because aio+dio completions may happen from irq context but we need
process context for converting unwritten extents.  We also queue regular
direct I/O completions to workqueue for regularity, there's only one
queue_work call per syscall.

SGI-PV: 934766
SGI-Modid: xfs-linux:xfs-kern:196857a
Signed-off-by: NChristoph Hellwig <hch@sgi.com>
Signed-off-by: NNathan Scott <nathans@sgi.com>

SGI-PV: 931572
SGI-Modid: xfs-linux-melb:xfs-kern:189560a
Signed-off-by: NDean Roehrich <roehrich@sgi.com>
Signed-off-by: NNathan Scott <nathans@sgi.com>

direct I/O locking changes it is just a wrapper around
VOP_FLUSHINVAL_PAGES, so it's not nessecary anymore.  Keep a simplified
version for kernels < 2.4.22, as these don't have the changed direct I/O
locking.

SGI-PV: 938064
SGI-Modid: xfs-linux:xfs-kern:194420a
Signed-off-by: NChristoph Hellwig <hch@sgi.com>
Signed-off-by: NNathan Scott <nathans@sgi.com>

handling for unwritten extents can be moved out of interrupt context.

SGI Modid: xfs-linux:xfs-kern:22343a
Signed-off-by: NNathan Scott <nathans@sgi.com>
Signed-off-by: NChristoph Hellwig <hch@sgi.com>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!