ceph: size handling in MClientRequest, cap updates and inode traces

For encrypted inodes, transmit a rounded-up size to the MDS as the
normal file size and send the real inode size in fscrypt_file field.
Also, fix up creates and truncates to also transmit fscrypt_file.

When we get an inode trace from the MDS, grab the fscrypt_file field if
the inode is encrypted, and use it to populate the i_size field instead
of the regular inode size field.

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

fs/ceph/caps.c

@@ -1217,10 +1217,9 @@ struct cap_msg_args {
 	umode_t			mode;
 	bool			inline_data;
 	bool			wake;
+	bool			encrypted;
 	u32			fscrypt_auth_len;
-	u32			fscrypt_file_len;
 	u8			fscrypt_auth[sizeof(struct ceph_fscrypt_auth)]; // for context
-	u8			fscrypt_file[sizeof(u64)]; // for size
 };
 
 /* Marshal up the cap msg to the MDS */
@@ -1255,7 +1254,13 @@ static void encode_cap_msg(struct ceph_msg *msg, struct cap_msg_args *arg)
 	fc->ino = cpu_to_le64(arg->ino);
 	fc->snap_follows = cpu_to_le64(arg->follows);
 
-	fc->size = cpu_to_le64(arg->size);
+#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
+	if (arg->encrypted)
+		fc->size = cpu_to_le64(round_up(arg->size,
+						CEPH_FSCRYPT_BLOCK_SIZE));
+	else
+#endif
+		fc->size = cpu_to_le64(arg->size);
 	fc->max_size = cpu_to_le64(arg->max_size);
 	ceph_encode_timespec64(&fc->mtime, &arg->mtime);
 	ceph_encode_timespec64(&fc->atime, &arg->atime);
@@ -1315,11 +1320,17 @@ static void encode_cap_msg(struct ceph_msg *msg, struct cap_msg_args *arg)
 	ceph_encode_64(&p, 0);
 
 #if IS_ENABLED(CONFIG_FS_ENCRYPTION)
-	/* fscrypt_auth and fscrypt_file (version 12) */
+	/*
+	 * fscrypt_auth and fscrypt_file (version 12)
+	 *
+	 * fscrypt_auth holds the crypto context (if any). fscrypt_file
+	 * tracks the real i_size as an __le64 field (and we use a rounded-up
+	 * i_size in the traditional size field).
+	 */
 	ceph_encode_32(&p, arg->fscrypt_auth_len);
 	ceph_encode_copy(&p, arg->fscrypt_auth, arg->fscrypt_auth_len);
-	ceph_encode_32(&p, arg->fscrypt_file_len);
-	ceph_encode_copy(&p, arg->fscrypt_file, arg->fscrypt_file_len);
+	ceph_encode_32(&p, sizeof(__le64));
+	ceph_encode_64(&p, arg->size);
 #else /* CONFIG_FS_ENCRYPTION */
 	ceph_encode_32(&p, 0);
 	ceph_encode_32(&p, 0);
@@ -1391,7 +1402,6 @@ static void __prep_cap(struct cap_msg_args *arg, struct ceph_cap *cap,
 	arg->follows = flushing ? ci->i_head_snapc->seq : 0;
 	arg->flush_tid = flush_tid;
 	arg->oldest_flush_tid = oldest_flush_tid;
-
 	arg->size = i_size_read(inode);
 	ci->i_reported_size = arg->size;
 	arg->max_size = ci->i_wanted_max_size;
@@ -1445,6 +1455,7 @@ static void __prep_cap(struct cap_msg_args *arg, struct ceph_cap *cap,
 		}
 	}
 	arg->flags = flags;
+	arg->encrypted = IS_ENCRYPTED(inode);
 #if IS_ENABLED(CONFIG_FS_ENCRYPTION)
 	if (ci->fscrypt_auth_len &&
 	    WARN_ON_ONCE(ci->fscrypt_auth_len > sizeof(struct ceph_fscrypt_auth))) {
@@ -1456,21 +1467,21 @@ static void __prep_cap(struct cap_msg_args *arg, struct ceph_cap *cap,
 		       min_t(size_t, ci->fscrypt_auth_len,
 			     sizeof(arg->fscrypt_auth)));
 	}
-	/* FIXME: use this to track "real" size */
-	arg->fscrypt_file_len = 0;
 #endif /* CONFIG_FS_ENCRYPTION */
 }
 
