From: Trond Myklebust Date: Mon, 5 May 2008 15:45:41 +0000 (-0400) Subject: NFS: Ensure that 'noac' and/or 'actimeo=0' turn off attribute caching X-Git-Tag: v2.6.26-rc4~126^2~7 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b0b539739fe9b7d75002412a787cfdf4efddbc33;p=linux-2.6 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 --- diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index 5cb3345eb6..2501b864f7 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); }