[RFC PATCH v5 20/19] ceph: make ceph_get_name decrypt filenames

[Jeff Layton <jlayton@xxxxxxxxxx>]

When we do a lookupino to the MDS, we get a filename in the trace.
ceph_get_name uses that name directly, so we must properly decrypt
it before copying it to the name buffer.

Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
 fs/ceph/export.c | 42 +++++++++++++++++++++++++++++++-----------
 1 file changed, 31 insertions(+), 11 deletions(-)

This patch is what's needed to fix the "busy inodes after umount"
issue I was seeing with xfstest generic/477, and also makes that
test pass reliably with mounts using -o test_dummy_encryption.

diff --git a/fs/ceph/export.c b/fs/ceph/export.c
index 17d8c8f4ec89..f4e3a17ffc01 100644
--- a/fs/ceph/export.c
+++ b/fs/ceph/export.c
@@ -7,6 +7,7 @@
 
 #include "super.h"
 #include "mds_client.h"
+#include "crypto.h"
 
 /*
  * Basic fh
@@ -516,7 +517,9 @@ static int ceph_get_name(struct dentry *parent, char *name,
 {
 	struct ceph_mds_client *mdsc;
 	struct ceph_mds_request *req;
+	struct inode *dir = d_inode(parent);
 	struct inode *inode = d_inode(child);
+	struct ceph_mds_reply_info_parsed *rinfo;
 	int err;
 
 	if (ceph_snap(inode) != CEPH_NOSNAP)
@@ -528,29 +531,46 @@ static int ceph_get_name(struct dentry *parent, char *name,
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
-	inode_lock(d_inode(parent));
-
+	inode_lock(dir);
 	req->r_inode = inode;
 	ihold(inode);
 	req->r_ino2 = ceph_vino(d_inode(parent));
-	req->r_parent = d_inode(parent);
+	req->r_parent = dir;
 	set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);
 	req->r_num_caps = 2;
 	err = ceph_mdsc_do_request(mdsc, NULL, req);
+	inode_unlock(dir);
 
-	inode_unlock(d_inode(parent));
+	if (err)
+		goto out;
 
-	if (!err) {
-		struct ceph_mds_reply_info_parsed *rinfo = &req->r_reply_info;
+	rinfo = &req->r_reply_info;
+	if (!IS_ENCRYPTED(dir)) {
 		memcpy(name, rinfo->dname, rinfo->dname_len);
 		name[rinfo->dname_len] = 0;
-		dout("get_name %p ino %llx.%llx name %s\n",
-		     child, ceph_vinop(inode), name);
 	} else {
-		dout("get_name %p ino %llx.%llx err %d\n",
-		     child, ceph_vinop(inode), err);
-	}
+		struct fscrypt_str oname = FSTR_INIT(NULL, 0);
+		struct ceph_fname fname = { .dir	= dir,
+					    .name	= rinfo->dname,
+					    .ctext	= rinfo->altname,
+					    .name_len	= rinfo->dname_len,
+					    .ctext_len	= rinfo->altname_len };
+
+		err = ceph_fname_alloc_buffer(dir, &oname);
+		if (err < 0)
+			goto out;
 
+		err = ceph_fname_to_usr(&fname, NULL, &oname, NULL);
+		if (!err) {
+			memcpy(name, oname.name, oname.len);
+			name[oname.len] = 0;
+		}
+		ceph_fname_free_buffer(dir, &oname);
+	}
+out:
+	dout("get_name %p ino %llx.%llx err %d %s%s\n",
+		     child, ceph_vinop(inode), err,
+		     err ? "" : "name ", err ? "" : name);
 	ceph_mdsc_put_request(req);
 	return err;
 }
-- 
2.30.2