Re: [PATCH v2] fs: Convert return type int to vm_fault_t

[Matthew Wilcox]

On Thu, Aug 30, 2018 at 10:55:47PM +0530, Souptick Joarder wrote:
> +vm_fault_t block_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf,
> +			 get_block_t get_block, int *err)

I don't like returning both the errno and the vm_fault_t.  To me that's a
sign we need to rethink this interface.

I have two suggestions.  First, we could allocate a new VM_FAULT_NOSPC
bit.  Second, we could repurpose one of the existing bits, such as
VM_FAULT_RETRY for this purpose.

> -int ext4_page_mkwrite(struct vm_fault *vmf)
> +vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf)

I also think perhaps we could start by _not_ converting block_page_mkwrite().
Just convert ext4_page_mkwrite(), and save converting block_page_mkwrite()
for later.