Re: [PATCH V2] btrfs: implement delayed inode items operation

[Chris Mason <chris.mason@oracle.com>]

Excerpts from Miao Xie's message of 2011-02-18 04:08:12 -0500:
> Hi, Chris
> CC Tsutomu Itoh
> 
> On Thu, 17 Feb 2011 20:09:00 -0500, Chris Mason wrote:
> > Excerpts from Miao Xie's message of 2011-02-17 00:48:40 -0500:
> >> Compare with Ext3/4, the performance of file creation and deletion on btrfs
> >> is very poor. the reason is that btrfs must do a lot of b+ tree insertions,
> >> such as inode item, directory name item, directory name index and so on.
> >>
> >> If we can do some delayed b+ tree insertion or deletion, we can improve the
> >> performance, so we made this patch which implemented delayed directory name
> >> index insertion/deletion and delayed inode update.
> >
> > This work is really cool, thanks for doing it.  I'm starting a run on
> > this tonight and if all goes well I'll review in detail and try to queue
> > it along with the per-subvolume storage bits for .39.
> 
> There is a hang-up problem in this patch, that is the task which does delayed item
> balance and the task which commits the transaction will wait for each other, and
> the filesystem will hang up. This is reported by Tsutomu Itoh.
> 
> I have made the third version of this patch, will post it later.

BUG: spinlock cpu recursion on CPU#2, btrfs-delayed-m/2762
 lock: ffff88004f47bfb0, .magic: dead4ead, .owner: btrfs-delayed-m/2763, .owner_cpu: 2
Pid: 2762, comm: btrfs-delayed-m Not tainted 2.6.38-rc4-josef+ #209
Call Trace:
 [<ffffffff812621f1>] ? spin_bug+0x9c/0xa3
 [<ffffffff8126225b>] ? do_raw_spin_lock+0x63/0x13c
 [<ffffffff815c31c5>] ? _raw_spin_lock+0xe/0x10
 [<ffffffffa004e5e3>] ? btrfs_try_spin_lock+0x2a/0x86 [btrfs]
 [<ffffffffa000ddc1>] ? btrfs_search_slot+0x5dd/0x73d [btrfs]
 [<ffffffffa001e77e>] ? btrfs_lookup_inode+0x2f/0x91 [btrfs]
 [<ffffffff815c21b2>] ? mutex_lock+0x31/0x48
 [<ffffffffa0061ac8>] ? btrfs_update_delayed_inode+0x73/0x11e [btrfs]
 [<ffffffffa0025454>] ? start_transaction+0x19f/0x1e3 [btrfs]
 [<ffffffffa0062026>] ? btrfs_async_run_delayed_node_done+0xd6/0x180 [btrfs]
 [<ffffffff8107c0e9>] ? process_timeout+0x0/0x10
 [<ffffffffa004a44f>] ? worker_loop+0x17e/0x49f [btrfs]
 [<ffffffffa004a2d1>] ? worker_loop+0x0/0x49f [btrfs]
 [<ffffffffa004a2d1>] ? worker_loop+0x0/0x49f [btrfs]
 [<ffffffff81089d9c>] ? kthread+0x82/0x8a
 [<ffffffff810347d4>] ? kernel_thread_helper+0x4/0x10
 [<ffffffff81089d1a>] ? kthread+0x0/0x8a
 [<ffffffff810347d0>] ? kernel_thread_helper+0x0/0x10


I hit this one overnight with spinlock debugging on.  Is it the same
problem you've fixed?

-chris