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s=MBO0001; t=1710508866; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=uL8B8rxdNzZ1QT1jmn8Si5bf2Isce5VLmVW1+mlinGY=; b=0dRpwze54JbtFZYv1021iFawCCzzS/F8earDM4Utcgva9wOF+U/UIJ3TePCdr3If0MjxZM zzTbiM3XRek/OATou7PoENHWHTXGR0kSvT+nBLo/W/Da39wxs8z5AlE65Idzx0ZdSTIwPS 8cHKj+IytBGODedJIzr+vcZDnSEX+LEmUUwmsiWaq6vFAf4JYVAqol4u2nba7TeTYFvCds 197BXrYfukht9gw4Z2umxZ7ahUuTAxrLxOhxIvbObQwhS0yxBK6HIRzdc6WWUCtv6VnN8P JhZjNWtHwp4ftJXBe/9j0WBAz0V+vVQiiTevPLL8hT8X6mhXsPcmrRZthiDVbw== Date: Fri, 15 Mar 2024 14:21:02 +0100 From: "Pankaj Raghav (Samsung)" To: willy@infradead.org Cc: gost.dev@samsung.com, chandan.babu@oracle.com, hare@suse.de, mcgrof@kernel.org, djwong@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, david@fromorbit.com, akpm@linux-foundation.org, Pankaj Raghav , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v3 03/11] filemap: allocate mapping_min_order folios in the page cache Message-ID: References: <20240313170253.2324812-1-kernel@pankajraghav.com> <20240313170253.2324812-4-kernel@pankajraghav.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240313170253.2324812-4-kernel@pankajraghav.com> X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 439EAC0013 X-Stat-Signature: ydzwf6n8ppk38cui6ykko5136z5ts3s3 X-Rspam-User: X-HE-Tag: 1710508870-264021 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi willy, > filemap_create_folio() and do_read_cache_folio() were always allocating > folio of order 0. __filemap_get_folio was trying to allocate higher > order folios when fgp_flags had higher order hint set but it will default > to order 0 folio if higher order memory allocation fails. > > Supporting mapping_min_order implies that we guarantee each folio in the > page cache has at least an order of mapping_min_order. When adding new > folios to the page cache we must also ensure the index used is aligned to > the mapping_min_order as the page cache requires the index to be aligned > to the order of the folio. > > Signed-off-by: Luis Chamberlain > Co-developed-by: Pankaj Raghav > Signed-off-by: Pankaj Raghav > --- > mm/filemap.c | 24 +++++++++++++++++------- > 1 file changed, 17 insertions(+), 7 deletions(-) Are the changes more inline with what you had in mind? > > diff --git a/mm/filemap.c b/mm/filemap.c > index a1cb3ea55fb6..57889f206829 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -849,6 +849,8 @@ noinline int __filemap_add_folio(struct address_space *mapping, > > VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); > VM_BUG_ON_FOLIO(folio_test_swapbacked(folio), folio); > + VM_BUG_ON_FOLIO(folio_order(folio) < mapping_min_folio_order(mapping), > + folio); > mapping_set_update(&xas, mapping); > > if (!huge) { > @@ -1886,8 +1888,10 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index, > folio_wait_stable(folio); > no_page: > if (!folio && (fgp_flags & FGP_CREAT)) { > - unsigned order = FGF_GET_ORDER(fgp_flags); > + unsigned int min_order = mapping_min_folio_order(mapping); > + unsigned int order = max(min_order, FGF_GET_ORDER(fgp_flags)); > int err; > + index = mapping_align_start_index(mapping, index); > > if ((fgp_flags & FGP_WRITE) && mapping_can_writeback(mapping)) > gfp |= __GFP_WRITE; > @@ -1927,7 +1931,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index, > break; > folio_put(folio); > folio = NULL; > - } while (order-- > 0); > + } while (order-- > min_order); > > if (err == -EEXIST) > goto repeat; > @@ -2416,13 +2420,16 @@ static int filemap_update_page(struct kiocb *iocb, > } > > static int filemap_create_folio(struct file *file, > - struct address_space *mapping, pgoff_t index, > + struct address_space *mapping, loff_t pos, > struct folio_batch *fbatch) > { > struct folio *folio; > int error; > + unsigned int min_order = mapping_min_folio_order(mapping); > + pgoff_t index; > > - folio = filemap_alloc_folio(mapping_gfp_mask(mapping), 0); > + folio = filemap_alloc_folio(mapping_gfp_mask(mapping), > + min_order); > if (!folio) > return -ENOMEM; > > @@ -2440,6 +2447,8 @@ static int filemap_create_folio(struct file *file, > * well to keep locking rules simple. > */ > filemap_invalidate_lock_shared(mapping); > + /* index in PAGE units but aligned to min_order number of pages. */ > + index = (pos >> (PAGE_SHIFT + min_order)) << min_order; > error = filemap_add_folio(mapping, folio, index, > mapping_gfp_constraint(mapping, GFP_KERNEL)); > if (error == -EEXIST) > @@ -2500,8 +2509,7 @@ static int filemap_get_pages(struct kiocb *iocb, size_t count, > if (!folio_batch_count(fbatch)) { > if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ)) > return -EAGAIN; > - err = filemap_create_folio(filp, mapping, > - iocb->ki_pos >> PAGE_SHIFT, fbatch); > + err = filemap_create_folio(filp, mapping, iocb->ki_pos, fbatch); > if (err == AOP_TRUNCATED_PAGE) > goto retry; > return err; > @@ -3662,9 +3670,11 @@ static struct folio *do_read_cache_folio(struct address_space *mapping, > repeat: > folio = filemap_get_folio(mapping, index); > if (IS_ERR(folio)) { > - folio = filemap_alloc_folio(gfp, 0); > + folio = filemap_alloc_folio(gfp, > + mapping_min_folio_order(mapping)); > if (!folio) > return ERR_PTR(-ENOMEM); > + index = mapping_align_start_index(mapping, index); > err = filemap_add_folio(mapping, folio, index, gfp); > if (unlikely(err)) { > folio_put(folio); > -- > 2.43.0 > -- Pankaj Raghav