Messages in this thread | | | Date | Wed, 29 Jan 2003 16:38:20 +0100 | From | Jens Axboe <> | Subject | Re: [PATCH] IDE: Do not call bh_phys() on buffers with invalid b_page. |
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On Wed, Jan 29 2003, Benjamin Herrenschmidt wrote: > On Wed, 2003-01-29 at 16:22, Jens Axboe wrote: > > > Ehm no, if b_data is < PAGE_SIZE, it's probably an offset and not a > > valid address. So it should be exactly where it is -- for b_page, it's > > _not_ buggy for b_data to be < PAGE_SIZE. That's expected. Submitter > > would have to be buggy for it to trigger, though, so you can just remove > > it if you want. > > Ah, I see what you wanted to check now :) Ok, I won't remove it, though > it would still make sense to extend the test to PAGE_OFFSET I beleive, > any b_data < PAGE_OFFSET is wrong.
No, any b_data < PAGE_OFFSET is not wrong, that's the point. For highmem b_page, b_data will be the offset into the page. So it could be 2048, for instance.
The test is meant to catch an invalid buffer_head, where b_page is not set but b_data isn't valid either. So to make it complete, you could do:
if (bh->b_page) { ... if (bh->b_data >= PAGE_SIZE) BUG(); } else { ... if (bh->b_data < PAGE_SIZE) BUG(); if (bh->b_data < PAGE_OFFSET) BUG(); }
as they are two different bugs.
> Anyway, let's leave 2.4 as it is now.
:-)
-- Jens Axboe
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