diff options
| author | Vivek Goyal <vgoyal@redhat.com> | 2020-08-19 18:19:39 -0400 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2020-09-10 11:39:22 +0200 |
| commit | 1a9d5d405962d134acb8efb4ccb4bc17805134c7 (patch) | |
| tree | a68ee728ad2e5f65ba5bd049360bdc395100d3a7 | |
| parent | 27bd6129a4c5b1269540c925bfda1c280cbb9f1d (diff) | |
dax: Modify bdev_dax_pgoff() to handle NULL bdev
virtiofs does not have a block device but it has dax device.
Modify bdev_dax_pgoff() to be able to handle that.
If there is no bdev, that means dax offset is 0. (It can't be a partition
block device starting at an offset in dax device).
This is little hackish. There have been discussions about getting rid
of dax not supporting partitions.
https://lore.kernel.org/linux-fsdevel/20200107125159.GA15745@infradead.org/
IMHO, this path can easily break exisitng users. For example
ioctl(BLKPG_ADD_PARTITION) will start breaking on block devices
supporting DAX. Also, I personally find it very useful to be able to
partition dax devices and still be able to use DAX.
Alternatively, I tried to store offset into dax device information in iomap
interface, but that got NACKed.
https://lore.kernel.org/linux-fsdevel/20200217133117.GB20444@infradead.org/
I can't think of a good path to solve this issue properly. So to make
progress, it seems this patch is least bad option for now and I hope
we can take it.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Vishal L Verma <vishal.l.verma@intel.com>
Cc: "Weiny, Ira" <ira.weiny@intel.com>
Cc: linux-nvdimm@lists.01.org
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
| -rw-r--r-- | drivers/dax/super.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/dax/super.c b/drivers/dax/super.c index 32642634c1bb..2378d51eb5e8 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); |