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 <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230811063610.2980059-12-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 279e37c..0eee238 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1106,26 +1106,6 @@ static const struct blk_holder_ops ext4_holder_ops = {
 };
 
 /*
- * 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
  */
 static void ext4_blkdev_remove(struct ext4_sb_info *sbi)
@@ -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;
 }