Hi,
On Tue, Sep 10, 2024 at 11:45 AM Jeff Layton <jlayton@xxxxxxxxxx> wrote:
>
> On Tue, 2024-09-10 at 10:18 -0400, Benjamin Coddington wrote:
> > On 23 Aug 2023, at 17:33, Alexander Aring wrote:
> >
> > > This patch reverts mostly commit 40595cdc93ed ("nfs: block notification
> > > on fs with its own ->lock") and introduces an EXPORT_OP_SAFE_ASYNC_LOCK
> > > export flag to signal that the "own ->lock" implementation supports
> > > async lock requests. The only main user is DLM that is used by GFS2 and
> > > OCFS2 filesystem. Those implement their own lock() implementation and
> > > return FILE_LOCK_DEFERRED as return value. Since commit 40595cdc93ed
> > > ("nfs: block notification on fs with its own ->lock") the DLM
> > > implementation were never updated. This patch should prepare for DLM
> > > to set the EXPORT_OP_SAFE_ASYNC_LOCK export flag and update the DLM
> > > plock implementation regarding to it.
> > >
> > > Acked-by: Jeff Layton <jlayton@xxxxxxxxxx>
> > > Signed-off-by: Alexander Aring <aahringo@xxxxxxxxxx>
> > > ---
> > > fs/lockd/svclock.c | 5 ++---
> > > fs/nfsd/nfs4state.c | 13 ++++++++++---
> > > include/linux/exportfs.h | 8 ++++++++
> > > 3 files changed, 20 insertions(+), 6 deletions(-)
> > >
> > > diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
> > > index c43ccdf28ed9..6e3b230e8317 100644
> > > --- a/fs/lockd/svclock.c
> > > +++ b/fs/lockd/svclock.c
> > > @@ -470,9 +470,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
> > > struct nlm_host *host, struct nlm_lock *lock, int wait,
> > > struct nlm_cookie *cookie, int reclaim)
> > > {
> > > -#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
> > > struct inode *inode = nlmsvc_file_inode(file);
> > > -#endif
> > > struct nlm_block *block = NULL;
> > > int error;
> > > int mode;
> > > @@ -486,7 +484,8 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
> > > (long long)lock->fl.fl_end,
> > > wait);
> > >
> > > - if (nlmsvc_file_file(file)->f_op->lock) {
> > > + if (!export_op_support_safe_async_lock(inode->i_sb->s_export_op,
> > > + nlmsvc_file_file(file)->f_op)) {
> >
> > ... but don't most filesystem use VFS' posix_lock_file(), which does the
> > right thing? I think this patch has broken async lock callbacks for NLM for
> > all the other filesystems that just use posix_lock_file().
> >
> > Maybe I'm missing something, but why was that necessary?
> >
>
> Good catch. Yeah, I think that probably should have been an &&
> condition. IOW:
>
> if (nlmsvc_file_file(file)->f_op->lock &&
> !export_op_support_safe_async_lock(inode->i_sb->s_export_op,
>
> Alex, thoughts?
The question is here if we ever want that posix_lock_file() receives a
posix lock that has flc_flags and the FL_SLEEP set. As mentioned, may
"posix_lock_file()" can just deal with it and will not block?
This patch indeed broke it as posix_lock_file() will never see a lock
request with FL_SLEEP set, but I remembered that nfs is only polling
locks and "probably" never set FL_SLEEP?
Thanks.
- Alex
