Theodore Tso wrote:
On Fri, Nov 06, 2009 at 05:26:51PM -0700, Andreas Dilger wrote:
If the choice is between adding a proper transaction here, or not
doing this at all, I'd rather just not do it at all. Of course, I'd
like to work out some kind of compromise, like only updating the
superblock when there is already a shadow BH that is being used to
write to the journal, or similar.
In practice, the superblock is never going to modified in normal
operations, unless a resize happens to be happening. Since we already
force the superblock summary counters to be correct during an unmount
or file system freeze, we really only need this so that it's correct
after a file system crash.
I don't think people generally end up calling statfs() all that
frequently, so it's not clear how much adding a 30 second throttle
would help. Maybe we should just not bother trying to update the
superblock at all on a statfs()?
for now maybe that's better....
But don't we journal the superblock sometimes, not others ... for
example write_super -> ext4_write_super -> ext4_commit_super does no
journaling of superblock modifications. ext4_orphan_add, however, does.
This would likely lead to trouble w/ the debugging patch ... though I
didn't see it ... ?
So I was premature w/ this patch, I think.
Maybe we could unconditionally do the copy-out in
jbd2_journal_write_metadata_buffer() ...?
-Eric
Hmm...
- Ted
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