From: Jeff Layton <jlayton@redhat.com>
Date: Wed, 26 Sep 2007 09:24:20 -0400
Subject: [nfs] reset any fields set in attrmask
Message-id: 200709261324.l8QDOKmv031563@barsoom.rdu.redhat.com
O-Subject: [RHEL5.2 PATCH 2/2] BZ#242482: for NFS4_CREATE_EXCLUSIVE, reset any fields set in attrmask
Bugzilla: 242482

The Linux NFS4 client simply skips over the bitmask in an O_EXCL open
call and so it doesn't bother to reset any fields that may be holding
the verifier. This patch has us save the first two words of the bitmask
(which is all the current client has #defines for). The client then
later checks this bitmask and turns on the appropriate flags in the
sattr->ia_verify field for the following SETATTR call.

This patch only currently checks to see if the server used the atime and
mtime slots for the verifier (which is what the Linux server uses for
this). I'm not sure of what other fields the server could reasonably
use, but adding checks for others should be trivial.

This patch went upstream in early June. Verified with a simple
reproducer that checks the mtime after doing an O_EXCL create.

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index b4922c5..b7250ab 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -948,6 +948,22 @@ static struct nfs4_state *nfs4_open_delegated(struct inode *inode, int flags, st
 }
 
 /*
+ * on an EXCLUSIVE create, the server should send back a bitmask with FATTR4-*
+ * fields corresponding to attributes that were used to store the verifier.
+ * Make sure we clobber those fields in the later setattr call
+ */
+static inline void nfs4_exclusive_attrset(struct nfs4_opendata *opendata, struct iattr *sattr)
+{
+	if ((opendata->o_res.attrset[1] & FATTR4_WORD1_TIME_ACCESS) &&
+	    !(sattr->ia_valid & ATTR_ATIME_SET))
+		sattr->ia_valid |= ATTR_ATIME;
+
+	if ((opendata->o_res.attrset[1] & FATTR4_WORD1_TIME_MODIFY) &&
+	    !(sattr->ia_valid & ATTR_MTIME_SET))
+		sattr->ia_valid |= ATTR_MTIME;
+}
+
+/*
  * Returns a referenced nfs4_state
  */
 static int _nfs4_do_open(struct inode *dir, struct path *path, int flags, struct iattr *sattr, struct rpc_cred *cred, struct nfs4_state **res)
@@ -978,6 +994,9 @@ static int _nfs4_do_open(struct inode *dir, struct path *path, int flags, struct
 	if (status != 0)
 		goto err_opendata_free;
 
+	if (opendata->o_arg.open_flags & O_EXCL)
+		nfs4_exclusive_attrset(opendata, sattr);
+
 	status = -ENOMEM;
 	state = nfs4_opendata_to_nfs4_state(opendata);
 	if (state == NULL)
@@ -1912,6 +1931,7 @@ nfs4_proc_create(struct inode *dir, struct dentry *dentry, struct iattr *sattr,
 		status = nfs4_do_setattr(state->inode, &fattr, sattr, state);
 		if (status == 0)
 			nfs_setattr_update_inode(state->inode, sattr);
+		nfs_post_op_update_inode(state->inode, &fattr);
 	}
 	if (status == 0 && (nd->flags & LOOKUP_OPEN))
 		status = nfs4_intent_set_file(nd, &path, state);
diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 713693f..c70826f 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -3262,7 +3262,7 @@ static int decode_delegation(struct xdr_stream *xdr, struct nfs_openres *res)
 static int decode_open(struct xdr_stream *xdr, struct nfs_openres *res)
 {
         uint32_t *p;
-        uint32_t bmlen;
+        uint32_t savewords, bmlen, i;
         int status;
 
         status = decode_op_hdr(xdr, OP_OPEN);
@@ -3280,7 +3280,12 @@ static int decode_open(struct xdr_stream *xdr, struct nfs_openres *res)
                 goto xdr_error;
 
         READ_BUF(bmlen << 2);
-        p += bmlen;
+	savewords = min_t(uint32_t, bmlen, NFS4_BITMAP_SIZE);
+	for (i = 0; i < savewords; ++i) 
+		READ32(res->attrset[i]);
+	for (; i < NFS4_BITMAP_SIZE; i++)
+		res->attrset[i] = 0;
+
 	return decode_delegation(xdr, res);
 xdr_error:
 	dprintk("%s: Bitmap too large! Length = %u\n", __FUNCTION__, bmlen);
diff --git a/include/linux/nfs4.h b/include/linux/nfs4.h
index db05182..d5e67e6 100644
--- a/include/linux/nfs4.h
+++ b/include/linux/nfs4.h
@@ -15,6 +15,7 @@
 
 #include <linux/types.h>
 
+#define NFS4_BITMAP_SIZE	2
 #define NFS4_VERIFIER_SIZE	8
 #define NFS4_FHSIZE		128
 #define NFS4_MAXPATHLEN		PATH_MAX
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 30d5a64..fe2980d 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -145,6 +145,7 @@ struct nfs_openres {
 	nfs4_stateid		delegation;
 	__u32			do_recall;
 	__u64			maxsize;
+	__u32			attrset[NFS4_BITMAP_SIZE];
 };
 
 /*