On Saturday 30 April 2011 01:15 AM, Amir Goldstein wrote:
On Tue, Apr 26, 2011 at 3:25 PM, Ted Ts'o<tytso@xxxxxxx> wrote:
On Tue, Apr 26, 2011 at 05:23:21PM +0800, Ding Dinghua wrote:
I think it's not only a performance issue but more important, a
correctness issue.
Revoke table is used for preventing the wrong replay of journal which
cause data corruption:
If block A has been journalled its modification, committed to journal
and hasn't been checkpointed,
and in later transactions block A is freed and reused for data in
no-journalled-data mode, then If
we don't have revoke table which recording the releasing event, replay
of journal will overwrite the new data,
which causing data corruption.
Yes, this is correct. It should be covered fairly well in Stephen
Tweedie's, "Journaling the ext2fs file system" paper, which you can
find at:
https://ext4.wiki.kernel.org/index.php/Publications
Actually, the original paper has no mention of revoke records.
I went out to look for useful documentation on journal forget/revoke
and came back empty handed as well.
if you'd like more details.
Hope this helps!
- Ted
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Yes, I tried some other papers too, but no use. Anyway I've figured out
that for my change, I dont need any kind of journalling related
facilities, so I am going to bypass it completely.
Niraj
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