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Tue, 13 Feb 2024 12:20:50 +0000 (UTC) Received: from dovecot-director2.suse.de ([10.150.64.162]) by imap1.dmz-prg2.suse.org with ESMTPSA id f9brJqJey2WSBwAAD6G6ig (envelope-from ); Tue, 13 Feb 2024 12:20:50 +0000 Message-ID: <487c0bec-4229-4add-bec4-1711f0b9bbee@suse.de> Date: Tue, 13 Feb 2024 13:20:50 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC v2 02/14] filemap: align the index to mapping_min_order in the page cache Content-Language: en-US To: "Pankaj Raghav (Samsung)" , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org Cc: mcgrof@kernel.org, gost.dev@samsung.com, akpm@linux-foundation.org, kbusch@kernel.org, djwong@kernel.org, chandan.babu@oracle.com, p.raghav@samsung.com, linux-kernel@vger.kernel.org, willy@infradead.org, linux-mm@kvack.org, david@fromorbit.com References: <20240213093713.1753368-1-kernel@pankajraghav.com> <20240213093713.1753368-3-kernel@pankajraghav.com> From: Hannes Reinecke In-Reply-To: <20240213093713.1753368-3-kernel@pankajraghav.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Authentication-Results: smtp-out1.suse.de; none X-Spamd-Result: default: False [-3.09 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; XM_UA_NO_VERSION(0.01)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; BAYES_HAM(-3.00)[100.00%]; MIME_GOOD(-0.10)[text/plain]; RCVD_COUNT_THREE(0.00)[3]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; RCPT_COUNT_TWELVE(0.00)[14]; DBL_BLOCKED_OPENRESOLVER(0.00)[samsung.com:email]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_TLS_ALL(0.00)[]; MID_RHS_MATCH_FROM(0.00)[] X-Spam-Level: X-Spam-Flag: NO X-Spam-Score: -3.09 On 2/13/24 10:37, Pankaj Raghav (Samsung) wrote: > From: Luis Chamberlain > > Supporting mapping_min_order implies that we guarantee each folio in the > page cache has at least an order of mapping_min_order. So when adding new > folios to the page cache we must 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. > > A higher order folio than min_order by definition is a multiple of the > min_order. If an index is aligned to an order higher than a min_order, it > will also be aligned to the min order. > > This effectively introduces no new functional changes when min order is > not set other than a few rounding computations that should result in the > same value. > > Signed-off-by: Luis Chamberlain > Signed-off-by: Pankaj Raghav > --- > mm/filemap.c | 34 ++++++++++++++++++++++++++-------- > 1 file changed, 26 insertions(+), 8 deletions(-) > > diff --git a/mm/filemap.c b/mm/filemap.c > index 750e779c23db..323a8e169581 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -2479,14 +2479,16 @@ static int filemap_get_pages(struct kiocb *iocb, size_t count, > { > struct file *filp = iocb->ki_filp; > struct address_space *mapping = filp->f_mapping; > + unsigned int min_nrpages = mapping_min_folio_nrpages(mapping); > struct file_ra_state *ra = &filp->f_ra; > - pgoff_t index = iocb->ki_pos >> PAGE_SHIFT; > + pgoff_t index = round_down(iocb->ki_pos >> PAGE_SHIFT, min_nrpages); > pgoff_t last_index; > struct folio *folio; > int err = 0; > > /* "last_index" is the index of the page beyond the end of the read */ > last_index = DIV_ROUND_UP(iocb->ki_pos + count, PAGE_SIZE); > + last_index = round_up(last_index, min_nrpages); Huh? 