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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 92D83C00140 for ; Sat, 6 Aug 2022 00:34:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233833AbiHFAej (ORCPT ); Fri, 5 Aug 2022 20:34:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52310 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233588AbiHFAei (ORCPT ); Fri, 5 Aug 2022 20:34:38 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E44692D1F2 for ; Fri, 5 Aug 2022 17:34:36 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 928C9B80CD7 for ; Sat, 6 Aug 2022 00:34:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1AFC4C433D7; Sat, 6 Aug 2022 00:34:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659746074; bh=WqkLQBvIlMKPsjMJavLeBh5eluKHTB/YZH3PqkHllvQ=; h=Date:From:To:Cc:Subject:From; b=QTP9ENYrVGNwltLIpvmzZmla3dCXn/le8PeVoQZpUl6MdNdgwgA3bF2qyd2i0Qvj4 iS956iceOeVTjPd/Bv4X84kTKKm1QYN8iMtm1Ro5tJx2SPepzLJJNMKy7kyxmcS2C/ wM45xTWdbjT+GyV342XNE/RPLEfFMFVPPbYy5HMbtPAdQlHHgJoVcOHRwUAVXzQzzJ 6GaKIVd3uxKvSpx37V/Es9M+qs4KG2th7hYglyVXHBa63L1A44QK03X0zaGg4NZqFX nkromVlyLWCzX+sKx2ZyyvDozG+2+JXof8WqbetPlcdGglcnYkxeT6hK69UfugJ3l/ Q4wmcfSkk7zIA== Date: Fri, 5 Aug 2022 17:34:33 -0700 From: "Darrick J. Wong" To: xfs Cc: Chandan Babu R , Chandan Babu R Subject: [PATCH v2] xfs: Fix false ENOSPC when performing direct write on a delalloc extent in cow fork Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org From: Chandan Babu R On a higly fragmented filesystem a Direct IO write can fail with -ENOSPC error even though the filesystem has sufficient number of free blocks. This occurs if the file offset range on which the write operation is being performed has a delalloc extent in the cow fork and this delalloc extent begins much before the Direct IO range. In such a scenario, xfs_reflink_allocate_cow() invokes xfs_bmapi_write() to allocate the blocks mapped by the delalloc extent. The extent thus allocated may not cover the beginning of file offset range on which the Direct IO write was issued. Hence xfs_reflink_allocate_cow() ends up returning -ENOSPC. The following script reliably recreates the bug described above. #!/usr/bin/bash device=/dev/loop0 shortdev=$(basename $device) mntpnt=/mnt/ file1=${mntpnt}/file1 file2=${mntpnt}/file2 fragmentedfile=${mntpnt}/fragmentedfile punchprog=/root/repos/xfstests-dev/src/punch-alternating errortag=/sys/fs/xfs/${shortdev}/errortag/bmap_alloc_minlen_extent umount $device > /dev/null 2>&1 echo "Create FS" mkfs.xfs -f -m reflink=1 $device > /dev/null 2>&1 if [[ $? != 0 ]]; then echo "mkfs failed." exit 1 fi echo "Mount FS" mount $device $mntpnt > /dev/null 2>&1 if [[ $? != 0 ]]; then echo "mount failed." exit 1 fi echo "Create source file" xfs_io -f -c "pwrite 0 32M" $file1 > /dev/null 2>&1 sync echo "Create Reflinked file" xfs_io -f -c "reflink $file1" $file2 &>/dev/null echo "Set cowextsize" xfs_io -c "cowextsize 16M" $file1 > /dev/null 2>&1 echo "Fragment FS" xfs_io -f -c "pwrite 0 64M" $fragmentedfile > /dev/null 2>&1 sync $punchprog $fragmentedfile echo "Allocate block sized extent from now onwards" echo -n 1 > $errortag echo "Create 16MiB delalloc extent in CoW fork" xfs_io -c "pwrite 0 4k" $file1 > /dev/null 2>&1 sync echo "Direct I/O write at offset 12k" xfs_io -d -c "pwrite 12k 8k" $file1 This commit fixes the bug by invoking xfs_bmapi_write() in