PATCH [2/7] Fix posix locking code

PATCH [2/7] Fix posix locking code

[Trond Myklebust]

 VFS: Enable filesystems and to hook certain functions for copying
      locks, and freeing locks using the new struct file_lock_operations.

 VFS: Enable lock managers (i.e. lockd) to hook functions for comparing
      lock ownership using the new struct lock_manager_operations.

 Signed-off-by: Trond Myklebust <trond.myklebust@fys.uio.no>

 fs/locks.c         |   33 +++++++++++++++++++++++++++------
 include/linux/fs.h |   11 +++++++++++
 2 files changed, 38 insertions(+), 6 deletions(-)

diff -u --recursive --new-file --show-c-function linux-2.6.8.1-01-fix_locks/fs/locks.c linux-2.6.8.1-02-fix_locks2/fs/locks.c
--- linux-2.6.8.1-01-fix_locks/fs/locks.c	2004-08-14 14:28:58.000000000 -0400
+++ linux-2.6.8.1-02-fix_locks2/fs/locks.c	2004-08-14 14:29:12.000000000 -0400
@@ -167,6 +167,12 @@ static inline void locks_free_lock(struc
 	if (!list_empty(&fl->fl_link))
 		panic("Attempting to free lock on active lock list");
 
+	if (fl->fl_ops && fl->fl_ops->fl_release_private) {
+		fl->fl_ops->fl_release_private(fl);
+		fl->fl_ops = NULL;
+	}
+	fl->fl_lmops = NULL;
+
 	kmem_cache_free(filelock_cache, fl);
 }
 
@@ -186,6 +192,8 @@ void locks_init_lock(struct file_lock *f
 	fl->fl_notify = NULL;
 	fl->fl_insert = NULL;
 	fl->fl_remove = NULL;
+	fl->fl_ops = NULL;
+	fl->fl_lmops = NULL;
 }
 
 EXPORT_SYMBOL(locks_init_lock);
@@ -220,7 +228,10 @@ void locks_copy_lock(struct file_lock *n
 	new->fl_notify = fl->fl_notify;
 	new->fl_insert = fl->fl_insert;
 	new->fl_remove = fl->fl_remove;
-	new->fl_u = fl->fl_u;
+	new->fl_ops = fl->fl_ops;
+	new->fl_lmops = fl->fl_lmops;
+	if (fl->fl_ops && fl->fl_ops->fl_copy_lock)
+		fl->fl_ops->fl_copy_lock(new, fl);
 }
 
 EXPORT_SYMBOL(locks_copy_lock);
@@ -324,6 +335,8 @@ static int flock_to_posix_lock(struct fi
 	fl->fl_notify = NULL;
 	fl->fl_insert = NULL;
 	fl->fl_remove = NULL;
+	fl->fl_ops = NULL;
+	fl->fl_lmops = NULL;
 
 	return assign_type(fl, l->l_type);
 }
@@ -364,6 +377,8 @@ static int flock64_to_posix_lock(struct 
 	fl->fl_notify = NULL;
 	fl->fl_insert = NULL;
 	fl->fl_remove = NULL;
+	fl->fl_ops = NULL;
+	fl->fl_lmops = NULL;
 
 	switch (l->l_type) {
 	case F_RDLCK:
@@ -400,6 +415,8 @@ static int lease_alloc(struct file *filp
 	fl->fl_notify = NULL;
 	fl->fl_insert = NULL;
 	fl->fl_remove = NULL;
+	fl->fl_ops = NULL;
+	fl->fl_lmops = NULL;
 
 	*flp = fl;
 	return 0;
@@ -419,10 +436,9 @@ static inline int locks_overlap(struct f
 static inline int
 posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
 {
-	/* FIXME: Replace this sort of thing with struct file_lock_operations */
-	if ((fl1->fl_type | fl2->fl_type) & FL_LOCKD)
-		return fl1->fl_owner == fl2->fl_owner &&
-			fl1->fl_pid == fl2->fl_pid;
+	if (fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner)
+		return fl2->fl_lmops == fl1->fl_lmops &&
+			fl1->fl_lmops->fl_compare_owner(fl1, fl2);
 	return fl1->fl_owner == fl2->fl_owner;
 }
 
