btrfs: don't redirty locked_page in run_delalloc_zoned

extent_write_locked_range currently expects that either all or no
pages are dirty when it is called.  Bur run_delalloc_zoned is called
directly in the writepages path, and has the dirty bit cleared only
for locked_page and which the extent_write_cache_pages currently
operates.  It currently works around this by redirtying locked_page,
but that is a bit inefficient and cumbersome.  Pass a locked_page
argument to run_delalloc_zoned so that clearing the dirty bit can
be skipped on just that page.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent_io.c

@@ -2161,8 +2161,9 @@ static int extent_write_cache_pages(struct address_space *mapping,
  * already been ran (aka, ordered extent inserted) and all pages are still
  * locked.
  */
-void extent_write_locked_range(struct inode *inode, u64 start, u64 end,
-			       struct writeback_control *wbc, bool pages_dirty)
+void extent_write_locked_range(struct inode *inode, struct page *locked_page,
+			       u64 start, u64 end, struct writeback_control *wbc,
+			       bool pages_dirty)
 {
 	bool found_error = false;
 	int ret = 0;
@@ -2189,7 +2190,7 @@ void extent_write_locked_range(struct inode *inode, u64 start, u64 end,
 
 		page = find_get_page(mapping, cur >> PAGE_SHIFT);
 		ASSERT(PageLocked(page));
-		if (pages_dirty) {
+		if (pages_dirty && page != locked_page) {
 			ASSERT(PageDirty(page));
 			clear_page_dirty_for_io(page);
 		}

fs/btrfs/extent_io.h

@@ -177,8 +177,9 @@ 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);
-void extent_write_locked_range(struct inode *inode, u64 start, u64 end,
-			       struct writeback_control *wbc, bool pages_dirty);
+void extent_write_locked_range(struct inode *inode, struct page *locked_page,
+			       u64 start, u64 end, struct writeback_control *wbc,
+			       bool pages_dirty);
 int extent_writepages(struct address_space *mapping,
 		      struct writeback_control *wbc);
 int btree_write_cache_pages(struct address_space *mapping,

fs/btrfs/inode.c

@@ -1105,7 +1105,8 @@ static void submit_uncompressed_range(struct btrfs_inode *inode,
 
 	/* All pages will be unlocked, including @locked_page */
 	wbc_attach_fdatawrite_inode(&wbc, &inode->vfs_inode);
-	extent_write_locked_range(&inode->vfs_inode, start, end, &wbc, false);
+	extent_write_locked_range(&inode->vfs_inode, NULL, start, end, &wbc,
+				  false);
 	wbc_detach_inode(&wbc);
 }
 
@@ -1719,7 +1720,6 @@ static noinline int run_delalloc_zoned(struct btrfs_inode *inode,
 {
 	u64 done_offset = end;
 	int ret;
-	bool locked_page_done = false;
 
 	while (start <= end) {
 		ret = cow_file_range(inode, locked_page, start, end, &done_offset,
@@ -1727,13 +1727,8 @@ static noinline int run_delalloc_zoned(struct btrfs_inode *inode,
 		if (ret)
 			return ret;
 
-		if (!locked_page_done) {
-			__set_page_dirty_nobuffers(locked_page);
-			account_page_redirty(locked_page);
-		}
-		locked_page_done = true;
-		extent_write_locked_range(&inode->vfs_inode, start, done_offset,
-					  wbc, true);
+		extent_write_locked_range(&inode->vfs_inode, locked_page, start,
+					  done_offset, wbc, true);
 		start = done_offset + 1;
 	}