+#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
+#define CAP_MSG_FIXED_FIELDS (sizeof(struct ceph_mds_caps) + \
+		      4 + 8 + 4 + 4 + 8 + 4 + 4 + 4 + 8 + 8 + 4 + 8 + 8 + 4 + 4 + 8)
+
+static inline int cap_msg_size(struct cap_msg_args *arg)
+{
+	return CAP_MSG_FIXED_FIELDS + arg->fscrypt_auth_len;
+}
+#else
 #define CAP_MSG_FIXED_FIELDS (sizeof(struct ceph_mds_caps) + \
 		      4 + 8 + 4 + 4 + 8 + 4 + 4 + 4 + 8 + 8 + 4 + 8 + 8 + 4 + 4)
 
-#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
-static inline int cap_msg_size(struct cap_msg_args *arg)
-{
-	return CAP_MSG_FIXED_FIELDS + arg->fscrypt_auth_len +
-			arg->fscrypt_file_len;
-}
-#else
 static inline int cap_msg_size(struct cap_msg_args *arg)
 {
 	return CAP_MSG_FIXED_FIELDS;
@@ -1550,13 +1561,10 @@ static inline int __send_flush_snap(struct inode *inode,
 	arg.inline_data = capsnap->inline_data;
 	arg.flags = 0;
 	arg.wake = false;
+	arg.encrypted = IS_ENCRYPTED(inode);
 
-	/*
-	 * No fscrypt_auth changes from a capsnap. It will need
-	 * to update fscrypt_file on size changes (TODO).
-	 */
+	/* No fscrypt_auth changes from a capsnap.*/
 	arg.fscrypt_auth_len = 0;
-	arg.fscrypt_file_len = 0;
 
 	msg = ceph_msg_new(CEPH_MSG_CLIENT_CAPS, cap_msg_size(&arg),
 			   GFP_NOFS, false);

fs/ceph/dir.c

@@ -915,6 +915,9 @@ static int ceph_mknod(struct mnt_idmap *idmap, struct inode *dir,
 		goto out_req;
 	}
 
+	if (S_ISREG(mode) && IS_ENCRYPTED(dir))
+		set_bit(CEPH_MDS_R_FSCRYPT_FILE, &req->r_req_flags);
+
 	req->r_dentry = dget(dentry);
 	req->r_num_caps = 2;
 	req->r_parent = dir;

fs/ceph/file.c

@@ -790,6 +790,7 @@ int ceph_atomic_open(struct inode *dir, struct dentry *dentry,
 	req->r_parent = dir;
 	ihold(dir);
 	if (IS_ENCRYPTED(dir)) {
+		set_bit(CEPH_MDS_R_FSCRYPT_FILE, &req->r_req_flags);
 		if (!fscrypt_has_encryption_key(dir)) {
 			spin_lock(&dentry->d_lock);
 			dentry->d_flags |= DCACHE_NOKEY_NAME;

fs/ceph/inode.c

@@ -1028,6 +1028,7 @@ int ceph_fill_inode(struct inode *inode, struct page *locked_page,
 
 	if (new_version ||
 	    (new_issued & (CEPH_CAP_ANY_FILE_RD | CEPH_CAP_ANY_FILE_WR))) {
+		u64 size = le64_to_cpu(info->size);
 		s64 old_pool = ci->i_layout.pool_id;
 		struct ceph_string *old_ns;
 
@@ -1041,10 +1042,22 @@ int ceph_fill_inode(struct inode *inode, struct page *locked_page,
 
 		pool_ns = old_ns;
 
