Re: [PATCH 11/20] filelock: convert the IS_* macros to take file_lock_core

[Jeff Layton]

On Wed, 2024-01-17 at 09:16 +1100, NeilBrown wrote:
> On Wed, 17 Jan 2024, Jeff Layton wrote:
> > I couldn't get them to work properly as macros, so convert them
> > to static inlines instead (which is probably better for the type safety
> > anyway).
> > 
> > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> > ---
> >  fs/locks.c | 46 +++++++++++++++++++++++++++++++++-------------
> >  1 file changed, 33 insertions(+), 13 deletions(-)
> > 
> > diff --git a/fs/locks.c b/fs/locks.c
> > index 770aaa5809ba..eddf4d767d5d 100644
> > --- a/fs/locks.c
> > +++ b/fs/locks.c
> > @@ -70,10 +70,26 @@
> >  
> >  #include <linux/uaccess.h>
> >  
> > -#define IS_POSIX(fl)	(fl->fl_core.fl_flags & FL_POSIX)
> Used 3 times... once as
> 	if (IS_POSIX(blocker) && !IS_OFDLCK(blocker))
> Can an IS_POSIX lock also be IS_OFDLCK ??
> 

Yes. They conflict with one another so they're both considered POSIX
locks.

> 
> > -#define IS_FLOCK(fl)	(fl->fl_core.fl_flags & FL_FLOCK)
> Used once.
> 
> > -#define IS_LEASE(fl)	(fl->fl_core.fl_flags & (FL_LEASE|FL_DELEG|FL_LAYOUT))
> Used twice.  Either "IS_LEASE" approves things that aren't leases, or
> FL_LEASE is not set on all leases.... Names could be improved.
> 

Good point.

> > -#define IS_OFDLCK(fl)	(fl->fl_core.fl_flags & FL_OFDLCK)
> 
> used 4 times - a clear winner :-)
> 
> If it would me, I would simply discard these macros and open-code the
> tests.  I don't think IS_FLOCK() is easier to read for someone who knows
> the code, and I think IS_LEASE() is actually harder to read for someone
> who doesn't know the code, as that it does it not really obvious.
> 
> But this is just a suggestion, I won't push it.
> 
> Thanks,
> NeilBrown
> 
> 

It's a good suggestion, and I considered doing this when I converted
over the macros to inlines. I may go ahead and make this change for v2.

