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2024-02-19 151fecfb72a0d602dfe79790602ef64b4e241574 
 kernel/fs/ext4/mmp.c
....@@ -39,26 +39,34 @@
3939  * Write the MMP block using REQ_SYNC to try to get the block on-disk
4040  * faster.
4141  */
42
-static int write_mmp_block(struct super_block *sb, struct buffer_head *bh)
42
+static int write_mmp_block_thawed(struct super_block *sb,
43
+				  struct buffer_head *bh)
4344 {
4445 	struct mmp_struct *mmp = (struct mmp_struct *)(bh->b_data);
4546 
46
-	/*
47
-	 * We protect against freezing so that we don't create dirty buffers
48
-	 * on frozen filesystem.
49
-	 */
50
-	sb_start_write(sb);
5147 	ext4_mmp_csum_set(sb, mmp);
5248 	lock_buffer(bh);
5349 	bh->b_end_io = end_buffer_write_sync;
5450 	get_bh(bh);
5551 	submit_bh(REQ_OP_WRITE, REQ_SYNC | REQ_META | REQ_PRIO, bh);
5652 	wait_on_buffer(bh);
57
-	sb_end_write(sb);
5853 	if (unlikely(!buffer_uptodate(bh)))
59
-		return 1;
60
-
54
+		return -EIO;
6155 	return 0;
56
+}
57
+
58
+static int write_mmp_block(struct super_block *sb, struct buffer_head *bh)
59
+{
60
+	int err;
61
+
62
+	/*
63
+	 * We protect against freezing so that we don't create dirty buffers
64
+	 * on frozen filesystem.
65
+	 */
66
+	sb_start_write(sb);
67
+	err = write_mmp_block_thawed(sb, bh);
68
+	sb_end_write(sb);
69
+	return err;
6270 }
6371 
6472 /*
....@@ -85,15 +93,11 @@
8593 		}
8694 	}
8795 
88
-	get_bh(*bh);
8996 	lock_buffer(*bh);
90
-	(*bh)->b_end_io = end_buffer_read_sync;
91
-	submit_bh(REQ_OP_READ, REQ_META | REQ_PRIO, *bh);
92
-	wait_on_buffer(*bh);
93
-	if (!buffer_uptodate(*bh)) {
94
-		ret = -EIO;
97
+	ret = ext4_read_bh(*bh, REQ_META | REQ_PRIO, NULL);
98
+	if (ret)
9599 		goto warn_exit;
96
-	}
100
+
97101 	mmp = (struct mmp_struct *)((*bh)->b_data);
98102 	if (le32_to_cpu(mmp->mmp_magic) != EXT4_MMP_MAGIC) {
99103 		ret = -EFSCORRUPTED;
....@@ -131,9 +135,9 @@
131135  */
132136 static int kmmpd(void *data)
133137 {
134
-	struct super_block *sb = ((struct mmpd_data *) data)->sb;
135
-	struct buffer_head *bh = ((struct mmpd_data *) data)->bh;
138
+	struct super_block *sb = (struct super_block *) data;
136139 	struct ext4_super_block *es = EXT4_SB(sb)->s_es;
140
+	struct buffer_head *bh = EXT4_SB(sb)->s_mmp_bh;
137141 	struct mmp_struct *mmp;
138142 	ext4_fsblk_t mmp_block;
139143 	u32 seq = 0;
....@@ -160,7 +164,12 @@
160164 	memcpy(mmp->mmp_nodename, init_utsname()->nodename,
161165 	       sizeof(mmp->mmp_nodename));
162166 
163
-	while (!kthread_should_stop()) {
167
+	while (!kthread_should_stop() && !sb_rdonly(sb)) {
168
+		if (!ext4_has_feature_mmp(sb)) {
169
+			ext4_warning(sb, "kmmpd being stopped since MMP feature"
170
+				     " has been disabled.");
171
+			goto wait_to_exit;
172
+		}
164173 		if (++seq > EXT4_MMP_SEQ_MAX)
165174 			seq = 1;
166175 
....@@ -174,20 +183,12 @@
174183 		 * (s_mmp_update_interval * 60) seconds.
