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

NeilBrown
2024-01-16T22:17:18Z

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@kernel.org>
> ---
> 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 ??

> -#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 <= 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
>
>