> > +static inline bool IS_POSIX(struct file_lock_core *flc)
> > +{
> > +	return flc->fl_flags & FL_POSIX;
> > +}
> > +
> > +static inline bool IS_FLOCK(struct file_lock_core *flc)
> > +{
> > +	return flc->fl_flags & FL_FLOCK;
> > +}
> > +
> > +static inline bool IS_OFDLCK(struct file_lock_core *flc)
> > +{
> > +	return flc->fl_flags & FL_OFDLCK;
> > +}
> > +
> > +static inline bool IS_LEASE(struct file_lock_core *flc)
> > +{
> > +	return flc->fl_flags & (FL_LEASE|FL_DELEG|FL_LAYOUT);
> > +}
> > +
> >  #define IS_REMOTELCK(fl)	(fl->fl_core.fl_pid <= 0)
> >  
> >  static bool lease_breaking(struct file_lock *fl)
> > @@ -761,6 +777,7 @@ static void __locks_insert_block(struct file_lock *blocker,
> >  					       struct file_lock *))
> >  {
> >  	struct file_lock *fl;
> > +	struct file_lock_core *bflc;
> >  	BUG_ON(!list_empty(&waiter->fl_core.fl_blocked_member));
> >  
> >  new_blocker:
> > @@ -773,7 +790,9 @@ static void __locks_insert_block(struct file_lock *blocker,
> >  	waiter->fl_core.fl_blocker = blocker;
> >  	list_add_tail(&waiter->fl_core.fl_blocked_member,
> >  		      &blocker->fl_core.fl_blocked_requests);
> > -	if (IS_POSIX(blocker) && !IS_OFDLCK(blocker))
> > +
> > +	bflc = &blocker->fl_core;
> > +	if (IS_POSIX(bflc) && !IS_OFDLCK(bflc))
> >  		locks_insert_global_blocked(&waiter->fl_core);
> >  
> >  	/* The requests in waiter->fl_blocked are known to conflict with
> > @@ -998,6 +1017,7 @@ static int posix_locks_deadlock(struct file_lock *caller_fl,
> >  				struct file_lock *block_fl)
> >  {
> >  	int i = 0;
> > +	struct file_lock_core *flc = &caller_fl->fl_core;
> >  
> >  	lockdep_assert_held(&blocked_lock_lock);
> >  
> > @@ -1005,7 +1025,7 @@ static int posix_locks_deadlock(struct file_lock *caller_fl,
> >  	 * This deadlock detector can't reasonably detect deadlocks with
> >  	 * FL_OFDLCK locks, since they aren't owned by a process, per-se.
> >  	 */
> > -	if (IS_OFDLCK(caller_fl))
> > +	if (IS_OFDLCK(flc))
> >  		return 0;
> >  
> >  	while ((block_fl = what_owner_is_waiting_for(block_fl))) {
> > @@ -2157,7 +2177,7 @@ static pid_t locks_translate_pid(struct file_lock *fl, struct pid_namespace *ns)
> >  	pid_t vnr;
> >  	struct pid *pid;
> >  
> > -	if (IS_OFDLCK(fl))
> > +	if (IS_OFDLCK(&fl->fl_core))
> >  		return -1;
> >  	if (IS_REMOTELCK(fl))
> >  		return fl->fl_core.fl_pid;
> > @@ -2721,19 +2741,19 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
> >  	if (repeat)
> >  		seq_printf(f, "%*s", repeat - 1 + (int)strlen(pfx), pfx);
> >  
> > -	if (IS_POSIX(fl)) {
> > +	if (IS_POSIX(&fl->fl_core)) {
> >  		if (fl->fl_core.fl_flags & FL_ACCESS)
> >  			seq_puts(f, "ACCESS");
> > -		else if (IS_OFDLCK(fl))
> > +		else if (IS_OFDLCK(&fl->fl_core))
> >  			seq_puts(f, "OFDLCK");
> >  		else
> >  			seq_puts(f, "POSIX ");
> >  
> >  		seq_printf(f, " %s ",
> >  			     (inode == NULL) ? "*NOINODE*" : "ADVISORY ");
> > -	} else if (IS_FLOCK(fl)) {
> > +	} else if (IS_FLOCK(&fl->fl_core)) {
> >  		seq_puts(f, "FLOCK  ADVISORY  ");
> > -	} else if (IS_LEASE(fl)) {
> > +	} else if (IS_LEASE(&fl->fl_core)) {
> >  		if (fl->fl_core.fl_flags & FL_DELEG)
> >  			seq_puts(f, "DELEG  ");
> >  		else
> > @@ -2748,7 +2768,7 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
> >  	} else {
> >  		seq_puts(f, "UNKNOWN UNKNOWN  ");
> >  	}
> > -	type = IS_LEASE(fl) ? target_leasetype(fl) : fl->fl_core.fl_type;
> > +	type = IS_LEASE(&fl->fl_core) ? target_leasetype(fl) : fl->fl_core.fl_type;
> >  
> >  	seq_printf(f, "%s ", (type == F_WRLCK) ? "WRITE" :
> >  			     (type == F_RDLCK) ? "READ" : "UNLCK");
> > @@ -2760,7 +2780,7 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
> >  	} else {
> >  		seq_printf(f, "%d <none>:0 ", fl_pid);
> >  	}
> > -	if (IS_POSIX(fl)) {
> > +	if (IS_POSIX(&fl->fl_core)) {
> >  		if (fl->fl_end == OFFSET_MAX)
> >  			seq_printf(f, "%Ld EOF\n", fl->fl_start);
> >  		else
> > 
> > -- 
> > 2.43.0
> > 
> > 
> 

-- 
Jeff Layton <jlayton@xxxxxxxxxx>