Re: [PATCH 12/20] filelock: make __locks_delete_block and __locks_wake_up_blocks take file_lock_core

NeilBrown
2024-01-16T22:23:25Z

On Wed, 17 Jan 2024, Jeff Layton wrote:
> Convert __locks_delete_block and __locks_wake_up_blocks to take a struct
> file_lock_core pointer. Note that to accomodate this, we need to add a
> new file_lock() wrapper to go from file_lock_core to file_lock.

Actually we don't need it.... see below.

>
> Signed-off-by: Jeff Layton <jlayton@kernel.org>
> ---
> fs/locks.c | 43 ++++++++++++++++++++++++++-----------------
> 1 file changed, 26 insertions(+), 17 deletions(-)
>
> diff --git a/fs/locks.c b/fs/locks.c
> index eddf4d767d5d..6b8e8820dec9 100644
> --- a/fs/locks.c
> +++ b/fs/locks.c
> @@ -92,6 +92,11 @@ static inline bool IS_LEASE(struct file_lock_core *flc)
>
> #define IS_REMOTELCK(fl) (fl->fl_core.fl_pid <= 0)
>
> +struct file_lock *file_lock(struct file_lock_core *flc)
> +{
> + return container_of(flc, struct file_lock, fl_core);
> +}
> +
> static bool lease_breaking(struct file_lock *fl)
> {
> return fl->fl_core.fl_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING);
> @@ -677,31 +682,35 @@ static void locks_delete_global_blocked(struct file_lock_core *waiter)
> *
> * Must be called with blocked_lock_lock held.
> */
> -static void __locks_delete_block(struct file_lock *waiter)
> +static void __locks_delete_block(struct file_lock_core *waiter)
> {
> - locks_delete_global_blocked(&waiter->fl_core);
> - list_del_init(&waiter->fl_core.fl_blocked_member);
> + locks_delete_global_blocked(waiter);
> + list_del_init(&waiter->fl_blocked_member);
> }
>
> -static void __locks_wake_up_blocks(struct file_lock *blocker)
> +static void __locks_wake_up_blocks(struct file_lock_core *blocker)
> {
> - while (!list_empty(&blocker->fl_core.fl_blocked_requests)) {
> - struct file_lock *waiter;
> + while (!list_empty(&blocker->fl_blocked_requests)) {
> + struct file_lock_core *waiter;
> + struct file_lock *fl;
> +
> + waiter = list_first_entry(&blocker->fl_blocked_requests,
> + struct file_lock_core, fl_blocked_member);
>
> - waiter = list_first_entry(&blocker->fl_core.fl_blocked_requests,
> - struct file_lock, fl_core.fl_blocked_member);

> + fl = file_lock(waiter);

fl = list_first_entry(&blocker->fl_core.fl_blocked_requests,
struct file_lock, fl_core.fl_blocked_member);

waiter = &fl->fl_core;

achieves the same result without needing file_lock().

If you really want to add file_lock() then do so, but you need a better
justification :-)

NeilBrown

> __locks_delete_block(waiter);
> - if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
> - waiter->fl_lmops->lm_notify(waiter);
> + if ((IS_POSIX(waiter) || IS_FLOCK(waiter)) &&
> + fl->fl_lmops && fl->fl_lmops->lm_notify)
> + fl->fl_lmops->lm_notify(fl);
> else
> - wake_up(&waiter->fl_core.fl_wait);
> + wake_up(&waiter->fl_wait);
>
> /*
> * The setting of fl_blocker to NULL marks the "done"
> * point in deleting a block. Paired with acquire at the top
> * of locks_delete_block().
> */
> - smp_store_release(&waiter->fl_core.fl_blocker, NULL);
> + smp_store_release(&waiter->fl_blocker, NULL);
> }
> }
>
> @@ -743,8 +752,8 @@ int locks_delete_block(struct file_lock *waiter)
> spin_lock(&blocked_lock_lock);
> if (waiter->fl_core.fl_blocker)
> status = 0;
> - __locks_wake_up_blocks(waiter);
> - __locks_delete_block(waiter);
> + __locks_wake_up_blocks(&waiter->fl_core);
> + __locks_delete_block(&waiter->fl_core);
>
> /*
> * The setting of fl_blocker to NULL marks the "done" point in deleting
> @@ -799,7 +808,7 @@ static void __locks_insert_block(struct file_lock *blocker,
> * waiter, but might not conflict with blocker, or the requests
> * and lock which block it. So they all need to be woken.
> */
> - __locks_wake_up_blocks(waiter);
> + __locks_wake_up_blocks(&waiter->fl_core);
> }
>
> /* Must be called with flc_lock held. */
> @@ -831,7 +840,7 @@ static void locks_wake_up_blocks(struct file_lock *blocker)
> return;
>
> spin_lock(&blocked_lock_lock);
> - __locks_wake_up_blocks(blocker);
> + __locks_wake_up_blocks(&blocker->fl_core);
> spin_unlock(&blocked_lock_lock);
> }
>
> @@ -1186,7 +1195,7 @@ static int posix_lock_inode(struct inode *inode, struct file_lock *request,
> * Ensure that we don't find any locks blocked on this
> * request during deadlock detection.
> */
> - __locks_wake_up_blocks(request);
> + __locks_wake_up_blocks(&request->fl_core);
> if (likely(!posix_locks_deadlock(request, fl))) {
> error = FILE_LOCK_DEFERRED;
> __locks_insert_block(fl, request,
>
> --
> 2.43.0
>
>