Add a function to install a monitor on the page lock waitqueue for a particular page, thus allowing the page being unlocked to be detected. This is used by CacheFiles to detect read completion on a page in the backing filesystem so that it can then copy the data to the waiting netfs page. Signed-off-by: David Howells <dhowells@xxxxxxxxxx> --- include/linux/pagemap.h | 5 +++++ mm/filemap.c | 18 ++++++++++++++++++ 2 files changed, 23 insertions(+), 0 deletions(-) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index c8bd762..76b5307 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -242,6 +242,11 @@ static inline void wait_on_page_owner_priv_2(struct page *page) extern void end_page_owner_priv_2(struct page *page); /* + * Add an arbitrary waiter to a page's wait queue + */ +extern void add_page_wait_queue(struct page *page, wait_queue_t *waiter); + +/* * Fault a userspace page into pagetables. Return non-zero on a fault. * * This assumes that two userspace pages are always sufficient. That's diff --git a/mm/filemap.c b/mm/filemap.c index a583f44..561e6c7 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -548,6 +548,24 @@ void wait_on_page_bit(struct page *page, int bit_nr) EXPORT_SYMBOL(wait_on_page_bit); /** + * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue + * @page - Page defining the wait queue of interest + * @waiter - Waiter to add to the queue + * + * Add an arbitrary @waiter to the wait queue for the nominated @page. + */ +void add_page_wait_queue(struct page *page, wait_queue_t *waiter) +{ + wait_queue_head_t *q = page_waitqueue(page); + unsigned long flags; + + spin_lock_irqsave(&q->lock, flags); + __add_wait_queue(q, waiter); + spin_unlock_irqrestore(&q->lock, flags); +} +EXPORT_SYMBOL_GPL(add_page_wait_queue); + +/** * unlock_page - unlock a locked page * @page: the page * - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html