4 files changed, 52 insertions, 30 deletions

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 97edb32be77f..e12e5a4ad502 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2965,7 +2965,9 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
 			goto out;
 	}
 
-	err = vfs_getattr(&path, &stat, STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT);
+	err = vfs_getattr(&path, &stat,
+			  STATX_BASIC_STATS | STATX_BTIME | STATX_CHANGE_COOKIE,
+			  AT_STATX_SYNC_AS_STAT);
 	if (err)
 		goto out_nfserr;
 	if (!(stat.result_mask & STATX_BTIME))
diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c
index 8c52b6c9d31a..76ea268dc420 100644
--- a/fs/nfsd/nfsfh.c
+++ b/fs/nfsd/nfsfh.c
@@ -628,6 +628,10 @@ void fh_fill_pre_attrs(struct svc_fh *fhp)
 		stat.mtime = inode->i_mtime;
 		stat.ctime = inode->i_ctime;
 		stat.size  = inode->i_size;
+		if (v4 && IS_I_VERSION(inode)) {
+			stat.change_cookie = inode_query_iversion(inode);
+			stat.result_mask |= STATX_CHANGE_COOKIE;
+		}
 	}
 	if (v4)
 		fhp->fh_pre_change = nfsd4_change_attribute(&stat, inode);
@@ -659,6 +663,10 @@ void fh_fill_post_attrs(struct svc_fh *fhp)
 	if (err) {
 		fhp->fh_post_saved = false;
 		fhp->fh_post_attr.ctime = inode->i_ctime;
+		if (v4 && IS_I_VERSION(inode)) {
+			fhp->fh_post_attr.change_cookie = inode_query_iversion(inode);
+			fhp->fh_post_attr.result_mask |= STATX_CHANGE_COOKIE;
+		}
 	} else
 		fhp->fh_post_saved = true;
 	if (v4)
@@ -748,3 +756,37 @@ enum fsid_source fsid_source(const struct svc_fh *fhp)
 		return FSIDSOURCE_UUID;
 	return FSIDSOURCE_DEV;
 }
+
+/*
+ * We could use i_version alone as the change attribute.  However, i_version
+ * can go backwards on a regular file after an unclean shutdown.  On its own
+ * that doesn't necessarily cause a problem, but if i_version goes backwards
+ * and then is incremented again it could reuse a value that was previously
+ * used before boot, and a client who queried the two values might incorrectly
+ * assume nothing changed.
+ *
+ * By using both ctime and the i_version counter we guarantee that as long as
+ * time doesn't go backwards we never reuse an old value. If the filesystem
+ * advertises STATX_ATTR_CHANGE_MONOTONIC, then this mitigation is not
+ * needed.
+ *
+ * We only need to do this for regular files as well. For directories, we
+ * assume that the new change attr is always logged to stable storage in some
+ * fashion before the results can be seen.
+ */
+u64 nfsd4_change_attribute(struct kstat *stat, struct inode *inode)
+{
+	u64 chattr;
+
+	if (stat->result_mask & STATX_CHANGE_COOKIE) {
+		chattr = stat->change_cookie;
+		if (S_ISREG(inode->i_mode) &&
+		    !(stat->attributes & STATX_ATTR_CHANGE_MONOTONIC)) {
+			chattr += (u64)stat->ctime.tv_sec << 30;
+			chattr += stat->ctime.tv_nsec;
+		}
+	} else {
+		chattr = time_to_chattr(&stat->ctime);
+	}
+	return chattr;
+}
diff --git a/fs/nfsd/nfsfh.h b/fs/nfsd/nfsfh.h
index 513e028b0bbe..4e0ecf0ae2cf 100644
--- a/fs/nfsd/nfsfh.h
+++ b/fs/nfsd/nfsfh.h
@@ -293,34 +293,7 @@ static inline void fh_clear_pre_post_attrs(struct svc_fh *fhp)
 	fhp->fh_pre_saved = false;
 }
 
-/*
- * We could use i_version alone as the change attribute.  However,
- * i_version can go backwards after a reboot.  On its own that doesn't
- * necessarily cause a problem, but if i_version goes backwards and then
- * is incremented again it could reuse a value that was previously used
- * before boot, and a client who queried the two values might
- * incorrectly assume nothing changed.
- *
- * By using both ctime and the i_version counter we guarantee that as
- * long as time doesn't go backwards we never reuse an old value.
- */
-static inline u64 nfsd4_change_attribute(struct kstat *stat,
-					 struct inode *inode)
-{
-	if (inode->i_sb->s_export_op->fetch_iversion)
-		return inode->i_sb->s_export_op->fetch_iversion(inode);
-	else if (IS_I_VERSION(inode)) {
-		u64 chattr;
-
-		chattr =  stat->ctime.tv_sec;
-		chattr <<= 30;
-		chattr += stat->ctime.tv_nsec;
-		chattr += inode_query_iversion(inode);
-		return chattr;
-	} else
-		return time_to_chattr(&stat->ctime);
-}
-
+u64 nfsd4_change_attribute(struct kstat *stat, struct inode *inode);
 extern void fh_fill_pre_attrs(struct svc_fh *fhp);
 extern void fh_fill_post_attrs(struct svc_fh *fhp);
 extern void fh_fill_both_attrs(struct svc_fh *fhp);
diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
index dbdfef7ae85b..43fb57a301d3 100644
--- a/fs/nfsd/vfs.h
+++ b/fs/nfsd/vfs.h
@@ -170,9 +170,14 @@ static inline void fh_drop_write(struct svc_fh *fh)
 
 static inline __be32 fh_getattr(const struct svc_fh *fh, struct kstat *stat)
 {
+	u32 request_mask = STATX_BASIC_STATS;
 	struct path p = {.mnt = fh->fh_export->ex_path.mnt,
 			 .dentry = fh->fh_dentry};
-	return nfserrno(vfs_getattr(&p, stat, STATX_BASIC_STATS,
+
+	if (fh->fh_maxsize == NFS4_FHSIZE)
+		request_mask |= (STATX_BTIME | STATX_CHANGE_COOKIE);
+
+	return nfserrno(vfs_getattr(&p, stat, request_mask,
 				    AT_STATX_SYNC_AS_STAT));
 }