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block: Prevent hang_check firing during long I/O

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During long I/O operations, the hang_check timer may fire,
trigger stack dumps that unnecessarily alarm the user.

Eg.  hdparm --security-erase NULL /dev/sdb  ## can take *hours* to complete

So, if hang_check is armed, we should wake up periodically
to prevent it from triggering.  This patch uses a wake-up interval
equal to half the hang_check timer period, which keeps overhead low enough.

Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
This commit is contained in:
Mark Lord 2010-09-24 09:51:13 -04:00 committed by Jens Axboe
parent 749ef9f842
commit 4b1977698c
1 changed files with 8 additions and 1 deletions
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9
block/blk-exec.c
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@ -80,6 +80,7 @@ int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
DECLARE_COMPLETION_ONSTACK(wait);
char sense[SCSI_SENSE_BUFFERSIZE];
int err = 0;
unsigned long hang_check;
/*
* we need an extra reference to the request, so we can look at
@ -95,7 +96,13 @@ int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
rq->end_io_data = &wait;
blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
wait_for_completion(&wait);
/* Prevent hang_check timer from firing at us during very long I/O */
hang_check = sysctl_hung_task_timeout_secs;
if (hang_check)
while (!wait_for_completion_timeout(&wait, hang_check * (HZ/2)));
else
wait_for_completion(&wait);
if (rq->errors)
err = -EIO;