From a23f0ea8dd68fe24d544feef24b6fb089e470482 Mon Sep 17 00:00:00 2001 From: Shiyang Ruan Date: Wed, 22 Mar 2023 11:11:09 +0000 Subject: [PATCH] fsdax: unshare: zero destination if srcmap is HOLE or UNWRITTEN commit 13dd4e04625f600e5affb1b3f0b6c35268ab839b upstream. unshare copies data from source to destination. But if the source is HOLE or UNWRITTEN extents, we should zero the destination, otherwise the HOLE or UNWRITTEN part will be user-visible old data of the new allocated extent. Found by running generic/649 while mounting with -o dax=always on pmem. Link: https://lkml.kernel.org/r/1679483469-2-1-git-send-email-ruansy.fnst@fujitsu.com Fixes: d984648e428b ("fsdax,xfs: port unshare to fsdax") Signed-off-by: Shiyang Ruan Cc: Dan Williams Cc: Darrick J. Wong Cc: Jan Kara Cc: Matthew Wilcox (Oracle) Cc: Alistair Popple Cc: Jason Gunthorpe Cc: John Hubbard Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- fs/dax.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index 8b1c371d6b28..72a437892b4a 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -1234,15 +1234,20 @@ static s64 dax_unshare_iter(struct iomap_iter *iter) /* don't bother with blocks that are not shared to start with */ if (!(iomap->flags & IOMAP_F_SHARED)) return length; - /* don't bother with holes or unwritten extents */ - if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN) - return length; id = dax_read_lock(); ret = dax_iomap_direct_access(iomap, pos, length, &daddr, NULL); if (ret < 0) goto out_unlock; + /* zero the distance if srcmap is HOLE or UNWRITTEN */ + if (srcmap->flags & IOMAP_F_SHARED || srcmap->type == IOMAP_UNWRITTEN) { + memset(daddr, 0, length); + dax_flush(iomap->dax_dev, daddr, length); + ret = length; + goto out_unlock; + } + ret = dax_iomap_direct_access(srcmap, pos, length, &saddr, NULL); if (ret < 0) goto out_unlock;