Re: [PATCH] jbd2: add jbd2_journal_init() helper

[Eric Ren]

Hi Geliang,

On 08/31/2016 08:23 PM, Geliang Tang wrote:
> There are some repetitive code in jbd2_journal_init_dev() and
> jbd2_journal_init_inode(). So this patch extracts the common code into
> jbd2_journal_init() helper to simplify the code. And fix the coding
> style warnings reported by checkpatch.pl by the way.
journal_init_common() is already there for the same purpose, right?
Do we really need another helper?

Thanks,
Eric

> Signed-off-by: Geliang Tang <geliangtang@xxxxxxxxx>
> ---
>   fs/jbd2/journal.c | 130 +++++++++++++++++++++++++++---------------------------
>   1 file changed, 66 insertions(+), 64 deletions(-)
>
> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
> index 46261a6..c10f657 100644
> --- a/fs/jbd2/journal.c
> +++ b/fs/jbd2/journal.c
> @@ -1143,30 +1143,13 @@ static journal_t * journal_init_common (void)
>    *
>    */
>   
> -/**
> - *  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.
> - *  @start: Block nr Start of journal.
> - *  @len:  Length of the journal in blocks.
> - *  @blocksize: blocksize of journalling device
> - *
> - *  Returns: a newly created journal_t *
> - *
> - *  jbd2_journal_init_dev creates a journal which maps a fixed contiguous
> - *  range of blocks on an arbitrary block device.
> - *
> - */
> -journal_t * jbd2_journal_init_dev(struct block_device *bdev,
> -			struct block_device *fs_dev,
> -			unsigned long long start, int len, int blocksize)
> +static int jbd2_journal_init(journal_t *journal, struct block_device *bdev,
> +			struct block_device *fs_dev, unsigned long long start,
> +			int len, int blocksize, gfp_t gfp)
>   {
> -	journal_t *journal = journal_init_common();
>   	struct buffer_head *bh;
>   	int n;
> -
> -	if (!journal)
> -		return NULL;
> +	int err = 0;
>   
>   	/* journal descriptor can store up to n blocks -bzzz */
>   	journal->j_blocksize = blocksize;
> @@ -1183,94 +1166,113 @@ journal_t * jbd2_journal_init_dev(struct block_device *bdev,
>   	if (!journal->j_wbuf) {
>   		printk(KERN_ERR "%s: Can't allocate bhs for commit thread\n",
>   			__func__);
> +		err = -ENOMEM;
>   		goto out_err;
>   	}
>   
> -	bh = __getblk(journal->j_dev, start, journal->j_blocksize);
> +	bh = __getblk_gfp(journal->j_dev, start, journal->j_blocksize, gfp);
>   	if (!bh) {
>   		printk(KERN_ERR
>   		       "%s: Cannot get buffer for journal superblock\n",
>   		       __func__);
> +		err = -EIO;
>   		goto out_err;
>   	}
>   	journal->j_sb_buffer = bh;
>   	journal->j_superblock = (journal_superblock_t *)bh->b_data;
>   
> -	return journal;
> +	return 0;
>   out_err:
>   	kfree(journal->j_wbuf);
>   	jbd2_stats_proc_exit(journal);
> +	return err;
> +}
> +
> +/**
> + * 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.
> + * @start: Block nr Start of journal.
> + * @len:  Length of the journal in blocks.
> + * @blocksize: blocksize of journalling device
> + *
> + * Returns: a newly created journal_t *
> + *
> + * jbd2_journal_init_dev creates a journal which maps a fixed contiguous
> + * range of blocks on an arbitrary block device.
> + */
> +journal_t *jbd2_journal_init_dev(struct block_device *bdev,
> +			struct block_device *fs_dev,
> +			unsigned long long start, int len, int blocksize)
> +{
> +	journal_t *journal = journal_init_common();
> +	int err;
