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charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.60.1 (by Flathub.org) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Tue, 2026-10-06 at 17:48 +0900, Ryusuke Konishi wrote: > When removing an empty directory with a corrupted link count (e.g., > i_nlink is 1 due to filesystem corruption), nilfs_rmdir() calls > drop_nlink() via nilfs_do_unlink() and then calls drop_nlink() again > on the directory inode.=C2=A0 This second call causes an underflow of > i_nlink, triggering a kernel WARNING in drop_nlink(). >=20 > Fix this issue by using clear_nlink() instead of drop_nlink() to > finalize the link count reset for the target directory in > nilfs_rmdir(). > Additionally, log a warning message when i_nlink is not 2 before > removing an empty directory to notify about the link count > inconsistency. >=20 > Reported-by: syzbot+c388db0347b7fc88fa7a@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=3Dc388db0347b7fc88fa7a > Fixes: d25006523d0b ("nilfs2: pathname operations") > Signed-off-by: Ryusuke Konishi > --- > Hi Viacheslav, >=20 > Please apply this for the next cycle. >=20 > This fixes a link count underflow during rmdir on a directory with a > corrupted link count (an issue recently reported by syzbot). >=20 > Thanks, > Ryusuke Konishi >=20 > =C2=A0fs/nilfs2/namei.c | 8 +++++++- > =C2=A01 file changed, 7 insertions(+), 1 deletion(-) >=20 > diff --git a/fs/nilfs2/namei.c b/fs/nilfs2/namei.c > index e037e0c6e31a..d326bb1acb11 100644 > --- a/fs/nilfs2/namei.c > +++ b/fs/nilfs2/namei.c > @@ -341,10 +341,16 @@ static int nilfs_rmdir(struct inode *dir, > struct dentry *dentry) > =C2=A0 > =C2=A0 err =3D -ENOTEMPTY; > =C2=A0 if (nilfs_empty_dir(inode)) { > + if (unlikely(inode->i_nlink !=3D 2)) > + nilfs_warn(dir->i_sb, > + "inconsistent empty directory link > count %u (ino=3D%llu)", > + inode->i_nlink, > + (unsigned long long)inode->i_ino); > + > =C2=A0 err =3D nilfs_do_unlink(dir, dentry); > =C2=A0 if (!err) { > =C2=A0 inode->i_size =3D 0; > - drop_nlink(inode); > + clear_nlink(inode); > =C2=A0 nilfs_mark_inode_dirty(inode); > =C2=A0 drop_nlink(dir); > =C2=A0 nilfs_mark_inode_dirty(dir); Applied. Thanks, Slava.