lkml.org 
[lkml]   [2000]   [Oct]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Meaning of blk_size
On Mon, Oct 02, 2000 at 02:33:20AM +0200, Daniel Phillips wrote:
> On Mon, 02 Oct 2000, Andries Brouwer wrote:

> > [you sounded as if you noticed a discrepancy somewhere - so I expected:
> > foo.c uses this in line 123 but bar.c uses that in line 666.]
>
> No, I'm just trying to understand the meaning of the "+ 1" in ll_rw_block.c,
> generic_make_request:
>
> unsigned long maxsector = (blk_size[major][MINOR(bh->b_rdev)] << 1) + 1;

blk_size[][] gives a block count
blk_size[][]<<1 gives a sector count

but if the device had an odd number of sectors, the sector count
is one larger than twice the block count.

(thus, this is not the precisely correct test; the knowledge about
the number of sectors lives in the dev->sizes array; here we only
have a rough check)

Andries
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 12:39    [from the cache]
©2003-2011 Jasper Spaans