Re: [EXT3/JBD] Periodic journal flush not enough?

From: Chris Mason
Date: Mon Mar 29 2004 - 14:18:59 EST

On Mon, 2004-03-29 at 13:56, Stephen C. Tweedie wrote:

> Sounds like it's due to the "b_committed_data" avoidance code. Ext3
> cannot immediately reuse disk space after a delete, because of lazy
> writeback --- until the final writeback of the delete hits disk, we have
> to be able to undo it. And because in non-data-journaled modes we allow
> new disk writes to hit disk before a transaction commit, that means we
> can't reuse deleted blocks until after they are committed.
> I've never seen it reported as a problem outside of artificial test
> scenarios, but if it is something we need to address, Andreas Dilger's
> patch looks good.

Just FYI, reiserfs does something slightly different. When
reiserfs_file_write and get_block routines see -ENOSPC, they get things
into a consistent state, commit the running transaction and try again
(once). It didn't end up very complex...


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