FAILED: patch "[PATCH] f2fs: fix fsck inconsistency caused by incorrect nat_entry" failed to apply to 6.12-stable tree

The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x 019f9dda7f66e55eb94cd32e1d3fff5835f73fbc
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026051203-startle-dowry-1f63@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 019f9dda7f66e55eb94cd32e1d3fff5835f73fbc Mon Sep 17 00:00:00 2001
From: Yongpeng Yang <[email protected]>
Date: Tue, 10 Mar 2026 17:36:12 +0800
Subject: [PATCH] f2fs: fix fsck inconsistency caused by incorrect nat_entry
flag usage

f2fs_need_dentry_mark() reads nat_entry flags without mutual exclusion with the checkpoint path, which can result in an incorrect inode block marking state. The scenario is as follows:

create & write & fsync 'file A' write checkpoint
- f2fs_do_sync_file // inline inode
- f2fs_write_inode // inode folio is dirty
- f2fs_write_checkpoint
- f2fs_flush_merged_writes
- f2fs_sync_node_pages
- f2fs_fsync_node_pages // no dirty node
- f2fs_need_inode_block_update // return true
- f2fs_fsync_node_pages // inode dirtied
- f2fs_need_dentry_mark //return true
- f2fs_flush_nat_entries
- f2fs_write_checkpoint end
- __write_node_folio // inode with DENT_BIT_SHIFT set
SPO, "fsck --dry-run" find inode has already checkpointed but still with DENT_BIT_SHIFT set

The state observed by f2fs_need_dentry_mark() can differ from the state observed in __write_node_folio() after acquiring sbi->node_write. The root cause is that the semantics of IS_CHECKPOINTED and HAS_FSYNCED_INODE are only guaranteed after the checkpoint write has fully completed.

This patch moves set_dentry_mark() into __write_node_folio() and protects it with the sbi->node_write lock.

index e027c388207f..630fd3b43a08 100644
@@ -1799,13 +1799,12 @@ static bool __write_node_folio(struct folio *folio, bool atomic, bool *submitted
 		goto redirty_out;
 	}
 
-	if (atomic) {
-		if (!test_opt(sbi, NOBARRIER))
-			fio.op_flags |= REQ_PREFLUSH | REQ_FUA;
-		if (IS_INODE(folio))
-			set_dentry_mark(folio,
+	if (atomic && !test_opt(sbi, NOBARRIER))
+		fio.op_flags |= REQ_PREFLUSH | REQ_FUA;
+
+	if (IS_INODE(folio) && (atomic || is_fsync_dnode(folio)))
+		set_dentry_mark(folio,
 				f2fs_need_dentry_mark(sbi, ino_of_node(folio)));
-	}
 
 	/* should add to global list before clearing PAGECACHE status */
 	if (f2fs_in_warm_node_list(folio)) {

@@ -1956,9 +1955,6 @@ int f2fs_fsync_node_pages(struct f2fs_sb_info *sbi, struct inode *inode,
 					if (is_inode_flag_set(inode,
 								FI_DIRTY_INODE))
 						f2fs_update_inode(inode, folio);
-					if (!atomic)
-						set_dentry_mark(folio,
-							f2fs_need_dentry_mark(sbi, ino));
 				}
 				/* may be written by other thread */
 				if (!folio_test_dirty(folio))