On Wed, Oct 27 2021 at 8:16P -0400,
Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
> I am going to change the subject of this patch to:
>
> dax: remove ->dax_supported()
>
> On Sun, Oct 17, 2021 at 9:41 PM Christoph Hellwig <hch@xxxxxx> wrote:
> >
>
> I'll add a bit more background to help others review this.
>
> The ->dax_supported() operation arranges for a stack of devices to
> each answer the question "is dax operational". That request routes to
> generic_fsdax_supported() at last level device and that attempted an
> actual dax_direct_access() call and did some sanity checks. However,
> those sanity checks can be validated in other ways and with those
> removed the only question to answer is "has each block device driver
> in the stack performed dax_add_host()". That can be validated without
> a dax_operation. So, just open code the block size and dax_dev == NULL
> checks in the callers, and delete ->dax_supported().
>
> Mike, let me know if you have any concerns.
Thanks for your additional background, it helped.
>
> > Just open code the block size and dax_dev == NULL checks in the callers.
> >
> > Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> > ---
> > drivers/dax/super.c | 36 ------------------------------------
> > drivers/md/dm-table.c | 22 +++++++++++-----------
> > drivers/md/dm.c | 21 ---------------------
> > drivers/md/dm.h | 4 ----
> > drivers/nvdimm/pmem.c | 1 -
> > drivers/s390/block/dcssblk.c | 1 -
> > fs/erofs/super.c | 11 +++++++----
> > fs/ext2/super.c | 6 ++++--
> > fs/ext4/super.c | 9 ++++++---
> > fs/xfs/xfs_super.c | 21 ++++++++-------------
> > include/linux/dax.h | 14 --------------
> > 11 files changed, 36 insertions(+), 110 deletions(-)
> >
> > diff --git a/drivers/dax/super.c b/drivers/dax/super.c
> > index 482fe775324a4..803942586d1b6 100644
> > --- a/drivers/dax/super.c
> > +++ b/drivers/dax/super.c
> > @@ -108,42 +108,6 @@ struct dax_device *fs_dax_get_by_bdev(struct block_device *bdev)
> > return dax_dev;
> > }
> > EXPORT_SYMBOL_GPL(fs_dax_get_by_bdev);
> > -
> > -bool generic_fsdax_supported(struct dax_device *dax_dev,
> > - struct block_device *bdev, int blocksize, sector_t start,
> > - sector_t sectors)
> > -{
> > - if (blocksize != PAGE_SIZE) {
> > - pr_info("%pg: error: unsupported blocksize for dax\n", bdev);
> > - return false;
> > - }
> > -
> > - if (!dax_dev) {
> > - pr_debug("%pg: error: dax unsupported by block device\n", bdev);
> > - return false;
> > - }
> > -
> > - return true;
> > -}
> > -EXPORT_SYMBOL_GPL(generic_fsdax_supported);
> > -
> > -bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev,
> > - int blocksize, sector_t start, sector_t len)
> > -{
> > - bool ret = false;
> > - int id;
> > -
> > - if (!dax_dev)
> > - return false;
> > -
> > - id = dax_read_lock();
> > - if (dax_alive(dax_dev) && dax_dev->ops->dax_supported)
> > - ret = dax_dev->ops->dax_supported(dax_dev, bdev, blocksize,
> > - start, len);
> > - dax_read_unlock(id);
> > - return ret;
> > -}
> > -EXPORT_SYMBOL_GPL(dax_supported);
> > #endif /* CONFIG_BLOCK && CONFIG_FS_DAX */
> >
> > enum dax_device_flags {
> > diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> > index 1fa4d5582dca5..4ae671c2168ea 100644
> > --- a/drivers/md/dm-table.c
> > +++ b/drivers/md/dm-table.c
> > @@ -807,12 +807,14 @@ void dm_table_set_type(struct dm_table *t, enum dm_queue_mode type)
> > EXPORT_SYMBOL_GPL(dm_table_set_type);
> >
> > /* validate the dax capability of the target device span */
> > -int device_not_dax_capable(struct dm_target *ti, struct dm_dev *dev,
> > +static int device_not_dax_capable(struct dm_target *ti, struct dm_dev *dev,
> > sector_t start, sector_t len, void *data)
> > {
> > - int blocksize = *(int *) data;
> > + if (dev->dax_dev)
> > + return false;
> >
> > - return !dax_supported(dev->dax_dev, dev->bdev, blocksize, start, len);
> > + pr_debug("%pg: error: dax unsupported by block device\n", dev->bdev);
Would prefer the use of DMDEBUG() here (which doesn't need trailing \n)
But otherwise:
Acked-by: Mike Snitzer <snitzer@xxxxxxxxxx>
