[patch 015/198] filemap_getpage can block when MAP_NONBLOCK specified

[akpm]

From: Jeff Moyer <[EMAIL PROTECTED]>

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 <[EMAIL PROTECTED]>
---

 25-akpm/mm/filemap.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletion(-)

diff -puN mm/filemap.c~filemap_getpage-can-block-when-map_nonblock-specified 
mm/filemap.c
--- 25/mm/filemap.c~filemap_getpage-can-block-when-map_nonblock-specified       
2005-04-12 03:21:07.024069080 -0700
+++ 25-akpm/mm/filemap.c        2005-04-12 03:21:07.028068472 -0700
@@ -1379,8 +1379,13 @@ retry_find:
         * 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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