Attachment 306286 Details for Bug 446083 – [PATCH] NFS: Fix nfs_attribute_timeout to ensure it works with actimeo=0

[patch] [PATCH] NFS: Fix nfs_attribute_timeout to ensure it works with actimeo=0

linux-2.6.9-fix_nfs_attribute_timeout.dif (text/plain), 1.38 KB, created by Trond Myklebust on 2008-05-21 17:52:45 UTC

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Creator: Trond Myklebust

Created: 2008-05-21 17:52:45 UTC

Size: 1.38 KB

patch

obsolete

>From: Trond Myklebust <Trond.Myklebust@netapp.com>
>Date: Tue, 29 Apr 2008 17:01:02 -0400
>NFS: Fix nfs_attribute_timeout to ensure it works with actimeo=0
>
>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 <Trond.Myklebust@netapp.com>
>---
>
> fs/nfs/inode.c |    7 +++++++
> 1 files changed, 7 insertions(+), 0 deletions(-)
>
>diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
>index cdd20f2..2bb58f9 100644
>--- a/fs/nfs/inode.c
>+++ b/fs/nfs/inode.c
>@@ -1084,6 +1084,13 @@ 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 we
>+	 *               treat the cache as having expired (unless we
>+	 *               have a delegation).
>+	 */
>+	if (nfsi->attrtimeo == 0)
>+		return 1;
> 	return time_after(jiffies, nfsi->read_cache_jiffies+nfsi->attrtimeo);
> }
>

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