On Sun, 17 Aug 2014 21:42:21 +0800
Kinglong Mee <kinglongmee@xxxxxxxxx> wrote:
> On 8/16/2014 21:35, Kinglong Mee wrote:
> > On 8/15/2014 22:33, Kinglong Mee wrote:
> >> On 8/15/2014 19:14, Jeff Layton wrote:
> >>> On Fri, 15 Aug 2014 08:07:12 +0800
> >>> Kinglong Mee <kinglongmee@xxxxxxxxx> wrote:
> >>>
> >>>> Commit d5b9026a67 ([PATCH] knfsd: locks: flag NFSv4-owned locks) using
> >>>> fl_lmops field in file_lock for checking nfsd4 lockowner.
> >>>>
> >>>> But, commit 1a747ee0cc (locks: don't call ->copy_lock methods on return
> >>>> of conflicting locks) causes the fl_lmops of conflock always be NULL.
> >>>>
> >>>> Also, commit 0996905f93 (lockd: posix_test_lock() should not call
> >>>> locks_copy_lock()) caused the fl_lmops of conflock always be NULL too.
> >>>>
> >>>> Make sure copy the private information by fl_copy_lock() in struct
> >>>> file_lock_operations, merge __locks_copy_lock() to fl_copy_lock().
> >>>>
> >>>> v3: Update based on Joe and Jeff's patch.
> >>>>
> >>>> Signed-off-by: Kinglong Mee <kinglongmee@xxxxxxxxx>
> >>>> ---
> >>>> fs/locks.c | 24 +++++++-----------------
> >>>> include/linux/fs.h | 6 ------
> >>>> 2 files changed, 7 insertions(+), 23 deletions(-)
> >>>>
> >>>> diff --git a/fs/locks.c b/fs/locks.c
> >>>> index cb66fb0..fe52abb 100644
> >>>> --- a/fs/locks.c
> >>>> +++ b/fs/locks.c
> >>>> @@ -281,33 +281,23 @@ static void locks_copy_private(struct file_lock *new, struct file_lock *fl)
> >>>> /*
> >>>> * Initialize a new lock from an existing file_lock structure.
> >>>> */
> >>>> -void __locks_copy_lock(struct file_lock *new, const struct file_lock *fl)
> >>>> +void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
> >>>> {
> >>>> + /* "new" must be a freshly-initialized lock */
> >>>> + WARN_ON_ONCE(new->fl_ops);
> >>>> +
> >>>> new->fl_owner = fl->fl_owner;
> >>>> new->fl_pid = fl->fl_pid;
> >>>> - new->fl_file = NULL;
> >>>> + new->fl_file = fl->fl_file;
> >>>> new->fl_flags = fl->fl_flags;
> >>>> new->fl_type = fl->fl_type;
> >>>> new->fl_start = fl->fl_start;
> >>>> new->fl_end = fl->fl_end;
> >>>> new->fl_ops = NULL;
> >>>> new->fl_lmops = NULL;
> >>>> -}
> >>>> -EXPORT_SYMBOL(__locks_copy_lock);
> >>>> -
> >>>> -void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
> >>>> -{
> >>>> - /* "new" must be a freshly-initialized lock */
> >>>> - WARN_ON_ONCE(new->fl_ops);
> >>>> -
> >>>> - __locks_copy_lock(new, fl);
> >>>> - new->fl_file = fl->fl_file;
> >>>> - new->fl_ops = fl->fl_ops;
> >>>> - new->fl_lmops = fl->fl_lmops;
> >>>>
> >>>> locks_copy_private(new, fl);
> >>>> }
> >>>> -
> >>>> EXPORT_SYMBOL(locks_copy_lock);
> >>>>
> >>>> static inline int flock_translate_cmd(int cmd) {
> >>>> @@ -735,7 +725,7 @@ posix_test_lock(struct file *filp, struct file_lock *fl)
> >>>> break;
> >>>> }
> >>>> if (cfl) {
> >>>> - __locks_copy_lock(fl, cfl);
> >>>> + locks_copy_lock(fl, cfl);
> >>>> if (cfl->fl_nspid)
> >>>> fl->fl_pid = pid_vnr(cfl->fl_nspid);
> >>>> } else
> >>>> @@ -941,7 +931,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
> >>>> if (!posix_locks_conflict(request, fl))
> >>>> continue;
> >>>> if (conflock)
> >>>> - __locks_copy_lock(conflock, fl);
> >>>> + locks_copy_lock(conflock, fl);
> >>>> error = -EAGAIN;
> >>>> if (!(request->fl_flags & FL_SLEEP))
> >>>> goto out;
> >>>> diff --git a/include/linux/fs.h b/include/linux/fs.h
> >>>> index 908af4f..a383a30 100644
> >>>> --- a/include/linux/fs.h
> >>>> +++ b/include/linux/fs.h
> >>>> @@ -966,7 +966,6 @@ void locks_free_lock(struct file_lock *fl);
