Re: [PATCH v3 2/2] ext4: fix possible tid_t sequence overflows

[harshad shirwadkar]

Looks good, thanks for the patch!

Reviewed-by: Harshad Shirwadkar <harshadshirwadkar@xxxxxxxxx>


On Wed, May 29, 2024 at 2:51 AM Jan Kara <jack@xxxxxxx> wrote:
>
> On Wed 29-05-24 10:20:30, Luis Henriques (SUSE) wrote:
> > In the fast commit code there are a few places where tid_t variables are
> > being compared without taking into account the fact that these sequence
> > numbers may wrap.  Fix this issue by using the helper functions tid_gt()
> > and tid_geq().
> >
> > Signed-off-by: Luis Henriques (SUSE) <luis.henriques@xxxxxxxxx>
>
> Thanks! Feel free to add:
>
> Reviewed-by: Jan Kara <jack@xxxxxxx>
>
>                                                                 Honza
>
> > ---
> >  fs/ext4/fast_commit.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
> > index 088bd509b116..30d312e16916 100644
> > --- a/fs/ext4/fast_commit.c
> > +++ b/fs/ext4/fast_commit.c
> > @@ -353,7 +353,7 @@ void ext4_fc_mark_ineligible(struct super_block *sb, int reason, handle_t *handl
> >               read_unlock(&sbi->s_journal->j_state_lock);
> >       }
> >       spin_lock(&sbi->s_fc_lock);
> > -     if (sbi->s_fc_ineligible_tid < tid)
> > +     if (tid_gt(tid, sbi->s_fc_ineligible_tid))
> >               sbi->s_fc_ineligible_tid = tid;
> >       spin_unlock(&sbi->s_fc_lock);
> >       WARN_ON(reason >= EXT4_FC_REASON_MAX);
> > @@ -1207,7 +1207,7 @@ int ext4_fc_commit(journal_t *journal, tid_t commit_tid)
> >       if (ret == -EALREADY) {
> >               /* There was an ongoing commit, check if we need to restart */
> >               if (atomic_read(&sbi->s_fc_subtid) <= subtid &&
> > -                     commit_tid > journal->j_commit_sequence)
> > +                 tid_gt(commit_tid, journal->j_commit_sequence))
> >                       goto restart_fc;
> >               ext4_fc_update_stats(sb, EXT4_FC_STATUS_SKIPPED, 0, 0,
> >                               commit_tid);
> > @@ -1282,7 +1282,7 @@ static void ext4_fc_cleanup(journal_t *journal, int full, tid_t tid)
> >               list_del_init(&iter->i_fc_list);
> >               ext4_clear_inode_state(&iter->vfs_inode,
> >                                      EXT4_STATE_FC_COMMITTING);
> > -             if (iter->i_sync_tid <= tid) {
> > +             if (tid_geq(tid, iter->i_sync_tid)) {
> >                       ext4_fc_reset_inode(&iter->vfs_inode);
> >               } else {
> >                       /*
> > @@ -1322,7 +1322,7 @@ static void ext4_fc_cleanup(journal_t *journal, int full, tid_t tid)
> >       list_splice_init(&sbi->s_fc_q[FC_Q_STAGING],
> >                               &sbi->s_fc_q[FC_Q_MAIN]);
> >
> > -     if (tid >= sbi->s_fc_ineligible_tid) {
> > +     if (tid_geq(tid, sbi->s_fc_ineligible_tid)) {
> >               sbi->s_fc_ineligible_tid = 0;
> >               ext4_clear_mount_flag(sb, EXT4_MF_FC_INELIGIBLE);
> >       }
> >
> --
> Jan Kara <jack@xxxxxxxx>
> SUSE Labs, CR