Updating code base on PR code comments. I adjusted the following parts
of the code base on the comments:
1. Updated zfs_check_direct_enabled() so it now just returns an error.
This removed the need for the added enum and cleaned up the code.
2. Moved acquiring the rangelock from zfs_fillpage() out to
zfs_getpage(). This cleans up the code and gets rid of the need to
pass a boolean into zfs_fillpage() to conditionally gra the
rangelock.
3. Cleaned up the code in both zfs_uio_get_dio_pages() and
zfs_uio_get_dio_pages_iov(). There was no need to have wanted and
maxsize as they were the same thing. Also, since the previous
commit cleaned up the call to zfs_uio_iov_step() the code is much
cleaner over all.
4. Removed dbuf_get_dirty_direct() function.
5. Unified dbuf_read() to account for both block clones and direct I/O
writes. This removes redundant code from dbuf_read_impl() for
grabbingthe BP.
6. Removed zfs_map_page() and zfs_unmap_page() declarations from Linux
headers as those were never called.
Signed-off-by: Brian Atkinson <batkinson@lanl.gov>
b1ee363675