From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp2130.oracle.com ([156.151.31.86]:44682 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725887AbeKUJ2T (ORCPT ); Wed, 21 Nov 2018 04:28:19 -0500 Date: Tue, 20 Nov 2018 14:56:40 -0800 From: "Darrick J. Wong" Subject: Re: [PATCH 7/7] xfs: flush removing page cache in xfs_reflink_remap_prep Message-ID: <20181120225640.GJ6792@magnolia> References: <20181119210459.8506-1-david@fromorbit.com> <20181119210459.8506-8-david@fromorbit.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181119210459.8506-8-david@fromorbit.com> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Dave Chinner Cc: linux-xfs@vger.kernel.org On Tue, Nov 20, 2018 at 08:04:59AM +1100, Dave Chinner wrote: > From: Dave Chinner > > On a sub-page block size filesystem, fsx is failing with a data > corruption after a series of operations involving copying a file > with the destination offset beyond EOF of the destination of the file: > > 8093(157 mod 256): TRUNCATE DOWN from 0x7a120 to 0x50000 ******WWWW > 8094(158 mod 256): INSERT 0x25000 thru 0x25fff (0x1000 bytes) > 8095(159 mod 256): COPY 0x18000 thru 0x1afff (0x3000 bytes) to 0x2f400 > 8096(160 mod 256): WRITE 0x5da00 thru 0x651ff (0x7800 bytes) HOLE > 8097(161 mod 256): COPY 0x2000 thru 0x5fff (0x4000 bytes) to 0x6fc00 > > The second copy here is beyond EOF, and it is to sub-page (4k) but > block aligned (1k) offset. The clone runs the EOF zeroing, landing > in a pre-existing post-eof delalloc extent. This zeroes the post-eof > extents in the page cache just fine, dirtying the pages correctly. > > The problem is that xfs_reflink_remap_prep() now truncates the page > cache over the range that it is copying it to, and rounds that down > to cover the entire start page. This removes the dirty page over the > delalloc extent from the page cache without having written it back. > Hence later, when the page cache is flushed, the page at offset > 0x6f000 has not been written back and hence exposes stale data, > which fsx trips over less than 10 operations later. > > Fix this by changing xfs_reflink_remap_prep() to use > xfs_flush_unmap_range(). > > Signed-off-by: Dave Chinner > --- > fs/xfs/xfs_bmap_util.c | 2 +- > fs/xfs/xfs_bmap_util.h | 3 +++ > fs/xfs/xfs_reflink.c | 17 +++++++++++++---- > 3 files changed, 17 insertions(+), 5 deletions(-) > > diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c > index cc7a0d47c529..3e66cf0520a9 100644 > --- a/fs/xfs/xfs_bmap_util.c > +++ b/fs/xfs/xfs_bmap_util.c > @@ -1042,7 +1042,7 @@ xfs_unmap_extent( > goto out_unlock; > } > > -static int > +int > xfs_flush_unmap_range( > struct xfs_inode *ip, > xfs_off_t offset, > diff --git a/fs/xfs/xfs_bmap_util.h b/fs/xfs/xfs_bmap_util.h > index 87363d136bb6..7a78229cf1a7 100644 > --- a/fs/xfs/xfs_bmap_util.h > +++ b/fs/xfs/xfs_bmap_util.h > @@ -80,4 +80,7 @@ int xfs_bmap_count_blocks(struct xfs_trans *tp, struct xfs_inode *ip, > int whichfork, xfs_extnum_t *nextents, > xfs_filblks_t *count); > > +int xfs_flush_unmap_range(struct xfs_inode *ip, xfs_off_t offset, > + xfs_off_t len); > + > #endif /* __XFS_BMAP_UTIL_H__ */ > diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c > index ecdb086bc23e..a41590b7c229 100644 > --- a/fs/xfs/xfs_reflink.c > +++ b/fs/xfs/xfs_reflink.c > @@ -1351,10 +1351,19 @@ xfs_reflink_remap_prep( > if (ret) > goto out_unlock; > > - /* Zap any page cache for the destination file's range. */ > - truncate_inode_pages_range(&inode_out->i_data, > - round_down(pos_out, PAGE_SIZE), > - round_up(pos_out + *len, PAGE_SIZE) - 1); > + /* > + * If pos_out > EOF, we make have dirtied blocks between EOF and Looks ok, will s/make/may/ on the way in (unless you send a new version); Reviewed-by: Darrick J. Wong --D > + * pos_out. In that case, we need to extend the flush and unmap to cover > + * from EOF to the end of the copy length. > + */ > + if (pos_out > XFS_ISIZE(dest)) { > + loff_t flen = *len + (pos_out - XFS_ISIZE(dest)); > + ret = xfs_flush_unmap_range(dest, XFS_ISIZE(dest), flen); > + } else { > + ret = xfs_flush_unmap_range(dest, pos_out, *len); > + } > + if (ret) > + goto out_unlock; > > return 1; > out_unlock: > -- > 2.19.1 >