From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 15 Oct 2020 17:43:33 +0100 From: Matthew Wilcox Subject: Re: [PATCH v2 16/16] iomap: Make readpage synchronous Message-ID: <20201015164333.GA20115@casper.infradead.org> References: <20201009143104.22673-1-willy@infradead.org> <20201009143104.22673-17-willy@infradead.org> <20201015094203.GA21420@infradead.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201015094203.GA21420@infradead.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-um" Errors-To: linux-um-bounces+geert=linux-m68k.org@lists.infradead.org To: Christoph Hellwig Cc: linux-cifs@vger.kernel.org, Richard Weinberger , ecryptfs@vger.kernel.org, linux-um@lists.infradead.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, ceph-devel@vger.kernel.org, linux-afs@lists.infradead.org On Thu, Oct 15, 2020 at 10:42:03AM +0100, Christoph Hellwig wrote: > > +static void iomap_read_page_end_io(struct bio_vec *bvec, > > + struct completion *done, bool error) > > I really don't like the parameters here. Part of the problem is > that ctx is only assigned to bi_private conditionally, which can > easily be fixed. The other part is the strange bool error when > we can just pass on bi_stats. See the patch at the end of what > I'd do intead. I prefer assigning ctx conditionally to propagating the knowledge that !rac means synchronous. I've gone with this: static void iomap_read_page_end_io(struct bio_vec *bvec, - struct completion *done, bool error) + struct iomap_readpage_ctx *ctx, blk_status_t status) { struct page *page = bvec->bv_page; struct iomap_page *iop = to_iomap_page(page); - if (!error) + if (status == BLK_STS_OK) { iomap_set_range_uptodate(page, bvec->bv_offset, bvec->bv_len); + } else if (ctx && ctx->status == BLK_STS_OK) { + ctx->status = status; + } if (!iop || atomic_sub_and_test(bvec->bv_len, &iop->read_bytes_pending)) { - if (done) - complete(done); + if (ctx) + complete(&ctx->done); else unlock_page(page); } > > } else { > > WARN_ON_ONCE(ctx.cur_page_in_bio); > > - unlock_page(page); > > + complete(&ctx.done); > > } > > > > + wait_for_completion(&ctx.done); > > I don't think we need the complete / wait_for_completion dance in > this case. > > > + if (ret >= 0) > > + ret = blk_status_to_errno(ctx.status); > > + if (ret == 0) > > + return AOP_UPDATED_PAGE; > > + unlock_page(page); > > + return ret; > > Nipick, but I'd rather have a goto out_unlock for both error case > and have the AOP_UPDATED_PAGE for the normal path straight in line. > > Here is an untested patch with my suggestions: I think we can go a little further here: @@ -340,16 +335,12 @@ iomap_readpage(struct page *page, const struct iomap_ops * ops) if (ctx.bio) { submit_bio(ctx.bio); - WARN_ON_ONCE(!ctx.cur_page_in_bio); - } else { - WARN_ON_ONCE(ctx.cur_page_in_bio); - complete(&ctx.done); + wait_for_completion(&ctx.done); + if (ret > 0) + ret = blk_status_to_errno(ctx.status); } - wait_for_completion(&ctx.done); if (ret >= 0) - ret = blk_status_to_errno(ctx.status); - if (ret == 0) return AOP_UPDATED_PAGE; unlock_page(page); return ret; ... there's no need to call blk_status_to_errno if we never submitted a bio. _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um