On Mon, Jan 28, 2013 at 07:02:55PM +0400, Dmitry Monakhov wrote:
> Actually this patch consists of two peaces
> 1) disable merging of uninitialized extents. (1 line change) I'm
> absolutely agree with it.
To be clear, that's this patch chunk (one line change not including
comments :-), right?
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -1579,11 +1576,13 @@ int
ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
struct ext4_extent *ex2)
{
/*
- * Make sure that either both extents are uninitialized, or
- * both are _not_.
+ * Make sure that both extents are initialized. We don't merge
+ * uninitialized extents so that we can be sure that end_io code has
+ * the extent that was written properly split out and conversion to
+ * initialized is trivial.
*/
- if (ext4_ext_is_uninitialized(ex1) ^ ext4_ext_is_uninitialized(ex2))
+ if (ext4_ext_is_uninitialized(ex1) || ext4_ext_is_uninitialized(ex2))
return 0;
The one thing I'm a bit worried about is how much worse will extent
fragmentation be once we do this, but it's clear we need to strive for
correctness first.
- Ted
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