nfsd: update mtime on truncate

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>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 89d1ae3bcff7..965cffd17a0c 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;