From 385e1ca5f21c4680ad6a46a3aa2ea8af99e99c92 Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 3 Apr 2009 16:42:39 +0100 Subject: [PATCH] CacheFiles: Permit the page lock state to be monitored 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 Acked-by: Steve Dickson Acked-by: Trond Myklebust Acked-by: Rik van Riel Acked-by: Al Viro Tested-by: Daire Byrne --- include/linux/pagemap.h | 5 +++++ mm/filemap.c | 18 ++++++++++++++++++ 2 files changed, 23 insertions(+) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 076a7dc67c2b..34da5230faab 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -383,6 +383,11 @@ static inline void wait_on_page_writeback(struct page *page) extern void end_page_writeback(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. * diff --git a/mm/filemap.c b/mm/filemap.c index cbc5772e7171..fc11974f2bee 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -564,6 +564,24 @@ 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 -- GitLab