This is a note to let you know that I've just added the patch titled
fsdax: unshare: zero destination if srcmap is HOLE or UNWRITTEN
to the 6.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fsdax-unshare-zero-destination-if-srcmap-is-hole-or-unwritten.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 13dd4e04625f600e5affb1b3f0b6c35268ab839b Mon Sep 17 00:00:00 2001
From: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx>
Date: Wed, 22 Mar 2023 11:11:09 +0000
Subject: fsdax: unshare: zero destination if srcmap is HOLE or UNWRITTEN
From: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx>
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@xxxxxxxxxxx
Fixes: d984648e428b ("fsdax,xfs: port unshare to fsdax")
Signed-off-by: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Darrick J. Wong <djwong@xxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/dax.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1258,15 +1258,20 @@ static s64 dax_unshare_iter(struct iomap
/* 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;
Patches currently in stable-queue which might be from ruansy.fnst@xxxxxxxxxxx are
queue-6.2/fsdax-unshare-zero-destination-if-srcmap-is-hole-or-unwritten.patch
queue-6.2/fsdax-force-clear-dirty-mark-if-cow.patch
queue-6.2/fsdax-dedupe-should-compare-the-min-of-two-iters-length.patch
