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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 BD161C433E0 for ; Tue, 26 May 2020 13:47:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 902C3208A9 for ; Tue, 26 May 2020 13:47:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Qxfbqard" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726856AbgEZNrH (ORCPT ); Tue, 26 May 2020 09:47:07 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:24670 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726618AbgEZNrG (ORCPT ); Tue, 26 May 2020 09:47:06 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1590500824; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=cjvnMK0418wEKyzy21neiB1jctudOYI7ItQnlw1+pLg=; b=QxfbqardziDuSaOjaWjMTCCLYlU/9JZmq1MfJb4X3Dym64msE89/k/CehhQsP7jVkkTYub EA+oAmu/h+wkg50Xazt0Llr3zWvhID59IqnPRgYs9CClBMyrrnNo2YhrGEdEw+pMWhfkFJ dpgtLjLf5K9YGuFELxGTRBOSuwAQ2xI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-269-BSXvXThqMSuFeYy-4KjN5g-1; Tue, 26 May 2020 09:46:56 -0400 X-MC-Unique: BSXvXThqMSuFeYy-4KjN5g-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A0825100CCD3; Tue, 26 May 2020 13:46:55 +0000 (UTC) Received: from bfoster (dhcp-41-2.bos.redhat.com [10.18.41.2]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1CCCC6EDAA; Tue, 26 May 2020 13:46:55 +0000 (UTC) Date: Tue, 26 May 2020 09:46:53 -0400 From: Brian Foster To: "Darrick J. Wong" Cc: Christoph Hellwig , Christoph Hellwig , linux-xfs@vger.kernel.org Subject: Re: [PATCH v2 3/4] xfs: refactor xfs_iomap_prealloc_size Message-ID: <20200526134653.GB5462@bfoster> References: <159025257178.493629.12621189512718182426.stgit@magnolia> <159025259150.493629.14462334296980108072.stgit@magnolia> <20200524171709.GI8230@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200524171709.GI8230@magnolia> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Sun, May 24, 2020 at 10:17:09AM -0700, Darrick J. Wong wrote: > From: Darrick J. Wong > > Refactor xfs_iomap_prealloc_size to be the function that dynamically > computes the per-file preallocation size by moving the allocsize= case > to the caller. Break up the huge comment preceding the function to > annotate the relevant parts of the code, and remove the impossible > check_writeio case. > > Suggested-by: Christoph Hellwig > Signed-off-by: Darrick J. Wong > Reviewed-by: Christoph Hellwig > --- > v2: minor rebase due to changes in previous patch > --- Reviewed-by: Brian Foster > fs/xfs/xfs_iomap.c | 83 ++++++++++++++++++++++------------------------------ > 1 file changed, 35 insertions(+), 48 deletions(-) > > diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c > index e74a8c2c94ce..b9a8c3798e08 100644 > --- a/fs/xfs/xfs_iomap.c > +++ b/fs/xfs/xfs_iomap.c > @@ -352,22 +352,10 @@ xfs_quota_calc_throttle( > } > > /* > - * If we are doing a write at the end of the file and there are no allocations > - * past this one, then extend the allocation out to the file system's write > - * iosize. > - * > * If we don't have a user specified preallocation size, dynamically increase > * the preallocation size as the size of the file grows. Cap the maximum size > * at a single extent or less if the filesystem is near full. The closer the > - * filesystem is to full, the smaller the maximum prealocation. > - * > - * As an exception we don't do any preallocation at all if the file is smaller > - * than the minimum preallocation and we are using the default dynamic > - * preallocation scheme, as it is likely this is the only write to the file that > - * is going to be done. > - * > - * We clean up any extra space left over when the file is closed in > - * xfs_inactive(). > + * filesystem is to being full, the smaller the maximum preallocation. > */ > STATIC xfs_fsblock_t > xfs_iomap_prealloc_size( > @@ -389,41 +377,28 @@ xfs_iomap_prealloc_size( > int shift = 0; > int qshift = 0; > > - if (offset + count <= XFS_ISIZE(ip)) > - return 0; > - > - if (!