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block: add cond_resched() to potentially long running ioctl discard loop 

When mkfs issues a full device discard and the device only
supports discards of a smallish size, we can loop in
blkdev_issue_discard() for a long time. If preempt isn't enabled,
this can turn into a softlock situation and the kernel will
start complaining.

Add an explicit cond_resched() at the end of the loop to avoid
that.

Cc: stable@kernel.org
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Jens Axboe 2014-02-12 09:34:01 -07:00
parent abb97b8c50
commit c8123f8c9c
1 changed files with 8 additions and 0 deletions
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8
block/blk-lib.c
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@ -119,6 +119,14 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
atomic_inc(&bb.done);
submit_bio(type, bio);
/*
* We can loop for a long time in here, if someone does
* full device discards (like mkfs). Be nice and allow
* us to schedule out to avoid softlocking if preempt
* is disabled.
*/
cond_resched();
}
blk_finish_plug(&plug);