From patchwork Tue Dec 10 16:24:52 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jens Axboe X-Patchwork-Id: 11282945 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 837EC15AB for ; Tue, 10 Dec 2019 16:25:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 58A6020838 for ; Tue, 10 Dec 2019 16:25:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="Zpixa69l" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727573AbfLJQZC (ORCPT ); Tue, 10 Dec 2019 11:25:02 -0500 Received: from mail-io1-f66.google.com ([209.85.166.66]:33568 "EHLO mail-io1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727550AbfLJQZC (ORCPT ); Tue, 10 Dec 2019 11:25:02 -0500 Received: by mail-io1-f66.google.com with SMTP id s25so4724935iob.0 for ; Tue, 10 Dec 2019 08:25:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=o/x6NjL9O5h2Ux7aJEFNccuj0M9CNUr2pjvWBBusJd4=; b=Zpixa69lHW83t2ZbBBOHojQxENx5w2X0sKlji5l+ZpBo6tA/3fj9yn2HfnjrlJQ6Ob U8FY3MOCg7q0XHIPvND9EpFk53qsIhRbPB/9HbD1ilihLRNcBtOuwWUXkIqNVoGnuzdD 5XOtCxdmCCmO2Arsi/KYjMVTyNg6egphSQmKqqQfmQkq1VyVM8Gj0Xtm9JJX4Led8WKe zmbD/SLsl+MyHYWuaQHEb1/hAAYeSbscwPIu0vVxe909vlonZb4pS3Y0AjqklnvTPNnZ 6/Cw7617YWeJqBJwlZJAG0ivRv7q+hmVouVZ8mhUmu2zs+i9PsKCc/s41pHKmnnSHHi9 5YdQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=o/x6NjL9O5h2Ux7aJEFNccuj0M9CNUr2pjvWBBusJd4=; b=SANzaqwDlcK1BvwGsV8jFHUA/TugxkTLJIRPivgIda54CYp1vxwsOpB3RvQglVYGCN TRZlH7bfJJgjWEBqvrSQMZDSz+8YuhAcXSw5ObHLanJIHCw8jMedV4zNjUlL3RAPlZhz jeXU6Gu+p+IfCVuNB9WSvv1h4mJfSTaofbsPoLn/KbkUdUlBn2cEJclC9QwMiVlVTXr7 L2FCBlvnVwfC23m+nMEuW5ALNAo16aHzF0j3W5Bj8aUN62uLoSAfuCppmovJj0zGL7cc wX3VeFC3etC/LwJFZVuZPOrXuPUJoIQti9WuzZoTWApo1EK3zC8soE3kVNAvzeDr+GGQ 08vw== X-Gm-Message-State: APjAAAW2KRMrEVyzH5+tebKkIbGHj/Ob2WcqhCaGiayNtDXh5Q98Ew9u YmOk4RVlmcSrCj9ZDAP0JyvFAA== X-Google-Smtp-Source: APXvYqxxtEmqFA3byjJGnmrQmrrH3TRgfkvrkxj17L5ofRuCP+Z2MTkeccUYnzTdzqEGwVD/DbWwww== X-Received: by 2002:a02:c6d5:: with SMTP id r21mr32752498jan.129.1575995101208; Tue, 10 Dec 2019 08:25:01 -0800 (PST) Received: from x1.thefacebook.com ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id y11sm791174iol.23.2019.12.10.08.24.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Dec 2019 08:25:00 -0800 (PST) From: Jens Axboe To: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org Cc: Jens Axboe Subject: [PATCH 3/5] mm: make buffered writes work with RWF_UNCACHED Date: Tue, 10 Dec 2019 09:24:52 -0700 Message-Id: <20191210162454.8608-4-axboe@kernel.dk> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191210162454.8608-1-axboe@kernel.dk> References: <20191210162454.8608-1-axboe@kernel.dk> MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org If RWF_UNCACHED is set for io_uring (or pwritev2(2)), we'll drop the cache instantiated for buffered writes. If new pages aren't instantiated, we leave them alone. This provides similar semantics to reads with RWF_UNCACHED set. Signed-off-by: Jens Axboe --- include/linux/fs.h | 3 ++ mm/filemap.c | 78 +++++++++++++++++++++++++++++++++++++++++++--- 2 files changed, 76 insertions(+), 5 deletions(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index bf58db1bc032..bcf486c132a8 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -285,6 +285,7 @@ enum positive_aop_returns { #define AOP_FLAG_NOFS 0x0002 /* used by filesystem to direct * helper code (eg buffer layer) * to clear GFP_FS from alloc */ +#define AOP_FLAG_UNCACHED 0x0004 /* * oh the beauties of C type declarations. @@ -3105,6 +3106,8 @@ extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *); extern ssize_t generic_file_direct_write(struct kiocb *, struct iov_iter *); extern ssize_t generic_perform_write(struct file *, struct iov_iter *, struct kiocb *); +extern void write_drop_cached_pages(struct page **, + struct address_space *mapping, unsigned *); ssize_t vfs_iter_read(struct file *file, struct iov_iter *iter, loff_t *ppos, rwf_t flags); diff --git a/mm/filemap.c b/mm/filemap.c index fe37bd2b2630..d6171bf705f9 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3287,10 +3287,12 @@ struct page *grab_cache_page_write_begin(struct address_space *mapping, pgoff_t index, unsigned flags) { struct page *page; - int fgp_flags = FGP_LOCK|FGP_WRITE|FGP_CREAT; + int fgp_flags = FGP_LOCK|FGP_WRITE; if (flags & AOP_FLAG_NOFS) fgp_flags |= FGP_NOFS; + if (!