> +
> +	if (!journal)
> +		return NULL;
> +
> +	err = jbd2_journal_init(journal, bdev, fs_dev, start, len,
> +				blocksize, __GFP_MOVABLE);
> +	if (err) {
> +		pr_err("%s: journal init error\n",
> +		       __func__);
> +		goto out_err;
> +	}
> +
> +	return journal;
> +
> +out_err:
>   	kfree(journal);
>   	return NULL;
>   }
>   
>   /**
> - *  journal_t * jbd2_journal_init_inode () - creates a journal which maps to a inode.
> - *  @inode: An inode to create the journal in
> + * journal_t *jbd2_journal_init_inode() - creates a journal which maps to a
> + * inode.
> + * @inode: An inode to create the journal in
> + *
> + * Returns: a newly created journal_t *
>    *
>    * jbd2_journal_init_inode creates a journal which maps an on-disk inode as
> - * the journal.  The inode must exist already, must support bmap() and
> - * must have all data blocks preallocated.
> + * the journal.  The inode must exist already, must support bmap() and must
> + * have all data blocks preallocated.
>    */
> -journal_t * jbd2_journal_init_inode (struct inode *inode)
> +journal_t *jbd2_journal_init_inode(struct inode *inode)
>   {
> -	struct buffer_head *bh;
>   	journal_t *journal = journal_init_common();
> -	char *p;
> -	int err;
> -	int n;
>   	unsigned long long blocknr;
> +	int err;
>   
>   	if (!journal)
>   		return NULL;
>   
> -	journal->j_dev = journal->j_fs_dev = inode->i_sb->s_bdev;
>   	journal->j_inode = inode;
> -	bdevname(journal->j_dev, journal->j_devname);
> -	p = strreplace(journal->j_devname, '/', '!');
> -	sprintf(p, "-%lu", journal->j_inode->i_ino);
> -	jbd_debug(1,
> -		  "journal %p: inode %s/%ld, size %Ld, bits %d, blksize %ld\n",
> -		  journal, 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->j_maxlen = inode->i_size >> inode->i_sb->s_blocksize_bits;
> -	journal->j_blocksize = inode->i_sb->s_blocksize;
> -	jbd2_stats_proc_init(journal);
> -
> -	/* journal descriptor can store up to n blocks -bzzz */
> -	n = journal->j_blocksize / sizeof(journal_block_tag_t);
> -	journal->j_wbufsize = n;
> -	journal->j_wbuf = kmalloc(n * sizeof(struct buffer_head*), GFP_KERNEL);
> -	if (!journal->j_wbuf) {
> -		printk(KERN_ERR "%s: Can't allocate bhs for commit thread\n",
> -			__func__);
> -		goto out_err;
> -	}
>   
>   	err = jbd2_journal_bmap(journal, 0, &blocknr);
>   	/* If that failed, give up */
>   	if (err) {
> -		printk(KERN_ERR "%s: Cannot locate journal superblock\n",
> +		pr_err("%s: Cannot locate journal superblock\n",
>   		       __func__);
>   		goto out_err;
>   	}
>   
> -	bh = getblk_unmovable(journal->j_dev, blocknr, journal->j_blocksize);
> -	if (!bh) {
> -		printk(KERN_ERR
> -		       "%s: Cannot get buffer for journal superblock\n",
> +	err = jbd2_journal_init(journal, inode->i_sb->s_bdev,
> +				inode->i_sb->s_bdev, blocknr,
> +				inode->i_size >> inode->i_sb->s_blocksize_bits,
> +				inode->i_sb->s_blocksize, 0);
> +	if (err) {
> +		pr_err("%s: journal init error\n",
>   		       __func__);
>   		goto out_err;
>   	}
> -	journal->j_sb_buffer = bh;
> -	journal->j_superblock = (journal_superblock_t *)bh->b_data;
> +
> +	sprintf(journal->j_devname, "%s-%lu",
> +		journal->j_devname, journal->j_inode->i_ino);
>   
>   	return journal;
> +
>   out_err:
> -	kfree(journal->j_wbuf);
> -	jbd2_stats_proc_exit(journal);
>   	kfree(journal);
>   	return NULL;
>   }