Hi,
This patch solves the 2 problems:
1) cramfs is not marked readonly and it is possible to
truncate files on it. This part is obvious and trivial.
2) Even setting MS_RDONLY in cramfs_read_super is not enough,
since remount -wno remount still makes it possible (the same
seems to be valid for all readonly filesystems).
I solved it implementing super_operations.remount_fs.
Is it a desired way of solving the problem ? If so,
i could do the same for the others as well (isofs, romfs).
Although patch was diffed against 2.4.3, it still applies (at least
against 2.4.20-rc1). Bug is present in 2.4 as well as in 2.5.
Regards,
pkx
--
Peter Kundrat
[email protected]
diff -ur -x *~ -x *.o -x .* Linux-2.4.3.orig/fs/cramfs/inode.c Linux-2.4.3.isdn.kgdb/fs/cramfs/inode.c
--- Linux-2.4.3.orig/fs/cramfs/inode.c Fri Apr 6 08:09:07 2001
+++ Linux-2.4.3.isdn.kgdb/fs/cramfs/inode.c Tue May 15 12:56:32 2001
@@ -192,6 +192,8 @@
goto out;
}
+ sb->s_flags |= MS_RDONLY;
+
/* Set it all up.. */
sb->s_op = &cramfs_ops;
sb->s_root = d_alloc_root(get_cramfs_inode(sb, &super.root));
@@ -212,6 +214,14 @@
return 0;
}
+static int cramfs_remount (struct super_block * sb, int * flags, char * data)
+{
+ if (*flags & MS_RDONLY)
+ return 0;
+ else
+ return -EROFS;
+}
+
/*
* Read a cramfs directory entry.
*/
@@ -358,6 +368,7 @@
static struct super_operations cramfs_ops = {
statfs: cramfs_statfs,
+ remount_fs: cramfs_remount,
};
static DECLARE_FSTYPE_DEV(cramfs_fs_type, "cramfs", cramfs_read_super);