[PATCH] nfsd: update mtime on truncate

[Christoph Hellwig <hch@lst.de>]

This fixes a failure in xfstests generic/313 because nfs doesn't update
mtime on a truncate.  The protocol requires this to be done implicity
for a size changing setattr.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/nfsd/vfs.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index f501a9b..60ed117 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -445,6 +445,16 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp, struct iattr *iap,
 		if (err)
 			goto out;
 		size_change = 1;
+
+		/*
+		 * RFC5661, Section 18.30.4:
+		 *   Changing the size of a file with SETATTR indirectly
+		 *   changes the time_modify and change attributes.
+		 *
+		 * (and similar for the older RFCs)
+		 */
+		if (iap->ia_size != i_size_read(inode))
+			iap->ia_valid |= ATTR_MTIME;
 	}
 
 	iap->ia_valid |= ATTR_CTIME;
-- 
1.9.1