Re: [PATCH 1/2] fs: Replace direct ->bmap calls by bmap()

[Eric Sandeen <sandeen@redhat.com>]

On 9/5/18 8:57 AM, Carlos Maiolino wrote:
> Prepare the field to use ->fiemap for FIBMAP ioctl
> 
> Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
> ---
>  fs/cachefiles/rdwr.c |  5 ++---
>  fs/ecryptfs/mmap.c   |  5 ++---
>  fs/ioctl.c           | 14 ++++++++------
>  3 files changed, 12 insertions(+), 12 deletions(-)
> 
> diff --git a/fs/cachefiles/rdwr.c b/fs/cachefiles/rdwr.c
> index 40f7595aad10..186e203d64a7 100644
> --- a/fs/cachefiles/rdwr.c
> +++ b/fs/cachefiles/rdwr.c
> @@ -435,7 +435,7 @@ int cachefiles_read_or_alloc_page(struct fscache_retrieval *op,
>  	block0 = page->index;
>  	block0 <<= shift;
>  
> -	block = inode->i_mapping->a_ops->bmap(inode->i_mapping, block0);
> +	block = bmap(inode, block0);

Prior to this there's an ASSERT that inode->i_mapping->a_ops->bmap
exists.  Should that stay, if the goal is to move all ->bmap use out
of calling code?  OTOH, what will this code do if bmap() finds that there
is no ->bmap present and returns 0?

>  	_debug("%llx -> %llx",
>  	       (unsigned long long) block0,
>  	       (unsigned long long) block);
> @@ -737,8 +737,7 @@ int cachefiles_read_or_alloc_pages(struct fscache_retrieval *op,
>  		block0 = page->index;
>  		block0 <<= shift;
>  
> -		block = inode->i_mapping->a_ops->bmap(inode->i_mapping,
> -						      block0);
> +		block = bmap(inode, block0);
>  		_debug("%llx -> %llx",
>  		       (unsigned long long) block0,
>  		       (unsigned long long) block);
> diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c
> index cdf358b209d9..16626fce5754 100644
> --- a/fs/ecryptfs/mmap.c
> +++ b/fs/ecryptfs/mmap.c
> @@ -544,9 +544,8 @@ static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
>  
>  	inode = (struct inode *)mapping->host;
>  	lower_inode = ecryptfs_inode_to_lower(inode);
> -	if (lower_inode->i_mapping->a_ops->bmap)
> -		rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping,
> -							 block);
> +
> +	rc = bmap(lower_inode, block);
>  	return rc;
>  }
>  
> diff --git a/fs/ioctl.c b/fs/ioctl.c
> index 3212c29235ce..413585d58415 100644
> --- a/fs/ioctl.c
> +++ b/fs/ioctl.c
> @@ -53,19 +53,21 @@ EXPORT_SYMBOL(vfs_ioctl);
>  
>  static int ioctl_fibmap(struct file *filp, int __user *p)
>  {
> -	struct address_space *mapping = filp->f_mapping;
> +	struct inode *inode = filp->f_inode;
>  	int res, block;
>  
> -	/* do we support this mess? */
> -	if (!mapping->a_ops->bmap)
> -		return -EINVAL;
>  	if (!capable(CAP_SYS_RAWIO))
>  		return -EPERM;
>  	res = get_user(block, p);
>  	if (res)
>  		return res;
> -	res = mapping->a_ops->bmap(mapping, block);
> -	return put_user(res, p);
> +
> +	res = bmap(inode, block);
> +
> +	if (res)
> +		return put_user(res, p);
> +	else
> +		return -EINVAL;

So now mapping a hole will return -EINVAL?  I don't think that change
in behavior is ok.

-Eric

>  }
>  
>  /**
>