Re: 2.5.37 broke the floppy driver

From: Jens Axboe (axboe@suse.de)
Date: Mon Sep 23 2002 - 04:10:41 EST

On Sun, Sep 22 2002, Mikael Pettersson wrote:
> With 2.5.37, doing a write to floppy makes the kernel print
> "blk: request botched" and a few seconds later instantly reboot
> the machine (w/o any further messages). 2.5.36 works fine.
>
> "dd bs=8k if=bzImage of=/dev/fd0" triggers this every time.

Attached patch should fix the partial completion thing for floppy.

# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or higher.
# This patch includes the following deltas:
# ChangeSet 1.601 -> 1.602
# drivers/block/ll_rw_blk.c 1.107 -> 1.108
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 02/09/23 axboe@burns.home.kernel.dk 1.602
# cleanup end_that_request_first() end_io handling, and fix bug where
# partial completes didn't get accounted right wrt blk_recalc_rq_sectors()
# --------------------------------------------
#
diff -Nru a/drivers/block/ll_rw_blk.c b/drivers/block/ll_rw_blk.c
--- a/drivers/block/ll_rw_blk.c Mon Sep 23 11:10:18 2002
+++ b/drivers/block/ll_rw_blk.c Mon Sep 23 11:10:18 2002
@@ -1904,18 +1904,19 @@
 
 int end_that_request_first(struct request *req, int uptodate, int nr_sectors)
 {
- int nsect, total_nsect;
+ int total_nsect = 0, error = 0;
         struct bio *bio;
 
         req->errors = 0;
- if (!uptodate)
+ if (!uptodate) {
                 printk("end_request: I/O error, dev %s, sector %lu\n",
                         kdevname(req->rq_dev), req->sector);
+ error = -EIO;
+ }
 
- total_nsect = 0;
         while ((bio = req->bio)) {
- nsect = bio_iovec(bio)->bv_len >> 9;
- total_nsect += nsect;
+ const int nsect = bio_iovec(bio)->bv_len >> 9;
+ int new_bio = 0;
 
                 BIO_BUG_ON(bio_iovec(bio)->bv_len > bio->bi_size);
 
@@ -1927,36 +1928,52 @@
 
                         bio_iovec(bio)->bv_offset += partial;
                         bio_iovec(bio)->bv_len -= partial;
- blk_recalc_rq_sectors(req, total_nsect);
- blk_recalc_rq_segments(req);
- bio_endio(bio, partial, !uptodate ? -EIO : 0);
- return 1;
+ bio_endio(bio, partial, error);
+ total_nsect += nr_sectors;
+ break;
                 }
 
                 /*
- * if bio->bi_end_io returns 0, this bio is done. move on
+ * we are ending the last part of the bio, advance req pointer
                  */
- req->bio = bio->bi_next;
- if (bio_endio(bio, nsect << 9, !uptodate ? -EIO : 0)) {
- bio->bi_idx++;
- req->bio = bio;
+ if ((nsect << 9) >= bio->bi_size) {
+ req->bio = bio->bi_next;
+ new_bio = 1;
                 }
 
+ bio_endio(bio, nsect << 9, error);
+
+ total_nsect += nsect;
                 nr_sectors -= nsect;
 
+ /*
+ * if we didn't advance the req->bio pointer, advance bi_idx
+ * to indicate we are now on the next bio_vec
+ */
+ if (!new_bio)
+ bio->bi_idx++;
+
                 if ((bio = req->bio)) {
                         /*
                          * end more in this run, or just return 'not-done'
                          */
- if (unlikely(nr_sectors <= 0)) {
- blk_recalc_rq_sectors(req, total_nsect);
- blk_recalc_rq_segments(req);
- return 1;
- }
+ if (unlikely(nr_sectors <= 0))
+ break;
                 }
         }
 
- return 0;
+ /*
+ * completely done
+ */
+ if (!req->bio)
+ return 0;
+
+ /*
+ * if the request wasn't completed, update state
+ */
+ blk_recalc_rq_sectors(req, total_nsect);
+ blk_recalc_rq_segments(req);
+ return 1;
 }
 
 void end_that_request_last(struct request *req) 

-- 
Jens Axboe

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This archive was generated by hypermail 2b29 : Mon Sep 23 2002 - 22:00:38 EST