From: lijian <[email protected]>
removed unneeded variable 'ret'.
Signed-off-by: lijian <[email protected]>
---
fs/btrfs/extent_map.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 4a8e02f7b6c7..70d3e76e30c5 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -296,7 +296,6 @@ static void try_merge_map(struct extent_map_tree *tree, struct extent_map *em)
int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len,
u64 gen)
{
- int ret = 0;
struct extent_map *em;
bool prealloc = false;
@@ -328,8 +327,7 @@ int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len,
free_extent_map(em);
out:
write_unlock(&tree->lock);
- return ret;
-
+ return 0;
}
void clear_em_logging(struct extent_map_tree *tree, struct extent_map *em)
--
2.17.1
On 29/06/2021 10:51, [email protected] wrote:
> From: lijian <[email protected]>
>
> removed unneeded variable 'ret'.
Wouldn't it make more sense to return an error (-ENOENT??) in case
the em lookup fails and handle the error in btrfs_finish_ordered_io()
as this is the only caller of unpin_extent_cache()?
I've actually tripped over this a couple of times already when
investigating extent map and ordered extent splitting problems
on zoned filesystems:
em = lookup_extent_mapping(tree, start, len);
WARN_ON(!em || em->start != start);
Maybe even turn this WARN_ON() into an ASSERT() when introducing proper
error handling, as we shouldn't really get there unless we have a logical
error.
On Tue, Jun 29, 2021 at 09:04:40AM +0000, Johannes Thumshirn wrote:
> On 29/06/2021 10:51, [email protected] wrote:
> > From: lijian <[email protected]>
> >
> > removed unneeded variable 'ret'.
>
> Wouldn't it make more sense to return an error (-ENOENT??) in case
> the em lookup fails and handle the error in btrfs_finish_ordered_io()
> as this is the only caller of unpin_extent_cache()?
>
> I've actually tripped over this a couple of times already when
> investigating extent map and ordered extent splitting problems
> on zoned filesystems:
>
> em = lookup_extent_mapping(tree, start, len);
> WARN_ON(!em || em->start != start);
>
> Maybe even turn this WARN_ON() into an ASSERT() when introducing proper
> error handling, as we shouldn't really get there unless we have a logical
> error.
If you have real workloads hitting the warning then it really should be
proper error handling, not even an assert.
On 30/06/2021 12:01, David Sterba wrote:
> On Tue, Jun 29, 2021 at 09:04:40AM +0000, Johannes Thumshirn wrote:
>> On 29/06/2021 10:51, [email protected] wrote:
>>> From: lijian <[email protected]>
>>>
>>> removed unneeded variable 'ret'.
>>
>> Wouldn't it make more sense to return an error (-ENOENT??) in case
>> the em lookup fails and handle the error in btrfs_finish_ordered_io()
>> as this is the only caller of unpin_extent_cache()?
>>
>> I've actually tripped over this a couple of times already when
>> investigating extent map and ordered extent splitting problems
>> on zoned filesystems:
>>
>> em = lookup_extent_mapping(tree, start, len);
>> WARN_ON(!em || em->start != start);
>>
>> Maybe even turn this WARN_ON() into an ASSERT() when introducing proper
>> error handling, as we shouldn't really get there unless we have a logical
>> error.
>
> If you have real workloads hitting the warning then it really should be
> proper error handling, not even an assert.
>
Up to now it's been coding errors from my side so I think it warrants an
ASSERT().
But still we should handle the error in the caller.