ext4: cleanup ext4_get_dev_journal() and ext4_get_journal()

Factor out a new helper form ext4_get_dev_journal() to get external
journal bdev and check validation of this device, drop ext4_blkdev_get()
helper, and also remove duplicate check of journal feature. It makes
ext4_get_dev_journal() more clear than before.

Signed-off-by: Zhang Yi <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Theodore Ts'o <[email protected]>

Author: zhangyi089

fs/ext4/super.c

@@ -1105,26 +1105,6 @@ static const struct blk_holder_ops ext4_holder_ops = {
 	.mark_dead		= ext4_bdev_mark_dead,
 };
 
-/*
- * Open the external journal device
- */
-static struct block_device *ext4_blkdev_get(dev_t dev, struct super_block *sb)
-{
-	struct block_device *bdev;
-
-	bdev = blkdev_get_by_dev(dev, BLK_OPEN_READ | BLK_OPEN_WRITE, sb,
-				 &ext4_holder_ops);
-	if (IS_ERR(bdev))
-		goto fail;
-	return bdev;
-
-fail:
-	ext4_msg(sb, KERN_ERR,
-		 "failed to open journal device unknown-block(%u,%u) %ld",
-		 MAJOR(dev), MINOR(dev), PTR_ERR(bdev));
-	return NULL;
-}
-
 /*
  * Release the journal device
  */
@@ -5768,14 +5748,14 @@ static struct inode *ext4_get_journal_inode(struct super_block *sb,
 		ext4_msg(sb, KERN_ERR, "journal inode is deleted");
 		return NULL;
 	}
-
-	ext4_debug("Journal inode found at %p: %lld bytes\n",
-		  journal_inode, journal_inode->i_size);
 	if (!S_ISREG(journal_inode->i_mode) || IS_ENCRYPTED(journal_inode)) {
 		ext4_msg(sb, KERN_ERR, "invalid journal inode");
 		iput(journal_inode);
 		return NULL;
 	}
+
+	ext4_debug("Journal inode found at %p: %lld bytes\n",
+		  journal_inode, journal_inode->i_size);
 	return journal_inode;
 }
 
@@ -5807,9 +5787,6 @@ static journal_t *ext4_get_journal(struct super_block *sb,
 	struct inode *journal_inode;
 	journal_t *journal;
 
-	if (WARN_ON_ONCE(!ext4_has_feature_journal(sb)))
-		return NULL;
-
 	journal_inode = ext4_get_journal_inode(sb, journal_inum);
 	if (!journal_inode)
 		return NULL;
@@ -5826,25 +5803,25 @@ static journal_t *ext4_get_journal(struct super_block *sb,
 	return journal;
 }
 
-static journal_t *ext4_get_dev_journal(struct super_block *sb,
-				       dev_t j_dev)
+static struct block_device *ext4_get_journal_blkdev(struct super_block *sb,
+					dev_t j_dev, ext4_fsblk_t *j_start,
+					ext4_fsblk_t *j_len)
 {
 	struct buffer_head *bh;
-	journal_t *journal;
-	ext4_fsblk_t start;
-	ext4_fsblk_t len;
+	struct block_device *bdev;
 	int hblock, blocksize;
 	ext4_fsblk_t sb_block;
 	unsigned long offset;
 	struct ext4_super_block *es;
-	struct block_device *bdev;
 
-	if (WARN_ON_ONCE(!ext4_has_feature_journal(sb)))
-		return NULL;
-
-	bdev = ext4_blkdev_get(j_dev, sb);
-	if (bdev == NULL)
+	bdev = blkdev_get_by_dev(j_dev, BLK_OPEN_READ | BLK_OPEN_WRITE, sb,
+				 &ext4_holder_ops);
+	if (IS_ERR(bdev)) {
+		ext4_msg(sb, KERN_ERR,
+			 "failed to open journal device unknown-block(%u,%u) %ld",
+			 MAJOR(j_dev), MINOR(j_dev), PTR_ERR(bdev));
 		return NULL;
+	}
 
