On Fri, Sep 14, 2012 at 08:45:16AM -0400, Josef Bacik wrote:
> On Fri, Sep 14, 2012 at 02:58:07AM -0600, Liu Bo wrote:
> > nocow_only is now an obsolete argument.
> >
>
> Why is it obsolete, it looks like it's being used to me? Thanks,
It's always 0 so the removed code never executes.
I'm tracking where it started, pretty long ago:
commit 7ea394f1192bee1af67ea4762c88ef4b7b0487a8
Author: Yan Zheng <zheng.yan@xxxxxxxxxx>
Date: Tue Aug 5 13:05:02 2008 -0400
without any explanations what it fixes, so I'd be rather cautious here.
I found this hunk from
commit 24bbcf0442ee04660a5a030efdbb6d03f1c275cb
Author: Yan, Zheng <zheng.yan@xxxxxxxxxx>
Date: Thu Nov 12 09:36:34 2009 +0000
Subject: Btrfs: Add delayed iput
does something suspicious:
@@ -991,11 +994,11 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
mutex_unlock(&root->fs_info->trans_mutex);
if (flush_on_commit) {
- btrfs_start_delalloc_inodes(root);
- ret = btrfs_wait_ordered_extents(root, 0);
+ btrfs_start_delalloc_inodes(root, 1);
+ ret = btrfs_wait_ordered_extents(root, 0, 1);
BUG_ON(ret);
} else if (snap_pending) {
- ret = btrfs_wait_ordered_extents(root, 1);
+ ret = btrfs_wait_ordered_extents(root, 0, 1);
BUG_ON(ret);
}
---
The purpose was to add the dealy_iput argument to the end of the list,
but why does it change the nocow from 1 -> 0 in the if(snap_pending) branch?
The code was last touched by Sage in commit
commit 0bdb1db297ab36865a63ee722d35ff0a1f0ae522
Author: Sage Weil <sage@xxxxxxxxxxxx>
Date: Fri Feb 19 14:13:50 2010 -0800
Subject: Btrfs: flush data on snapshot creation
Flush any delalloc extents when we create a snapshot, so that recently
written file data is always included in the snapshot.
A later commit will add the ability to snapshot without the flush, but
most people expect flushing.
Signed-off-by: Sage Weil <sage@xxxxxxxxxxxx>
Signed-off-by: Chris Mason <chris.mason@xxxxxxxxxx>
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 2a36e23..2d654c1 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -997,13 +997,10 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
mutex_unlock(&root->fs_info->trans_mutex);
- if (flush_on_commit) {
+ if (flush_on_commit || snap_pending) {
btrfs_start_delalloc_inodes(root, 1);
ret = btrfs_wait_ordered_extents(root, 0, 1);
BUG_ON(ret);
- } else if (snap_pending) {
- ret = btrfs_wait_ordered_extents(root, 0, 1);
- BUG_ON(ret);
}
---
the calls to btrfs_wait_ordered_extents were same and thus mergeable.
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