cmsfscp doesn't handle sparse files. I had some files under CMS which
had large chunks of zeros in them, and cmsfscp failed trying to seek to
(-4096). Problem is that for 4K blocks of zeros, CMS does allocate any
disk space - it just sets the corresponding indirect pointer on disk to
zero. Attached patch fixes userland cmsfs; havn't looked at the kernel
module. Maybe it should really try to create a corresponding sparse
file on the unix side, but this fix was good enough for me.
Cheers,
Richard
--- cmsfsany.c.ori Fri Nov 22 18:50:33 2002
+++ cmsfsany.c Fri Nov 22 18:55:37 2002
@@ -643,6 +643,14 @@
bp += b1 * inode->psize;
b2 = cmsfsbex(bp,4);
+ /* if the block pointer is null this is a block of zeros and
+ * CMS didn't bother to allocate disk space. Return a buffer
+ * of zeros.
+ */
+ if (b2 == 0) {
+ memset(buffer, 0, inode->cmssuper->blksz);
+ break;
+ }
/* read next block for indirection */
rc = cmsfs_bread(inode->cmssuper,buffer,
b2-1,inode->cmssuper->blksz);
