hfs/hfsplus: use WARN_ON for sanity check

gcc warns about a couple of instances in which a sanity check exists but
the author wasn't sure how to react to it failing, which makes it look
like a possible bug:

  fs/hfsplus/inode.c: In function 'hfsplus_cat_read_inode':
  fs/hfsplus/inode.c:503:37: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
    503 |                         /* panic? */;
        |                                     ^
  fs/hfsplus/inode.c:524:37: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
    524 |                         /* panic? */;
        |                                     ^
  fs/hfsplus/inode.c: In function 'hfsplus_cat_write_inode':
  fs/hfsplus/inode.c:582:37: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
    582 |                         /* panic? */;
        |                                     ^
  fs/hfsplus/inode.c:608:37: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
    608 |                         /* panic? */;
        |                                     ^
  fs/hfs/inode.c: In function 'hfs_write_inode':
  fs/hfs/inode.c:464:37: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
    464 |                         /* panic? */;
        |                                     ^
  fs/hfs/inode.c:485:37: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
    485 |                         /* panic? */;
        |                                     ^

panic() is probably not the correct choice here, but a WARN_ON
seems appropriate and avoids the compile-time warning.

Link: https://lkml.kernel.org/r/20210927102149.1809384-1-arnd@kernel.org
Link: https://lore.kernel.org/all/20210322223249.2632268-1-arnd@kernel.org/Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/hfs/inode.c

@@ -462,8 +462,7 @@ int hfs_write_inode(struct inode *inode, struct writeback_control *wbc)
 		goto out;
 
 	if (S_ISDIR(main_inode->i_mode)) {
-		if (fd.entrylength < sizeof(struct hfs_cat_dir))
-			/* panic? */;
+		WARN_ON(fd.entrylength < sizeof(struct hfs_cat_dir));
 		hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
 			   sizeof(struct hfs_cat_dir));
 		if (rec.type != HFS_CDR_DIR ||
@@ -483,8 +482,7 @@ int hfs_write_inode(struct inode *inode, struct writeback_control *wbc)
 		hfs_bnode_write(fd.bnode, &rec, fd.entryoffset,
 				sizeof(struct hfs_cat_file));
 	} else {
-		if (fd.entrylength < sizeof(struct hfs_cat_file))
-			/* panic? */;
+		WARN_ON(fd.entrylength < sizeof(struct hfs_cat_file));
 		hfs_bnode_read(fd.bnode, &rec, fd.entryoffset,
 			   sizeof(struct hfs_cat_file));
 		if (rec.type != HFS_CDR_FIL ||

fs/hfsplus/inode.c

@@ -509,8 +509,7 @@ int hfsplus_cat_read_inode(struct inode *inode, struct hfs_find_data *fd)
 	if (type == HFSPLUS_FOLDER) {
 		struct hfsplus_cat_folder *folder = &entry.folder;
 
-		if (fd->entrylength < sizeof(struct hfsplus_cat_folder))
-			/* panic? */;
+		WARN_ON(fd->entrylength < sizeof(struct hfsplus_cat_folder));
 		hfs_bnode_read(fd->bnode, &entry, fd->entryoffset,
 					sizeof(struct hfsplus_cat_folder));
 		hfsplus_get_perms(inode, &folder->permissions, 1);
@@ -530,8 +529,7 @@ int hfsplus_cat_read_inode(struct inode *inode, struct hfs_find_data *fd)
 	} else if (type == HFSPLUS_FILE) {
 		struct hfsplus_cat_file *file = &entry.file;
 
-		if (fd->entrylength < sizeof(struct hfsplus_cat_file))
-			/* panic? */;
+		WARN_ON(fd->entrylength < sizeof(struct hfsplus_cat_file));
 		hfs_bnode_read(fd->bnode, &entry, fd->entryoffset,
 					sizeof(struct hfsplus_cat_file));
 
@@ -588,8 +586,7 @@ int hfsplus_cat_write_inode(struct inode *inode)
 	if (S_ISDIR(main_inode->i_mode)) {
 		struct hfsplus_cat_folder *folder = &entry.folder;
 
-		if (fd.entrylength < sizeof(struct hfsplus_cat_folder))
-			/* panic? */;
+		WARN_ON(fd.entrylength < sizeof(struct hfsplus_cat_folder));
 		hfs_bnode_read(fd.bnode, &entry, fd.entryoffset,
 					sizeof(struct hfsplus_cat_folder));
 		/* simple node checks? */
@@ -614,8 +611,7 @@ int hfsplus_cat_write_inode(struct inode *inode)
 	} else {
 		struct hfsplus_cat_file *file = &entry.file;
 
-		if (fd.entrylength < sizeof(struct hfsplus_cat_file))
-			/* panic? */;
+		WARN_ON(fd.entrylength < sizeof(struct hfsplus_cat_file));
 		hfs_bnode_read(fd.bnode, &entry, fd.entryoffset,
 					sizeof(struct hfsplus_cat_file));
 		hfsplus_inode_write_fork(inode, &file->data_fork);