On Mon 19-04-21 17:36:34, Vivek Goyal wrote:
> Dan mentioned that he is not very fond of passing around a boolean true/false
> to specify if only next waiter should be woken up or all waiters should be
> woken up. He instead prefers that we introduce an enum and make it very
> explicity at the callsite itself. Easier to read code.
>
> This patch should not introduce any change of behavior.
>
> Suggested-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
> ---
> fs/dax.c | 23 +++++++++++++++++------
> 1 file changed, 17 insertions(+), 6 deletions(-)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index b3d27fdc6775..00978d0838b1 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -144,6 +144,16 @@ struct wait_exceptional_entry_queue {
> struct exceptional_entry_key key;
> };
>
> +/**
> + * enum dax_entry_wake_mode: waitqueue wakeup toggle
> + * @WAKE_NEXT: entry was not mutated
> + * @WAKE_ALL: entry was invalidated, or resized
Let's document the constants in terms of what they do, not when they are
expected to be called. So something like:
@WAKE_NEXT: wake only the first waiter in the waitqueue
@WAKE_ALL: wake all waiters in the waitqueue
Otherwise the patch looks good so feel free to add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> + */
> +enum dax_entry_wake_mode {
> + WAKE_NEXT,
> + WAKE_ALL,
> +};
> +
> static wait_queue_head_t *dax_entry_waitqueue(struct xa_state *xas,
> void *entry, struct exceptional_entry_key *key)
> {
> @@ -182,7 +192,8 @@ static int wake_exceptional_entry_func(wait_queue_entry_t *wait,
> * The important information it's conveying is whether the entry at
> * this index used to be a PMD entry.
> */
> -static void dax_wake_entry(struct xa_state *xas, void *entry, bool wake_all)
> +static void dax_wake_entry(struct xa_state *xas, void *entry,
> + enum dax_entry_wake_mode mode)
> {
> struct exceptional_entry_key key;
> wait_queue_head_t *wq;
> @@ -196,7 +207,7 @@ static void dax_wake_entry(struct xa_state *xas, void *entry, bool wake_all)
> * must be in the waitqueue and the following check will see them.
> */
> if (waitqueue_active(wq))
> - __wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key);
> + __wake_up(wq, TASK_NORMAL, mode == WAKE_ALL ? 0 : 1, &key);
> }
>
> /*
> @@ -268,7 +279,7 @@ static void put_unlocked_entry(struct xa_state *xas, void *entry)
> {
> /* If we were the only waiter woken, wake the next one */
> if (entry && !dax_is_conflict(entry))
> - dax_wake_entry(xas, entry, false);
> + dax_wake_entry(xas, entry, WAKE_NEXT);
> }
>
> /*
> @@ -286,7 +297,7 @@ static void dax_unlock_entry(struct xa_state *xas, void *entry)
> old = xas_store(xas, entry);
> xas_unlock_irq(xas);
> BUG_ON(!dax_is_locked(old));
> - dax_wake_entry(xas, entry, false);
> + dax_wake_entry(xas, entry, WAKE_NEXT);
> }
>
> /*
> @@ -524,7 +535,7 @@ static void *grab_mapping_entry(struct xa_state *xas,
>
> dax_disassociate_entry(entry, mapping, false);
> xas_store(xas, NULL); /* undo the PMD join */
> - dax_wake_entry(xas, entry, true);
> + dax_wake_entry(xas, entry, WAKE_ALL);
> mapping->nrexceptional--;
> entry = NULL;
> xas_set(xas, index);
> @@ -937,7 +948,7 @@ static int dax_writeback_one(struct xa_state *xas, struct dax_device *dax_dev,
> xas_lock_irq(xas);
> xas_store(xas, entry);
> xas_clear_mark(xas, PAGECACHE_TAG_DIRTY);
> - dax_wake_entry(xas, entry, false);
> + dax_wake_entry(xas, entry, WAKE_NEXT);
>
> trace_dax_writeback_one(mapping->host, index, count);
> return ret;
> --
> 2.25.4
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
