From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 61FA1223DE7 for ; Thu, 27 Aug 2026 12:36:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787834171; cv=none; b=VdRdM24LKEasVai3lob1qCN/X89BL1RdUO/Yh0OP9plAKcpMn6XLNBvvlKROIpID/e7Hk761N3CtoHfOeZ4qeWXDPgdOCzTjTRy7H63rPy6Yg/224L9nx6HjlWFgd6BZNjWZheMZf6aAB8elP2LnOrV5xCzi7pqKaacJ8SawsSg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787834171; c=relaxed/simple; bh=ATDAhOfZZnlrlcsvyKLDT4FGIXGZJDEMA0sKKjzUFAI=; h=Message-ID:Date:MIME-Version:From:Subject:To:Cc:References: In-Reply-To:Content-Type; b=j4K9cRpPhiHGE6s+7ab5RpxNPPuR9hGaPHbZkLmzb8oxG001CkPGT2H7PkfayYyMO6F8Sweqvz/O2/GGnhxZnqTIsIiOLbzNeOfFOL86zZClDHNgOmkeIXZYVhWE+MJ+saomxTNhTwi0W6F1wOmy7o3Q8BtOXAgw8IGfEAGy1fA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Xw7NucEi; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Xw7NucEi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 514B81F000E9; Thu, 27 Aug 2026 12:36:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787834166; bh=hsQSocOw1V6LIZ0bZ5/AEmq7U0N0qqOB9IfyW0+PBaA=; h=Date:From:Subject:To:Cc:References:In-Reply-To; b=Xw7NucEit5a9fn57CYlVKcqnM+3mVOvXgfMkpu/1ykyrdNsYj4rYOPpgAL4JnrStE 5mVOcsSidSYGLA/SqrgMgAbYCwBJnIBi+Rehx9BKb4yorKpcUa5oSkDh/Fj3hUwHJ+ ZywCIF38WZLrJCx/slrWCp7DFKi0xYAcrHRIX5V2VdOwx+cituNiqQ67jraw8iJUfI 1zdH4gs4MImN2W5nUk2kpRqJ5GuP0fKwja9Xw6LdaMIjX7RxROfSwdTMqLER8nEX1T SspgrmU2IkN8iDm1nwfGUjXMSD99mU72pT/beoQqIRc4Qki+n46JDJpTlgFqfFXmlW fgXyj13Tegt9w== Message-ID: Date: Thu, 27 Aug 2026 20:36:02 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: Chao Yu Subject: Re: [PATCH 06/14] f2fs: prepare mmap write faults for large folios To: Nanzhe Zhao , Barry Song Cc: chao@kernel.org, Nanzhe Zhao , Juan Yescas , Dev Jain , linux-kernel@vger.kernel.org, David Hildenbrand , Bo Zhang , Kalesh Singh , Ryan Roberts , Pengfei Li , linux-f2fs-devel@lists.sourceforge.net, Jaegeuk Kim References: <20260826082641.2007658-1-zhaonanzhe@xiaomi.com> <20260826082641.2007658-7-zhaonanzhe@xiaomi.com> Content-Language: en-US In-Reply-To: <20260826082641.2007658-7-zhaonanzhe@xiaomi.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/26/26 16:26, Nanzhe Zhao wrote: > Now write protect `mmap` also need to support large folio, > Change `f2fs_vm_page_mkwrite` to acheive that. > > Note it currently marks the whole large folio dirty > to avoid data loss which causes write amplification. > Further optimization is welcome. > > PG_mappedtodisk is useless in f2fs, so drop the > folio_test_mappedtodisk() check and its goto out_sem Can you send a separated patch to clean up logic on mappedtodisk flag? > shortcut in f2fs_vm_page_mkwrite(). We extend the > folio_zero_segment() in mkwrite to zero the post-EOF part > of the faulted folio for both order-0 and large folios, so > the f2fs_zero_post_eof_page() call added to cover that > shortcut is no longer needed. > > Signed-off-by: Nanzhe Zhao > --- > fs/f2fs/f2fs.h | 5 +++++ > fs/f2fs/file.c | 59 +++++++++++++++++++++++++++++++------------------- > 2 files changed, 42 insertions(+), 22 deletions(-) > > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h > index ae6031693700..71e6d7e34c7b 100644 > --- a/fs/f2fs/f2fs.h > +++ b/fs/f2fs/f2fs.h > @@ -4343,6 +4343,11 @@ int f2fs_write_single_data_page(struct folio *folio, int *submitted, > enum iostat_type io_type, > int compr_blocks, bool allow_balance); > bool f2fs_ffs_test_blk_uptodate(const struct folio *folio, pgoff_t index); > +struct f2fs_folio_state *f2fs_ffs_find_or_alloc(struct folio *folio); > +void f2fs_ffs_mark_subrange_dirty(struct folio *folio, size_t offset, size_t len); > +bool f2fs_ffs_clear_subrange_dirty_and_test(struct folio *folio, size_t offset, > + size_t len); > +void f2fs_ffs_clear_subrange_dirty(struct folio *folio, size_t offset, size_t len); > void f2fs_write_failed(struct inode *inode, loff_t to); > void f2fs_invalidate_folio(struct folio *folio, size_t offset, size_t length); > bool f2fs_release_folio(struct folio *folio, gfp_t wait); > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c > index e40285d4f9c2..02d687527241 100644 > --- a/fs/f2fs/file.c > +++ b/fs/f2fs/file.c > @@ -124,6 +124,13 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) > struct f2fs_sb_info *sbi = F2FS_I_SB(inode); > struct dnode_of_data dn; > bool need_alloc = !f2fs_is_pinned_file(inode); > + pgoff_t pidx = folio->index + folio_page_idx(folio, vmf->page); > + loff_t pos = (loff_t)pidx << PAGE_SHIFT; > + loff_t isize; > + loff_t folio_start; > + loff_t valid_end; > + size_t dirty_len; > + size_t subpage_off; > int err = 0; > vm_fault_t ret; > > @@ -160,7 +167,7 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) > > #ifdef CONFIG_F2FS_FS_COMPRESSION > if (f2fs_compressed_file(inode)) { > - int ret = f2fs_is_compressed_cluster(inode, folio->index); > + int ret = f2fs_is_compressed_cluster(inode, pidx); > > if (ret < 0) { > err = ret; > @@ -178,18 +185,20 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) > > f2fs_bug_on(sbi, f2fs_has_inline_data(inode)); > > - err = f2fs_zero_post_eof_page(inode, > - (folio->index + 1) << PAGE_SHIFT, true, false); > - if (err) > - goto out_pagefault; > - > file_update_time(vmf->vma->vm_file); > filemap_invalidate_lock_shared(inode->i_mapping); > > folio_lock(folio); > + isize = i_size_read(inode); > + folio_start = folio_pos(folio); > + subpage_off = offset_in_folio(folio, pos); > + valid_end = min_t(loff_t, folio_start + folio_size(folio), isize); > + dirty_len = valid_end > folio_start ? valid_end - folio_start : 0; > + > if (unlikely(folio->mapping != inode->i_mapping || > - folio_pos(folio) > i_size_read(inode) || > - !folio_test_uptodate(folio))) { > + pos >= isize || > + !f2fs_ffs_test_blk_uptodate(folio, > + folio->index + (subpage_off >> PAGE_SHIFT)))) { > folio_unlock(folio); > err = -EFAULT; > goto out_sem; > @@ -198,9 +207,19 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) > set_new_dnode(&dn, inode, NULL, NULL, 0); > if (need_alloc) { > /* block allocation */ > - err = f2fs_get_block_locked(&dn, folio->index); > + if (folio_test_large(folio)) { > + pgoff_t i, nr = DIV_ROUND_UP(dirty_len, PAGE_SIZE); > + > + for (i = 0; i < nr; i++) { > + err = f2fs_get_block_locked(&dn, folio->index + i); > + if (err) > + break; We only need to call f2fs_get_block_locked() for vmf->page? Hi Barry, could you please help to confirm this? Only vmf->page contain dirty data, rather than whole large folio contain dirty data? Thanks, > + } > + } else { > + err = f2fs_get_block_locked(&dn, pidx); > + } > } else { > - err = f2fs_get_dnode_of_data(&dn, folio->index, LOOKUP_NODE); > + err = f2fs_get_dnode_of_data(&dn, pidx, LOOKUP_NODE); > f2fs_put_dnode(&dn); > if (f2fs_is_pinned_file(inode) && > !__is_valid_data_blkaddr(dn.data_blkaddr)) > @@ -217,20 +236,17 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) > /* wait for GCed page writeback via META_MAPPING */ > f2fs_wait_on_block_writeback(inode, dn.data_blkaddr); > > - /* > - * check to see if the page is mapped already (no holes) > - */ > - if (folio_test_mappedtodisk(folio)) > - goto out_sem; > - > /* page is wholly or partially inside EOF */ > - if (((loff_t)(folio->index + 1) << PAGE_SHIFT) > > - i_size_read(inode)) { > - loff_t offset; > + if (folio_start + folio_size(folio) > isize) { > + size_t offset = offset_in_folio(folio, isize); > > - offset = i_size_read(inode) & ~PAGE_MASK; > folio_zero_segment(folio, offset, folio_size(folio)); > } > + > + if (folio_test_large(folio)) { > + f2fs_ffs_find_or_alloc(folio); > + f2fs_ffs_mark_subrange_dirty(folio, 0, dirty_len); > + } > folio_mark_dirty(folio); > > f2fs_update_iostat(sbi, inode, APP_MAPPED_IO, F2FS_BLKSIZE); > @@ -238,12 +254,11 @@ static vm_fault_t f2fs_vm_page_mkwrite(struct vm_fault *vmf) > > out_sem: > filemap_invalidate_unlock_shared(inode->i_mapping); > -out_pagefault: > sb_end_pagefault(inode->i_sb); > out: > ret = vmf_fs_error(err); > > - trace_f2fs_vm_page_mkwrite(inode, folio->index, vmf->vma->vm_flags, ret); > + trace_f2fs_vm_page_mkwrite(inode, pidx, vmf->vma->vm_flags, ret); > return ret; > } >