nilfs2: fix BUG in nilfs_copy_dirty_pages() on dirty state mismatch

Syzbot reported a kernel BUG triggered within nilfs_copy_dirty_pages(),
which copies dirty DAT file folios/pages to its shadow page cache.  The
BUG occurs when a retrieved dirty folio/page unexpectedly loses its
'dirty' status.

This issue arises because, since the commit referenced below, the 'dirty'
flag of a folio/page can be cleared asynchronously after the filesystem
detects metadata corruption and transitions to read-only mode.

Resolve the issue by returning an -EROFS error if the filesystem has
transitioned to read-only mode.  Also change the behavior to issue a
kernel warning only once instead of triggering a kernel BUG when this
unexpected 'dirty' state is detected while the filesystem is not in
read-only mode.

Reported-by: syzbot+8baf9a79a3ffc6271cb6@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=8baf9a79a3ffc6271cb6
Fixes: 8c26c4e269 ("nilfs2: fix issue with flush kernel thread after remount in RO mode because of driver's internal error or metadata corruption")
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
This commit is contained in:
Ryusuke Konishi 2026-07-20 23:16:52 +09:00 • committed by Viacheslav Dubeyko
commit 66f4ad3ce1