Re: [PATCH 02/15] ceph: Convert ceph_page_mkwrite() to use a folio

[Xiubo Li <xiubli@redhat.com>]

On 8/26/23 04:12, Matthew Wilcox (Oracle) wrote:
> Operate on the entire folio instead of just the page.  There was an
> earlier effort to do this with thp_size(), but it had the exact type
> confusion between head & tail pages that folios are designed to avoid.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>   fs/ceph/addr.c | 35 +++++++++++++++++------------------
>   1 file changed, 17 insertions(+), 18 deletions(-)
>
> diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
> index 9a0a79833eb0..7c7dfcd63cd1 100644
> --- a/fs/ceph/addr.c
> +++ b/fs/ceph/addr.c
> @@ -1677,8 +1677,8 @@ static vm_fault_t ceph_page_mkwrite(struct vm_fault *vmf)
>   	struct ceph_inode_info *ci = ceph_inode(inode);
>   	struct ceph_file_info *fi = vma->vm_file->private_data;
>   	struct ceph_cap_flush *prealloc_cf;
> -	struct page *page = vmf->page;
> -	loff_t off = page_offset(page);
> +	struct folio *folio = page_folio(vmf->page);
> +	loff_t pos = folio_pos(folio);
>   	loff_t size = i_size_read(inode);
>   	size_t len;
>   	int want, got, err;
> @@ -1695,50 +1695,49 @@ static vm_fault_t ceph_page_mkwrite(struct vm_fault *vmf)
>   	sb_start_pagefault(inode->i_sb);
>   	ceph_block_sigs(&oldset);
>   
> -	if (off + thp_size(page) <= size)
> -		len = thp_size(page);
> -	else
> -		len = offset_in_thp(page, size);
> +	len = folio_size(folio);
> +	if (pos + folio_size(folio) > size)

s/folio_size(folio)/len/ ?


> +		len = size - pos;
>   
>   	dout("page_mkwrite %p %llx.%llx %llu~%zd getting caps i_size %llu\n",
> -	     inode, ceph_vinop(inode), off, len, size);
> +	     inode, ceph_vinop(inode), pos, len, size);
>   	if (fi->fmode & CEPH_FILE_MODE_LAZY)
>   		want = CEPH_CAP_FILE_BUFFER | CEPH_CAP_FILE_LAZYIO;
>   	else
>   		want = CEPH_CAP_FILE_BUFFER;
>   
>   	got = 0;
> -	err = ceph_get_caps(vma->vm_file, CEPH_CAP_FILE_WR, want, off + len, &got);
> +	err = ceph_get_caps(vma->vm_file, CEPH_CAP_FILE_WR, want, pos + len, &got);
>   	if (err < 0)
>   		goto out_free;
>   
>   	dout("page_mkwrite %p %llu~%zd got cap refs on %s\n",
> -	     inode, off, len, ceph_cap_string(got));
> +	     inode, pos, len, ceph_cap_string(got));
>   
> -	/* Update time before taking page lock */
> +	/* Update time before taking folio lock */
>   	file_update_time(vma->vm_file);
>   	inode_inc_iversion_raw(inode);
>   
>   	do {
>   		struct ceph_snap_context *snapc;
>   
> -		lock_page(page);
> +		folio_lock(folio);
>   
> -		if (page_mkwrite_check_truncate(page, inode) < 0) {
> -			unlock_page(page);
> +		if (folio_mkwrite_check_truncate(folio, inode) < 0) {
> +			folio_unlock(folio);
>   			ret = VM_FAULT_NOPAGE;
>   			break;
>   		}
>   
> -		snapc = ceph_find_incompatible(page);
> +		snapc = ceph_find_incompatible(&folio->page);
>   		if (!snapc) {
> -			/* success.  we'll keep the page locked. */
> -			set_page_dirty(page);
> +			/* success.  we'll keep the folio locked. */
> +			folio_mark_dirty(folio);
>   			ret = VM_FAULT_LOCKED;
>   			break;
>   		}
>   
> -		unlock_page(page);
> +		folio_unlock(folio);
>   
>   		if (IS_ERR(snapc)) {
>   			ret = VM_FAULT_SIGBUS;
> @@ -1762,7 +1761,7 @@ static vm_fault_t ceph_page_mkwrite(struct vm_fault *vmf)
>   	}
>   
>   	dout("page_mkwrite %p %llu~%zd dropping cap refs on %s ret %x\n",
> -	     inode, off, len, ceph_cap_string(got), ret);
> +	     inode, pos, len, ceph_cap_string(got), ret);
>   	ceph_put_cap_refs_async(ci, got);
>   out_free:
>   	ceph_restore_sigs(&oldset);