On Sun, 2016-05-08 at 12:14 -0700, Dan Williams wrote:
> On Thu, May 5, 2016 at 5:29 PM, Toshi Kani <toshi.kani@xxxxxxx> wrote:
:
> > +int bdev_supports_dax(struct super_block *sb, int blocksize)
> > +{
> > + struct blk_dax_ctl dax = {
> > + .sector = 0,
> > + .size = PAGE_SIZE,
> > + };
> > + int err;
> > +
> > + if (blocksize != PAGE_SIZE) {
> > + vfs_msg(sb, KERN_ERR, "error: unsupported blocksize for
> > dax");
> > + return -EINVAL;
> > + }
> > +
> > + err = bdev_direct_access(sb->s_bdev, &dax);
> > + if (err < 0) {
> > + switch (err) {
> > + case -EOPNOTSUPP:
> > + vfs_msg(sb, KERN_ERR,
> > + "error: device does not support dax");
> > + break;
> > + case -EINVAL:
> > + vfs_msg(sb, KERN_ERR,
> > + "error: unaligned partition for dax");
> > + break;
> > + default:
> > + vfs_msg(sb, KERN_ERR,
> > + "error: dax access failed (%d)", err);
> > + }
> > + return err;
> > + }
> > +
> > + return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(bdev_supports_dax);
>
> This patch should replace blkdev_dax_capable(), or just reuse that
> existing routine, or am I missing something?
Good question. bdev_supports_dax() is a helper function tailored for the
filesystem's mount -o dax case. While blkdev_dax_capable() is similar, it
does not need error messages like "device does not support dax" since it
implicitly enables dax when capable. So, I think we can keep
blkdev_dax_capable(), but change it to call bdev_direct_access() so that
actual check is performed in a single place.
Thanks,
-Toshi
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