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From:   "NeilBrown" <neilb@suse.de>
To:     "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
        torvalds@linux-foundation.org, stable@vger.kernel.org, lwn@lwn.net,
        jslaby@suse.cz, "Greg Kroah-Hartman" <gregkh@linuxfoundation.org>
Subject: Re: Linux 6.1.58
In-reply-to: <2023101518-subscript-entity-be71@gregkh>
References: <2023101518-subscript-entity-be71@gregkh>
Date:   Fri, 20 Oct 2023 18:22:47 +1100
Message-id: <169778656748.20306.1670865069010793541@noble.neil.brown.name>
Precedence: bulk

On Mon, 16 Oct 2023, Greg Kroah-Hartman wrote:
> I'm announcing the release of the 6.1.58 kernel.
>=20
> All users of the 6.1 kernel series must upgrade.
>=20
> The updated 6.1.y git tree can be found at:
> 	git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git linu=
x-6.1.y
> and can be browsed at the normal kernel.org git web browser:
> 	https://git.kernel.org/?p=3Dlinux/kernel/git/stable/linux-stable.git;a=3Ds=
ummary
>=20
> thanks,
>=20
> greg k-h
>=20
> ------------
>=20
>  Makefile                 |    2=20
>  fs/nfs/direct.c          |  134 ++++++++++++++----------------------------=
-----
>  fs/nfs/write.c           |   23 +++-----
>  include/linux/nfs_page.h |    4 -
>  lib/test_meminit.c       |    2=20
>  5 files changed, 55 insertions(+), 110 deletions(-)
>=20
> Greg Kroah-Hartman (7):
>       Revert "NFS: More fixes for nfs_direct_write_reschedule_io()"
>       Revert "NFS: Use the correct commit info in nfs_join_page_group()"
>       Revert "NFS: More O_DIRECT accounting fixes for error paths"
>       Revert "NFS: Fix O_DIRECT locking issues"
>       Revert "NFS: Fix error handling for O_DIRECT write scheduling"

FYI the problem with these NFS patch is now described in comment #4 of
https://bugzilla.kernel.org/show_bug.cgi?id=3D217999
which I include below.  They can be reapplied if the "Fix error
handling..." patch is fixed up as described.

NeilBrown

FYI the cause of this corruption is that the  backport of
   NFS: Fix error handling for O_DIRECT write scheduling

had an error.
The backported patch f16fd0b11f0f4d41846b5102b1656ea1fc9ac7a0
moves "pos +=3D req_len" in nfs_direct_write_schedule_iovec() from after
    req->wb_index =3D pos >> PAGE_SHIFT;
to before that statement.  This ->wb_index is wrong.
Possibly a better way to look at this is the use of "pos" is moved to *after*=
 it is updated.

The upstream patch 954998b60caa8f2a3bf3abe490de6f08d283687a
doesn't move the use of pos because
Commit 70e9db69f927 ("NFS: Clean up O_DIRECT request allocation")

removes the use.

v6.1.56 can be fixed with

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 5a976fa343df..69134e11e7d0 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -864,6 +864,8 @@ static ssize_t nfs_direct_write_schedule_iovec(struct nfs=
_direct_req *dreq,
                                result =3D PTR_ERR(req);
                                break;
                        }
+                       req->wb_index =3D pos >> PAGE_SHIFT;
+                       req->wb_offset =3D pos & ~PAGE_MASK;
=20
                        if (desc.pg_error < 0) {
                                nfs_free_request(req);
@@ -883,8 +885,6 @@ static ssize_t nfs_direct_write_schedule_iovec(struct nfs=
_direct_req *dreq,
                        }
=20
                        nfs_lock_request(req);
-                       req->wb_index =3D pos >> PAGE_SHIFT;
-                       req->wb_offset =3D pos & ~PAGE_MASK;
                        if (nfs_pageio_add_request(&desc, req))
                                continue;