[Devel] [vzlin-dev] [PATCH rh7 3/4] ploop: get rid of dio_fsync()

[Dmitry Monakhov]

Maxim Patlasov <mpatlasov at virtuozzo.com> writes:

> For ext4 dio_fsync() is actually equivalent to direct call to fsync fop:
>
> 1) file->f_op cannot be NULL;
> 2) file->f_op->fsync is always equal to ext4_sync_file;
> 3) ext4_sync_file() does filemap_write_and_wait() internally,
>    no need to call it explicitly.
>
> The patch also fixes a potential problem: if fsync() fails, it's better
> to pass error code up to the stack of callers.
>
> Signed-off-by: Maxim Patlasov <mpatlasov at virtuozzo.com>
Acked-by:dmonakhov at openvz.org
> ---
>  drivers/block/ploop/io_direct.c |   52 ++++++++++++++++++---------------------
>  1 file changed, 24 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/block/ploop/io_direct.c b/drivers/block/ploop/io_direct.c
> index a37f296..1ff848c 100644
> --- a/drivers/block/ploop/io_direct.c
> +++ b/drivers/block/ploop/io_direct.c
> @@ -844,21 +844,6 @@ static int dio_fsync_thread(void * data)
>  	return 0;
>  }
>  
> -static int dio_fsync(struct file * file)
> -{
> -	int err, ret;
> -	struct address_space *mapping = file->f_mapping;
> -
> -	ret = filemap_write_and_wait(mapping);
> -	err = 0;
> -	if (file->f_op && file->f_op->fsync) {
> -		err = file->f_op->fsync(file, 0, LLONG_MAX, 0);
> -		if (!ret)
> -			ret = err;
> -	}
> -	return ret;
> -}
> -
>  /* Invalidate page cache. It is called with inode mutex taken
>   * and mapping mapping must be synced. If some dirty pages remained,
>   * it will fail.
> @@ -949,20 +934,17 @@ static void dio_destroy(struct ploop_io * io)
>  static int dio_sync(struct ploop_io * io)
>  {
>  	struct file * file = io->files.file;
> +	int err = 0;
>  
>  	if (file)
> -		dio_fsync(file);
> -	return 0;
> +		err = file->f_op->fsync(file, 0, LLONG_MAX, 0);
> +
> +	return err;
>  }
>  
>  static int dio_stop(struct ploop_io * io)
>  {
> -	struct file * file = io->files.file;
> -
> -	if (file) {
> -		dio_fsync(file);
> -	}
> -	return 0;
> +	return io->ops->sync(io);
>  }
>  
>  static int dio_open(struct ploop_io * io)
> @@ -979,7 +961,9 @@ static int dio_open(struct ploop_io * io)
>  	io->files.inode = io->files.mapping->host;
>  	io->files.bdev = io->files.inode->i_sb->s_bdev;
>  
> -	dio_fsync(file);
> +	err = io->ops->sync(io);
> +	if (err)
> +		return err;
>  
>  	mutex_lock(&io->files.inode->i_mutex);
>  	em_tree = ploop_dio_open(io, (delta->flags & PLOOP_FMT_RDONLY));
> @@ -1646,7 +1630,11 @@ static int dio_prepare_snapshot(struct ploop_io * io, struct ploop_snapdata *sd)
>  		return -EINVAL;
>  	}
>  
> -	dio_fsync(file);
> +	err = io->ops->sync(io);
> +	if (err) {
> +		fput(file);
> +		return err;
> +	}
>  
>  	mutex_lock(&io->files.inode->i_mutex);
>  	err = dio_invalidate_cache(io->files.mapping, io->files.bdev);
> @@ -1713,7 +1701,11 @@ static int dio_prepare_merge(struct ploop_io * io, struct ploop_snapdata *sd)
>  		return -EINVAL;
>  	}
>  
> -	dio_fsync(file);
> +	err = io->ops->sync(io);
> +	if (err) {
> +		fput(file);
> +		return err;
> +	}
>  
>  	mutex_lock(&io->files.inode->i_mutex);
>  
> @@ -1772,8 +1764,12 @@ static int dio_truncate(struct ploop_io * io, struct file * file,
>  	atomic_long_sub(*io->size_ptr - new_size, &ploop_io_images_size);
>  	*io->size_ptr = new_size;
>  
> -	if (!err)
> -		err = dio_fsync(file);
> +	if (!err) {
> +		if (io->files.file == file)
> +			err = io->ops->sync(io);
> +		else
> +			err = file->f_op->fsync(file, 0, LLONG_MAX, 0);
> +	}
>  
>  	return err;
>  }
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