nilfs2: fix kernel bug due to missing clearing of buffer delay flag

commit 6ed469df0bfbef3e4b44fca954a781919db9f7ab upstream.

Syzbot reported that after nilfs2 reads a corrupted file system image
and degrades to read-only, the BUG_ON check for the buffer delay flag
in submit_bh_wbc() may fail, causing a kernel bug.

This is because the buffer delay flag is not cleared when clearing the
buffer state flags to discard a page/folio or a buffer head. So, fix
this.

This became necessary when the use of nilfs2's own page clear routine
was expanded.  This state inconsistency does not occur if the buffer
is written normally by log writing.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Link: https://lore.kernel.org/r/20241015213300.7114-1-konishi.ryusuke@gmail.com
Fixes: 8c26c4e2694a ("nilfs2: fix issue with flush kernel thread after remount in RO mode because of driver's internal error or metadata corruption")
Reported-by: syzbot+985ada84bf055a575c07@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=985ada84bf055a575c07
Cc: stable@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/nilfs2/page.c b/fs/nilfs2/page.c
index 14e470fb88706a403f4e31954906f07492314482..7f9073d5c5a56733302bd3dd40b3bc3192b2b2e8 100644 (file)
--- a/fs/nilfs2/page.c
+++ b/fs/nilfs2/page.c
@@ -77,7 +77,8 @@ void nilfs_forget_buffer(struct buffer_head *bh)
        const unsigned long clear_bits =
                (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
                 BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
-                BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));
+                BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected) |
+                BIT(BH_Delay));
 
        lock_buffer(bh);
        set_mask_bits(&bh->b_state, clear_bits, 0);
@@ -414,7 +415,8 @@ void nilfs_clear_folio_dirty(struct folio *folio, bool silent)
                const unsigned long clear_bits =
                        (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
                         BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
-                        BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));
+                        BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected) |
+                        BIT(BH_Delay));
 
                bh = head;
                do {