nfsd: Record NFSv4 pre/post-op attributes as non-atomic

For the case of NFSv4, specify to the client that the pre/post-op
attributes were not recorded atomically with the main operation.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfs/export.c

@@ -172,5 +172,6 @@ const struct export_operations nfs_export_ops = {
 	.fh_to_dentry = nfs_fh_to_dentry,
 	.get_parent = nfs_get_parent,
 	.flags = EXPORT_OP_NOWCC|EXPORT_OP_NOSUBTREECHK|
-		EXPORT_OP_CLOSE_BEFORE_UNLINK|EXPORT_OP_REMOTE_FS,
+		EXPORT_OP_CLOSE_BEFORE_UNLINK|EXPORT_OP_REMOTE_FS|
+		EXPORT_OP_NOATOMIC_ATTR,
 };

fs/nfsd/nfsfh.c

@@ -301,6 +301,10 @@ static __be32 nfsd_set_fh_dentry(struct svc_rqst *rqstp, struct svc_fh *fhp)
 	fhp->fh_export = exp;
 
 	switch (rqstp->rq_vers) {
+	case 4:
+		if (dentry->d_sb->s_export_op->flags & EXPORT_OP_NOATOMIC_ATTR)
+			fhp->fh_no_atomic_attr = true;
+		break;
 	case 3:
 		if (dentry->d_sb->s_export_op->flags & EXPORT_OP_NOWCC)
 			fhp->fh_no_wcc = true;

fs/nfsd/nfsfh.h

@@ -36,6 +36,11 @@ typedef struct svc_fh {
 	bool			fh_locked;	/* inode locked by us */
 	bool			fh_want_write;	/* remount protection taken */
 	bool			fh_no_wcc;	/* no wcc data needed */
+	bool			fh_no_atomic_attr;
+						/*
+						 * wcc data is not atomic with
+						 * operation
+						 */
 	int			fh_flags;	/* FH flags */
 #ifdef CONFIG_NFSD_V3
 	bool			fh_post_saved;	/* post-op attrs saved */

fs/nfsd/xdr4.h

@@ -748,7 +748,7 @@ static inline void
 set_change_info(struct nfsd4_change_info *cinfo, struct svc_fh *fhp)
 {
 	BUG_ON(!fhp->fh_pre_saved);
-	cinfo->atomic = (u32)fhp->fh_post_saved;
+	cinfo->atomic = (u32)(fhp->fh_post_saved && !fhp->fh_no_atomic_attr);
 
 	cinfo->before_change = fhp->fh_pre_change;
 	cinfo->after_change = fhp->fh_post_change;

include/linux/exportfs.h

@@ -217,6 +217,9 @@ struct export_operations {
 #define	EXPORT_OP_NOSUBTREECHK		(0x2) /* no subtree checking */
 #define	EXPORT_OP_CLOSE_BEFORE_UNLINK	(0x4) /* close files before unlink */
 #define EXPORT_OP_REMOTE_FS		(0x8) /* Filesystem is remote */
+#define EXPORT_OP_NOATOMIC_ATTR		(0x10) /* Filesystem cannot supply
+						  atomic attribute updates
+						*/
 	unsigned long	flags;
 };