> >>>> extern void locks_init_lock(struct file_lock *);
> >>>> extern struct file_lock * locks_alloc_lock(void);
> >>>> extern void locks_copy_lock(struct file_lock *, struct file_lock *);
> >>>> -extern void __locks_copy_lock(struct file_lock *, const struct file_lock *);
> >>>> extern void locks_remove_posix(struct file *, fl_owner_t);
> >>>> extern void locks_remove_file(struct file *);
> >>>> extern void locks_release_private(struct file_lock *);
> >>>> @@ -1026,11 +1025,6 @@ static inline void locks_init_lock(struct file_lock *fl)
> >>>> return;
> >>>> }
> >>>>
> >>>> -static inline void __locks_copy_lock(struct file_lock *new, struct file_lock *fl)
> >>>> -{
> >>>> - return;
> >>>> -}
> >>>> -
> >>>> static inline void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
> >>>> {
> >>>> return;
> >>>
> >>> I'm not sure this is really what you want to do. Calling fl_copy_lock
> >>> for a conflock looks relatively harmless for nfs and nlm. AFS though
> >>> seems to add the lock to a list associated with the inode. That seems a
> >>> little suspicious for a conflock and could be problematic. It may be
> >>> best to avoid dealing with fl_ops for a conflock.
> >>>
> >>> Also in the case of fcntl_getlk, the struct file_lock lives on the
> >>> stack, and locks_release_private is never called on it. You'll need to
> >>> audit all of the current callers of __locks_copy_lock to ensure that
> >>> any resources you end up taking references on when copying the conflock
> >>> are eventually released.
> >>
> >> Sorry for my no further think about it.
> >> I will check that again next day.
> >
> > I think we should not change the logical of coping lock,
> > leave fl_ops and fl_lmops as private data as right now.
Why not? I think we'd benefit from making conflock creation a more
distinct operation.
> >
> > I have plan to,
> > 1. move fl_owner assign from __locks_copy_lock() to locks_copy_private(),
> > I think it should be a private data, am I right?
> > 2. call locks_copy_private() coping private data specifically.
> > a. add an argument for posix_test_lock() and __posix_lock_file() and etc,
> > to point whether coping private data.
> > b. hack the conflock's fl_flags to do the same thing as a,
> > adds FL_NEED_PRIV fl_flags only valid for conflock.
> >
> > I don't think 2.a is a nice resolve, because it changes the interface
> > and many caller don't care the private data (I think contains fl_owner)
> > for conflock except nfsd.
> >
> > So, I'd like *2.b*. A draft is appended as following,
>
> I'm so sorry for the first draft, there is a bug of it.
> Please using the new draft.
>
> thanks,
> Kinglong Mee
>
Personally, I'm not a fan of the approach below. I don't think we need
a new flag for this and it doesn't do anything to solve the problem
where the lockowner could go away while you're operating on it in a
conflock.
I think we need several smaller changes:
1. Right now __locks_copy_lock is only used to copy conflocks. It would
be good to rename that to something more distinct (i.e.
locks_copy_conflock), to make it clear that we're generating a conflock
there.
2. Set fl_lmops on conflocks, but don't set fl_ops. fl_ops are
superfluous, since they are callbacks into the filesystem. There should
be no need to bother the filesystem at all with info in a conflock.
But, lock _ownership_ matters for conflocks and that's indicated by the
fl_lmops. So you really do want to copy the fl_lmops for conflocks I
think.