@@ -981,6 +997,8 @@ int locks_mandatory_area(int read_write,
 		break;
 	}
 
+	if (fl.fl_ops && fl.fl_ops->fl_release_private)
+		fl.fl_ops->fl_release_private(&fl);
 	return error;
 }
 
@@ -1415,7 +1433,6 @@ int fcntl_getlk(struct file *filp, struc
 	error = -EFAULT;
 	if (!copy_to_user(l, &flock, sizeof(flock)))
 		error = 0;
-  
 out:
 	return error;
 }
@@ -1665,6 +1682,8 @@ void locks_remove_posix(struct file *fil
 	lock.fl_owner = owner;
 	lock.fl_pid = current->tgid;
 	lock.fl_file = filp;
+	lock.fl_ops = NULL;
+	lock.fl_lmops = NULL;
 
 	if (filp->f_op && filp->f_op->lock != NULL) {
 		filp->f_op->lock(filp, F_SETLK, &lock);
@@ -1684,6 +1703,8 @@ void locks_remove_posix(struct file *fil
 		before = &fl->fl_next;
 	}
 	unlock_kernel();
+	if (lock.fl_ops && lock.fl_ops->fl_release_private)
+		lock.fl_ops->fl_release_private(&lock);
 }
 
 EXPORT_SYMBOL(locks_remove_posix);
diff -u --recursive --new-file --show-c-function linux-2.6.8.1-01-fix_locks/include/linux/fs.h linux-2.6.8.1-02-fix_locks2/include/linux/fs.h
--- linux-2.6.8.1-01-fix_locks/include/linux/fs.h	2004-08-14 14:25:55.000000000 -0400
+++ linux-2.6.8.1-02-fix_locks2/include/linux/fs.h	2004-08-14 14:40:11.000000000 -0400
@@ -626,6 +626,15 @@ extern void close_private_file(struct fi
  */
 typedef struct files_struct *fl_owner_t;
 
+struct file_lock_operations {
+	void (*fl_copy_lock)(struct file_lock *, struct file_lock *);
+	void (*fl_release_private)(struct file_lock *);
+};
+
+struct lock_manager_operations {
+	int (*fl_compare_owner)(struct file_lock *, struct file_lock *);
+};
+
 /* that will die - we need it for nfs_lock_info */
 #include <linux/nfs_fs_i.h>
 
@@ -649,6 +658,8 @@ struct file_lock {
 	struct fasync_struct *	fl_fasync; /* for lease break notifications */
 	unsigned long fl_break_time;	/* for nonblocking lease breaks */
 
+	struct file_lock_operations *fl_ops;	/* Callbacks for filesystems */
+	struct lock_manager_operations *fl_lmops;	/* Callbacks for lockmanagers */
 	union {
 		struct nfs_lock_info	nfs_fl;
 	} fl_u;

Re: PATCH [2/7] Fix posix locking code

[Christoph Hellwig]

On Sat, Aug 14, 2004 at 03:29:53PM -0400, Trond Myklebust wrote:
>  VFS: Enable filesystems and to hook certain functions for copying
>       locks, and freeing locks using the new struct file_lock_operations.
> 
>  VFS: Enable lock managers (i.e. lockd) to hook functions for comparing
>       lock ownership using the new struct lock_manager_operations.

Please document these operations and their locking rules in
Documentation/filesystems/Locking

Re: PATCH [2/7] Fix posix locking code

[Matthew Wilcox]

On Sat, Aug 14, 2004 at 03:29:53PM -0400, Trond Myklebust wrote:
>  	if (!list_empty(&fl->fl_link))
>  		panic("Attempting to free lock on active lock list");
>  
> +	if (fl->fl_ops && fl->fl_ops->fl_release_private) {
> +		fl->fl_ops->fl_release_private(fl);
> +		fl->fl_ops = NULL;
> +	}
> +	fl->fl_lmops = NULL;

So if fl_ops is set, but fl_ops->fl_release_private isn't, we won't set
fl_ops to NULL -- we should probably just do:

	if (fl->fl_ops && fl->fl_ops->fl_release_private)
		fl->fl_ops->fl_release_private(fl);
	fl->fl_ops = NULL;
	fl->fl_lmops = NULL;

> @@ -981,6 +997,8 @@ int locks_mandatory_area(int read_write,
>  		break;
>  	}
>  
> +	if (fl.fl_ops && fl.fl_ops->fl_release_private)
> +		fl.fl_ops->fl_release_private(&fl);
>  	return error;
>  }
>  

I don't see how fl.fl_ops can be non-null here.  We initialise it to
NULL in locks_init_lock() and then don't give the underlying filesystem
an opportunity to set it.

