Re: regression: disk error loop (panic?) ide_do_rw_disk-bad:

From: Jens Axboe
Date: Thu Jul 19 2007 - 02:13:31 EST


On Wed, Jul 18 2007, Linus Torvalds wrote:
>
>
> On Thu, 19 Jul 2007, Bartlomiej Zolnierkiewicz wrote:
> >
> > Thanks for finding and fixing this.
> >
> > The latest patch (with additional cleanups) also looks good and should be
> > safe enough (unchanged behavior for all non-pc requests) to merge it now.
> >
> > Acked-by: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx>
>
> Ok, Jens - mind signing off on the patch you sent out, and writing an
> explanatory message? Feel free to just crib from my explanation of my
> original patch, or whatever.

Sure thing, it's below.

> And it would be beautiful if people who saw the bad behaviour before
> reverting the ide.c changes were to go back to that broken state, and
> try the patch, and just verify that it acts like it should (ie you
> should see just a few error messages, and it shouldn't cause the IDE
> layer to go ballistic any more).

---

[PATCH] IDE: fix termination of non-fs requests

ide-disk calls

ide_end_request(drive, 0, 0);

to finish an unknown request, but this doesn't work so well for non-fs
requests, since ide_end_request() internally looks at ->hard_cur_sectors
to see how much data to end. Only file system requests store a transfer
value in there, pc requests fill out ->data_len as a byte based transfer
value instead.

Since we ask to end 0 bytes of that request, it will never be terminated
and ide-disk gets stuck in a loop "handling" that same request over and
over.

Switch __ide_end_request() to take a byte based transfer count, and
adjust ide_end_request() to look at the right field to determine how
much IO to end when it's being passed in 0.

Acked-by: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx>
Signed-off-by: Jens Axboe <jens.axboe@xxxxxxxxxx>

diff --git a/drivers/ide/ide-io.c b/drivers/ide/ide-io.c
index c5b5011..f9de798 100644
--- a/drivers/ide/ide-io.c
+++ b/drivers/ide/ide-io.c
@@ -55,7 +55,7 @@
#include <asm/bitops.h>

static int __ide_end_request(ide_drive_t *drive, struct request *rq,
- int uptodate, int nr_sectors)
+ int uptodate, unsigned int nr_bytes)
{
int ret = 1;

@@ -64,7 +64,7 @@ static int __ide_end_request(ide_drive_t *drive, struct request *rq,
* complete the whole request right now
*/
if (blk_noretry_request(rq) && end_io_error(uptodate))
- nr_sectors = rq->hard_nr_sectors;
+ nr_bytes = rq->hard_nr_sectors << 9;

if (!blk_fs_request(rq) && end_io_error(uptodate) && !rq->errors)
rq->errors = -EIO;
@@ -78,7 +78,7 @@ static int __ide_end_request(ide_drive_t *drive, struct request *rq,
HWGROUP(drive)->hwif->ide_dma_on(drive);
}

- if (!end_that_request_first(rq, uptodate, nr_sectors)) {
+ if (!end_that_request_chunk(rq, uptodate, nr_bytes)) {
add_disk_randomness(rq->rq_disk);
if (!list_empty(&rq->queuelist))
blkdev_dequeue_request(rq);
@@ -103,6 +103,7 @@ static int __ide_end_request(ide_drive_t *drive, struct request *rq,

int ide_end_request (ide_drive_t *drive, int uptodate, int nr_sectors)
{
+ unsigned int nr_bytes = nr_sectors << 9;
struct request *rq;
unsigned long flags;
int ret = 1;
@@ -114,10 +115,14 @@ int ide_end_request (ide_drive_t *drive, int uptodate, int nr_sectors)
spin_lock_irqsave(&ide_lock, flags);
rq = HWGROUP(drive)->rq;

- if (!nr_sectors)
- nr_sectors = rq->hard_cur_sectors;
+ if (!nr_bytes) {
+ if (blk_pc_request(rq))
+ nr_bytes = rq->data_len;
+ else
+ nr_bytes = rq->hard_cur_sectors << 9;
+ }

- ret = __ide_end_request(drive, rq, uptodate, nr_sectors);
+ ret = __ide_end_request(drive, rq, uptodate, nr_bytes);

spin_unlock_irqrestore(&ide_lock, flags);
return ret;

--
Jens Axboe

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