On 12/10/2014 03:09 AM, Dongsheng Yang wrote:
On 12/09/2014 11:42 PM, Josef Bacik wrote:
On 12/09/2014 06:27 AM, Dongsheng Yang wrote:
When we exceed quota limit in writing, we will free
some reserved extent when we need to drop but not free
account in qgroup. It means, each time we exceed quota
in writing, there will be some remain space in qg->reserved
we can not use any more. If things go on like this, the
all space will be ate up.
Signed-off-by: Dongsheng Yang <yangds.f...@cn.fujitsu.com>
---
fs/btrfs/extent-tree.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index a84e00d..014b7f2 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -5262,8 +5262,11 @@ out_fail:
to_free = 0;
}
spin_unlock(&BTRFS_I(inode)->lock);
- if (dropped)
+ if (dropped) {
+ if (root->fs_info->quota_enabled)
+ btrfs_qgroup_free(root, dropped * root->nodesize);
This needs to be num_bytes + dropped * root->nodesize. Thanks,
Let me try to explain why it did not free num_bytes here.
In out_fail, we did not reserve num_bytes in qgroup successfully, then
we do not need
to free it in out_fail.
The problem this patch attempts to solve is that, when we run into
out_fail here,
we will drop a outstanding extent. That said, in out_fail here, the
extra reserved
nodesize for some extents should be freed.
Example:
1). BTRFS_I(inode)->reserved_extents: 2,
BTRFS_I(inode)->outstanding_extents: 1.
In this case, we go intobtrfs_delalloc_reserve_metadata().
outstanding_extents
will be increased at first. then
BTRFS_I(inode)->outstanding_extents is 2.
If we want to reserve space and failed. it will goto out_fail.
2). In out_failed: reserved_extents is 2, outstanding_extents is 2.
we will get a dropped of 1
from dropping_outstanding_extent(). And now,
reserved_extents:1, outstanding_extents:1.
In step 2, we just decrease the reserved_extents without freeing the
related nodesize in qgroup
at the same time. So it will cause the problem I described in changelog
which will eat the space.
Therefore, this patch here will free the nodesize related with the
dropped extents in step 2.
About the num_bytes, as we did not reserve it successfully, no need to
free it.
With my poor english, there must be something confusing in my
description. Please correct me
if anything is wrong or not-good-explained.
So none of this made sense, I went back and read the code just now and
this was the part I was missing
if (unlikely(ret)) {
if (root->fs_info->quota_enabled)
btrfs_qgroup_free(root, num_bytes +
nr_extents * root->nodesize);
goto out_fail;
}
All you needed to say was we already free up what we reserved, we're
just dropping anything we needed to free because of
drop_outstanding_extents ;). You can add
Reviewed-by: Josef Bacik <jba...@fb.com>
Thanks,
Josef
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