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2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/fs/ext4/mmp.c
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@@ -39,26 +39,34 @@
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  * Write the MMP block using REQ_SYNC to try to get the block on-disk
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  * faster.
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  */
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-static int write_mmp_block(struct super_block *sb, struct buffer_head *bh)
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+static int write_mmp_block_thawed(struct super_block *sb,
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+				  struct buffer_head *bh)
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 {
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 	struct mmp_struct *mmp = (struct mmp_struct *)(bh->b_data);
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46
 
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-	/*
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-	 * We protect against freezing so that we don't create dirty buffers
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-	 * on frozen filesystem.
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-	 */
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-	sb_start_write(sb);
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 	ext4_mmp_csum_set(sb, mmp);
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 	lock_buffer(bh);
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 	bh->b_end_io = end_buffer_write_sync;
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 	get_bh(bh);
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 	submit_bh(REQ_OP_WRITE, REQ_SYNC | REQ_META | REQ_PRIO, bh);
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 	wait_on_buffer(bh);
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-	sb_end_write(sb);
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 	if (unlikely(!buffer_uptodate(bh)))
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 		return -EIO;
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-
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 	return 0;
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+}
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+
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+static int write_mmp_block(struct super_block *sb, struct buffer_head *bh)
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+{
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+	int err;
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+
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+	/*
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+	 * We protect against freezing so that we don't create dirty buffers
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+	 * on frozen filesystem.
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+	 */
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+	sb_start_write(sb);
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+	err = write_mmp_block_thawed(sb, bh);
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+	sb_end_write(sb);
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+	return err;
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 }
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 /*
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@@ -290,6 +298,7 @@
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 	if (mmp_block < le32_to_cpu(es->s_first_data_block) ||
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 	    mmp_block >= ext4_blocks_count(es)) {
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 		ext4_warning(sb, "Invalid MMP block in superblock");
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+		retval = -EINVAL;
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 		goto failed;
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 	}
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@@ -315,6 +324,7 @@
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 	if (seq == EXT4_MMP_SEQ_FSCK) {
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 		dump_mmp_msg(sb, mmp, "fsck is running on the filesystem");
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+		retval = -EBUSY;
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 		goto failed;
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 	}
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@@ -328,6 +338,7 @@
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 	if (schedule_timeout_interruptible(HZ * wait_time) != 0) {
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 		ext4_warning(sb, "MMP startup interrupted, failing mount\n");
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+		retval = -ETIMEDOUT;
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 		goto failed;
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 	}
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@@ -338,6 +349,7 @@
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 	if (seq != le32_to_cpu(mmp->mmp_seq)) {
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 		dump_mmp_msg(sb, mmp,
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 			     "Device is already active on another node.");
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+		retval = -EBUSY;
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 		goto failed;
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 	}
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@@ -348,7 +360,11 @@
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 	seq = mmp_new_seq();
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 	mmp->mmp_seq = cpu_to_le32(seq);
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-	retval = write_mmp_block(sb, bh);
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+	/*
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+	 * On mount / remount we are protected against fs freezing (by s_umount
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+	 * semaphore) and grabbing freeze protection upsets lockdep
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+	 */
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+	retval = write_mmp_block_thawed(sb, bh);
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 	if (retval)
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 		goto failed;
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@@ -357,6 +373,7 @@
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 	 */
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 	if (schedule_timeout_interruptible(HZ * wait_time) != 0) {
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 		ext4_warning(sb, "MMP startup interrupted, failing mount");
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+		retval = -ETIMEDOUT;
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 		goto failed;
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 	}
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@@ -367,6 +384,7 @@
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 	if (seq != le32_to_cpu(mmp->mmp_seq)) {
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 		dump_mmp_msg(sb, mmp,
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 			     "Device is already active on another node.");
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+		retval = -EBUSY;
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 		goto failed;
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 	}
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@@ -383,6 +401,7 @@
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 		EXT4_SB(sb)->s_mmp_tsk = NULL;
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 		ext4_warning(sb, "Unable to create kmmpd thread for %s.",
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 			     sb->s_id);
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+		retval = -ENOMEM;
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 		goto failed;
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 	}
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@@ -390,5 +409,5 @@
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 failed:
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 	brelse(bh);
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-	return 1;
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+	return retval;
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 }