Re: [PATCH 1/2] mm: move filemap_range_needs_writeback() into header

[Jens Axboe <axboe@kernel.dk>]

On 12/3/21 9:24 AM, Jens Axboe wrote:
> On 12/3/21 9:16 AM, Matthew Wilcox wrote:
>> On Fri, Dec 03, 2021 at 08:38:28AM -0700, Jens Axboe wrote:
>>> +++ b/include/linux/fs.h
>>
>> fs.h is the wrong place for these functions; they're pagecache
>> functionality, so they should be in pagemap.h.
>>
>>> +/* Returns true if writeback might be needed or already in progress. */
>>> +static inline bool mapping_needs_writeback(struct address_space *mapping)
>>> +{
>>> +	return mapping->nrpages;
>>> +}
>>
>> I don't like this function -- mapping_needs_writeback says to me that it
>> tests a flag in mapping->flags.  Plus, it does exactly the same thing as
>> !mapping_empty(), so perhaps ...
>>
>>> +static inline bool filemap_range_needs_writeback(struct address_space *mapping,
>>> +						 loff_t start_byte,
>>> +						 loff_t end_byte)
>>> +{
>>> +	if (!mapping_needs_writeback(mapping))
>>> +		return false;
>>
>> just make this
>> 	if (mapping_empty(mapping))
>> 		return false;
>>
>> Other than that, no objections to making this static inline.
> 
> Good idea, I'll make that change.

That does introduce a dependency from fs.h -> pagemap.h which isn't trivially
resolvable...

What if we just rename the above funciton to mapping_has_pages() or something
instead?

-- 
Jens Axboe