(mp->m_flags & XFS_MOUNT_ALLOCSIZE) && > - (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_allocsize_blocks))) > + /* > + * As an exception we don't do any preallocation at all if the file is > + * smaller than the minimum preallocation and we are using the default > + * dynamic preallocation scheme, as it is likely this is the only write > + * to the file that is going to be done. > + */ > + if (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_allocsize_blocks)) > return 0; > > /* > - * If an explicit allocsize is set, the file is small, or we > - * are writing behind a hole, then use the minimum prealloc: > + * Use the minimum preallocation size for small files or if we are > + * writing right after a hole. > */ > - if ((mp->m_flags & XFS_MOUNT_ALLOCSIZE) || > - XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign) || > + if (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign) || > !xfs_iext_prev_extent(ifp, &ncur, &prev) || > prev.br_startoff + prev.br_blockcount < offset_fsb) > return mp->m_allocsize_blocks; > > /* > - * Determine the initial size of the preallocation. We are beyond the > - * current EOF here, but we need to take into account whether this is > - * a sparse write or an extending write when determining the > - * preallocation size. Hence we need to look up the extent that ends > - * at the current write offset and use the result to determine the > - * preallocation size. > - * > - * If the extent is a hole, then preallocation is essentially disabled. > - * Otherwise we take the size of the preceding data extents as the basis > - * for the preallocation size. Note that we don't care if the previous > - * extents are written or not. > - * > - * If the size of the extents is greater than half the maximum extent > - * length, then use the current offset as the basis. This ensures that > - * for large files the preallocation size always extends to MAXEXTLEN > - * rather than falling short due to things like stripe unit/width > - * alignment of real extents. > + * Take the size of the preceding data extents as the basis for the > + * preallocation size. Note that we don't care if the previous extents > + * are written or not. > */ > plen = prev.br_blockcount; > while (xfs_iext_prev_extent(ifp, &ncur, &got)) { > @@ -435,19 +410,25 @@ xfs_iomap_prealloc_size( > plen += got.br_blockcount; > prev = got; > } > + > + /* > + * If the size of the extents is greater than half the maximum extent > + * length, then use the current offset as the basis. This ensures that > + * for large files the preallocation size always extends to MAXEXTLEN > + * rather than falling short due to things like stripe unit/width > + * alignment of real extents. > + */ > alloc_blocks = plen * 2; > if (alloc_blocks > MAXEXTLEN) > alloc_blocks = XFS_B_TO_FSB(mp, offset); > - if (!alloc_blocks) > - goto check_writeio; > qblocks = alloc_blocks; > > /* > * MAXEXTLEN is not a power of two value but we round the prealloc down > * to the nearest power of two value after throttling. To prevent the > - * round down from unconditionally reducing the maximum supported prealloc > - * size, we round up first, apply appropriate throttling, round down and > - * cap the value to MAXEXTLEN. > + * round down from unconditionally reducing the maximum supported > + * prealloc size, we round up first, apply appropriate throttling, > + * round down and cap the value to MAXEXTLEN. > */ > alloc_blocks = XFS_FILEOFF_MIN(roundup_pow_of_two(MAXEXTLEN), > alloc_blocks); > @@ -508,7 +489,6 @@ xfs_iomap_prealloc_size( > */ > while (alloc_blocks && alloc_blocks >= freesp) > alloc_blocks >>= 4; > -check_writeio: > if (alloc_blocks < mp->m_allocsize_blocks) > alloc_blocks = mp->m_allocsize_blocks; > trace_xfs_iomap_prealloc_size(ip, alloc_blocks, shift, > @@ -975,9 +955,16 @@ xfs_buffered_write_iomap_begin( > if (error) > goto out_unlock; > > - if (eof) { > - prealloc_blocks = xfs_iomap_prealloc_size(ip, allocfork, offset, > - count, &icur); > + if (eof && offset + count > XFS_ISIZE(ip)) { > + /* > + * Determine the initial size of the preallocation. > + * We clean up any extra preallocation when the file is closed. > + */ > + if (mp->m_flags & XFS_MOUNT_ALLOCSIZE) > + prealloc_blocks = mp->m_allocsize_blocks; > + else > + prealloc_blocks = xfs_iomap_prealloc_size(ip, allocfork, > + offset, count, &icur); > if (prealloc_blocks) { > xfs_extlen_t align; > xfs_off_t end_offset; >