> @@ -626,6 +626,15 @@ extern void close_private_file(struct fi
>   */
>  typedef struct files_struct *fl_owner_t;
>  
> +struct file_lock_operations {
> +	void (*fl_copy_lock)(struct file_lock *, struct file_lock *);
> +	void (*fl_release_private)(struct file_lock *);
> +};
> +
> +struct lock_manager_operations {
> +	int (*fl_compare_owner)(struct file_lock *, struct file_lock *);
> +};
> +
>  /* that will die - we need it for nfs_lock_info */
>  #include <linux/nfs_fs_i.h>
>  
> @@ -649,6 +658,8 @@ struct file_lock {
>  	struct fasync_struct *	fl_fasync; /* for lease break notifications */
>  	unsigned long fl_break_time;	/* for nonblocking lease breaks */
>  
> +	struct file_lock_operations *fl_ops;	/* Callbacks for filesystems */
> +	struct lock_manager_operations *fl_lmops;	/* Callbacks for lockmanagers */
>  	union {
>  		struct nfs_lock_info	nfs_fl;
>  	} fl_u;

I know I said I thought file_lock_operations was the right thing to
do ...  but now I think that this isn't a property of the file_lock so
much as it is a property of the underlying filesystem.  I think putting a
lock_operations into struct file is maybe a bit much.  How about adding
a lock_operations pointer to file_operations?  It'd be a little clunky
to get to -- fl->fl_file->f_op->lock_ops, so I'd be interested in other
suggestions.

-- 
"Next the statesmen will invent cheap lies, putting the blame upon 
the nation that is attacked, and every man will be glad of those
conscience-soothing falsities, and will diligently study them, and refuse
to examine any refutations of them; and thus he will by and by convince 
himself that the war is just, and will thank God for the better sleep 
he enjoys after this process of grotesque self-deception." -- Mark Twain

Re: PATCH [2/7] Fix posix locking code

[Trond Myklebust]

På lau , 14/08/2004 klokka 16:00, skreiv Matthew Wilcox:

> I know I said I thought file_lock_operations was the right thing to
> do ...  but now I think that this isn't a property of the file_lock so
> much as it is a property of the underlying filesystem.  I think putting a
> lock_operations into struct file is maybe a bit much.  How about adding
> a lock_operations pointer to file_operations?

Lock operations are as much a property of the lock *type*. A BSD lock
may/will have an entirely different set of callbacks.

Trond
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Re: PATCH [2/7] Fix posix locking code

[Trond Myklebust]

På lau , 14/08/2004 klokka 15:53, skreiv Christoph Hellwig:
> On Sat, Aug 14, 2004 at 03:29:53PM -0400, Trond Myklebust wrote:
> >  VFS: Enable filesystems and to hook certain functions for copying
> >       locks, and freeing locks using the new struct file_lock_operations.
> > 
> >  VFS: Enable lock managers (i.e. lockd) to hook functions for comparing
> >       lock ownership using the new struct lock_manager_operations.
> 
> Please document these operations and their locking rules in
> Documentation/filesystems/Locking

Right here...

diff -u --recursive --new-file linux-2.6.8.1-07-cleanup_posix/Documentation/filesystems/Locking linux-2.6.8.1-08-Documentation/Documentation/filesystems/Locking
--- linux-2.6.8.1-07-cleanup_posix/Documentation/filesystems/Locking	2004-08-14 14:27:32.000000000 -0400
+++ linux-2.6.8.1-08-Documentation/Documentation/filesystems/Locking	2004-08-14 16:07:11.000000000 -0400
@@ -276,21 +276,34 @@
 internal fs locking and real critical areas are much smaller than the areas
 filesystems protect now.
 
