Commit dbc62659 authored Jun 26, 2018 by Ross Zwisler Committed by Mike Snitzer Jun 28, 2018

dm: prevent DAX mounts if not supported



Currently device_supports_dax() just checks to see if the QUEUE_FLAG_DAX
flag is set on the device's request queue to decide whether or not the
device supports filesystem DAX.  Really we should be using
bdev_dax_supported() like filesystems do at mount time.  This performs
other tests like checking to make sure the dax_direct_access() path works.

We also explicitly clear QUEUE_FLAG_DAX on the DM device's request queue if
any of the underlying devices do not support DAX.  This makes the handling
of QUEUE_FLAG_DAX consistent with the setting/clearing of most other flags
in dm_table_set_restrictions().

Now that bdev_dax_supported() explicitly checks for QUEUE_FLAG_DAX, this
will ensure that filesystems built upon DM devices will only be able to
mount with DAX if all underlying devices also support DAX.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Fixes: commit 545ed20e ("dm: add infrastructure for DAX support")
Cc: stable@vger.kernel.org
Acked-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

parent 15256f6c

drivers/md/dm-table.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -885,9 +885,7 @@ EXPORT_SYMBOL_GPL(dm_table_set_type);
		static int device_supports_dax(struct dm_target ti, struct dm_dev dev,
		sector_t start, sector_t len, void *data)
		{
		struct request_queue *q = bdev_get_queue(dev->bdev);

		return q && blk_queue_dax(q);
		return bdev_dax_supported(dev->bdev, PAGE_SIZE);
		}

		static bool dm_table_supports_dax(struct dm_table *t)
		@@ -1907,6 +1905,9 @@ void dm_table_set_restrictions(struct dm_table t, struct request_queue q,

		if (dm_table_supports_dax(t))
		blk_queue_flag_set(QUEUE_FLAG_DAX, q);
		else
		blk_queue_flag_clear(QUEUE_FLAG_DAX, q);

		if (dm_table_supports_dax_write_cache(t))
		dax_write_cache(t->md->dax_dev, true);

drivers/md/dm.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -1056,7 +1056,6 @@ static long dm_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
		if (len < 1)
		goto out;
		nr_pages = min(len, nr_pages);
		if (ti->type->direct_access)
		ret = ti->type->direct_access(ti, pgoff, nr_pages, kaddr, pfn);

		out:

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