+		if (IS_ENCRYPTED(inode) && size &&
+		    iinfo->fscrypt_file_len == sizeof(__le64)) {
+			u64 fsize = __le64_to_cpu(*(__le64 *)iinfo->fscrypt_file);
+
+			if (size == round_up(fsize, CEPH_FSCRYPT_BLOCK_SIZE)) {
+				size = fsize;
+			} else {
+				pr_warn("fscrypt size mismatch: size=%llu fscrypt_file=%llu, discarding fscrypt_file size.\n",
+					info->size, size);
+			}
+		}
+
 		queue_trunc = ceph_fill_file_size(inode, issued,
 					le32_to_cpu(info->truncate_seq),
 					le64_to_cpu(info->truncate_size),
-					le64_to_cpu(info->size));
+					size);
 		/* only update max_size on auth cap */
 		if ((info->cap.flags & CEPH_CAP_FLAG_AUTH) &&
 		    ci->i_max_size != le64_to_cpu(info->max_size)) {
@@ -2388,11 +2401,25 @@ int __ceph_setattr(struct inode *inode, struct iattr *attr,
 			}
 		} else if ((issued & CEPH_CAP_FILE_SHARED) == 0 ||
 			   attr->ia_size != isize) {
-			req->r_args.setattr.size = cpu_to_le64(attr->ia_size);
-			req->r_args.setattr.old_size = cpu_to_le64(isize);
 			mask |= CEPH_SETATTR_SIZE;
 			release |= CEPH_CAP_FILE_SHARED | CEPH_CAP_FILE_EXCL |
 				   CEPH_CAP_FILE_RD | CEPH_CAP_FILE_WR;
+			if (IS_ENCRYPTED(inode) && attr->ia_size) {
+				set_bit(CEPH_MDS_R_FSCRYPT_FILE, &req->r_req_flags);
+				mask |= CEPH_SETATTR_FSCRYPT_FILE;
+				req->r_args.setattr.size =
+					cpu_to_le64(round_up(attr->ia_size,
+							     CEPH_FSCRYPT_BLOCK_SIZE));
+				req->r_args.setattr.old_size =
+					cpu_to_le64(round_up(isize,
+							     CEPH_FSCRYPT_BLOCK_SIZE));
+				req->r_fscrypt_file = attr->ia_size;
+				/* FIXME: client must zero out any partial blocks! */
+			} else {
+				req->r_args.setattr.size = cpu_to_le64(attr->ia_size);
+				req->r_args.setattr.old_size = cpu_to_le64(isize);
+				req->r_fscrypt_file = 0;
+			}
 		}
 	}
 	if (ia_valid & ATTR_MTIME) {

fs/ceph/mds_client.c

@@ -2832,7 +2832,12 @@ static void encode_mclientrequest_tail(void **p,
 	} else {
 		ceph_encode_32(p, 0);
 	}
-	ceph_encode_32(p, 0); // fscrypt_file for now
+	if (test_bit(CEPH_MDS_R_FSCRYPT_FILE, &req->r_req_flags)) {
+		ceph_encode_32(p, sizeof(__le64));
+		ceph_encode_64(p, req->r_fscrypt_file);
+	} else {
+		ceph_encode_32(p, 0);
+	}
 }
 
 /*
@@ -2922,6 +2927,8 @@ static struct ceph_msg *create_request_message(struct ceph_mds_session *session,
 
 	/* fscrypt_file */
 	len += sizeof(u32);
+	if (test_bit(CEPH_MDS_R_FSCRYPT_FILE, &req->r_req_flags))
+		len += sizeof(__le64);
 
 	msg = ceph_msg_new2(CEPH_MSG_CLIENT_REQUEST, len, 1, GFP_NOFS, false);
 	if (!msg) {

fs/ceph/mds_client.h

@@ -282,6 +282,7 @@ struct ceph_mds_request {
 #define CEPH_MDS_R_DID_PREPOPULATE	(6) /* prepopulated readdir */
 #define CEPH_MDS_R_PARENT_LOCKED	(7) /* is r_parent->i_rwsem wlocked? */
 #define CEPH_MDS_R_ASYNC		(8) /* async request */
+#define CEPH_MDS_R_FSCRYPT_FILE		(9) /* must marshal fscrypt_file field */
 	unsigned long	r_req_flags;
 
 	struct mutex r_fill_mutex;
@@ -289,6 +290,7 @@ struct ceph_mds_request {
 	union ceph_mds_request_args r_args;
 
 	struct ceph_fscrypt_auth *r_fscrypt_auth;
+	u64	r_fscrypt_file;
 
 	u8 *r_altname;		    /* fscrypt binary crypttext for long filenames */
 	u32 r_altname_len;	    /* length of r_altname */