On Mon, May 9, 2016 at 11:12 AM, Toshi Kani <toshi.kani@xxxxxxx> wrote:
> 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.
Sounds good to me.
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