ceph_d_revalidate(): propagate stable name down into request encoding

Currently get_fscrypt_altname() requires ->r_dentry->d_name to be stable
and it gets that in almost all cases.  The only exception is ->d_revalidate(),
where we have a stable name, but it's passed separately - dentry->d_name
is not stable there.

Propagate it down to get_fscrypt_altname() as a new field of struct
ceph_mds_request - ->r_dname, to be used instead ->r_dentry->d_name
when non-NULL.

Reviewed-by: Jeff Layton <[email protected]>
Signed-off-by: Al Viro <[email protected]>

Author: Al Viro

fs/ceph/dir.c

@@ -1998,6 +1998,8 @@ static int ceph_d_revalidate(struct inode *dir, const struct qstr *name,
 			req->r_parent = dir;
 			ihold(dir);
 
+			req->r_dname = name;
+
 			mask = CEPH_STAT_CAP_INODE | CEPH_CAP_AUTH_SHARED;
 			if (ceph_security_xattr_wanted(dir))
 				mask |= CEPH_CAP_XATTR_SHARED;

fs/ceph/mds_client.c

@@ -2621,6 +2621,7 @@ static u8 *get_fscrypt_altname(const struct ceph_mds_request *req, u32 *plen)
 {
 	struct inode *dir = req->r_parent;
 	struct dentry *dentry = req->r_dentry;
+	const struct qstr *name = req->r_dname;
 	u8 *cryptbuf = NULL;
 	u32 len = 0;
 	int ret = 0;
@@ -2641,8 +2642,10 @@ static u8 *get_fscrypt_altname(const struct ceph_mds_request *req, u32 *plen)
 	if (!fscrypt_has_encryption_key(dir))
 		goto success;
 
-	if (!fscrypt_fname_encrypted_size(dir, dentry->d_name.len, NAME_MAX,
-					  &len)) {
+	if (!name)
+		name = &dentry->d_name;
+
+	if (!fscrypt_fname_encrypted_size(dir, name->len, NAME_MAX, &len)) {
 		WARN_ON_ONCE(1);
 		return ERR_PTR(-ENAMETOOLONG);
 	}
@@ -2657,7 +2660,7 @@ static u8 *get_fscrypt_altname(const struct ceph_mds_request *req, u32 *plen)
 	if (!cryptbuf)
 		return ERR_PTR(-ENOMEM);
 
-	ret = fscrypt_fname_encrypt(dir, &dentry->d_name, cryptbuf, len);
+	ret = fscrypt_fname_encrypt(dir, name, cryptbuf, len);
 	if (ret) {
 		kfree(cryptbuf);
 		return ERR_PTR(ret);

fs/ceph/mds_client.h

@@ -299,6 +299,8 @@ struct ceph_mds_request {
 	struct inode *r_target_inode;       /* resulting inode */
 	struct inode *r_new_inode;	    /* new inode (for creates) */
 
+	const struct qstr *r_dname;	    /* stable name (for ->d_revalidate) */
+
 #define CEPH_MDS_R_DIRECT_IS_HASH	(1) /* r_direct_hash is valid */
 #define CEPH_MDS_R_ABORTED		(2) /* call was aborted */
 #define CEPH_MDS_R_GOT_UNSAFE		(3) /* got an unsafe reply */