Messages in this thread | | | From | Dave Peterson <> | Subject | Re: [PATCH] fixes for linked list bugs in block I/O code | Date | Wed, 7 May 2003 17:09:57 -0700 |
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On Wednesday 07 May 2003 04:42 pm, Bartlomiej Zolnierkiewicz wrote: > > ========== START OF 2.5.69 PATCH FOR drivers/block/ll_rw_blk.c > > =========== --- ll_rw_blk.c.old Wed May 7 15:55:18 2003 > > +++ ll_rw_blk.c.new Wed May 7 16:01:56 2003 > > @@ -1721,6 +1721,7 @@ > > break; > > } > > > > + bio->bi_next = req->biotail->bi_next; > > This is simply wrong, look at the line below. > > > req->biotail->bi_next = bio; > > req->bio - first bio > req->bio->bi_next - next bio > ... > req->biotail - last bio > > so req->biotail->bi_next should be NULL
I believe it is correct. Assuming that the list is initially in a sane state, req->biotail->bi_next will be NULL immediately before executing the statement that I added. Therefore, my fix will set bio->bi_next to NULL, which is what we want because bio becomes the new end of the list.
> > req->biotail = bio; > > req->nr_sectors = req->hard_nr_sectors += > > nr_sectors; @@ -1811,6 +1812,7 @@ > > req->buffer = bio_data(bio); /* see ->buffer comment above */ > > req->waiting = NULL; > > req->bio = req->biotail = bio; > > + bio->bi_next = NULL; > > No need for that, look at bio_init() in fs/bio.c.
Yes, it looks like bio_init has been added in the 2.5 kernels, solving the problem. However, this is still a bug in 2.4.20.
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