Re: [f2fs-dev] [PATCH v2 04/14] f2fs: support atomic file large folios buffered write

[Nanzhe Zhao]

Hi Chao,

Thanks for the review.

I think I can extract the duplicate logic in a helper and the full change
may be like this?

--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -4721,6 +4721,31 @@
 	return 0;
 }
 
+static bool f2fs_try_balance_folio(struct folio *folio,
+		struct address_space *mapping, bool node_changed)
+{
+	struct inode *inode = folio->mapping->host;
+	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
+	unsigned int orig_order;
+
+	if (!node_changed || IS_NOQUOTA(inode) ||
+			!has_not_enough_free_secs(sbi, 0, 0))
+		return false;
+
+	orig_order = folio_order(folio);
+	folio_unlock(folio);
+	f2fs_balance_fs(sbi, true);
+	folio_lock(folio);
+
+	if (folio->mapping != mapping)
+		return true;
+
+	if (folio_order(folio) != orig_order)
+		return true;
+
+	return false;
+}
+
 static int prepare_large_folio_atomic_write_begin(struct inode *inode,
 		struct address_space *mapping, struct folio *folio, loff_t pos,
 		unsigned int len)
@@ -4728,7 +4753,6 @@
 	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
 	size_t ori_off = offset_in_folio(folio, pos);
 	pgoff_t start, end, index;
-	unsigned int orig_order;
 	int err = 0;
 
 	len = min_t(unsigned int, len, folio_size(folio) - ori_off);
@@ -4774,16 +4798,8 @@
 		 * Expand the 4K-page balance decision per subpage: check
 		 * right after each preallocated block.
 		 */
-		if (node_changed && !IS_NOQUOTA(inode) &&
-		    has_not_enough_free_secs(sbi, 0, 0)) {
-			orig_order = folio_order(folio);
-			folio_unlock(folio);
-			f2fs_balance_fs(sbi, true);
-			folio_lock(folio);
-			if (unlikely(folio->mapping != mapping ||
-				     folio_order(folio) != orig_order))
-				return -EAGAIN;
-		}
+		if (f2fs_try_balance_folio(folio, mapping, node_changed))
+			return -EAGAIN;
 	}
 
 	return 0;
@@ -4876,17 +4892,10 @@
 	if (err)
 		goto put_folio;
 
-	if (need_balance && !IS_NOQUOTA(inode) &&
-			has_not_enough_free_secs(sbi, 0, 0)) {
+	if (f2fs_try_balance_folio(folio, mapping, need_balance)) {
 		folio_unlock(folio);
-		f2fs_balance_fs(sbi, true);
-		folio_lock(folio);
-		if (folio->mapping != mapping) {
-			/* The folio got truncated from under us */
-			folio_unlock(folio);
-			folio_put(folio);
-			goto repeat;
-		}
+		folio_put(folio);
+		goto repeat;
 	}
 
 	f2fs_folio_wait_writeback(folio, DATA, false, true);
-- 
Nanzhe Zhao