nfsd4: support change_attr_type attribute

The change attribute is what is used by clients to revalidate their
caches.  Our server may use i_version or ctime for that purpose.  Those
choices behave slightly differently, and it may be useful to the client
to know which we're using.  This attribute tells the client that.  The
Linux client doesn't yet use this attribute yet, though.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 4161031..fb49918 100644 (file)
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2891,6 +2891,16 @@ out_acl:
                        goto out;
        }
 
+       if (bmval2 & FATTR4_WORD2_CHANGE_ATTR_TYPE) {
+               p = xdr_reserve_space(xdr, 4);
+               if (!p)
+                       goto out_resource;
+               if (IS_I_VERSION(d_inode(dentry)))
+                       *p++ = cpu_to_be32(NFS4_CHANGE_TYPE_IS_MONOTONIC_INCR);
+               else
+                       *p++ = cpu_to_be32(NFS4_CHANGE_TYPE_IS_TIME_METADATA);
+       }
+
        if (bmval2 & FATTR4_WORD2_SECURITY_LABEL) {
                status = nfsd4_encode_security_label(xdr, rqstp, context,
                                                                contextlen);

diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 3fce905..0668999 100644 (file)
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -360,6 +360,7 @@ void                nfsd_lockd_shutdown(void);
 
 #define NFSD4_2_SUPPORTED_ATTRS_WORD2 \
        (NFSD4_1_SUPPORTED_ATTRS_WORD2 | \
+       FATTR4_WORD2_CHANGE_ATTR_TYPE | \
        FATTR4_WORD2_MODE_UMASK | \
        NFSD4_2_SECURITY_ATTRS)
 

diff --git a/include/linux/nfs4.h b/include/linux/nfs4.h
index 57ffaa2..0877ed3 100644 (file)
--- a/include/linux/nfs4.h
+++ b/include/linux/nfs4.h
@@ -374,6 +374,13 @@ enum lock_type4 {
        NFS4_WRITEW_LT = 4
 };
 
+enum change_attr_type4 {
+       NFS4_CHANGE_TYPE_IS_MONOTONIC_INCR = 0,
+       NFS4_CHANGE_TYPE_IS_VERSION_COUNTER = 1,
+       NFS4_CHANGE_TYPE_IS_VERSION_COUNTER_NOPNFS = 2,
+       NFS4_CHANGE_TYPE_IS_TIME_METADATA = 3,
+       NFS4_CHANGE_TYPE_IS_UNDEFINED = 4
+};
 
 /* Mandatory Attributes */
 #define FATTR4_WORD0_SUPPORTED_ATTRS    (1UL << 0)
@@ -441,6 +448,7 @@ enum lock_type4 {
 #define FATTR4_WORD2_LAYOUT_BLKSIZE     (1UL << 1)
 #define FATTR4_WORD2_MDSTHRESHOLD       (1UL << 4)
 #define FATTR4_WORD2_CLONE_BLKSIZE     (1UL << 13)
+#define FATTR4_WORD2_CHANGE_ATTR_TYPE  (1UL << 15)
 #define FATTR4_WORD2_SECURITY_LABEL     (1UL << 16)
 #define FATTR4_WORD2_MODE_UMASK                (1UL << 17)