a loop until disk blocks are allocated for atleast the starting file offset of the Direct IO write range. Fixes: 3c68d44a2b49 ("xfs: allocate direct I/O COW blocks in iomap_begin") Reported-and-Root-caused-by: Wengang Wang Signed-off-by: Chandan Babu R Reviewed-by: Darrick J. Wong [djwong: slight editing to make the locking less grody, and fix some style things] Signed-off-by: Darrick J. Wong --- v2: slight style editing by darrick; if nobody complains, I'll push this next week... --- fs/xfs/xfs_reflink.c | 198 +++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 163 insertions(+), 35 deletions(-) diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index 724806c7ce3e..0a32b54456eb 100644 --- a/fs/xfs/xfs_reflink.c +++ b/fs/xfs/xfs_reflink.c @@ -341,9 +341,41 @@ xfs_find_trim_cow_extent( return 0; } -/* Allocate all CoW reservations covering a range of blocks in a file. */ -int -xfs_reflink_allocate_cow( +static int +xfs_reflink_convert_unwritten( + struct xfs_inode *ip, + struct xfs_bmbt_irec *imap, + struct xfs_bmbt_irec *cmap, + bool convert_now) +{ + xfs_fileoff_t offset_fsb = imap->br_startoff; + xfs_filblks_t count_fsb = imap->br_blockcount; + int error; + + /* + * cmap might larger than imap due to cowextsize hint. + */ + xfs_trim_extent(cmap, offset_fsb, count_fsb); + + /* + * COW fork extents are supposed to remain unwritten until we're ready + * to initiate a disk write. For direct I/O we are going to write the + * data and need the conversion, but for buffered writes we're done. + */ + if (!convert_now || cmap->br_state == XFS_EXT_NORM) + return 0; + + trace_xfs_reflink_convert_cow(ip, cmap); + + error = xfs_reflink_convert_cow_locked(ip, offset_fsb, count_fsb); + if (!error) + cmap->br_state = XFS_EXT_NORM; + + return error; +} + +static int +xfs_reflink_fill_cow_hole( struct xfs_inode *ip, struct xfs_bmbt_irec *imap, struct xfs_bmbt_irec *cmap, @@ -352,25 +384,12 @@ xfs_reflink_allocate_cow( bool convert_now) { struct xfs_mount *mp = ip->i_mount; - xfs_fileoff_t offset_fsb = imap->br_startoff; - xfs_filblks_t count_fsb = imap->br_blockcount; struct xfs_trans *tp; - int nimaps, error = 0; - bool found; xfs_filblks_t resaligned; - xfs_extlen_t resblks = 0; - - ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL)); - if (!ip->i_cowfp) { - ASSERT(!xfs_is_reflink_inode(ip)); - xfs_ifork_init_cow(ip); - } - - error = xfs_find_trim_cow_extent(ip, imap, cmap, shared, &found); - if (error || !*shared) - return error; - if (found) - goto convert; + xfs_extlen_t resblks; + int nimaps; + int error; + bool found; resaligned = xfs_aligned_fsb_count(imap->br_startoff, imap->br_blockcount, xfs_get_cowextsz_hint(ip)); @@ -386,17 +405,17 @@ xfs_reflink_allocate_cow( *lockmode = XFS_ILOCK_EXCL; - /* - * Check for an overlapping extent again now that we dropped the ilock. - */ error = xfs_find_trim_cow_extent(ip, imap, cmap, shared, &found); if (error || !