Commit f4fa3424 authored May 26, 2011 by Jens Axboe

block: fix oops on !disk->queue and sysfs discard alignment display



Eric Dumazet reports:

----

At boot, I have a crash in part_discard_alignment_show+0x1b/0x50

CR2 : 000006ac

fault in : mov    0x2c(%rcx),%edx

I suspect commit 23ceb5b7 (block: Remove extra
discard_alignment from hd_struct) being in fault

----

Not quite known how ->queue can be NULL while the sysfs entry
exists, but lets play it safe and check for a NULL queue.
The rest of the sysfs show strategies in check.c do not dereference
disk->queue.

Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

parent 4db70f73

fs/partitions/check.c

+5 −3

Original line number	Diff line number	Diff line
		@@ -256,10 +256,12 @@ ssize_t part_discard_alignment_show(struct device *dev,
		{
		struct hd_struct *p = dev_to_part(dev);
		struct gendisk *disk = dev_to_disk(dev);
		unsigned int alignment = 0;

		return sprintf(buf, "%u\n",
		queue_limit_discard_alignment(&disk->queue->limits,
		p->start_sect));
		if (disk->queue)
		alignment = queue_limit_discard_alignment(&disk->queue->limits,
		p->start_sect);
		return sprintf(buf, "%u\n", alignment);
		}

		ssize_t part_stat_show(struct device *dev,

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