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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 545ed20e6d ("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>
This commit is contained in:
Ross Zwisler 2018-06-26 16:30:41 -06:00 committed by Mike Snitzer
parent 15256f6cc4
commit dbc626597c
2 changed files with 5 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
drivers/md/dm-table.c
View File

@ -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);

3
drivers/md/dm.c
View File

@ -1056,8 +1056,7 @@ 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);
ret = ti->type->direct_access(ti, pgoff, nr_pages, kaddr, pfn);
out:
dm_put_live_table(md, srcu_idx);