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Sat, 15 Feb 2020 01:15:29 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=8vF3wmoykU6jc6+10TSp5NOFVxwRnMSI+FSzYO1WEQQ=; b=bYTz4ixAcXgUBn5lU/9H4Qkc8U psonlrVRSl1w2Efajn8sSvZ4fc66CBslbfJ8hYC7paJRLK+yJwFFKlpcmnCuSqQ3VgQIQc9bRKzS3 RKpTi9vip5bJenIXktMAoR2hmT8VH80rF4tgY3sf4QnBz8MWKa+ALVxAEtDMgRdz1VPOIaUeTItOS 2pxc8IX2HDPzzkM5B4sWPw6NpUySd6jYHfalkiD/26kIZxfM118k/TIVrruZyhX4bQ6tIJjKq3niB ldfXT72DOy+DLMs6ox4SNWF1RllK7qc+dkUXgtwEY31BR65L8+zEdJD+0mj8Hsxex+wOSOCKsfGso 5F0cnt9Q==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1j2m2z-0006lw-H3; Sat, 15 Feb 2020 01:15:05 +0000 Date: Fri, 14 Feb 2020 17:15:05 -0800 From: Matthew Wilcox To: John Hubbard Message-ID: <20200215011505.GD7778@bombadil.infradead.org> References: <20200211010348.6872-1-willy@infradead.org> <20200211010348.6872-5-willy@infradead.org> <755399a8-8fdf-bfac-9f23-81579ff63ddf@nvidia.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <755399a8-8fdf-bfac-9f23-81579ff63ddf@nvidia.com> X-Headers-End: 1j2m3L-004RNb-DF Subject: Re: [f2fs-dev] [PATCH v5 04/13] mm: Add readahead address space operation X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, linux-mm@kvack.org, ocfs2-devel@oss.oracle.com, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-btrfs@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On Thu, Feb 13, 2020 at 09:36:25PM -0800, John Hubbard wrote: > > +static inline struct page *readahead_page(struct readahead_control *rac) > > +{ > > + struct page *page; > > + > > + if (!rac->nr_pages) > > + return NULL; > > + > > + page = xa_load(&rac->mapping->i_pages, rac->start); > > > Is it worth asserting that the page was found: > > VM_BUG_ON_PAGE(!page || xa_is_value(page), page); > > ? Or is that overkill here? It shouldn't be possible since they were just added in a locked state. If it did happen, it'll be caught by the assert below -- dereferencing a NULL pointer or a shadow entry is not going to go well. > > + VM_BUG_ON_PAGE(!PageLocked(page), page); > > + rac->batch_count = hpage_nr_pages(page); > > + rac->start += rac->batch_count; > > The above was surprising, until I saw the other thread with Dave and you. > I was reviewing this patchset in order to have a chance at understanding the > follow-on patchset ("Large pages in the page cache"), and it seems like that > feature has a solid head start here. :) Right, I'll document that. _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel