LU-6260 llite: add support for direct IO api changes

LU-6260 llite: add support for direct IO api changes

For the 3.16 kernels the direct_IO api changed which
breaks the lustre build. This patch adds support back
for direct IO on newer kernels. Backported from the
upstream lustre client.

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Linux-commit: d8d3d94b80aa1a1c0ca75c58b8abdc7356f38418
pass iov_iter to ->direct_IO()

unmodified, for now

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Linux-commit: a6cbcd4a4a85e2fdb0b3344b88df2e8b3d526b9e
get rid of pointless iov_length() in ->direct_IO()

all callers have iov_length(iter->iov, iter->nr_segs) == iov_iter_count(iter)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Linux-commit: 886a39115005ced8b15ab067c9c2a8d546b40a5e

new primitive: iov_iter_alignment()

returns the value aligned as badly as the worst remaining segment
in iov_iter is.  Use instead of open-coded equivalents.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Linux-commit: 91f79c43d1b54d7154b118860d81b39bad07dfff

new helper: iov_iter_get_pages_alloc()

same as iov_iter_get_pages(), except that pages array is allocated
(kmalloc if possible, vmalloc if that fails) and left for caller to
free.  Lustre and NFS ->direct_IO() switched to it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Linux-commit: 1d8cb70c7bdda47125ed551fc390aa9597c5f264
drivers: staging: lustre: Fix space required after that ',' errors

Fix checkpatch.pl space required after that ',' errors

Signed-off-by: Greg Donald <gdonald@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Linux-commit: ef96fdddcd386c88fee1f2078a174943472b615e
staging: lustre: lustre: llite: use DIV_ROUND_UP

    The kernel.h macro DIV_ROUND_UP performs the computation (((n) + (d) - 1) /
    (d)) but is perhaps more readable.

    Coccinelle script used :

    // <smpl>
    @haskernel@
    @@
    @depends on haskernel@
    expression n,d;
    @@
    (
    - (n + d - 1) / d
    + DIV_ROUND_UP(n,d)
    |
    - (n + (d - 1)) / d
    + DIV_ROUND_UP(n,d)
    )
    @depends on haskernel@
    expression n,d;
    expression n,d;
    @@
    - DIV_ROUND_UP(n,(d))
    + DIV_ROUND_UP(n,d)
    // </smpl>

Signed-off-by: Tapasweni Pathak <tapaswenipathak@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Linux-commit: 9fb186cf6907ba4e873d8396d7e5abfa4f22ca4e

Staging: Lustre: rw26.c: include according to checkpatch.pl

Signed-off-by: Georges-Axel Jaloyan <georges-axel.jaloyan@ens.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Linux-commit: 6f67376318abea58589ebe6d69dffeabb6f6c26a

direct_IO: use iov_iter_rw() instead of rw everywhere

The rw parameter to direct_IO is redundant with iov_iter->type, and
treated slightly differently just about everywhere it's used: some users
do rw & WRITE, and others do rw == WRITE where they should be doing a
bitwise check. Simplify this with the new iov_iter_rw() helper, which
always returns either READ or WRITE.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Linux-commit: 22c6186ecea0be9eff1c399298ad36e94a59995f

direct_IO: remove rw from a_ops->direct_IO()

Now that no one is using rw, remove it completely.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Change-Id: I683e02a0952aec2d8fe387cf3ddaf75010858c7c
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: http://review.whamcloud.com/14665
Tested-by: Jenkins
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Thomas Stibor <t.stibor@gsi.de>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>