ceph: add support for encrypted snapshot names

Since filenames in encrypted directories are encrypted and shown as
a base64-encoded string when the directory is locked, make snapshot
names show a similar behaviour.

When creating a snapshot, .snap directories for every subdirectory will
show the snapshot name in the "long format":

  # mkdir .snap/my-snap
  # ls my-dir/.snap/
  _my-snap_1099511627782

Encrypted snapshots will need to be able to handle these by
encrypting/decrypting only the snapshot part of the string ('my-snap').

Also, since the MDS prevents snapshot names to be bigger than 240
characters it is necessary to adapt CEPH_NOHASH_NAME_MAX to accommodate
this extra limitation.

[ idryomov: drop const on !CONFIG_FS_ENCRYPTION branch too ]

Signed-off-by: Luís Henriques <lhenriques@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Milind Changire <mchangir@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/fs/ceph/crypto.h b/fs/ceph/crypto.h
index 6afa6d888fe0..47e0c319fc68 100644
--- a/fs/ceph/crypto.h
+++ b/fs/ceph/crypto.h
@@ -102,10 +102,10 @@ int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *inode,
 				 struct ceph_acl_sec_ctx *as);
 void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req,
 				struct ceph_acl_sec_ctx *as);
-int ceph_encode_encrypted_dname(const struct inode *parent,
-				struct qstr *d_name, char *buf);
-int ceph_encode_encrypted_fname(const struct inode *parent,
-				struct dentry *dentry, char *buf);
+int ceph_encode_encrypted_dname(struct inode *parent, struct qstr *d_name,
+				char *buf);
+int ceph_encode_encrypted_fname(struct inode *parent, struct dentry *dentry,
+				char *buf);
 
 static inline int ceph_fname_alloc_buffer(struct inode *parent,
 					  struct fscrypt_str *fname)
@@ -194,14 +194,14 @@ static inline void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req,
 {
 }
 
-static inline int ceph_encode_encrypted_dname(const struct inode *parent,
+static inline int ceph_encode_encrypted_dname(struct inode *parent,
 					      struct qstr *d_name, char *buf)
 {
 	memcpy(buf, d_name->name, d_name->len);
 	return d_name->len;
 }
 
-static inline int ceph_encode_encrypted_fname(const struct inode *parent,
+static inline int ceph_encode_encrypted_fname(struct inode *parent,
 					      struct dentry *dentry, char *buf)
 {
 	return -EOPNOTSUPP;