[PATCH v2 1/2] NFS: Fix inode fileid checks in attribute revalidation code

[Trond Myklebust]

We want to throw out the attrbute if it refers to the mounted on fileid,
and not the real fileid. However we do not want to block cache consistency
updates from NFSv4 writes.

Reported-by: Murphy Zhou <jencce.kernel at gmail.com>
Fixes: 7e10cc25bfa0 ("NFS: Don't refresh attributes with mounted-on-file...")
Signed-off-by: Trond Myklebust <trond.myklebust at hammerspace.com>
Signed-off-by: Christophe Leroy <christophe.leroy at c-s.fr>
---
 fs/nfs/inode.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index c764cfe456e5..2a03bfeec10a 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1403,11 +1403,12 @@ static int nfs_check_inode_attributes(struct inode *inode, struct nfs_fattr *fat
 	if (NFS_PROTO(inode)->have_delegation(inode, FMODE_READ))
 		return 0;
 
-	/* No fileid? Just exit */
-	if (!(fattr->valid & NFS_ATTR_FATTR_FILEID))
-		return 0;
+	if (!(fattr->valid & NFS_ATTR_FATTR_FILEID)) {
+		/* Only a mounted-on-fileid? Just exit */
+		if (fattr->valid & NFS_ATTR_FATTR_MOUNTED_ON_FILEID)
+			return 0;
 	/* Has the inode gone and changed behind our back? */
-	if (nfsi->fileid != fattr->fileid) {
+	} else if (nfsi->fileid != fattr->fileid) {
 		/* Is this perhaps the mounted-on fileid? */
 		if ((fattr->valid & NFS_ATTR_FATTR_MOUNTED_ON_FILEID) &&
 		    nfsi->fileid == fattr->mounted_on_fileid)
@@ -1807,11 +1808,12 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr)
 			nfs_display_fhandle_hash(NFS_FH(inode)),
 			atomic_read(&inode->i_count), fattr->valid);
 
-	/* No fileid? Just exit */
-	if (!(fattr->valid & NFS_ATTR_FATTR_FILEID))
-		return 0;
+	if (!(fattr->valid & NFS_ATTR_FATTR_FILEID)) {
+		/* Only a mounted-on-fileid? Just exit */
+		if (fattr->valid & NFS_ATTR_FATTR_MOUNTED_ON_FILEID)
+			return 0;
 	/* Has the inode gone and changed behind our back? */
-	if (nfsi->fileid != fattr->fileid) {
+	} else if (nfsi->fileid != fattr->fileid) {
 		/* Is this perhaps the mounted-on fileid? */
 		if ((fattr->valid & NFS_ATTR_FATTR_MOUNTED_ON_FILEID) &&
 		    nfsi->fileid == fattr->mounted_on_fileid)
-- 
2.13.3