Re: [PATCH 04/12] Btrfs: Fix disk_i_size update corner case

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

On Thu, Nov 12, 2009 at 05:34:21PM +0800, Yan, Zheng wrote:
> There are some cases file extents are inserted without involving
> ordered struct. In these cases, we update disk_i_size directly,
> without checking pending ordered extent and DELALLOC bit. This
> patch extends btrfs_ordered_update_i_size() to handle these cases.

I'm hitting problems with this one in testing.  I think the issue is
that the extent_mutex was protecting us from something like this:

proc1:
process end io for extent [0, 32768]
btrfs_ordered_update_i_size() -- update i_disk_size to 32768

proc2:
process end io for extent [32768, 55536]
btrfs_ordered_update_i_size() find the rbtree entry [0, 32768], exit

proc1:
remove extent [0, 32768] from rbtree

Because the first extent was still in the rbtree, we didn't update
i_size to the full 55536, even though the first extent was fully
processed.  I think I've got this fixed by removing the extents from the
rbtree when we're in btrfs_ordered_update_i_size().  The current patch
does this only when an ordered extent was passed in.

-chris