 	blocksize = sb->s_blocksize;
 	hblock = bdev_logical_block_size(bdev);
@@ -5857,7 +5834,8 @@ static journal_t *ext4_get_dev_journal(struct super_block *sb,
 	sb_block = EXT4_MIN_BLOCK_SIZE / blocksize;
 	offset = EXT4_MIN_BLOCK_SIZE % blocksize;
 	set_blocksize(bdev, blocksize);
-	if (!(bh = __bread(bdev, sb_block, blocksize))) {
+	bh = __bread(bdev, sb_block, blocksize);
+	if (!bh) {
 		ext4_msg(sb, KERN_ERR, "couldn't read superblock of "
 		       "external journal");
 		goto out_bdev;
@@ -5867,56 +5845,67 @@ static journal_t *ext4_get_dev_journal(struct super_block *sb,
 	if ((le16_to_cpu(es->s_magic) != EXT4_SUPER_MAGIC) ||
 	    !(le32_to_cpu(es->s_feature_incompat) &
 	      EXT4_FEATURE_INCOMPAT_JOURNAL_DEV)) {
-		ext4_msg(sb, KERN_ERR, "external journal has "
-					"bad superblock");
-		brelse(bh);
-		goto out_bdev;
+		ext4_msg(sb, KERN_ERR, "external journal has bad superblock");
+		goto out_bh;
 	}
 
 	if ((le32_to_cpu(es->s_feature_ro_compat) &
 	     EXT4_FEATURE_RO_COMPAT_METADATA_CSUM) &&
 	    es->s_checksum != ext4_superblock_csum(sb, es)) {
-		ext4_msg(sb, KERN_ERR, "external journal has "
-				       "corrupt superblock");
-		brelse(bh);
-		goto out_bdev;
+		ext4_msg(sb, KERN_ERR, "external journal has corrupt superblock");
+		goto out_bh;
 	}
 
 	if (memcmp(EXT4_SB(sb)->s_es->s_journal_uuid, es->s_uuid, 16)) {
 		ext4_msg(sb, KERN_ERR, "journal UUID does not match");
-		brelse(bh);
-		goto out_bdev;
+		goto out_bh;
 	}
 
-	len = ext4_blocks_count(es);
-	start = sb_block + 1;
-	brelse(bh);	/* we're done with the superblock */
+	*j_start = sb_block + 1;
+	*j_len = ext4_blocks_count(es);
+	brelse(bh);
+	return bdev;
+
+out_bh:
+	brelse(bh);
+out_bdev:
+	blkdev_put(bdev, sb);
+	return NULL;
+}
+
+static journal_t *ext4_get_dev_journal(struct super_block *sb,
+				       dev_t j_dev)
+{
+	journal_t *journal;
+	ext4_fsblk_t j_start;
+	ext4_fsblk_t j_len;
+	struct block_device *journal_bdev;
+
+	journal_bdev = ext4_get_journal_blkdev(sb, j_dev, &j_start, &j_len);
+	if (!journal_bdev)
+		return NULL;
 
-	journal = jbd2_journal_init_dev(bdev, sb->s_bdev,
-					start, len, blocksize);
+	journal = jbd2_journal_init_dev(journal_bdev, sb->s_bdev, j_start,
+					j_len, sb->s_blocksize);
 	if (IS_ERR(journal)) {
 		ext4_msg(sb, KERN_ERR, "failed to create device journal");
 		goto out_bdev;
 	}
-	journal->j_private = sb;
-	if (ext4_read_bh_lock(journal->j_sb_buffer, REQ_META | REQ_PRIO, true)) {
-		ext4_msg(sb, KERN_ERR, "I/O error on journal device");
-		goto out_journal;
-	}
 	if (be32_to_cpu(journal->j_superblock->s_nr_users) != 1) {
 		ext4_msg(sb, KERN_ERR, "External journal has more than one "
 					"user (unsupported) - %d",
 			be32_to_cpu(journal->j_superblock->s_nr_users));
 		goto out_journal;
 	}
-	EXT4_SB(sb)->s_journal_bdev = bdev;
+	journal->j_private = sb;
+	EXT4_SB(sb)->s_journal_bdev = journal_bdev;
 	ext4_init_journal_params(sb, journal);
 	return journal;
 
 out_journal:
 	jbd2_journal_destroy(journal);
 out_bdev:
-	blkdev_put(bdev, sb);
+	blkdev_put(journal_bdev, sb);
 	return NULL;
 }