[057/151] NFS: Fix nfs_migrate_page()

Greg KH
2009-12-17T04:37:51Z

From: Trond Myklebust <Trond.Myklebust@netapp.com>

commit 190f38e5cedc910940b1da9015f00458c18f97b4 upstream.

The call to migrate_page() will cause the page->private field to be
cleared.
Also fix up the locking around the page->private transfer, so that we ensure
that calls to nfs_page_find_request() don't end up racing.

Finally, fix up a double free bug: nfs_unlock_request() already calls
nfs_release_request() for us...

Reported-by: Wu Fengguang <fengguang.wu@intel.com>
Tested-by: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
fs/nfs/write.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1612,15 +1612,16 @@ int nfs_migrate_page(struct address_spac
if (ret)
goto out_unlock;
page_cache_get(newpage);
+ spin_lock(&mapping->host->i_lock);
req->wb_page = newpage;
SetPagePrivate(newpage);
- set_page_private(newpage, page_private(page));
+ set_page_private(newpage, (unsigned long)req);
ClearPagePrivate(page);
set_page_private(page, 0);
+ spin_unlock(&mapping->host->i_lock);
page_cache_release(page);
out_unlock:
nfs_clear_page_tag_locked(req);
- nfs_release_request(req);
out:
return ret;
}