linux-ext4 - Re: [RFCv1 3/4] ext4: Make mpage_journal_page

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Message-Id: <87zg77ici3.fsf@doe.com>
Date:   Mon, 17 Apr 2023 05:52:12 +0530
From:   Ritesh Harjani (IBM) <ritesh.list@...il.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     linux-ext4@...r.kernel.org, Jan Kara <jack@...e.cz>,
        Ojaswin Mujoo <ojaswin@...ux.ibm.com>,
        Disha Goel <disgoel@...ux.ibm.com>
Subject: Re: [RFCv1 3/4] ext4: Make mpage_journal_page_buffers use folio

Matthew Wilcox <willy@...radead.org> writes:

> On Mon, Apr 17, 2023 at 12:01:52AM +0530, Ritesh Harjani (IBM) wrote:
>> This patch converts mpage_journal_page_buffers() to use folio and also
>> removes the PAGE_SIZE assumption.
>
> Bit of an oversight on my part.  I neglected to do this after Jan added
> it.  Perils of parallel development ...
>

Yes, these got left overs because of the parallel series.

>> -static int ext4_journal_page_buffers(handle_t *handle, struct page *page,
>> -				     int len)
>> +static int ext4_journal_page_buffers(handle_t *handle, struct folio *folio,
>> +				     size_t len)
>
> Should this be called ext4_journal_folio_buffers?

Sure. Will make the change. Otherwise this patch looks good to you?
I also had a query regarding setting "len = size - folio_pos(folio)" in this patch.
Details of which I had pasted in the cover letter. Let me copy-paste
it here from the cover letter. Could you please take a look at it?

<copy-paste>
Also had a query w.r.t your change [1]. I couldn't understand this change diff
from [1]. Given if we are making the conversion to folio, then shouldn't we do
len = size - folio_pos(pos), instead of len = size & ~PAGE_MASK
Could you please tell if the current change in [1] is kept deliberately?
At other places you did make len as size - folio_pos(pos) which removes the
PAGE_SIZE assumption.

-static int mpage_submit_page(struct mpage_da_data *mpd, struct page *page)
+static int mpage_submit_folio(struct mpage_da_data *mpd, struct folio *folio)
 {
-	int len;
+	size_t len;

	<...>

	size = i_size_read(mpd->inode);
-	if (page->index == size >> PAGE_SHIFT &&
+	len = folio_size(folio);
+	if (folio_pos(folio) + len > size &&
 	    !ext4_verity_in_progress(mpd->inode))
 		len = size & ~PAGE_MASK;
-	else
-		len = PAGE_SIZE;
-	err = ext4_bio_write_page(&mpd->io_submit, page, len);
+	err = ext4_bio_write_page(&mpd->io_submit, &folio->page, len);
 	if (!err)
 		mpd->wbc->nr_to_write--;

[1]: https://lore.kernel.org/linux-ext4/20230324180129.1220691-7-willy@infradead.org/

Thanks for the quick review!

-ritesh