btrfs: migrate extent_buffer::pages[] to folio

For now extent_buffer::pages[] are still only accepting single page
pointer, thus we can migrate to folios pretty easily.

As for single page, page and folio are 1:1 mapped, including their page
flags.

This patch would just do the conversion from struct page to struct
folio, providing the first step to higher order folio in the future.

This conversion is pretty simple:

- extent_buffer::pages[] -> extent_buffer::folios[]

- page_address(eb->pages[i]) -> folio_address(eb->pages[i])

- eb->pages[i] -> folio_page(eb->folios[i], 0)

There would be more specific cleanups preparing for the incoming higher
order folio support.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index c73d53c22ec5..66c2e214b141 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -94,7 +94,12 @@ struct extent_buffer {
 
 	struct rw_semaphore lock;
 
-	struct page *pages[INLINE_EXTENT_BUFFER_PAGES];
+	/*
+	 * Pointers to all the folios of the extent buffer.
+	 *
+	 * For now the folio is always order 0 (aka, a single page).
+	 */
+	struct folio *folios[INLINE_EXTENT_BUFFER_PAGES];
 #ifdef CONFIG_BTRFS_DEBUG
 	struct list_head leak_list;
 	pid_t lock_owner;