From 6072f7491f5ef391a575e18a1165e72a3eef1601 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Wed, 31 Mar 2010 20:11:59 +0000 Subject: [PATCH] ide: Requeue request after DMA timeout I noticed that my KVM virtual machines were experiencing IDE issues resulting in processes stuck on waiting for buffers to complete. The root cause is of course race conditions in the ancient qemu backend that I'm using. However, the fact that the guest isn't recovering is a bug. I've tracked it down to the change made last year to dequeue requests at the start rather than at the end in the IDE layer. commit 8f6205cd572fece673da0255d74843680f67f879 Author: Tejun Heo Date: Fri May 8 11:53:59 2009 +0900 ide: dequeue in-flight request The problem is that the function ide_dma_timeout_retry does not requeue the current request, causing one request to be lost for each DMA timeout. This patch fixes this by requeueing the request. Signed-off-by: Herbert Xu Signed-off-by: David S. Miller --- drivers/ide/ide-dma.c | 1 + drivers/ide/ide-io.c | 2 +- include/linux/ide.h | 1 + 3 files changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/ide/ide-dma.c b/drivers/ide/ide-dma.c index ee58c88..fd40a81 100644 --- a/drivers/ide/ide-dma.c +++ b/drivers/ide/ide-dma.c @@ -492,6 +492,7 @@ ide_startstop_t ide_dma_timeout_retry(ide_drive_t *drive, int error) if (rq) { hwif->rq = NULL; rq->errors = 0; + ide_requeue_and_plug(drive, rq); } return ret; } diff --git a/drivers/ide/ide-io.c b/drivers/ide/ide-io.c index db96138..172ac92 100644 --- a/drivers/ide/ide-io.c +++ b/drivers/ide/ide-io.c @@ -566,7 +566,7 @@ plug_device_2: blk_plug_device(q); } -static void ide_requeue_and_plug(ide_drive_t *drive, struct request *rq) +void ide_requeue_and_plug(ide_drive_t *drive, struct request *rq) { struct request_queue *q = drive->queue; unsigned long flags; diff --git a/include/linux/ide.h b/include/linux/ide.h index 97e6ab4..3239d1c 100644 --- a/include/linux/ide.h +++ b/include/linux/ide.h @@ -1169,6 +1169,7 @@ extern void ide_stall_queue(ide_drive_t *drive, unsigned long timeout); extern void ide_timer_expiry(unsigned long); extern irqreturn_t ide_intr(int irq, void *dev_id); extern void do_ide_request(struct request_queue *); +extern void ide_requeue_and_plug(ide_drive_t *drive, struct request *rq); void ide_init_disk(struct gendisk *, ide_drive_t *); -- 1.8.2.3