On Wed, Jul 02, 2008 at 02:45:55PM -0700, Mingming Cao wrote:
> +In ext4/JBD2 this ordered mode implementation is different than ext3/JBD
> +ordered mode. First it get rid of using buffer heads to enforce the ordering
> +between metadata change with the related data chage. Instead, in the new
> +ordering mode, it keeps track of per transaction journalled inode list, and
> +flush all the dirty pages for those inodes, when committing that transaction.
> +Second, the new ordered mode reverse the lock ordering of the page lock and
> +transaction lock, to fixing the locking issue in the new mode, and also provide
> +easy support for delayed allocation over the new ordered mode
This is implementation detail that doesn't belong in
Documentation/filesystems/ext4.txt; a user won't care about this kind
of detail.
However, it is *perfect* for the the (as-yet-undocumented) patch
comment for the new ordered mode patch in the series. I rewrote it
for gramatical correctness and clarity thusly, for the patch
delalloc-new-ordered-mode.patch:
This provides a new ordered mode implementation which gets rid of using
buffer heads to enforce the ordering between metadata change with the
related data chage. Instead, in the new ordering mode, it keeps track
of all of the inodes touched by each transaction on a list, and when
that transaction is committed, it flushes all of the dirty pages for
those inodes. In addition, the new ordered mode reverses the lock
ordering of the page lock and transaction lock, which provides easier
support for delayed allocation.
- Ted
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