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Fri, 6 Nov 2020 08:37:49 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id A7CE368B02; Fri, 6 Nov 2020 09:37:46 +0100 (CET) Date: Fri, 6 Nov 2020 09:37:46 +0100 From: Christoph Hellwig To: "Matthew Wilcox (Oracle)" Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, hch@lst.de, kent.overstreet@gmail.com Subject: Re: [PATCH v2 11/18] mm/filemap: Convert filemap_update_page to return an errno Message-ID: <20201106083746.GA720@lst.de> References: <20201104204219.23810-1-willy@infradead.org> <20201104204219.23810-12-willy@infradead.org> <20201106081420.GF31585@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201106081420.GF31585@lst.de> User-Agent: Mutt/1.5.17 (2007-11-01) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Nov 06, 2020 at 09:14:20AM +0100, Christoph Hellwig wrote: > We could still consolidate the page unlocking by having another label. > Or even better move the put_page into the caller like I did in my > series, which would conceputally fit in pretty nicely here: FYI, this is what we should do for putting the page (on top of your whole series), which also catches the leak for the readahead NOIO case: diff --git a/mm/filemap.c b/mm/filemap.c index 500e9fd4232cf9..dacee60b92d3d9 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2268,40 +2268,35 @@ static int filemap_update_page(struct kiocb *iocb, struct address_space *mapping, struct iov_iter *iter, struct page *page) { - int error = -EAGAIN; + int error = 0; if (!trylock_page(page)) { if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_NOIO)) - goto error; + return -EAGAIN; if (!(iocb->ki_flags & IOCB_WAITQ)) { put_and_wait_on_page_locked(page, TASK_KILLABLE); return AOP_TRUNCATED_PAGE; } error = __lock_page_async(page, iocb->ki_waitq); if (error) - goto error; + return error; } - error = AOP_TRUNCATED_PAGE; - if (!page->mapping) - goto unlock; - if (filemap_range_uptodate(iocb, mapping, iter, page)) { + if (!page->mapping) { unlock_page(page); - return 0; + put_page(page); + return AOP_TRUNCATED_PAGE; } - error = -EAGAIN; - if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ)) - goto unlock; + if (!filemap_range_uptodate(iocb, mapping, iter, page)) { + error = -EAGAIN; + if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ)) + goto unlock; + return filemap_read_page(iocb->ki_filp, mapping, page); + } - error = filemap_read_page(iocb->ki_filp, mapping, page); - if (error) - goto error; - return 0; unlock: unlock_page(page); -error: - put_page(page); return error; } @@ -2396,8 +2391,9 @@ static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter, return 0; err: - pvec->nr--; - if (likely(pvec->nr)) + if (err < 0) + put_page(page); + if (likely(--pvec->nr)) return 0; if (err == AOP_TRUNCATED_PAGE) goto retry;