On Tue, Oct 11, 2016 at 9:58 AM, robbieko <robbi...@synology.com> wrote:
> Hi Filipe:
> because btrfs_calc_trunc_metadata_size is reserved leafsize + nodesize * (8
> - 1)
> assume leafsize is the same as nodesize
The leaf size is always the same as the node size. There are no exceptions.
> , we total reserved 8 nodesize
> when split leaf, we need 2 path
2 paths?? what do you mean?
> , if extent_tree level small than 4, it's OK
> because worst case is (leafsize + nodesize * 3) *2, is 8 nodesize.
> but if extent_tree is greater level 4, worst case is need (leafsize +
> nodesize * 7) * 2,
> is bigger than resvered size, so we should use
> is taken into account split leaf case.
I think I can make some sense of what you're saying, but you forgot to
mention that after splitting a leaf (therefore creating a new one), a
new node might be added to each level of the tree (since there's a new
key and every parent node was full).
Having detailed and well written change logs is important...
> Filipe Manana 於 2016-10-07 18:18 寫到:
>> On Fri, Oct 7, 2016 at 7:09 AM, robbieko <robbi...@synology.com> wrote:
>>> From: Robbie Ko <robbi...@synology.com>
>>> when extent-tree level > BTRFS_MAX_LEVEL / 2,
>>> __btrfs_drop_extents -> btrfs_duplicate_item ->
>>> setup_leaf_for_split -> split_leaf
>>> maybe enospc, because min_size is too small,
>>> need use btrfs_calc_trans_metadata_size.
>> This change log is terrible.
>> You should describe the problem and fix. That is, that hole punching
>> can result in adding new leafs (and as a consequence new nodes) to the
>> tree because when we find file extent items that span beyond the hole
>> range we may end up not deleting them (just adjusting them) and add
>> new file extent items representing holes.
>> And I don't see why this is exclusive for the case where the height of
>> the extent tree is greater than 4 (BTRFS_MAX_LEVEL / 2).
>> The code changes themselves look good to me.
>>> Signed-off-by: Robbie Ko <robbi...@synology.com>
>>> fs/btrfs/file.c | 4 ++--
>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
>>> index fea31a4..809ca85 100644
>>> --- a/fs/btrfs/file.c
>>> +++ b/fs/btrfs/file.c
>>> @@ -2322,7 +2322,7 @@ static int btrfs_punch_hole(struct inode *inode,
>>> loff_t offset, loff_t len)
>>> u64 tail_len;
>>> u64 orig_start = offset;
>>> u64 cur_offset;
>>> - u64 min_size = btrfs_calc_trunc_metadata_size(root, 1);
>>> + u64 min_size = btrfs_calc_trans_metadata_size(root, 1);
>>> u64 drop_end;
>>> int ret = 0;
>>> int err = 0;
>>> @@ -2469,7 +2469,7 @@ static int btrfs_punch_hole(struct inode *inode,
>>> loff_t offset, loff_t len)
>>> ret = -ENOMEM;
>>> goto out_free;
>>> - rsv->size = btrfs_calc_trunc_metadata_size(root, 1);
>>> + rsv->size = btrfs_calc_trans_metadata_size(root, 1);
>>> rsv->failfast = 1;
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Filipe David Manana,
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people will forget what you did,
but people will never forget how you made them feel."
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