[SCSI] sg: do not set VM_IO flag on mmap-ed pages

Further to the problem discussed in this post:
http://marc.theaimsgroup.com/?l=linux-scsi&m=112540053711489&w=2

It seems that the sg driver does not need to set the VM_IO flag
on pages that it memory maps to the user space since they are
not from the IO space. Ahmed Teirelbar <[e-mail]>
wants the facility and has tested this patch as I have without
adverse effects.

The oops protection is still important. Some users really did
try and use dio transfers from the sg driver to memory mapped
IO space (on a video capture card if my memory serves) during the
lk 2.4 series. I'm not sure how successful it was but that will
now be politely refused in lk 2.6.13+ .

Changelog:
- set the page flags for sg's reserved buffer mmap-ed
to the user space to VM_RESERVED (rather than
VM_RESERVED | VM_IO )

Signed-off-by: Douglas Gilbert <[e-mail]>
Signed-off-by: James Bottomley <[e-mail]>

drivers/scsi/sg.c

···
 
 #ifdef CONFIG_SCSI_PROC_FS
 #include <linux/proc_fs.h>
-static char *sg_version_date = "20050901";
+static char *sg_version_date = "20050908";
 
 static int sg_proc_init(void);
 static void sg_proc_cleanup(void);
···
 		sg_rb_correct4mmap(rsv_schp, 1);	/* do only once per fd lifetime */
 		sfp->mmap_called = 1;
 	}
-	vma->vm_flags |= (VM_RESERVED | VM_IO);
+	vma->vm_flags |= VM_RESERVED;
 	vma->vm_private_data = sfp;
 	vma->vm_ops = &sg_mmap_vm_ops;
 	return 0;