175184 		 */
176185 		if (retval) {
177
-			if ((failed_writes % 60) == 0)
178
-				ext4_error(sb, "Error writing to MMP block");
186
+			if ((failed_writes % 60) == 0) {
187
+				ext4_error_err(sb, -retval,
188
+					       "Error writing to MMP block");
189
+			}
179190 			failed_writes++;
180191 		}
181
-
182
-		if (!(le32_to_cpu(es->s_feature_incompat) &
183
-		    EXT4_FEATURE_INCOMPAT_MMP)) {
184
-			ext4_warning(sb, "kmmpd being stopped since MMP feature"
185
-				     " has been disabled.");
186
-			goto exit_thread;
187
-		}
188
-
189
-		if (sb_rdonly(sb))
190
-			break;
191192 
192193 		diff = jiffies - last_update_time;
193194 		if (diff < mmp_update_interval * HZ)
....@@ -206,9 +207,10 @@
206207 
207208 			retval = read_mmp_block(sb, &bh_check, mmp_block);
208209 			if (retval) {
209
-				ext4_error(sb, "error reading MMP data: %d",
210
-					   retval);
211
-				goto exit_thread;
210
+				ext4_error_err(sb, -retval,
211
+					       "error reading MMP data: %d",
212
+					       retval);
213
+				goto wait_to_exit;
212214 			}
213215 
214216 			mmp_check = (struct mmp_struct *)(bh_check->b_data);
....@@ -219,10 +221,10 @@
219221 					     "Error while updating MMP info. "
220222 					     "The filesystem seems to have been"
221223 					     " multiply mounted.");
222
-				ext4_error(sb, "abort");
224
+				ext4_error_err(sb, EBUSY, "abort");
223225 				put_bh(bh_check);
224226 				retval = -EBUSY;
225
-				goto exit_thread;
227
+				goto wait_to_exit;
226228 			}
227229 			put_bh(bh_check);
228230 		}
....@@ -245,11 +247,23 @@
245247 
246248 	retval = write_mmp_block(sb, bh);
247249 
248
-exit_thread:
249
-	EXT4_SB(sb)->s_mmp_tsk = NULL;
250
-	kfree(data);
251
-	brelse(bh);
250
+wait_to_exit:
251
+	while (!kthread_should_stop()) {
252
+		set_current_state(TASK_INTERRUPTIBLE);
253
+		if (!kthread_should_stop())
254
+			schedule();
255
+	}
256
+	set_current_state(TASK_RUNNING);
252257 	return retval;
258
+}
259
+
260
+void ext4_stop_mmpd(struct ext4_sb_info *sbi)
261
+{
262
+	if (sbi->s_mmp_tsk) {
263
+		kthread_stop(sbi->s_mmp_tsk);
264
+		brelse(sbi->s_mmp_bh);
265
+		sbi->s_mmp_tsk = NULL;
266
+	}
253267 }
254268 
255269 /*
....@@ -276,7 +290,6 @@
276290 	struct ext4_super_block *es = EXT4_SB(sb)->s_es;
277291 	struct buffer_head *bh = NULL;
278292 	struct mmp_struct *mmp = NULL;
279
-	struct mmpd_data *mmpd_data;
280293 	u32 seq;
281294 	unsigned int mmp_check_interval = le16_to_cpu(es->s_mmp_update_interval);
282295 	unsigned int wait_time = 0;
....@@ -285,6 +298,7 @@
285298 	if (mmp_block < le32_to_cpu(es->s_first_data_block) ||
286299 	    mmp_block >= ext4_blocks_count(es)) {
287300 		ext4_warning(sb, "Invalid MMP block in superblock");
301
+		retval = -EINVAL;
288302 		goto failed;
289303 	}
290304 
....@@ -310,6 +324,7 @@
310324 
311325 	if (seq == EXT4_MMP_SEQ_FSCK) {
312326 		dump_mmp_msg(sb, mmp, "fsck is running on the filesystem");
327
+		retval = -EBUSY;
313328 		goto failed;
314329 	}
315330 
....@@ -323,6 +338,7 @@
323338 
324339 	if (schedule_timeout_interruptible(HZ * wait_time) != 0) {
325340 		ext4_warning(sb, "MMP startup interrupted, failing mount\n");
341
+		retval = -ETIMEDOUT;
326342 		goto failed;
327343 	}
328344 
....@@ -333,6 +349,7 @@
333349 	if (seq != le32_to_cpu(mmp->mmp_seq)) {
334350 		dump_mmp_msg(sb, mmp,
335351 			     "Device is already active on another node.");
352
+		retval = -EBUSY;
336353 		goto failed;
337354 	}
338355 
....@@ -343,7 +360,11 @@
343360 	seq = mmp_new_seq();
344361 	mmp->mmp_seq = cpu_to_le32(seq);
345362 
346
-	retval = write_mmp_block(sb, bh);
363
+	/*
364
+	 * On mount / remount we are protected against fs freezing (by s_umount
365
+	 * semaphore) and grabbing freeze protection upsets lockdep
366
+	 */
367
+	retval = write_mmp_block_thawed(sb, bh);
347368 	if (retval)
348369 		goto failed;
349370 
....@@ -352,6 +373,7 @@
352373 	 */
353374 	if (schedule_timeout_interruptible(HZ * wait_time) != 0) {
354375 		ext4_warning(sb, "MMP startup interrupted, failing mount");
376
+		retval = -ETIMEDOUT;
355377 		goto failed;
356378 	}
357379 
....@@ -362,29 +384,24 @@
362384 	if (seq != le32_to_cpu(mmp->mmp_seq)) {
363385 		dump_mmp_msg(sb, mmp,
364386 			     "Device is already active on another node.");
387
+		retval = -EBUSY;
365388 		goto failed;
366389 	}
367390 
368
-	mmpd_data = kmalloc(sizeof(*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;
391
+	EXT4_SB(sb)->s_mmp_bh = bh;
375392 
376393 	/*
377394 	 * Start a kernel thread to update the MMP block periodically.
378395 	 */
379
-	EXT4_SB(sb)->s_mmp_tsk = kthread_run(kmmpd, mmpd_data, "kmmpd-%.*s",
396
+	EXT4_SB(sb)->s_mmp_tsk = kthread_run(kmmpd, sb, "kmmpd-%.*s",
380397 					     (int)sizeof(mmp->mmp_bdevname),
381398 					     bdevname(bh->b_bdev,
382399 						      mmp->mmp_bdevname));
383400 	if (IS_ERR(EXT4_SB(sb)->s_mmp_tsk)) {
384401 		EXT4_SB(sb)->s_mmp_tsk = NULL;
385
-		kfree(mmpd_data);
386402 		ext4_warning(sb, "Unable to create kmmpd thread for %s.",
387403 			     sb->s_id);
404
+		retval = -ENOMEM;
388405 		goto failed;
389406 	}
390407 
....@@ -392,7 +409,5 @@
392409 
393410 failed:
394411 	brelse(bh);
395
-	return 1;
412
+	return retval;
396413 }
397
-
398
-