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Commit 385e1ca5 authored by David Howells's avatar David Howells
Browse files

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: default avatarDavid Howells <dhowells@redhat.com>
Acked-by: default avatarSteve Dickson <steved@redhat.com>
Acked-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
Acked-by: default avatarRik van Riel <riel@redhat.com>
Acked-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Tested-by: default avatarDaire Byrne <Daire.Byrne@framestore.com>
parent b5108822

include/linux/pagemap.h

+5 −0
Original line number Diff line number Diff line
@@ -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.

 *

mm/filemap.c

+18 −0
Original line number Diff line number Diff line
@@ -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