On Mon, Sep 29, 2008 at 10:39 AM, Theodore Tso <tytso mit edu
> On Mon, Sep 29, 2008 at 09:24:33AM -0600, Chris Worley wrote:
>> On Tue, Sep 16, 2008 at 3:32 PM, Chris Worley <worleys gmail com
>> > For example, in balloc.c I'm seeing ext3_free_blocks_sb
>> > calls ext3_clear_bit_atomic at the bottom... is that when the block is
>> > freed? Are all blocks freed here?
>> David Woodhouse, in an article at http://lwn.net/Articles/293658/
>> implementing the T10/T13 committees "Trim" request in 2.6.28 kernels.
>> Would it be appropriate to call "blkdev_issue_discard" at the bottom
>> of ext3_free_blocks_sb where ext3_clear_bit_atomic is being called?
> Unfortunately, it's not as simple as that. The problem is that as
> soon as you call trim, the drive is allowed to discard the contents of
> that block so that future attempts to read from that block returns all
> zeros. Therefore we can't call Trim until after the transaction has
> committed. That means we have to keep a linked list of block extents
> that are to be trimmed attached to the commit object, and only send
> the trim requests once the commit block has been written to disk.
> It's on the ext4 developer's TODO list to add Trim support to ext3 and