3. Add the operations you added before to fl_lmops to copy and release
the owner (maybe even rename them lm_get_owner/lm_put_owner?), and
ensure that the places that copy conflocks call those operations
appropriately.
That should be all that's required here.
> ------------------snip---------------------------------------------------------
>
> diff --git a/fs/locks.c b/fs/locks.c
> index be1858e..128e34f 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -279,6 +279,7 @@ static void locks_copy_private(struct file_lock *new, struct file_lock *fl)
> new->fl_ops = fl->fl_ops;
> }
>
> + new->fl_owner = fl->fl_owner;
> if (fl->fl_lmops) {
> if (fl->fl_lmops->lm_copy_owner)
> fl->fl_lmops->lm_copy_owner(new, fl);
> @@ -291,7 +292,7 @@ static void locks_copy_private(struct file_lock *new, struct file_lock *fl)
> */
> void __locks_copy_lock(struct file_lock *new, const struct file_lock *fl)
> {
> - new->fl_owner = fl->fl_owner;
> + new->fl_owner = NULL;
> new->fl_pid = fl->fl_pid;
> new->fl_file = NULL;
> new->fl_flags = fl->fl_flags;
> @@ -734,6 +735,7 @@ posix_test_lock(struct file *filp, struct file_lock *fl)
> {
> struct file_lock *cfl;
> struct inode *inode = file_inode(filp);
> + bool need_priv = !!(fl->fl_flags & FL_NEED_PRIV);
>
> spin_lock(&inode->i_lock);
> for (cfl = file_inode(filp)->i_flock; cfl; cfl = cfl->fl_next) {
> @@ -746,6 +748,8 @@ posix_test_lock(struct file *filp, struct file_lock *fl)
> __locks_copy_lock(fl, cfl);
> if (cfl->fl_nspid)
> fl->fl_pid = pid_vnr(cfl->fl_nspid);
> + if (need_priv)
> + locks_copy_private(fl, cfl);
> } else
> fl->fl_type = F_UNLCK;
> spin_unlock(&inode->i_lock);
> @@ -919,7 +923,7 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
> struct file_lock *right = NULL;
> struct file_lock **before;
> int error;
> - bool added = false;
> + bool added = false, need_priv = false;
> LIST_HEAD(dispose);
>
> /*
> @@ -948,8 +952,12 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
> continue;
> if (!posix_locks_conflict(request, fl))
> continue;
> - if (conflock)
> + if (conflock) {
> + need_priv = !!(conflock->fl_flags & FL_NEED_PRIV);
> __locks_copy_lock(conflock, fl);
> + if (need_priv)
> + locks_copy_private(conflock, fl);
> + }
> error = -EAGAIN;
> if (!(request->fl_flags & FL_SLEEP))
> goto out;
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 5076497..3db43f9 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -5275,6 +5275,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> goto out;
> }
>
> + conflock->fl_flags = FL_NEED_PRIV;
> err = vfs_lock_file(filp, F_SETLK, file_lock, conflock);
> switch (-err) {
> case 0: /* success! */
> @@ -5396,7 +5397,7 @@ nfsd4_lockt(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> if (lo)
> file_lock->fl_owner = (fl_owner_t)lo;
> file_lock->fl_pid = current->tgid;
> - file_lock->fl_flags = FL_POSIX;
> + file_lock->fl_flags = FL_POSIX | FL_NEED_PRIV;
>
> file_lock->fl_start = lockt->lt_offset;
> file_lock->fl_end = last_byte_offset(lockt->lt_offset, lockt->lt_length);
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 56f2acd..f257d0d 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -844,6 +844,7 @@ static inline struct file *get_file(struct file *f)
> #define FL_DOWNGRADE_PENDING 256 /* Lease is being downgraded */
> #define FL_UNLOCK_PENDING 512 /* Lease is being broken */
> #define FL_OFDLCK 1024 /* lock is "owned" by struct file */
> +#define FL_NEED_PRIV 2048 /* Need copy private data from conflock */
>
> /*
> * Special return value from posix_lock_file() and vfs_lock_file() for
>
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--
Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
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