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From: "NeilBrown" <neilb@suse.de>
To: "Jeff Layton" <jlayton@kernel.org>
Cc: "Christian Brauner" <brauner@kernel.org>,
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Subject:
 Re: [PATCH 11/20] filelock: convert the IS_* macros to take file_lock_core
In-reply-to: <20240116-flsplit-v1-11-c9d0f4370a5d@kernel.org>
References: <20240116-flsplit-v1-0-c9d0f4370a5d@kernel.org>,
 <20240116-flsplit-v1-11-c9d0f4370a5d@kernel.org>
Date: Wed, 17 Jan 2024 09:16:56 +1100
Message-id: <170544341684.23031.11038222640477022046@noble.neil.brown.name>

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).
>=20
> Signed-off-by: Jeff Layton <jlayton@kernel.org>
> ---
>  fs/locks.c | 46 +++++++++++++++++++++++++++++++++-------------
>  1 file changed, 33 insertions(+), 13 deletions(-)
>=20
> 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 @@
> =20
>  #include <linux/uaccess.h>
> =20
> -#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 ??


> -#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.

> -#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


> +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 <=3D 0)
> =20
>  static bool lease_breaking(struct file_lock *fl)
> @@ -761,6 +777,7 @@ static void __locks_insert_block(struct file_lock *bloc=
ker,
>  					       struct file_lock *))
>  {
>  	struct file_lock *fl;
> +	struct file_lock_core *bflc;
>  	BUG_ON(!list_empty(&waiter->fl_core.fl_blocked_member));
> =20
>  new_blocker:
> @@ -773,7 +790,9 @@ static void __locks_insert_block(struct file_lock *bloc=
ker,
>  	waiter->fl_core.fl_blocker =3D blocker;
>  	list_add_tail(&waiter->fl_core.fl_blocked_member,
>  		      &blocker->fl_core.fl_blocked_requests);
> -	if (IS_POSIX(blocker) && !IS_OFDLCK(blocker))
> +
> +	bflc =3D &blocker->fl_core;
> +	if (IS_POSIX(bflc) && !IS_OFDLCK(bflc))
>  		locks_insert_global_blocked(&waiter->fl_core);
> =20
>  	/* The requests in waiter->fl_blocked are known to conflict with
> @@ -998,6 +1017,7 @@ static int posix_locks_deadlock(struct file_lock *call=
er_fl,
>  				struct file_lock *block_fl)
>  {
>  	int i =3D 0;
> +	struct file_lock_core *flc =3D &caller_fl->fl_core;
> =20
>  	lockdep_assert_held(&blocked_lock_lock);
> =20
> @@ -1005,7 +1025,7 @@ static int posix_locks_deadlock(struct file_lock *cal=
ler_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;
> =20
>  	while ((block_fl =3D 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;
> =20
> -	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, str=
uct file_lock *fl,
>  	if (repeat)
>  		seq_printf(f, "%*s", repeat - 1 + (int)strlen(pfx), pfx);
> =20
> -	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 ");
> =20
>  		seq_printf(f, " %s ",
>  			     (inode =3D=3D 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, struc=
t file_lock *fl,
>  	} else {
>  		seq_puts(f, "UNKNOWN UNKNOWN  ");
>  	}
> -	type =3D IS_LEASE(fl) ? target_leasetype(fl) : fl->fl_core.fl_type;
> +	type =3D IS_LEASE(&fl->fl_core) ? target_leasetype(fl) : fl->fl_core.fl_t=
ype;
> =20
>  	seq_printf(f, "%s ", (type =3D=3D F_WRLCK) ? "WRITE" :
>  			     (type =3D=3D F_RDLCK) ? "READ" : "UNLCK");
> @@ -2760,7 +2780,7 @@ static void lock_get_status(struct seq_file *f, struc=
t 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 =3D=3D OFFSET_MAX)
>  			seq_printf(f, "%Ld EOF\n", fl->fl_start);
>  		else
>=20
> --=20
> 2.43.0
>=20
>=20