Simplify devfs_fsync().

[trasz]

Summary

Simplify devfs_fsync(), by removing it. This might also be a minor
optimization, as vn_isdisk() needs to lock a global mutex.

Tested by: pho

[trasz]

Tested by: pho

[kib]

If doing this, you can simply point vop_fsync member of devfs_specops to vfs_stdfsync, without a need to create the trivial local wrapper.

That said, I believe that the printouts done by the current variant are useful, and the panic is justified until UFS is fixed.

[trasz]

The panic was changed into printf already, as it triggered every time, even when UFS or msdosfs could survive just fine. The warning - I kind of agree, it could be useful, but I don't think it's worth complicating the code just for that.

Also, good point with the vector. I'll fix that.

[trasz]

Remove the pointless wrapper.

[imp]

vop_stdfsync() handles these cases just fine, though the synchronous waiting code looks a bit odd since it only looks at the last bp in the bufobj's dirty chain for the error code, which seems like it would be wrong.
eg

TAILQ_FOREACH(bp, &bo->bo_dirty.bv_hd, b_bobufs)
        if ((error = bp->b_error) == 0)
                continue;

should be

TAILQ_FOREACH(bp, &bo->bo_dirty.bv_hd, b_bobufs)
        if ((error = bp->b_error) != 0)
                break;

but that's I guess unrelated.