On Tue, Sep 24, 2024 at 3:33 PM Sridhar, Kanchana P <kanchana.p.sridhar@xxxxxxxxx> wrote: > > > -----Original Message----- > > From: Yosry Ahmed <yosryahmed@xxxxxxxxxx> > > Sent: Tuesday, September 24, 2024 12:20 PM > > To: Sridhar, Kanchana P <kanchana.p.sridhar@xxxxxxxxx> > > Cc: linux-kernel@xxxxxxxxxxxxxxx; linux-mm@xxxxxxxxx; > > hannes@xxxxxxxxxxx; nphamcs@xxxxxxxxx; chengming.zhou@xxxxxxxxx; > > usamaarif642@xxxxxxxxx; shakeel.butt@xxxxxxxxx; ryan.roberts@xxxxxxx; > > Huang, Ying <ying.huang@xxxxxxxxx>; 21cnbao@xxxxxxxxx; akpm@linux- > > foundation.org; Zou, Nanhai <nanhai.zou@xxxxxxxxx>; Feghali, Wajdi K > > <wajdi.k.feghali@xxxxxxxxx>; Gopal, Vinodh <vinodh.gopal@xxxxxxxxx> > > Subject: Re: [PATCH v7 4/8] mm: zswap: Refactor code to delete stored > > offsets in case of errors. > > > > On Mon, Sep 23, 2024 at 6:17 PM Kanchana P Sridhar > > <kanchana.p.sridhar@xxxxxxxxx> wrote: > > > > > > Added a new procedure zswap_delete_stored_offsets() that can be > > > called to delete stored offsets in a folio in case zswap_store() > > > fails or zswap is disabled. > > > > I don't see the value in this helper. It will get called in one place > > AFAICT, and it is a bit inconsistent that we have to explicitly loop > > in zswap_store() to store pages, but the loop to delete pages upon > > failure is hidden in the helper. > > > > I am not against adding a trivial zswap_tree_delete() helper (or > > similar) that calls xa_erase() and zswap_entry_free() to match > > zswap_tree_store() if you prefer that. > > This is a good point. I had refactored this routine in the context > of my code that does batching and the same loop over the mTHP's > subpages would get called in multiple error condition cases. > > I am thinking it might probably make sense for say zswap_tree_delete() > to take a "folio" and "tree" and encapsulate deleting all stored offsets > for that folio. Since we have already done the computes for finding the > "tree", having that as an input parameter is mainly for latency, but if > it is cleaner to have "zswap_tree_delete(struct folio *folio)", that should > be Ok too. Please let me know your suggestion on this. > What I meant is "zswap_tree_delete(struct xarray *tree, pgoff_t offset)", and loop and call this in zswap_store(). This would be consistent on looping and calling zswap_store_page(). But we can keep the helper as-is actually and just rename it to zswap_tree_delete() and move the loop inside. No strong preference.
