From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 30 May 2018 08:23:37 +0200 From: Christoph Hellwig To: "Darrick J. Wong" Cc: Christoph Hellwig , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 15/34] iomap: add an iomap-based readpage and readpages implementation Message-ID: <20180530062337.GA25732@lst.de> References: <20180523144357.18985-1-hch@lst.de> <20180523144357.18985-16-hch@lst.de> <20180530061146.GD30110@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180530061146.GD30110@magnolia> Sender: owner-linux-mm@kvack.org List-ID: On Tue, May 29, 2018 at 11:11:46PM -0700, Darrick J. Wong wrote: > > + list_del(&page->lru); > > + if (!add_to_page_cache_lru(page, inode->i_mapping, page->index, > > + GFP_NOFS)) > > I'm curious about this line -- if add_to_page_cache_lru returns an > error, why don't we want to send that back up the stack? Is the idea > that the page doesn't become uptodate and something else notices? It > seems a little odd that on error we just skip to the next page. > > (If this /is/ correct then comment is needed here.) readpages is only used for read-ahead, so the upper layers literally don't care as long as we don't mess up the page refcount. This logic is taken straight from mpage_readpages, but I'll add a comment anyway.