Re: [PATCH 2/5] ext4: move ext4_file_dio_write() into ext4_file_write()

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On Sat 12-04-14 13:02:38, Ted Tso wrote:
> This commit doesn't actually change anything; it just moves code
> around in preparation for some code simplification work.
> 
> Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
  Looks good. You can add:
Reviewed-by: Jan Kara <jack@xxxxxxx>

								Honza

> ---
>  fs/ext4/file.c | 139 +++++++++++++++++++++++++++------------------------------
>  1 file changed, 65 insertions(+), 74 deletions(-)
> 
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index 8b22556..3ec0c09 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -92,82 +92,15 @@ ext4_unaligned_aio(struct inode *inode, const struct iovec *iov,
>  }
>  
>  static ssize_t
> -ext4_file_dio_write(struct kiocb *iocb, const struct iovec *iov,
> -		    unsigned long nr_segs, loff_t pos)
> +ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
> +		unsigned long nr_segs, loff_t pos)
>  {
>  	struct file *file = iocb->ki_filp;
> -	struct inode *inode = file->f_mapping->host;
> +	struct inode *inode = file_inode(iocb->ki_filp);
>  	struct blk_plug plug;
>  	int unaligned_aio = 0;
> -	ssize_t ret;
>  	int overwrite = 0;
>  	size_t length = iov_length(iov, nr_segs);
> -
> -	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
> -	    !is_sync_kiocb(iocb))
> -		unaligned_aio = ext4_unaligned_aio(inode, iov, nr_segs, pos);
> -
> -	/* Unaligned direct AIO must be serialized; see comment above */
> -	if (unaligned_aio) {
> -		mutex_lock(ext4_aio_mutex(inode));
> -		ext4_unwritten_wait(inode);
> -	}
> -
> -	mutex_lock(&inode->i_mutex);
> -	blk_start_plug(&plug);
> -
> -	iocb->private = &overwrite;
> -
> -	/* check whether we do a DIO overwrite or not */
> -	if (ext4_should_dioread_nolock(inode) && !unaligned_aio &&
> -	    !file->f_mapping->nrpages && pos + length <= i_size_read(inode)) {
> -		struct ext4_map_blocks map;
> -		unsigned int blkbits = inode->i_blkbits;
> -		int err, len;
> -
> -		map.m_lblk = pos >> blkbits;
> -		map.m_len = (EXT4_BLOCK_ALIGN(pos + length, blkbits) >> blkbits)
> -			- map.m_lblk;
> -		len = map.m_len;
> -
> -		err = ext4_map_blocks(NULL, inode, &map, 0);
> -		/*
> -		 * 'err==len' means that all of blocks has been preallocated no
> -		 * matter they are initialized or not.  For excluding
> -		 * unwritten extents, we need to check m_flags.  There are
> -		 * two conditions that indicate for initialized extents.
> -		 * 1) If we hit extent cache, EXT4_MAP_MAPPED flag is returned;
> -		 * 2) If we do a real lookup, non-flags are returned.
> -		 * So we should check these two conditions.
> -		 */
> -		if (err == len && (map.m_flags & EXT4_MAP_MAPPED))
> -			overwrite = 1;
> -	}
> -
> -	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
> -	mutex_unlock(&inode->i_mutex);
> -
> -	if (ret > 0) {
> -		ssize_t err;
> -
> -		err = generic_write_sync(file, iocb->ki_pos - ret, ret);
> -		if (err < 0)
> -			ret = err;
> -	}
> -	blk_finish_plug(&plug);
> -
> -	if (unaligned_aio)
> -		mutex_unlock(ext4_aio_mutex(inode));
> -
> -	return ret;
> -}
> -
> -static ssize_t
> -ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
> -		unsigned long nr_segs, loff_t pos)
> -{
> -	struct file *file = iocb->ki_filp;
> -	struct inode *inode = file_inode(iocb->ki_filp);
>  	ssize_t ret;
>  
>  	BUG_ON(iocb->ki_pos != pos);
> @@ -179,7 +112,6 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
>  
>  	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
>  		struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
> -		size_t length = iov_length(iov, nr_segs);
>  
>  		if ((pos > sbi->s_bitmap_maxbytes ||
>  		    (pos == sbi->s_bitmap_maxbytes && length > 0)))
> @@ -191,9 +123,68 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
>  		}
>  	}
>  
> -	if (unlikely(iocb->ki_filp->f_flags & O_DIRECT))
> -		ret = ext4_file_dio_write(iocb, iov, nr_segs, pos);
> -	else {
> +	if (unlikely(iocb->ki_filp->f_flags & O_DIRECT)) {
> +		if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) &&
> +		    !is_sync_kiocb(iocb))
> +			unaligned_aio = ext4_unaligned_aio(inode, iov,
> +							   nr_segs, pos);
> +
> +		/* Unaligned direct AIO must be serialized; see comment above */
> +		if (unaligned_aio) {
> +			mutex_lock(ext4_aio_mutex(inode));
> +			ext4_unwritten_wait(inode);
> +		}
> +
> +		mutex_lock(&inode->i_mutex);
> +		blk_start_plug(&plug);
> +
> +		iocb->private = &overwrite;
> +
> +		/* check whether we do a DIO overwrite or not */
> +		if (ext4_should_dioread_nolock(inode) && !unaligned_aio &&
> +		    !file->f_mapping->nrpages && pos + length <= i_size_read(inode)) {
> +			struct ext4_map_blocks map;
> +			unsigned int blkbits = inode->i_blkbits;
> +			int err, len;
> +
> +			map.m_lblk = pos >> blkbits;
> +			map.m_len = (EXT4_BLOCK_ALIGN(pos + length, blkbits) >> blkbits)
> +				- map.m_lblk;
> +			len = map.m_len;
> +
> +			err = ext4_map_blocks(NULL, inode, &map, 0);
> +			/*
> +			 * 'err==len' means that all of blocks has
> +			 * been preallocated no matter they are
> +			 * initialized or not.  For excluding
> +			 * unwritten extents, we need to check
> +			 * m_flags.  There are two conditions that
> +			 * indicate for initialized extents.  1) If we
> +			 * hit extent cache, EXT4_MAP_MAPPED flag is
> +			 * returned; 2) If we do a real lookup,
> +			 * non-flags are returned.  So we should check
> +			 * these two conditions.
> +			 */
> +			if (err == len && (map.m_flags & EXT4_MAP_MAPPED))
> +				overwrite = 1;
> +		}
> +
> +		ret = __generic_file_aio_write(iocb, iov, nr_segs,
> +					       &iocb->ki_pos);
> +		mutex_unlock(&inode->i_mutex);
> +
> +		if (ret > 0) {
> +			ssize_t err;
> +
> +			err = generic_write_sync(file, iocb->ki_pos - ret, ret);
> +			if (err < 0)
> +				ret = err;
> +		}
> +		blk_finish_plug(&plug);
> +
> +		if (unaligned_aio)
> +			mutex_unlock(ext4_aio_mutex(inode));
> +	} else {
>  		mutex_lock(&inode->i_mutex);
>  		ret = __generic_file_aio_write(iocb, iov, nr_segs,
>  					       &iocb->ki_pos);
> -- 
> 1.9.0
> 
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-- 
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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