On Sat 07-01-23 17:16:10, Zhihao Cheng wrote:
> 在 2023/1/6 22:22, Jan Kara 写道:
>
> Hi Jan, thanks for reviewing.Some discussions below:
>
>
> > > diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
> > > index 6a404ac1c178..06a5e7961ef2 100644
> > > --- a/fs/jbd2/transaction.c
> > > +++ b/fs/jbd2/transaction.c
> > > @@ -1010,36 +1010,37 @@ do_get_write_access(handle_t *handle, struct journal_head *jh,
> > > * ie. locked but not dirty) or tune2fs (which may actually have
> > > * the buffer dirtied, ugh.) */
> > > - if (buffer_dirty(bh)) {
> > > + if (buffer_dirty(bh) && jh->b_transaction) {
> > > /*
> > > * First question: is this buffer already part of the current
> > > * transaction or the existing committing transaction?
> > > */
> > > - if (jh->b_transaction) {
> > > - J_ASSERT_JH(jh,
> > > - jh->b_transaction == transaction ||
> > > - jh->b_transaction ==
> > > - journal->j_committing_transaction);
> > > - if (jh->b_next_transaction)
> > > - J_ASSERT_JH(jh, jh->b_next_transaction ==
> > > - transaction);
> > > - warn_dirty_buffer(bh);
> > > - }
> > > + J_ASSERT_JH(jh, jh->b_transaction == transaction ||
> > > + jh->b_transaction == journal->j_committing_transaction);
> > > + if (jh->b_next_transaction)
> > > + J_ASSERT_JH(jh, jh->b_next_transaction == transaction);
> > > + warn_dirty_buffer(bh);
> > > /*
> > > - * In any case we need to clean the dirty flag and we must
> > > - * do it under the buffer lock to be sure we don't race
> > > - * with running write-out.
> > > + * We need to clean the dirty flag and we must do it under the
> > > + * buffer lock to be sure we don't race with running write-out.
> > > */
> > > JBUFFER_TRACE(jh, "Journalling dirty buffer");
> > > clear_buffer_dirty(bh);
> > > + /*
> > > + * Setting jbddirty after clearing buffer dirty is necessary.
> > > + * Function jbd2_journal_restart() could keep buffer on
> > > + * BJ_Reserved list until the transaction committing, then the
> > > + * buffer won't be dirtied by jbd2_journal_refile_buffer()
> > > + * after committing, the buffer couldn't fall on disk even
> > > + * last checkpoint finished, which may corrupt filesystem.
> > > + */
> > > set_buffer_jbddirty(bh);
> > > }
> >
> > So I think the sequence:
> >
> > if (buffer_dirty(bh)) {
> > warn_dirty_buffer(bh);
> > JBUFFER_TRACE(jh, "Journalling dirty buffer");
> > clear_buffer_dirty(bh);
> > set_buffer_jbddirty(bh);
> > }
> >
> > can be moved into the branch
> >
> > if (jh->b_transaction == transaction ||
> > jh->b_next_transaction == transaction) {
> >
> > below. That way you can drop the assertions as well because they happen
> > later in do_get_write_access() again anyway.
>
> 1. If we move the squence:
> if (buffer_dirty(bh)) {
> warn_dirty_buffer(bh);
> JBUFFER_TRACE(jh, "Journalling dirty buffer");
> clear_buffer_dirty(bh);
> set_buffer_jbddirty(bh);
> }
>
> into the branch
>
> if (jh->b_transaction == transaction ||
> jh->b_next_transaction == transaction) {
>
> , then we have a new situation(jh->b_transaction ==
> journal->j_committing_transaction) to clear buffer dirty, so we need to add
> an else-branch like(based on v2 patch):
> --- a/fs/jbd2/transaction.c
> +++ b/fs/jbd2/transaction.c
> @@ -1092,6 +1092,10 @@ do_get_write_access(handle_t *handle, struct
> journal_head *jh,
> spin_unlock(&journal->j_list_lock);
> unlock_buffer(bh);
> goto done;
> + } else if (test_clear_buffer_dirty(bh)) {
> + warn_dirty_buffer(bh);
> + JBUFFER_TRACE(jh, "Journalling dirty buffer");
> + set_buffer_jbddirty(bh);
> }
> unlock_buffer(bh);
>
> I think we'd better not to move the sequence?
Oh, you're right. So yeah, keep this sequence where it was.
> 2. I agree that the assertions in branch 'if (jh->b_transaction)' are
> redundant, I will remove them in v3. Thanks for pointing that.
OK, thanks!
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
