[PATCH] btrfs: remove ->writepage

[Christoph Hellwig <hch@lst.de>]

->writepage is only used for single page writeback from memory reclaim,
and not called at all for cgroup writeback.  Follow the lead of XFS
and remove ->writepage and rely entirely on ->writepages.

Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/btrfs/extent_io.c | 14 --------------
 fs/btrfs/extent_io.h |  1 -
 fs/btrfs/inode.c     | 26 --------------------------
 fs/btrfs/subpage.c   |  2 +-
 4 files changed, 1 insertion(+), 42 deletions(-)

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 854999c2e139b..0681c0da7926d 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -5108,20 +5108,6 @@ static int extent_write_cache_pages(struct address_space *mapping,
 	return ret;
 }
 
-int extent_write_full_page(struct page *page, struct writeback_control *wbc)
-{
-	int ret;
-	struct extent_page_data epd = {
-		.bio_ctrl = { 0 },
-		.extent_locked = 0,
-		.sync_io = wbc->sync_mode == WB_SYNC_ALL,
-	};
-
-	ret = __extent_writepage(page, wbc, &epd);
-	submit_write_bio(&epd, ret);
-	return ret;
-}
-
 /*
  * Submit the pages in the range to bio for call sites which delalloc range has
  * already been ran (aka, ordered extent inserted) and all pages are still
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index c0f1fb63eeae7..a76c6ef74cd3c 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -146,7 +146,6 @@ int try_release_extent_mapping(struct page *page, gfp_t mask);
 int try_release_extent_buffer(struct page *page);
 
 int btrfs_read_folio(struct file *file, struct folio *folio);
-int extent_write_full_page(struct page *page, struct writeback_control *wbc);
 int extent_write_locked_range(struct inode *inode, u64 start, u64 end);
 int extent_writepages(struct address_space *mapping,
 		      struct writeback_control *wbc);
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index f6dc6e8c54e3a..b31b3360cc1f5 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8144,31 +8144,6 @@ static int btrfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 	return extent_fiemap(BTRFS_I(inode), fieinfo, start, len);
 }
 
-static int btrfs_writepage(struct page *page, struct writeback_control *wbc)
-{
-	struct inode *inode = page->mapping->host;
-	int ret;
-
-	if (current->flags & PF_MEMALLOC) {
-		redirty_page_for_writepage(wbc, page);
-		unlock_page(page);
-		return 0;
-	}
-
-	/*
-	 * If we are under memory pressure we will call this directly from the
-	 * VM, we need to make sure we have the inode referenced for the ordered
-	 * extent.  If not just return like we didn't do anything.
-	 */
-	if (!igrab(inode)) {
-		redirty_page_for_writepage(wbc, page);
-		return AOP_WRITEPAGE_ACTIVATE;
-	}
-	ret = extent_write_full_page(page, wbc);
-	btrfs_add_delayed_iput(inode);
-	return ret;
-}
-
 static int btrfs_writepages(struct address_space *mapping,
 			    struct writeback_control *wbc)
 {
@@ -11390,7 +11365,6 @@ static const struct file_operations btrfs_dir_file_operations = {
  */
 static const struct address_space_operations btrfs_aops = {
 	.read_folio	= btrfs_read_folio,
-	.writepage	= btrfs_writepage,
 	.writepages	= btrfs_writepages,
 	.readahead	= btrfs_readahead,
 	.direct_IO	= noop_direct_IO,
diff --git a/fs/btrfs/subpage.c b/fs/btrfs/subpage.c
index 0146fee730a09..6fc2b77ae5c34 100644
--- a/fs/btrfs/subpage.c
+++ b/fs/btrfs/subpage.c
@@ -731,7 +731,7 @@ void btrfs_page_assert_not_dirty(const struct btrfs_fs_info *fs_info,
  *   It should not have any subpage::writers count.
  *   Can be unlocked by unlock_page().
  *   This is the most common locked page for __extent_writepage() called
- *   inside extent_write_cache_pages() or extent_write_full_page().
+ *   inside extent_write_cache_pages().
  *   Rarer cases include the @locked_page from extent_write_locked_range().
  *
  * - Page locked by lock_delalloc_pages()
-- 
2.30.2