Messages in this thread |  | | Date | Thu, 8 May 2003 01:42:34 +0200 (MET DST) | From | Bartlomiej Zolnierkiewicz <> | Subject | Re: [PATCH] fixes for linked list bugs in block I/O code |
| |
On Wed, 7 May 2003, Dave Peterson wrote:
> I found a couple of small linked list bugs in __make_request() in > drivers/block/ll_rw_blk.c. The bugs exist in both kernels > 2.4.20 and 2.5.69. Therefore I have made patches for both > kernels. The problem is that when inserting a new buffer_head > into the linked list of buffer_head structures maintained by > "struct request", the b_reqnext field is not initialized. > > -Dave Peterson > dsp@llnl.gov > > > ========== START OF 2.4.20 PATCH FOR drivers/block/ll_rw_blk.c =========== > --- ll_rw_blk.c.old Wed May 7 15:54:58 2003 > +++ ll_rw_blk.c.new Wed May 7 15:58:07 2003 > @@ -973,6 +973,7 @@ > insert_here = &req->queue; > break; > } > + bh->b_reqnext = req->bhtail->b_reqnext; > req->bhtail->b_reqnext = bh; > req->bhtail = bh; > req->nr_sectors = req->hard_nr_sectors += count; > @@ -1061,6 +1062,7 @@ > req->waiting = NULL; > req->bh = bh; > req->bhtail = bh; > + bh->b_reqnext = NULL; > req->rq_dev = bh->b_rdev; > req->start_time = jiffies; > req_new_io(req, 0, count); > ========== END OF 2.4.20 PATCH FOR drivers/block/ll_rw_blk.c ============= > > > ========== 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
> 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.
> req->rq_disk = bio->bi_bdev->bd_disk; > req->start_time = jiffies; > add_request(q, req, insert_here); > ========== END OF 2.5.69 PATCH FOR drivers/block/ll_rw_blk.c =============
-- Bartlomiej
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|  |