6.1-stable review patch. If anyone has any objections, please let me know.
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From: Shiyang Ruan ruansy.fnst@fujitsu.com
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.... Fixes: d984648e428b ("fsdax,xfs: port unshare to fsdax") Signed-off-by: Shiyang Ruan ruansy.fnst@fujitsu.com Cc: Dan Williams dan.j.williams@intel.com Cc: Darrick J. Wong djwong@kernel.org Cc: Jan Kara jack@suse.cz Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Alistair Popple apopple@nvidia.com Cc: Jason Gunthorpe jgg@nvidia.com Cc: John Hubbard jhubbard@nvidia.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/dax.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
--- a/fs/dax.c +++ b/fs/dax.c @@ -1234,15 +1234,20 @@ 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;