corruption with mtdblock

[David Woodhouse]

nico at cam.org said:
>  Nope.  The only place where the queue can be plugged is:
>         if (list_empty(head)) {
>                 q->plug_device_fn(q, bh->b_rdev); /* is atomic */
> Therefore the queue can't be plugged until we emptied it.

But it starts off empty - so doesn't it get plugged the first time a 
request is added? But it doesn't actually bite us until requests are merged 
- when we do 'cat /dev/mtdblock0' or massive writes.

> To be sure I tried to disable plugging by providing a dummy plug
> function that does nothing.  No difference.

Ah. If something is mucking with the request at the head of the queue while 
 (q->head_active && !q->plugged) then I think that has to be a kernel bug.

Just before the end_request() in mtdblock_handle_request(), can you put in 
a sanity check for req->bh->b_end_io? If it's not a sane value, can you 
print the current values of q->head_active and q->plugged?

--
dwmw2




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