From b0b539739fe9b7d75002412a787cfdf4efddbc33 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Mon, 5 May 2008 11:45:41 -0400 Subject: [PATCH] NFS: Ensure that 'noac' and/or 'actimeo=0' turn off attribute caching Both the 'noac' and 'actimeo=0' mount options should ensure that attributes are not cached, however a bug in nfs_attribute_timeout() means that currently, the attributes may in fact get cached for up to one jiffy. This has been seen to cause corruption in some applications. The reason for the bug is that the time_in_range() test returns 'true' as long as the current time lies between nfsi->read_cache_jiffies and nfsi->read_cache_jiffies + nfsi->attrtimeo. In other words, if jiffies equals nfsi->read_cache_jiffies, then we still cache the attribute data. Signed-off-by: Trond Myklebust --- fs/nfs/inode.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index 5cb3345eb694..2501b864f7c3 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -707,6 +707,13 @@ int nfs_attribute_timeout(struct inode *inode) if (nfs_have_delegation(inode, FMODE_READ)) return 0; + /* + * Special case: if the attribute timeout is set to 0, then always + * treat the cache as having expired (unless holding + * a delegation). + */ + if (nfsi->attrtimeo == 0) + return 1; return !time_in_range(jiffies, nfsi->read_cache_jiffies, nfsi->read_cache_jiffies + nfsi->attrtimeo); }