Hello,

while finding out why I can't access my 6GB MS-DOS Fat32 partition
I found this piece of code in "src/sys/msdosfs/msdosfs_vfsops.c":

	if (pmp->pm_HugeSectors > 0xffffffff / pmp->pm_BytesPerSec + 1) {
		/*
		 * We cannot deal currently with this size of disk
		 * due to fileid limitations (see msdosfs_getattr and
		 * msdosfs_readdir)
		 */
		error = EINVAL;
		goto error_exit;
	}

This is the code segment from "src/sys/msdosfs/msdosfs_vnops.c":

int
msdosfs_getattr(v)
	void *v;
{
[...]
	u_long dirsperblk = pmp->pm_BytesPerSec / sizeof(struct direntry);
[...]
	if (dep->de_Attributes & ATTR_DIRECTORY) {
		fileid = cntobn(pmp, dep->de_StartCluster) * dirsperblk;
		if (dep->de_StartCluster == MSDOSFSROOT)
			fileid = 1;
	} else {
		fileid = cntobn(pmp, dep->de_dirclust) * dirsperblk;
		if (dep->de_dirclust == MSDOSFSROOT)
			fileid = roottobn(pmp, 0) * dirsperblk;
		fileid += dep->de_diroffset / sizeof(struct direntry);
	}

It looks like the block number is multiplied by "dirsperblk" so the size
check in  "msdosfs_vfsops.c" uses to small bounds. IMHO it should look
like this:

	if (pmp->pm_HugeSectors >
	    0xffffffff / (pmp->pm_BytesPerSec / sizeof(struct direntry)) + 1) {
[...]
	}

This would raise the maximum size of a MS-DOS partition from 4GB to 128GB.

-- 
Matthias Scheler                                http://home.owl.de/~tron/