(flags & AOP_FLAG_UNCACHED)) + fgp_flags |= FGP_CREAT; page = pagecache_get_page(mapping, index, fgp_flags, mapping_gfp_mask(mapping)); @@ -3301,21 +3303,67 @@ struct page *grab_cache_page_write_begin(struct address_space *mapping, } EXPORT_SYMBOL(grab_cache_page_write_begin); +/* + * Start writeback on the pages in pgs[], and then try and remove those pages + * from the page cached. Used with RWF_UNCACHED. + */ +void write_drop_cached_pages(struct page **pgs, struct address_space *mapping, + unsigned *nr) +{ + loff_t start, end; + int i; + + end = 0; + start = LLONG_MAX; + for (i = 0; i < *nr; i++) { + struct page *page = pgs[i]; + loff_t off; + + off = (loff_t) page_to_index(page) << PAGE_SHIFT; + if (off < start) + start = off; + if (off > end) + end = off; + get_page(page); + } + + __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_NONE); + + for (i = 0; i < *nr; i++) { + struct page *page = pgs[i]; + + lock_page(page); + if (page->mapping == mapping) { + wait_on_page_writeback(page); + if (!page_has_private(page) || + try_to_release_page(page, 0)) + remove_mapping(mapping, page); + } + unlock_page(page); + } + *nr = 0; +} +EXPORT_SYMBOL_GPL(write_drop_cached_pages); + +#define GPW_PAGE_BATCH 16 + ssize_t generic_perform_write(struct file *file, struct iov_iter *i, struct kiocb *iocb) { struct address_space *mapping = file->f_mapping; const struct address_space_operations *a_ops = mapping->a_ops; + struct page *drop_pages[GPW_PAGE_BATCH]; loff_t pos = iocb->ki_pos; long status = 0; ssize_t written = 0; - unsigned int flags = 0; + unsigned int flags = 0, drop_nr = 0; do { struct page *page; unsigned long offset; /* Offset into pagecache page */ unsigned long bytes; /* Bytes to write to page */ size_t copied; /* Bytes copied from user */ + bool drop_page = false; /* drop page after IO */ void *fsdata; offset = (pos & (PAGE_SIZE - 1)); @@ -3323,6 +3371,9 @@ ssize_t generic_perform_write(struct file *file, iov_iter_count(i)); again: + if (iocb->ki_flags & IOCB_UNCACHED) + flags |= AOP_FLAG_UNCACHED; + /* * Bring in the user page that we will copy from _first_. * Otherwise there's a nasty deadlock on copying from the @@ -3343,10 +3394,17 @@ ssize_t generic_perform_write(struct file *file, break; } +retry: status = a_ops->write_begin(file, mapping, pos, bytes, flags, &page, &fsdata); - if (unlikely(status < 0)) + if (unlikely(status < 0)) { + if (status == -ENOMEM && (flags & AOP_FLAG_UNCACHED)) { + drop_page = true; + flags &= ~AOP_FLAG_UNCACHED; + goto retry; + } break; + } if (mapping_writably_mapped(mapping)) flush_dcache_page(page); @@ -3376,12 +3434,22 @@ ssize_t generic_perform_write(struct file *file, iov_iter_single_seg_count(i)); goto again; } + if (drop_page && + ((pos >> PAGE_SHIFT) != ((pos + copied) >> PAGE_SHIFT))) { + drop_pages[drop_nr] = page; + if (++drop_nr == GPW_PAGE_BATCH) + write_drop_cached_pages(drop_pages, mapping, + &drop_nr); + } else + balance_dirty_pages_ratelimited(mapping); + pos += copied; written += copied; - - balance_dirty_pages_ratelimited(mapping); } while (iov_iter_count(i)); + if (drop_nr) + write_drop_cached_pages(drop_pages, mapping, &drop_nr); + return written ? written : status; } EXPORT_SYMBOL(generic_perform_write);