From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1FC50C47089 for ; Thu, 27 May 2021 23:10:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ECB82613D8 for ; Thu, 27 May 2021 23:10:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234744AbhE0XLd (ORCPT ); Thu, 27 May 2021 19:11:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:35202 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233726AbhE0XLd (ORCPT ); Thu, 27 May 2021 19:11:33 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 419AA61176; Thu, 27 May 2021 23:09:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1622156999; bh=ozv62m6+abCCQ6Q0TOzx10PK7EGAxHMBn//PtQqK9mQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=PnwQjJxupOpft1GYbsqCmUeyX347UDGfBUxf0YHPPGmdDg2r4CdcXiOntYWZQ1UDC qBIvcSKnTfHJyH+AT7h47Tozsen+Km66XCyk7h6kRUP6xdGBbb06pyuE0DXDxZX0HZ ROK2osLqx+lMuiyVfyhE/NQZOK0lUjab9kmkryIC3AOhoawLpbrHz1+EF5h1VqGQNc AIcjVM+jn2lm9AZnLEtA5p3eyQqgp19JNu6J83mAorzBO95Yf36QEoYbUZ7uEzNcr/ LKcYR8olxS6yt5C94aUpLnSuAHkiJifY1asAPxSBL5rePLa3ou7xG9gtp5odmvyB2T U/B2ea2a9vF0Q== Date: Thu, 27 May 2021 16:09:58 -0700 From: "Darrick J. Wong" To: Dave Chinner Cc: linux-xfs@vger.kernel.org, hch@lst.de Subject: Re: [PATCH 06/10] xfs: remove ->b_offset handling for page backed buffers Message-ID: <20210527230958.GG2402049@locust> References: <20210526224722.1111377-1-david@fromorbit.com> <20210526224722.1111377-7-david@fromorbit.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210526224722.1111377-7-david@fromorbit.com> Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Thu, May 27, 2021 at 08:47:18AM +1000, Dave Chinner wrote: > From : Christoph Hellwig > > ->b_offset can only be non-zero for _XBF_KMEM backed buffers, so > remove all code dealing with it for page backed buffers. > > Signed-off-by: Christoph Hellwig > [dgc: modified to fit this patchset] > Signed-off-by: Dave Chinner I think it's the case that the only time we'd end up with a nonzero b_offset is if the kmem_alloc returns a slab object in the middle of a page, right? i.e. vmalloc is supposed to give us full pages, and we hope that nobody ever sells a device with a 64k dma alignment...? Assuming that's right, Reviewed-by: Darrick J. Wong --D > --- > fs/xfs/xfs_buf.c | 8 +++----- > fs/xfs/xfs_buf.h | 3 ++- > 2 files changed, 5 insertions(+), 6 deletions(-) > > diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c > index d15999c41885..87151d78a0d8 100644 > --- a/fs/xfs/xfs_buf.c > +++ b/fs/xfs/xfs_buf.c > @@ -79,7 +79,7 @@ static inline int > xfs_buf_vmap_len( > struct xfs_buf *bp) > { > - return (bp->b_page_count * PAGE_SIZE) - bp->b_offset; > + return (bp->b_page_count * PAGE_SIZE); > } > > /* > @@ -281,7 +281,7 @@ xfs_buf_free_pages( > ASSERT(bp->b_flags & _XBF_PAGES); > > if (xfs_buf_is_vmapped(bp)) > - vm_unmap_ram(bp->b_addr - bp->b_offset, bp->b_page_count); > + vm_unmap_ram(bp->b_addr, bp->b_page_count); > > for (i = 0; i < bp->b_page_count; i++) { > if (bp->b_pages[i]) > @@ -442,7 +442,7 @@ _xfs_buf_map_pages( > ASSERT(bp->b_flags & _XBF_PAGES); > if (bp->b_page_count == 1) { > /* A single page buffer is always mappable */ > - bp->b_addr = page_address(bp->b_pages[0]) + bp->b_offset; > + bp->b_addr = page_address(bp->b_pages[0]); > } else if (flags & XBF_UNMAPPED) { > bp->b_addr = NULL; > } else { > @@ -469,7 +469,6 @@ _xfs_buf_map_pages( > > if (!bp->b_addr) > return -ENOMEM; > - bp->b_addr += bp->b_offset; > } > > return 0; > @@ -1680,7 +1679,6 @@ xfs_buf_offset( > if (bp->b_addr) > return bp->b_addr + offset; > > - offset += bp->b_offset; > page = bp->b_pages[offset >> PAGE_SHIFT]; > return page_address(page) + (offset & (PAGE_SIZE-1)); > } > diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h > index 459ca34f26f5..464dc548fa23 100644 > --- a/fs/xfs/xfs_buf.h > +++ b/fs/xfs/xfs_buf.h > @@ -167,7 +167,8 @@ struct xfs_buf { > atomic_t b_pin_count; /* pin count */ > atomic_t b_io_remaining; /* #outstanding I/O requests */ > unsigned int b_page_count; /* size of page array */ > - unsigned int b_offset; /* page offset in first page */ > + unsigned int b_offset; /* page offset of b_addr, > + only for _XBF_KMEM buffers */ > int b_error; /* error code on I/O */ > > /* > -- > 2.31.1 >