When pdflush is writing back inodes, it can get stuck on inode cluster
buffers that are currently under I/O. This occurs when we write data to
multiple inodes in the same inode cluster at the same time.

Effectively, delayed allocation marks the inode dirty during the data
writeback. Hence if the inode cluster was flushed during the writeback of
the first inode, the writeback of the second inode will block waiting for
the inode cluster write to complete before writing it again for the newly
dirtied inode.

Basically, we want to avoid this from happening so we don't block pdflush
and slow down all of writeback. Hence we introduce a non-blocking async
inode flush flag that pdflush uses. If this flag is set, we use
non-blocking operations (e.g. try locks) whereever we can to avoid
blocking or extra I/O being issued.

SGI-PV: 970925
SGI-Modid: xfs-linux-melb:xfs-kern:30501a
Signed-off-by: NDavid Chinner <dgc@sgi.com>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>

This reverts commit b394e43e.

Lachlan McIlroy says:
    It tried to fix an issue where log replay is replaying an inode cluster
    initialisation transaction that should not be replayed because the inode
    cluster on disk is more up to date.  Since we don't log file sizes (we
    rely on inode flushing to get them to disk) then we can't just replay
    all the transations in the log and expect the inode to be completely
    restored.  We lose file size updates.  Unfortunately this fix is causing
    more (serious) problems than it is fixing.

SGI-PV: 969656
SGI-Modid: xfs-linux-melb:xfs-kern:29804a
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>
Signed-off-by: NTim Shimmin <tes@sgi.com>

This reverts commit b394e43e.

SGI-PV: 969656
SGI-Modid: xfs-linux-melb:xfs-kern:29804a
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>
Signed-off-by: NTim Shimmin <tes@sgi.com>

SGI-PV: 969656
SGI-Modid: xfs-linux-melb:xfs-kern:29676a
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>
Signed-off-by: NDavid Chinner <dgc@sgi.com>
Signed-off-by: NTim Shimmin <tes@sgi.com>

pure bloat.

SGI-PV: 952969
SGI-Modid: xfs-linux-melb:xfs-kern:26251a
Signed-off-by: NNathan Scott <nathans@sgi.com>

interface.

SGI-PV: 953338
SGI-Modid: xfs-linux-melb:xfs-kern:26103a
Signed-off-by: NNathan Scott <nathans@sgi.com>

shutdown vop flags consistent with sync vop flags declarations too.

SGI-PV: 939911
SGI-Modid: xfs-linux-melb:xfs-kern:26096a
Signed-off-by: NNathan Scott <nathans@sgi.com>

boilerplate.

SGI-PV: 913862
SGI-Modid: xfs-linux:xfs-kern:23903a
Signed-off-by: NNathan Scott <nathans@sgi.com>

SGI-PV: 943122
SGI-Modid: xfs-linux:xfs-kern:23901a
Signed-off-by: NNathan Scott <nathans@sgi.com>

which can cause an extent hole to be filled and a free extent to be
processed. In this case, we make a few mistakes: forget to pass back the
transaction, forget to put a hold on the buffer and forget to add the buf
to the new transaction.

SGI-PV: 940366
SGI-Modid: xfs-linux:xfs-kern:23594a
Signed-off-by: NTim Shimmin <tes@sgi.com>
Signed-off-by: NNathan Scott <nathans@sgi.com>

SGI-PV: 932952
SGI-Modid: xfs-linux:xfs-kern:22805a
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!