Under heavy multi-way parallel create workloads, the VFS struggles
to write back all the inodes that have been changed in age order.
The bdi flusher thread becomes CPU bound, spending 85% of it's time
in the VFS code, mostly traversing the superblock dirty inode list
to separate dirty inodes old enough to flush.

We already keep an index of all metadata changes in age order - in
the AIL - and continued log pressure will do age ordered writeback
without any extra overhead at all. If there is no pressure on the
log, the xfssyncd will periodically write back metadata in ascending
disk address offset order so will be very efficient.

Hence we can stop marking VFS inodes dirty during transaction commit
or when changing timestamps during transactions. This will keep the
inodes in the superblock dirty list to those containing data or
unlogged metadata changes.

However, the timstamp changes are slightly more complex than this -
there are a couple of places that do unlogged updates of the
timestamps, and the VFS need to be informed of these. Hence add a
new function xfs_trans_ichgtime() for transactional changes,
and leave xfs_ichgtime() for the non-transactional changes.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NAlex Elder <aelder@sgi.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

Currently we need to either call IHOLD or xfs_trans_ihold on an inode when
joining it to a transaction via xfs_trans_ijoin.

This patches instead makes xfs_trans_ijoin usable on it's own by doing
an implicity xfs_trans_ihold, which also allows us to drop the third
argument.  For the case where we want to hold a reference on the inode
a xfs_trans_ijoin_ref wrapper is added which does the IHOLD and marks
the inode for needing an xfs_iput.  In addition to the cleaner interface
to the caller this also simplifies the implementation.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

Currently we track log item descriptor belonging to a transaction using a
complex opencoded chunk allocator.  This code has been there since day one
and seems to work around the lack of an efficient slab allocator.

This patch replaces it with dynamically allocated log item descriptors
from a dedicated slab pool, linked to the transaction by a linked list.

This allows to greatly simplify the log item descriptor tracking to the
point where it's just a couple hundred lines in xfs_trans.c instead of
a separate file.  The external API has also been simplified while we're
at it - the xfs_trans_add_item and xfs_trans_del_item functions to add/
delete items from a transaction have been simplified to the bare minium,
and the xfs_trans_find_item function is replaced with a direct dereference
of the li_desc field.  All debug code walking the list of log items in
a transaction is down to a simple list_for_each_entry.

Note that we could easily use a singly linked list here instead of the
double linked list from list.h as the fastpath only does deletion from
sequential traversal.  But given that we don't have one available as
a library function yet I use the list.h functions for simplicity.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDave Chinner <david@fromorbit.com>

Dmapi support was never merged upstream, but we still have a lot of hooks
bloating XFS for it, all over the fast pathes of the filesystem.

This patch drops over 700 lines of dmapi overhead.  If we'll ever get HSM
support in mainline at least the namespace events can be done much saner
in the VFS instead of the individual filesystem, so it's not like this
is much help for future work.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDave Chinner <dchinner@redhat.com>

The block number comes from bulkstat based inode lookups to shortcut
the mapping calculations. We ar enot able to trust anything from
bulkstat, so drop the block number as well so that the correct
lookups and mappings are always done.
Signed-off-by: NDave Chinner <dchinner@redhat.com>
Reviewed-by: NChristoph Hellwig <hch@lst.de>

xfs_trans_iget is a wrapper for xfs_iget that adds the inode to the
transaction after it is read.  Except when the inode already is in the
inode cache, in which case it returns the existing locked inode with
increment lock recursion counts.

Now, no one in the tree every decrements these lock recursion counts,
so any user of this gets a potential double unlock when both the original
owner of the inode and the xfs_trans_iget caller unlock it.  When looking
back in a git bisect in the historic XFS tree there was only one place
that decremented these counts, xfs_trans_iput.  Introduced in commit
ca25df7a840f426eb566d52667b6950b92bb84b5 by Adam Sweeney in 1993,
and removed in commit 19f899a3ab155ff6a49c0c79b06f2f61059afaf3 by
Steve Lord in 2003.  And as long as it didn't slip through git bisects
cracks never actually used in that time frame.

A quick audit of the callers of xfs_trans_iget shows that no caller
really relies on this behaviour fortunately - xfs_ialloc allows this
inode from disk so it must not be there before, and all the RT allocator
routines only every add each RT bitmap inode once.

In addition to removing lots of code and reducing the size of the inode
item this patch also avoids the double inode cache lookup in each
create/mkdir/mknod transaction.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NAlex Elder <aelder@sgi.com>
Signed-off-by: NFelix Blyakher <felixb@sgi.com>

Use xfs_trans_ijoin in xfs_trans_iget in case we need to join an inode into
a transaction instead of opencoding it.  Based on a discussion with and an
incomplete patch from Niv Sardi.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDave Chinner <david@fromorbit.com>
Signed-off-by: NNiv Sardi <xaiki@sgi.com>

kmem_free() function takes (ptr, size) arguments but doesn't actually use
second one.

This patch removes size argument from all callsites.

SGI-PV: 981498
SGI-Modid: xfs-linux-melb:xfs-kern:31050a
Signed-off-by: NDenys Vlasenko <vda.linux@googlemail.com>
Signed-off-by: NDavid Chinner <dgc@sgi.com>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>

The writer field is not needed for non_DEBU builds so remove it. While
we're at i also clean up the interface for is locked asserts to go through
and xfs_iget.c helper with an interface like the xfs_ilock routines to
isolated the XFS codebase from mrlock internals. That way we can kill
mrlock_t entirely once rw_semaphores grow an islocked facility. Also
remove unused flags to the ilock family of functions.

SGI-PV: 976035
SGI-Modid: xfs-linux-melb:xfs-kern:30902a
Signed-off-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NLachlan McIlroy <lachlan@sgi.com>

pure bloat.

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

these typos.

SGI-PV: 904196
SGI-Modid: xfs-linux-melb:xfs-kern:25539a
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>

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!