From: Stefan Hajnoczi <stefanha@xxxxxxxxxx> Although struct dax_device itself is not tied to a block device, some DAX code assumes there is a block device. Make block devices optional by allowing bdev to be NULL in commonly used DAX APIs. When there is no block device: * Skip the partition offset calculation in bdev_dax_pgoff() * Skip the blkdev_issue_zeroout() optimization Note that more block device assumptions remain but I haven't reach those code paths yet. Cc: Dan Williams <dan.j.williams@xxxxxxxxx> Signed-off-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx> --- drivers/dax/super.c | 3 ++- fs/dax.c | 7 ++++++- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/dax/super.c b/drivers/dax/super.c index 26a654dbc69a..3cbc97f3e653 100644 --- a/drivers/dax/super.c +++ b/drivers/dax/super.c @@ -46,7 +46,8 @@ EXPORT_SYMBOL_GPL(dax_read_unlock); int bdev_dax_pgoff(struct block_device *bdev, sector_t sector, size_t size, pgoff_t *pgoff) { - phys_addr_t phys_off = (get_start_sect(bdev) + sector) * 512; + sector_t start_sect = bdev ? get_start_sect(bdev) : 0; + phys_addr_t phys_off = (start_sect + sector) * 512; if (pgoff) *pgoff = PHYS_PFN(phys_off); diff --git a/fs/dax.c b/fs/dax.c index 6bf81f931de3..a11147bbaf9e 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -1046,7 +1046,12 @@ static vm_fault_t dax_load_hole(struct xa_state *xas, static bool dax_range_is_aligned(struct block_device *bdev, unsigned int offset, unsigned int length) { - unsigned short sector_size = bdev_logical_block_size(bdev); + unsigned short sector_size; + + if (!bdev) + return false; + + sector_size = bdev_logical_block_size(bdev); if (!IS_ALIGNED(offset, sector_size)) return false; -- 2.20.1