---------------------------- file_lock ------------------------------------
+----------------------- file_lock_operations ------------------------------
 prototypes:
-	void (*fl_notify)(struct file_lock *);	/* unblock callback */
 	void (*fl_insert)(struct file_lock *);	/* lock insertion callback */
 	void (*fl_remove)(struct file_lock *);	/* lock removal callback */
+	void (*fl_copy_lock)(struct file_lock *, struct file_lock *);
+	void (*fl_release_private)(struct file_lock *);
+
 
 locking rules:
-		BKL	may block
-fl_notify:	yes	no
-fl_insert:	yes	no
-fl_remove:	yes	no
+			BKL	may block
+fl_insert:		yes	no
+fl_remove:		yes	no
+fl_copy_lock:		yes	no
+fl_release_private:	yes	yes
+
+----------------------- lock_manager_operations ---------------------------
+prototypes:
+	int (*fl_compare_owner)(struct file_lock *, struct file_lock *);
+	void (*fl_notify)(struct file_lock *);  /* unblock callback */
+
+locking rules:
+			BKL	may block
+fl_compare_owner:	yes	no
+fl_notify:		yes	no
+
 	Currently only NLM provides instances of this class. None of the
 them block. If you have out-of-tree instances - please, show up. Locking
 in that area will change.
-
 --------------------------- buffer_head -----------------------------------
 prototypes:
 	void (*b_end_io)(struct buffer_head *bh, int uptodate);

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PATCH [2/7] Fix posix locking code (resend with fixes)

[Trond Myklebust]

 VFS: Enable filesystems and to hook certain functions for copying
      locks, and freeing locks using the new struct file_lock_operations.

 VFS: Enable lock managers (i.e. lockd) to hook functions for comparing
      lock ownership using the new struct lock_manager_operations.

 Signed-off-by: Trond Myklebust <trond.myklebust@fys.uio.no>

 fs/locks.c         |   32 ++++++++++++++++++++++++++------
 include/linux/fs.h |   11 +++++++++++
 2 files changed, 37 insertions(+), 6 deletions(-)

diff -u --recursive --new-file --show-c-function linux-2.6.8.1-01-fix_locks/fs/locks.c linux-2.6.8.1-02-fix_locks2/fs/locks.c
--- linux-2.6.8.1-01-fix_locks/fs/locks.c	2004-08-14 14:28:58.000000000 -0400
+++ linux-2.6.8.1-02-fix_locks2/fs/locks.c	2004-08-14 16:24:29.000000000 -0400
@@ -167,6 +167,13 @@ static inline void locks_free_lock(struc
 	if (!list_empty(&fl->fl_link))
 		panic("Attempting to free lock on active lock list");
 
+	if (fl->fl_ops) {
+		if (fl->fl_ops->fl_release_private)
+			fl->fl_ops->fl_release_private(fl);
+		fl->fl_ops = NULL;
+	}
+	fl->fl_lmops = NULL;
+
 	kmem_cache_free(filelock_cache, fl);
 }
 
@@ -186,6 +193,8 @@ void locks_init_lock(struct file_lock *f
 	fl->fl_notify = NULL;
 	fl->fl_insert = NULL;
 	fl->fl_remove = NULL;
+	fl->fl_ops = NULL;
+	fl->fl_lmops = NULL;
 }
 
 EXPORT_SYMBOL(locks_init_lock);
@@ -220,7 +229,10 @@ void locks_copy_lock(struct file_lock *n
 	new->fl_notify = fl->fl_notify;
 	new->fl_insert = fl->fl_insert;
 	new->fl_remove = fl->fl_remove;
-	new->fl_u = fl->fl_u;
+	new->fl_ops = fl->fl_ops;
+	new->fl_lmops = fl->fl_lmops;
+	if (fl->fl_ops && fl->fl_ops->fl_copy_lock)
+		fl->fl_ops->fl_copy_lock(new, fl);
 }
 