'last_index' is unset here; sure you mean 'iocb->ki_pos + count' ? And what's the rationale to replace 'DIV_ROUND_UP' with 'round_up' ? > retry: > if (fatal_signal_pending(current)) > return -EINTR; > @@ -2502,8 +2504,7 @@ 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, index, fbatch); > if (err == AOP_TRUNCATED_PAGE) > goto retry; > return err; > @@ -3095,7 +3096,10 @@ static struct file *do_sync_mmap_readahead(struct vm_fault *vmf) > struct file *file = vmf->vma->vm_file; > struct file_ra_state *ra = &file->f_ra; > struct address_space *mapping = file->f_mapping; > - DEFINE_READAHEAD(ractl, file, ra, mapping, vmf->pgoff); > + unsigned int min_order = mapping_min_folio_order(mapping); > + unsigned int min_nrpages = mapping_min_folio_nrpages(file->f_mapping); > + pgoff_t index = round_down(vmf->pgoff, min_nrpages); > + DEFINE_READAHEAD(ractl, file, ra, mapping, index); > struct file *fpin = NULL; > unsigned long vm_flags = vmf->vma->vm_flags; > unsigned int mmap_miss; > @@ -3147,10 +3151,11 @@ static struct file *do_sync_mmap_readahead(struct vm_fault *vmf) > */ > fpin = maybe_unlock_mmap_for_io(vmf, fpin); > ra->start = max_t(long, 0, vmf->pgoff - ra->ra_pages / 2); > + ra->start = round_down(ra->start, min_nrpages); > ra->size = ra->ra_pages; > ra->async_size = ra->ra_pages / 4; > ractl._index = ra->start; > - page_cache_ra_order(&ractl, ra, 0); > + page_cache_ra_order(&ractl, ra, min_order); > return fpin; > } > > @@ -3164,7 +3169,9 @@ static struct file *do_async_mmap_readahead(struct vm_fault *vmf, > { > struct file *file = vmf->vma->vm_file; > struct file_ra_state *ra = &file->f_ra; > - DEFINE_READAHEAD(ractl, file, ra, file->f_mapping, vmf->pgoff); > + unsigned int min_nrpages = mapping_min_folio_nrpages(file->f_mapping); > + pgoff_t index = round_down(vmf->pgoff, min_nrpages); > + DEFINE_READAHEAD(ractl, file, ra, file->f_mapping, index); > struct file *fpin = NULL; > unsigned int mmap_miss; > > @@ -3212,13 +3219,17 @@ vm_fault_t filemap_fault(struct vm_fault *vmf) > struct file *file = vmf->vma->vm_file; > struct file *fpin = NULL; > struct address_space *mapping = file->f_mapping; > + unsigned int min_order = mapping_min_folio_order(mapping); > + unsigned int nrpages = 1UL << min_order; > struct inode *inode = mapping->host; > - pgoff_t max_idx, index = vmf->pgoff; > + pgoff_t max_idx, index = round_down(vmf->pgoff, nrpages); > struct folio *folio; > vm_fault_t ret = 0; > bool mapping_locked = false; > > max_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); > + max_idx = round_up(max_idx, nrpages); > + Same here. (And the additional whitespace can probably go ...) > if (unlikely(index >= max_idx)) > return VM_FAULT_SIGBUS; > > @@ -3317,13 +3328,17 @@ vm_fault_t filemap_fault(struct vm_fault *vmf) > * We must recheck i_size under page lock. > */ > max_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); > + max_idx = round_up(max_idx, nrpages); > + See above. > if (unlikely(index >= max_idx)) { > folio_unlock(folio); > folio_put(folio); > return VM_FAULT_SIGBUS; > } > > - vmf->page = folio_file_page(folio, index); > + VM_BUG_ON_FOLIO(folio_order(folio) < min_order, folio); > + > + vmf->page = folio_file_page(folio, vmf->pgoff); > return ret | VM_FAULT_LOCKED; > > page_not_uptodate: > @@ -3658,6 +3673,9 @@ static struct folio *do_read_cache_folio(struct address_space *mapping, > { > struct folio *folio; > int err; > + unsigned int min_nrpages = mapping_min_folio_nrpages(mapping); > + > + index = round_down(index, min_nrpages); > > if (!filler) > filler = mapping->a_ops->read_folio; Cheers, Hannes