On Wed, Jun 03, 2020 at 10:44:29AM +1000, Dave Chinner wrote:
> On Tue, Jun 02, 2020 at 05:22:22PM -0700, Darrick J. Wong wrote:
> > On Tue, Jun 02, 2020 at 10:52:38PM +0800, Gao Xiang wrote:
> > > Sometimes no need to play with perag_tree since for many
> > > cases perag can also be accessed by agbp reliably.
> > >
> > > Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxx>
> > > ---
> ....
> > > @@ -2447,32 +2443,22 @@ xfs_iunlink_remove(
> > > * this inode's backref to point from the next inode.
> > > */
> > > if (next_agino != NULLAGINO) {
> > > - pag = xfs_perag_get(mp, agno);
> > > - error = xfs_iunlink_change_backref(pag, next_agino,
> > > + error = xfs_iunlink_change_backref(agibp->b_pag, next_agino,
> > > NULLAGINO);
> > > if (error)
> > > - goto out;
> > > + return error;
> > > }
> > >
> > > - if (head_agino == agino) {
> > > - /* Point the head of the list to the next unlinked inode. */
> > > - error = xfs_iunlink_update_bucket(tp, agno, agibp, bucket_index,
> > > - next_agino);
> > > - if (error)
> > > - goto out;
> > > - } else {
> > > + if (head_agino != agino) {
> > > struct xfs_imap imap;
> > > xfs_agino_t prev_agino;
> > >
> > > - if (!pag)
> > > - pag = xfs_perag_get(mp, agno);
> > > -
> > > /* We need to search the list for the inode being freed. */
> > > error = xfs_iunlink_map_prev(tp, agno, head_agino, agino,
> > > &prev_agino, &imap, &last_dip, &last_ibp,
> > > - pag);
> > > + agibp->b_pag);
> > > if (error)
> > > - goto out;
> > > + return error;
> > >
> > > /* Point the previous inode on the list to the next inode. */
> > > xfs_iunlink_update_dinode(tp, agno, prev_agino, last_ibp,
> > > @@ -2486,15 +2472,13 @@ xfs_iunlink_remove(
> > > * change_backref takes care of deleting the backref if
> > > * next_agino is NULLAGINO.
> > > */
> > > - error = xfs_iunlink_change_backref(pag, agino, next_agino);
> > > - if (error)
> > > - goto out;
> > > + return xfs_iunlink_change_backref(agibp->b_pag, agino,
> > > + next_agino);
> > > }
> > >
> > > -out:
> > > - if (pag)
> > > - xfs_perag_put(pag);
> > > - return error;
> > > + /* Point the head of the list to the next unlinked inode. */
> > > + return xfs_iunlink_update_bucket(tp, agno, agibp, bucket_index,
> > > + next_agino);
> >
> > Why not cut out the agno argument here too? Surely you could obtain it
> > from agibp->b_pag->pag_agno. Ditto for xfs_iunlink_map_prev.
>
> Those functions go away completely in the patchset I'm currently
> working on for tracking dirty inodes in ordered buffers. The
> in-memory unlinked list code needs to be completely reworked to
> acheive this (due to lock order constraints), so I'd much prefer
> unnecessary cleanup changes in this area are kept to a minimum
> because it will all away real soon.
>
> FWIW, it was the discovery we could use agibp->b_pag instead of
> get/put in my iunlink list rework that prompted me to ask Xiang to
> look at the rest of the code and see where the same pattern could be
> applied...
Aha! I wondered. Ok, let's just leave this part alone then? No harm
nor foul letting it stay in the meantime. :)
--D
> Cheers,
>
> Dave.
> --
> Dave Chinner
> david@xxxxxxxxxxxxx
