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authorVivek Goyal <vgoyal@redhat.com>2020-08-19 18:19:39 -0400
committerMiklos Szeredi <mszeredi@redhat.com>2020-09-10 11:39:22 +0200
commit1a9d5d405962d134acb8efb4ccb4bc17805134c7 (patch)
treea68ee728ad2e5f65ba5bd049360bdc395100d3a7 /drivers/dax
parent27bd6129a4c5b1269540c925bfda1c280cbb9f1d (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>
Diffstat (limited to 'drivers/dax')
-rw-r--r--drivers/dax/super.c3
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);