| Message ID | 1303919349-30207-1-git-send-email-jlayton@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, 2011-04-27 at 11:49 -0400, Jeff Layton wrote: > On a remount, the VFS layer will clear the MS_SYNCHRONOUS bit on the > assumption that the flags on the mount syscall will have it set if the > remounted fs is supposed to keep it. > > In the case of "noac" though, MS_SYNCHRONOUS is implied. A remount of > such a mount will lose the MS_SYNCHRONOUS flag since "sync" isn't part > of the mount options. > > Reported-by: Max Matveev <makc@redhat.com> > Signed-off-by: Jeff Layton <jlayton@redhat.com> Should this be 'Cc: stable@kernel.org'?
On Wed, 27 Apr 2011 14:01:47 -0400 Trond Myklebust <Trond.Myklebust@netapp.com> wrote: > On Wed, 2011-04-27 at 11:49 -0400, Jeff Layton wrote: > > On a remount, the VFS layer will clear the MS_SYNCHRONOUS bit on the > > assumption that the flags on the mount syscall will have it set if the > > remounted fs is supposed to keep it. > > > > In the case of "noac" though, MS_SYNCHRONOUS is implied. A remount of > > such a mount will lose the MS_SYNCHRONOUS flag since "sync" isn't part > > of the mount options. > > > > Reported-by: Max Matveev <makc@redhat.com> > > Signed-off-by: Jeff Layton <jlayton@redhat.com> > > Should this be 'Cc: stable@kernel.org'? Yes, it wouldn't hurt. Not an extremely critical bug, but it's a fairly straightforward fix. Can you add that, or would you rather I resend? Thanks,
diff --git a/fs/nfs/super.c b/fs/nfs/super.c index 2b8e9a5..2f30297 100644 --- a/fs/nfs/super.c +++ b/fs/nfs/super.c @@ -1976,6 +1976,15 @@ nfs_remount(struct super_block *sb, int *flags, char *raw_data) if (error < 0) goto out; + /* + * noac is a special case. It implies -o sync, but that's not + * necessarily reflected in the mtab options. do_remount_sb + * will clear MS_SYNCHRONOUS if -o sync wasn't specified in the + * remount options, so we have to explicitly reset it. + */ + if (data->flags & NFS_MOUNT_NOAC) + *flags |= MS_SYNCHRONOUS; + /* compare new mount options with old ones */ error = nfs_compare_remount_data(nfss, data); out:
On a remount, the VFS layer will clear the MS_SYNCHRONOUS bit on the assumption that the flags on the mount syscall will have it set if the remounted fs is supposed to keep it. In the case of "noac" though, MS_SYNCHRONOUS is implied. A remount of such a mount will lose the MS_SYNCHRONOUS flag since "sync" isn't part of the mount options. Reported-by: Max Matveev <makc@redhat.com> Signed-off-by: Jeff Layton <jlayton@redhat.com> --- fs/nfs/super.c | 9 +++++++++ 1 files changed, 9 insertions(+), 0 deletions(-)