From d345734267dbec642f4e34a9d392d2fd85b5fa9b Mon Sep 17 00:00:00 2001
From: Jeff Moyer <jmoyer@redhat.com>
Date: Sat, 16 Apr 2005 15:24:05 -0700
Subject: [PATCH] [PATCH] filemap_getpage can block when MAP_NONBLOCK specified
We will return NULL from filemap_getpage when a page does not exist in the
page cache and MAP_NONBLOCK is specified, here:
page = find_get_page(mapping, pgoff);
if (!page) {
if (nonblock)
return NULL;
goto no_cached_page;
}
But we forget to do so when the page in the cache is not uptodate. The
following could result in a blocking call:
/*
* Ok, found a page in the page cache, now we need to check
* that it's up-to-date.
*/
if (!PageUptodate(page))
goto page_not_uptodate;
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
mm/filemap.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index 439b2bea8e342..93595c327bbdc 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1379,8 +1379,13 @@ static struct page * filemap_getpage(struct file *file, unsigned long pgoff,
* Ok, found a page in the page cache, now we need to check
* that it's up-to-date.
*/
- if (!PageUptodate(page))
+ if (!PageUptodate(page)) {
+ if (nonblock) {
+ page_cache_release(page);
+ return NULL;
+ }
goto page_not_uptodate;
+ }
success:
/*
--
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