Re: [patch 9/16] direct-to-BIO writeback for writeback-mode ext3

[Andrew Morton <akpm@zip.com.au>]

Andreas Dilger wrote:
> 
> On Jun 01, 2002  01:42 -0700, Andrew Morton wrote:
> > Turn on direct-to-BIO writeback for ext3 in data=writeback mode.
> 
> A minor note on this (especially minor since I believe data=journal
> doesn't even work in 2.5), but you should probably also change the
> address ops in ext3/ioctl.c if you enable/disable per-inode data
> journaling.

hrm.  Actually, changing journalling mode against a file while
modifications are happening against it is almost certain to explode
if the timing is right.  ISTR that we have seen bug reports against
this on ext3-users.  This is just waaaay too hard to do.

But we can fix it by doing the opposite: create three separate
a_ops instances, one for each journalling mode.  Assign it at
new_inode/read_inode time.

This way, we don't have to do the `ext3_should_journal_data()'
tests all over the place and we just don't care if someone diddles
the journalling mode while the file is otherwise in use.

Another one for my todo list..

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