From patchwork Tue Dec 10 20:43:00 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jens Axboe X-Patchwork-Id: 11283251 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 7B0CF109A for ; Tue, 10 Dec 2019 20:43:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4D9F72073B for ; Tue, 10 Dec 2019 20:43:11 +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="VC4R6EkX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726708AbfLJUnK (ORCPT ); Tue, 10 Dec 2019 15:43:10 -0500 Received: from mail-pf1-f196.google.com ([209.85.210.196]:37888 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726366AbfLJUnK (ORCPT ); Tue, 10 Dec 2019 15:43:10 -0500 Received: by mail-pf1-f196.google.com with SMTP id x185so413896pfc.5 for ; Tue, 10 Dec 2019 12:43:10 -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=g934jRFitGK2n249ARajPKYt/UpPdfJOZffggpxpM9A=; b=VC4R6EkXXjbtQxDiwSsKD2cJRnJF2ODuAL3j8ivGaSeswr6nBQpNBzBjn+q/Vcpeil ycZ+Ao2nHQq7myQuMGD4fppkVnNgT+lLMObOnSHXDraX/2V7KQWkp73TSXf1iEqwkpvh kxQ8tBtG4h00b0Cq5hSe/+zR7dUYXOklLtS4yzNx4n754+9LRSDtzwF0BM5zDwGWJlI4 LCO18i09Xt9xIgLpbQJlOKGBukiM2Ye2CGcaYQrV5tIalX34nIHITLjJAnryr2uiaQnQ H1JJKa0QJQNhA30TOcOpwFn6uj1aSiDWyQ1shW2UC8FJjuPu8Dy3GnqYQgccuq7auwLV eXZQ== 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=g934jRFitGK2n249ARajPKYt/UpPdfJOZffggpxpM9A=; b=E3OpbeFqxvhaUiRyFWyQMCv7biYWoK/Oz0Mt/vt2Y3x1ufgQswWd22x8/tUYIspvyO 05n8GbTWDwZOjSmoQzdKPaZQcPmN3Y+bFRWqqO8GrHSxlqEakuumJYY0gxMT/ZSCVFgB i0hc71EeiT6ZjIUZ7UuhYX7cNVOM5rl0SrCQmrQ2+ILjLLeg8yTWmtOCb5rr+kvrCwql nX4DAmVKoH4R0PxPlbHqqj8EChVRZgTxxqhuhR560Q/buVpbNnyN1++7VZLTW5Aao8yE p03HHzMblpCuISnzbOLcwAjsyuwDE3Dc6+HrS74GRxTVSeZAz0ttUmxZdXfoVUPJfLQJ P5cQ== X-Gm-Message-State: APjAAAWRqiqG3A43+dszBTkEWNRBZsbtZhp8UefRk/ALWlY6DcMsKmk7 8RN2sDE1PiTndm15NPpBuQmhhQ== X-Google-Smtp-Source: APXvYqyE5WoFA/cmJn1vJRX9pzPgXF2eR410xgWfmk3FD8JEs9EuTw5uMmkjPyn17EKlZwqDrRxS2A== X-Received: by 2002:a62:788a:: with SMTP id t132mr29104312pfc.134.1576010589664; Tue, 10 Dec 2019 12:43:09 -0800 (PST) Received: from x1.thefacebook.com ([66.219.217.145]) by smtp.gmail.com with ESMTPSA id o15sm4387829pgf.2.2019.12.10.12.43.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Dec 2019 12:43:08 -0800 (PST) From: Jens Axboe To: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org Cc: willy@infradead.org, clm@fb.com, Jens Axboe Subject: [PATCH 1/5] fs: add read support for RWF_UNCACHED Date: Tue, 10 Dec 2019 13:43:00 -0700 Message-Id: <20191210204304.12266-2-axboe@kernel.dk> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191210204304.12266-1-axboe@kernel.dk> References: <20191210204304.12266-1-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 preadv2(2)), we'll drop the cache for buffered reads if we are the ones instantiating it. If the data is already cached, we leave it cached. Signed-off-by: Jens Axboe --- include/linux/fs.h | 3 +++ include/uapi/linux/fs.h | 5 ++++- mm/filemap.c | 46 ++++++++++++++++++++++++++++++++++++----- 3 files changed, 48 insertions(+), 6 deletions(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index 98e0349adb52..092ea2a4319b 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -314,6 +314,7 @@ enum rw_hint { #define IOCB_SYNC (1 << 5) #define IOCB_WRITE (1 << 6) #define IOCB_NOWAIT (1 << 7) +#define IOCB_UNCACHED (1 << 8) struct kiocb { struct file *ki_filp; @@ -3418,6 +3419,8 @@ static inline int kiocb_set_rw_flags(struct kiocb *ki, rwf_t flags) ki->ki_flags |= (IOCB_DSYNC | IOCB_SYNC); if (flags & RWF_APPEND) ki->ki_flags |= IOCB_APPEND; + if (flags & RWF_UNCACHED) + ki->ki_flags |= IOCB_UNCACHED; return 0; } diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h index 379a612f8f1d..357ebb0e0c5d 100644 --- a/include/uapi/linux/fs.h +++ b/include/uapi/linux/fs.h @@ -299,8 +299,11 @@ typedef int __bitwise __kernel_rwf_t; /* per-IO O_APPEND */ #define RWF_APPEND ((__force __kernel_rwf_t)0x00000010) +/* drop cache after reading or writing data */ +#define RWF_UNCACHED ((__force __kernel_rwf_t)0x00000040) + /* mask of flags supported by the kernel */ #define RWF_SUPPORTED (RWF_HIPRI | RWF_DSYNC | RWF_SYNC | RWF_NOWAIT |\ - RWF_APPEND) + RWF_APPEND | RWF_UNCACHED) #endif /* _UAPI_LINUX_FS_H */ diff --git a/mm/filemap.c b/mm/filemap.c index bf6aa30be58d..ed23a11b3e34 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -933,8 +933,8 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping, } EXPORT_SYMBOL(add_to_page_cache_locked); -int add_to_page_cache_lru(struct page *page, struct address_space *mapping, - pgoff_t offset, gfp_t gfp_mask) +static int __add_to_page_cache(struct page *page, struct address_space *mapping, + pgoff_t offset, gfp_t gfp_mask, bool lru) { void *shadow = NULL; int ret; @@ -956,9 +956,17 @@ int add_to_page_cache_lru(struct page *page, struct address_space *mapping, WARN_ON_ONCE(PageActive(page)); if (!(gfp_mask & __GFP_WRITE) && shadow) workingset_refault(page, shadow); - lru_cache_add(page); + if (lru) + lru_cache_add(page); } return ret; + +} + +int add_to_page_cache_lru(struct page *page, struct address_space *mapping, + pgoff_t offset, gfp_t gfp_mask) +{ + return __add_to_page_cache(page, mapping, offset, gfp_mask, true); } EXPORT_SYMBOL_GPL(add_to_page_cache_lru); @@ -2032,6 +2040,7 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb, offset = *ppos & ~PAGE_MASK; for (;;) { + bool drop_page = false; struct page *page; pgoff_t end_index; loff_t isize; @@ -2048,6 +2057,9 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb, if (!page) { if (iocb->ki_flags & IOCB_NOWAIT) goto would_block; + /* UNCACHED implies no read-ahead */ + if (iocb->ki_flags & IOCB_UNCACHED) + goto no_cached_page; page_cache_sync_readahead(mapping, ra, filp, index, last_index - index); @@ -2147,6 +2159,26 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb, offset &= ~PAGE_MASK; prev_offset = offset; + /* + * If we're dropping this page due to drop-behind, then + * lock it first. Ignore errors here, we can just leave it + * in the page cache. Note that we didn't add this page to + * the LRU when we added it to the page cache. So if we + * fail removing it, or lock it, add to the LRU. + */ + if (drop_page) { + bool addlru = true; + + if (!lock_page_killable(page)) { + if (page->mapping == mapping) + addlru = !remove_mapping(mapping, page); + else + addlru = false; + unlock_page(page); + } + if (addlru) + lru_cache_add(page); + } put_page(page); written += ret; if (!iov_iter_count(iter)) @@ -2234,8 +2266,12 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb, error = -ENOMEM; goto out; } - error = add_to_page_cache_lru(page, mapping, index, - mapping_gfp_constraint(mapping, GFP_KERNEL)); + if (iocb->ki_flags & IOCB_UNCACHED) + drop_page = true; + + error = __add_to_page_cache(page, mapping, index, + mapping_gfp_constraint(mapping, GFP_KERNEL), + !drop_page); if (error) { put_page(page); if (error == -EEXIST) {