[RFC v4 linux-next 14/19] jbd2: prevent direct access of bd_inode

[Yu Kuai <yukuai1@huaweicloud.com>]

From: Yu Kuai <yukuai3@huawei.com>

Now that all filesystems stash the bdev file, it's ok to get mapping
from the file.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
 fs/ext4/super.c      |  2 +-
 fs/jbd2/journal.c    | 26 +++++++++++++++-----------
 include/linux/jbd2.h | 18 ++++++++++++++----
 3 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 55b3df71bf5e..4df1a5cfe0a5 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -5918,7 +5918,7 @@ static journal_t *ext4_open_dev_journal(struct super_block *sb,
 	if (IS_ERR(bdev_file))
 		return ERR_CAST(bdev_file);
 
-	journal = jbd2_journal_init_dev(file_bdev(bdev_file), sb->s_bdev, j_start,
+	journal = jbd2_journal_init_dev(bdev_file, sb->s_bdev_file, j_start,
 					j_len, sb->s_blocksize);
 	if (IS_ERR(journal)) {
 		ext4_msg(sb, KERN_ERR, "failed to create device journal");
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index b6c114c11b97..abd42a6ccd0e 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1516,11 +1516,12 @@ static int journal_load_superblock(journal_t *journal)
  * very few fields yet: that has to wait until we have created the
  * journal structures from from scratch, or loaded them from disk. */
 
-static journal_t *journal_init_common(struct block_device *bdev,
-			struct block_device *fs_dev,
+static journal_t *journal_init_common(struct file *bdev_file,
+			struct file *fs_dev_file,
 			unsigned long long start, int len, int blocksize)
 {
 	static struct lock_class_key jbd2_trans_commit_key;
+	struct block_device *bdev = file_bdev(bdev_file);
 	journal_t *journal;
 	int err;
 	int n;
@@ -1531,7 +1532,9 @@ static journal_t *journal_init_common(struct block_device *bdev,
 
 	journal->j_blocksize = blocksize;
 	journal->j_dev = bdev;
-	journal->j_fs_dev = fs_dev;
+	journal->j_dev_file = bdev_file;
+	journal->j_fs_dev = file_bdev(fs_dev_file);
+	journal->j_fs_dev_file = fs_dev_file;
 	journal->j_blk_offset = start;
 	journal->j_total_len = len;
 	jbd2_init_fs_dev_write_error(journal);
@@ -1628,8 +1631,8 @@ static journal_t *journal_init_common(struct block_device *bdev,
 
 /**
  *  journal_t * jbd2_journal_init_dev() - creates and initialises a journal structure
- *  @bdev: Block device on which to create the journal
- *  @fs_dev: Device which hold journalled filesystem for this journal.
+ *  @bdev_file: Opened block device on which to create the journal
+ *  @fs_dev_file: Opened device which hold journalled filesystem for this journal.
  *  @start: Block nr Start of journal.
  *  @len:  Length of the journal in blocks.
  *  @blocksize: blocksize of journalling device
@@ -1640,13 +1643,13 @@ static journal_t *journal_init_common(struct block_device *bdev,
  *  range of blocks on an arbitrary block device.
  *
  */
-journal_t *jbd2_journal_init_dev(struct block_device *bdev,
-			struct block_device *fs_dev,
+journal_t *jbd2_journal_init_dev(struct file *bdev_file,
+			struct file *fs_dev_file,
 			unsigned long long start, int len, int blocksize)
 {
 	journal_t *journal;
 
-	journal = journal_init_common(bdev, fs_dev, start, len, blocksize);
+	journal = journal_init_common(bdev_file, fs_dev_file, start, len, blocksize);
 	if (IS_ERR(journal))
 		return ERR_CAST(journal);
 
@@ -1683,8 +1686,9 @@ journal_t *jbd2_journal_init_inode(struct inode *inode)
 		  inode->i_sb->s_id, inode->i_ino, (long long) inode->i_size,
 		  inode->i_sb->s_blocksize_bits, inode->i_sb->s_blocksize);
 
-	journal = journal_init_common(inode->i_sb->s_bdev, inode->i_sb->s_bdev,
-			blocknr, inode->i_size >> inode->i_sb->s_blocksize_bits,
+	journal = journal_init_common(inode->i_sb->s_bdev_file,
+			inode->i_sb->s_bdev_file, blocknr,
+			inode->i_size >> inode->i_sb->s_blocksize_bits,
 			inode->i_sb->s_blocksize);
 	if (IS_ERR(journal))
 		return ERR_CAST(journal);
@@ -2009,7 +2013,7 @@ static int __jbd2_journal_erase(journal_t *journal, unsigned int flags)
 		byte_count = (block_stop - block_start + 1) *
 				journal->j_blocksize;
 
-		truncate_inode_pages_range(journal->j_dev->bd_inode->i_mapping,
+		truncate_inode_pages_range(journal->j_dev_file->f_mapping,
 				byte_start, byte_stop);
 
 		if (flags & JBD2_JOURNAL_FLUSH_DISCARD) {
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 971f3e826e15..fc26730ae8ef 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -968,6 +968,11 @@ struct journal_s
 	 */
 	struct block_device	*j_dev;
 
+	/**
+	 * @j_dev_file: Opended device @j_dev.
+	 */
+	struct file		*j_dev_file;
+
 	/**
 	 * @j_blocksize: Block size for the location where we store the journal.
 	 */
@@ -993,6 +998,11 @@ struct journal_s
 	 */
 	struct block_device	*j_fs_dev;
 
+	/**
+	 * @j_fs_dev_file: Opened device @j_fs_dev.
+	 */
+	struct file		*j_fs_dev_file;
+
 	/**
 	 * @j_fs_dev_wb_err:
 	 *
@@ -1533,8 +1543,8 @@ extern void	 jbd2_journal_unlock_updates (journal_t *);
 
 void jbd2_journal_wait_updates(journal_t *);
 
-extern journal_t * jbd2_journal_init_dev(struct block_device *bdev,
-				struct block_device *fs_dev,
+extern journal_t *jbd2_journal_init_dev(struct file *bdev_file,
+				struct file *fs_dev_file,
 				unsigned long long start, int len, int bsize);
 extern journal_t * jbd2_journal_init_inode (struct inode *);
 extern int	   jbd2_journal_update_format (journal_t *);
@@ -1696,7 +1706,7 @@ static inline void jbd2_journal_abort_handle(handle_t *handle)
 
 static inline void jbd2_init_fs_dev_write_error(journal_t *journal)
 {
-	struct address_space *mapping = journal->j_fs_dev->bd_inode->i_mapping;
+	struct address_space *mapping = journal->j_fs_dev_file->f_mapping;
 
 	/*
 	 * Save the original wb_err value of client fs's bdev mapping which
@@ -1707,7 +1717,7 @@ static inline void jbd2_init_fs_dev_write_error(journal_t *journal)
 
 static inline int jbd2_check_fs_dev_write_error(journal_t *journal)
 {
-	struct address_space *mapping = journal->j_fs_dev->bd_inode->i_mapping;
+	struct address_space *mapping = journal->j_fs_dev_file->f_mapping;
 
 	return errseq_check(&mapping->wb_err,
 			    READ_ONCE(journal->j_fs_dev_wb_err));
-- 
2.39.2