*shared) goto out_trans_cancel; + if (found) { xfs_trans_cancel(tp); goto convert; } + ASSERT(cmap->br_startoff > imap->br_startoff); + /* Allocate the entire reservation as unwritten blocks. */ nimaps = 1; error = xfs_bmapi_write(tp, ip, imap->br_startoff, imap->br_blockcount, @@ -416,26 +435,135 @@ xfs_reflink_allocate_cow( */ if (nimaps == 0) return -ENOSPC; + convert: - xfs_trim_extent(cmap, offset_fsb, count_fsb); - /* - * COW fork extents are supposed to remain unwritten until we're ready - * to initiate a disk write. For direct I/O we are going to write the - * data and need the conversion, but for buffered writes we're done. - */ - if (!convert_now || cmap->br_state == XFS_EXT_NORM) - return 0; - trace_xfs_reflink_convert_cow(ip, cmap); - error = xfs_reflink_convert_cow_locked(ip, offset_fsb, count_fsb); - if (!error) - cmap->br_state = XFS_EXT_NORM; + return xfs_reflink_convert_unwritten(ip, imap, cmap, convert_now); + +out_trans_cancel: + xfs_trans_cancel(tp); return error; +} + +static int +xfs_reflink_fill_delalloc( + struct xfs_inode *ip, + struct xfs_bmbt_irec *imap, + struct xfs_bmbt_irec *cmap, + bool *shared, + uint *lockmode, + bool convert_now) +{ + struct xfs_mount *mp = ip->i_mount; + struct xfs_trans *tp; + int nimaps; + int error; + bool found; + + do { + xfs_iunlock(ip, *lockmode); + *lockmode = 0; + + error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, 0, 0, + false, &tp); + if (error) + return error; + + *lockmode = XFS_ILOCK_EXCL; + + error = xfs_find_trim_cow_extent(ip, imap, cmap, shared, + &found); + if (error || !*shared) + goto out_trans_cancel; + + if (found) { + xfs_trans_cancel(tp); + break; + } + + ASSERT(isnullstartblock(cmap->br_startblock) || + cmap->br_startblock == DELAYSTARTBLOCK); + + /* + * Replace delalloc reservation with an unwritten extent. + */ + nimaps = 1; + error = xfs_bmapi_write(tp, ip, cmap->br_startoff, + cmap->br_blockcount, + XFS_BMAPI_COWFORK | XFS_BMAPI_PREALLOC, 0, + cmap, &nimaps); + if (error) + goto out_trans_cancel; + + xfs_inode_set_cowblocks_tag(ip); + error = xfs_trans_commit(tp); + if (error) + return error; + + /* + * Allocation succeeded but the requested range was not even + * partially satisfied? Bail out! + */ + if (nimaps == 0) + return -ENOSPC; + } while (cmap->br_startoff + cmap->br_blockcount <= imap->br_startoff); + + return xfs_reflink_convert_unwritten(ip, imap, cmap, convert_now); out_trans_cancel: xfs_trans_cancel(tp); return error; } +/* Allocate all CoW reservations covering a range of blocks in a file. */ +int +xfs_reflink_allocate_cow( + struct xfs_inode *ip, + struct xfs_bmbt_irec *imap, + struct xfs_bmbt_irec *cmap, + bool *shared, + uint *lockmode, + bool convert_now) +{ + int error; + bool found; + + ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL)); + if (!ip->i_cowfp) { + ASSERT(!xfs_is_reflink_inode(ip)); + xfs_ifork_init_cow(ip); + } + + error = xfs_find_trim_cow_extent(ip, imap, cmap, shared, &found); + if (error || !*shared) + return error; + + /* CoW fork has a real extent */ + if (found) + return xfs_reflink_convert_unwritten(ip, imap, cmap, + convert_now); + + /* + * CoW fork does not have an extent and data extent is shared. + * Allocate a real extent in the CoW fork. + */ + if (cmap->br_startoff > imap->br_startoff) + return xfs_reflink_fill_cow_hole(ip, imap, cmap, shared, + lockmode, convert_now); + + /* + * CoW fork has a delalloc reservation. Replace it with a real extent. + * There may or may not be a data fork mapping. + */ + if (isnullstartblock(cmap->br_startblock) || + cmap->br_startblock == DELAYSTARTBLOCK) + return xfs_reflink_fill_delalloc(ip, imap, cmap, shared, + lockmode, convert_now); + + /* Shouldn't get here. */ + ASSERT(0); + return -EFSCORRUPTED; +} + /* * Cancel CoW reservations for some block range of an inode. *