 EXPORT_SYMBOL(locks_copy_lock);
@@ -324,6 +336,8 @@ static int flock_to_posix_lock(struct fi
 	fl->fl_notify = NULL;
 	fl->fl_insert = NULL;
 	fl->fl_remove = NULL;
+	fl->fl_ops = NULL;
+	fl->fl_lmops = NULL;
 
 	return assign_type(fl, l->l_type);
 }
@@ -364,6 +378,8 @@ static int flock64_to_posix_lock(struct 
 	fl->fl_notify = NULL;
 	fl->fl_insert = NULL;
 	fl->fl_remove = NULL;
+	fl->fl_ops = NULL;
+	fl->fl_lmops = NULL;
 
 	switch (l->l_type) {
 	case F_RDLCK:
@@ -400,6 +416,8 @@ static int lease_alloc(struct file *filp
 	fl->fl_notify = NULL;
 	fl->fl_insert = NULL;
 	fl->fl_remove = NULL;
+	fl->fl_ops = NULL;
+	fl->fl_lmops = NULL;
 
 	*flp = fl;
 	return 0;
@@ -419,10 +437,9 @@ static inline int locks_overlap(struct f
 static inline int
 posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
 {
-	/* FIXME: Replace this sort of thing with struct file_lock_operations */
-	if ((fl1->fl_type | fl2->fl_type) & FL_LOCKD)
-		return fl1->fl_owner == fl2->fl_owner &&
-			fl1->fl_pid == fl2->fl_pid;
+	if (fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner)
+		return fl2->fl_lmops == fl1->fl_lmops &&
+			fl1->fl_lmops->fl_compare_owner(fl1, fl2);
 	return fl1->fl_owner == fl2->fl_owner;
 }
 
@@ -1415,7 +1432,6 @@ int fcntl_getlk(struct file *filp, struc
 	error = -EFAULT;
 	if (!copy_to_user(l, &flock, sizeof(flock)))
 		error = 0;
-  
 out:
 	return error;
 }
@@ -1665,6 +1681,8 @@ void locks_remove_posix(struct file *fil
 	lock.fl_owner = owner;
 	lock.fl_pid = current->tgid;
 	lock.fl_file = filp;
+	lock.fl_ops = NULL;
+	lock.fl_lmops = NULL;
 
 	if (filp->f_op && filp->f_op->lock != NULL) {
 		filp->f_op->lock(filp, F_SETLK, &lock);
@@ -1684,6 +1702,8 @@ void locks_remove_posix(struct file *fil
 		before = &fl->fl_next;
 	}
 	unlock_kernel();
+	if (lock.fl_ops && lock.fl_ops->fl_release_private)
+		lock.fl_ops->fl_release_private(&lock);
 }
 
 EXPORT_SYMBOL(locks_remove_posix);
diff -u --recursive --new-file --show-c-function linux-2.6.8.1-01-fix_locks/include/linux/fs.h linux-2.6.8.1-02-fix_locks2/include/linux/fs.h
--- linux-2.6.8.1-01-fix_locks/include/linux/fs.h	2004-08-14 14:25:55.000000000 -0400
+++ linux-2.6.8.1-02-fix_locks2/include/linux/fs.h	2004-08-14 14:40:11.000000000 -0400
@@ -626,6 +626,15 @@ extern void close_private_file(struct fi
  */
 typedef struct files_struct *fl_owner_t;
 
+struct file_lock_operations {
+	void (*fl_copy_lock)(struct file_lock *, struct file_lock *);
+	void (*fl_release_private)(struct file_lock *);
+};
+
+struct lock_manager_operations {
+	int (*fl_compare_owner)(struct file_lock *, struct file_lock *);
+};
+
 /* that will die - we need it for nfs_lock_info */
 #include <linux/nfs_fs_i.h>
 
@@ -649,6 +658,8 @@ struct file_lock {
 	struct fasync_struct *	fl_fasync; /* for lease break notifications */
 	unsigned long fl_break_time;	/* for nonblocking lease breaks */
 
+	struct file_lock_operations *fl_ops;	/* Callbacks for filesystems */
+	struct lock_manager_operations *fl_lmops;	/* Callbacks for lockmanagers */
 	union {
 		struct nfs_lock_info	nfs_fl;
 	} fl_u;