Re: ext3-2.4-0.9.4

Andrew Morton
2001-07-26T15:42:57Z

Daniel Phillips wrote:
>
> Ext3 does *not* leave a
> lot of dirty blocks hanging around in normal operation, so sync is not
> nearly as slow as it is with good old Ext2.

eek.

In fully-journalled data mode, we write everything to the journal
in a linear chunk, wait on it, write a commit block, wait on that
and then release all the just-journalled data into the main
filesystem for conventional bdflush/kupdate writeback in twenty
seconds time.

Calling anything which uses fsync_dev() would cause all that writeback
data to be written out and waited on, with the consequential seeking
storm. Disastrous.

Note that fsync() is OK - in full data journalling mode nothing
is ever attached to i_dirty_buffers.

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