writes.  In addition flush the disk cache on fsync if the sync cached
operation didn't sync the log to disk (this requires some additional
bookeping in the transaction and log code). If the device doesn't claim to
support barriers, the filesystem has an extern log volume or the trial
superblock write with barriers enabled failed we disable barriers and
print a warning.  We should probably fail the mount completely, but that
could lead to nasty boot failures for the root filesystem.  Not enabled by
default yet, needs more destructive testing first.

SGI-PV: 912426
SGI-Modid: xfs-linux:xfs-kern:198723a
Signed-off-by: NChristoph Hellwig <hch@sgi.com>
Signed-off-by: NNathan Scott <nathans@sgi.com>

SGI-PV: 931456
SGI-Modid: xfs-linux:xfs-kern:23155a
Signed-off-by: NTim Shimmin <tes@sgi.com>
Signed-off-by: NNathan Scott <nathans@sgi.com>

SGI-PV: 936255
SGI-Modid: xfs-linux:xfs-kern:192760a
Signed-off-by: NChristoph Hellwig <hch@sgi.com>
Signed-off-by: NNathan Scott <nathans@sgi.com>

SGI-PV: 936255
SGI-Modid: xfs-linux:xfs-kern:192759a
Signed-off-by: NChristoph Hellwig <hch@sgi.com>
Signed-off-by: NNathan Scott <nathans@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!