 0 : if (retval)
291 : : goto failed;
292 : :
293 : 0 : mmp = (struct mmp_struct *)(bh->b_data);
294 : :
295 [ # # ]: 0 : 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 : : */
302 [ # # ]: 0 : if (le16_to_cpu(mmp->mmp_check_interval) > mmp_check_interval)
303 : : mmp_check_interval = le16_to_cpu(mmp->mmp_check_interval);
304 : :
305 : 0 : seq = le32_to_cpu(mmp->mmp_seq);
306 [ # # ]: 0 : if (seq == EXT4_MMP_SEQ_CLEAN)
307 : : goto skip;
308 : :
309 [ # # ]: 0 : if (seq == EXT4_MMP_SEQ_FSCK) {
310 : 0 : dump_mmp_msg(sb, mmp, "fsck is running on the filesystem");
311 : 0 : goto failed;
312 : : }
313 : :
314 : 0 : wait_time = min(mmp_check_interval * 2 + 1,
315 : : mmp_check_interval + 60);
316 : :
317 : : /* Print MMP interval if more than 20 secs. */
318 [ # # ]: 0 : if (wait_time > EXT4_MMP_MIN_CHECK_INTERVAL * 4)
319 : 0 : ext4_warning(sb, "MMP interval %u higher than expected, please"
320 : : " wait.\n", wait_time * 2);
321 : :
322 [ # # ]: 0 : if (schedule_timeout_interruptible(HZ * wait_time) != 0) {
323 : 0 : ext4_warning(sb, "MMP startup interrupted, failing mount\n");
324 : 0 : goto failed;
325 : : }
326 : :
327 : 0 : retval = read_mmp_block(sb, &bh, mmp_block);
328 [ # # ]: 0 : if (retval)
329 : : goto failed;
330 : 0 : mmp = (struct mmp_struct *)(bh->b_data);
331 [ # # ]: 0 : if (seq != le32_to_cpu(mmp->mmp_seq)) {
332 : 0 : dump_mmp_msg(sb, mmp,
333 : : "Device is already active on another node.");
334 : 0 : goto failed;
335 : : }
336 : :
337 : : skip:
338 : : /*
339 : : * write a new random sequence number.
340 : : */
341 : : seq = mmp_new_seq();
342 : 0 : mmp->mmp_seq = cpu_to_le32(seq);
343 : :
344 : 0 : retval = write_mmp_block(sb, bh);
345 [ # # ]: 0 : if (retval)
346 : : goto failed;
347 : :
348 : : /*
349 : : * wait for MMP interval and check mmp_seq.
350 : : */
351 [ # # ]: 0 : if (schedule_timeout_interruptible(HZ * wait_time) != 0) {
352 : 0 : ext4_warning(sb, "MMP startup interrupted, failing mount\n");
353 : 0 : goto failed;
354 : : }
355 : :
356 : 0 : retval = read_mmp_block(sb, &bh, mmp_block);
357 [ # # ]: 0 : if (retval)
358 : : goto failed;
359 : 0 : mmp = (struct mmp_struct *)(bh->b_data);
360 [ # # ]: 0 : if (seq != le32_to_cpu(mmp->mmp_seq)) {
361 : 0 : dump_mmp_msg(sb, mmp,
362 : : "Device is already active on another node.");
363 : 0 : goto failed;
364 : : }
365 : :
366 : : mmpd_data = kmalloc(sizeof(struct mmpd_data), GFP_KERNEL);
367 [ # # ]: 0 : if (!mmpd_data) {
368 : 0 : ext4_warning(sb, "not enough memory for mmpd_data");
369 : 0 : goto failed;
370 : : }
371 : 0 : mmpd_data->sb = sb;
372 : 0 : mmpd_data->bh = bh;
373 : :
374 : : /*
375 : : * Start a kernel thread to update the MMP block periodically.
376 : : */
377 [ # # ]: 0 : EXT4_SB(sb)->s_mmp_tsk = kthread_run(kmmpd, mmpd_data, "kmmpd-%s",
378 : : bdevname(bh->b_bdev,
379 : : mmp->mmp_bdevname));
380 [ # # ]: 0 : if (IS_ERR(EXT4_SB(sb)->s_mmp_tsk)) {
381 : 0 : EXT4_SB(sb)->s_mmp_tsk = NULL;
382 : 0 : kfree(mmpd_data);
383 : 0 : ext4_warning(sb, "Unable to create kmmpd thread for %s.",
384 : : sb->s_id);
385 : 0 : goto failed;
386 : : }
387 : :
388 : : return 0;
389 : :
390 : : failed:
391 : 0 : brelse(bh);
392 : : return 1;
393 : : }
394 : :
395 : :
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