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authorMark Lord <kernel@teksavvy.com>2010-09-24 09:51:13 -0400
committerJens Axboe <jaxboe@fusionio.com>2010-09-24 15:52:09 +0200
commit4b1977698ceb4c4caa800d475127139da49966f9 (patch)
tree9302bafc15dfb6d3923febaa982feb2cb12063cb /block
parent749ef9f8423054e326f3a246327ed2db4b6d395f (diff)
downloadlinux-4b1977698ceb4c4caa800d475127139da49966f9.tar.gz
block: Prevent hang_check firing during long I/O
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>
Diffstat (limited to 'block')
-rw-r--r--block/blk-exec.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/block/blk-exec.c b/block/blk-exec.c
index e1672f14840e..cf1456a02acd 100644
--- a/block/blk-exec.c
+++ b/block/blk-exec.c
@@ -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;