Hi Ted:
I think the following patch is sufficient. It explicitly sets the aops to
ext4_writeback_aops if there is no delayed allocation and no journal.
I tested the locale-gen example with all combinations of
data=writeback
data=ordered
data=journal
<no journal at all>
and
delalloc
nodelalloc
and it works correctly now. The paths for writeback seem fine to me for an
inode w/o a journal.
Signed-off-by: Curt Wohlgemuth <curtw@xxxxxxxxxx>
---
--- 2.6.26/fs/ext4/inode.c.orig 2009-06-09 20:05:27.000000000 -0700
+++ 2.6.26/fs/ext4/inode.c 2009-06-22 08:55:13.000000000 -0700
@@ -3442,15 +3442,12 @@ static const struct address_space_operat
void ext4_set_aops(struct inode *inode)
{
- if (ext4_should_order_data(inode) &&
- test_opt(inode->i_sb, DELALLOC))
+ if (test_opt(inode->i_sb, DELALLOC))
inode->i_mapping->a_ops = &ext4_da_aops;
else if (ext4_should_order_data(inode))
inode->i_mapping->a_ops = &ext4_ordered_aops;
- else if (ext4_should_writeback_data(inode) &&
- test_opt(inode->i_sb, DELALLOC))
- inode->i_mapping->a_ops = &ext4_da_aops;
- else if (ext4_should_writeback_data(inode))
+ else if (ext4_should_writeback_data(inode) ||
+ EXT4_JOURNAL(inode) == NULL)
inode->i_mapping->a_ops = &ext4_writeback_aops;
else
inode->i_mapping->a_ops = &ext4_journalled_aops;
On Wed, Jun 17, 2009 at 4:46 PM, Theodore Tso<tytso@xxxxxxx> wrote:
> Hi Curt,
>
> Thanks for your analysis of the bug. The reason for the strange logic
> in ext4_set_aops() is because at the moment the code doesn't support
> the combination of data=journalled && delalloc. That's why it was
> explicitly checking for ext4_should_order_data() and
> ext4_should_writeback_data().
>
> We have a check for this in ext4_fill_super(), so your patch should be
> safe, since the combination of ext4_should_journal_data &&
> test_opt(inode->i_sb, DELALLOC) should never happen.
>
> As to your question of whether the nodelalloc and nojournal case
> should really be ext4_journalled_aops, I suspect ext4_writeback_aops
> makes more sense. I haven't audited all of the code paths to make
> sure they DTRT in the non-journalled case yet, though.
>
> - Ted
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