diff mbox

[08/10] Btrfs: add WARN_ONCE to detect unexpected error from merge_extent_mapping

Message ID 20171221224256.18196-9-bo.li.liu@oracle.com (mailing list archive)
State New, archived
Headers show

Commit Message

Liu Bo Dec. 21, 2017, 10:42 p.m. UTC
This is a subtle case, so in order to understand the problem, it'd be good to
know the content of existing and em when any error occurs.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
---
 fs/btrfs/extent_map.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Comments

Nikolay Borisov Dec. 22, 2017, 8:52 a.m. UTC | #1
On 22.12.2017 00:42, Liu Bo wrote:
> This is a subtle case, so in order to understand the problem, it'd be good to
> know the content of existing and em when any error occurs.
> 
> Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
> ---
>  fs/btrfs/extent_map.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
> index d386cfb..a8b7e24 100644
> --- a/fs/btrfs/extent_map.c
> +++ b/fs/btrfs/extent_map.c
> @@ -550,17 +550,23 @@ int btrfs_add_extent_mapping(struct extent_map_tree *em_tree,
>  			*em_in = existing;
>  			ret = 0;
>  		} else {
> +			u64 orig_start = em->start;
> +			u64 orig_len = em->len;
> +
>  			/*
>  			 * The existing extent map is the one nearest to
>  			 * the [start, start + len) range which overlaps
>  			 */
>  			ret = merge_extent_mapping(em_tree, existing,
>  						   em, start, len);
> -			free_extent_map(existing);
>  			if (ret) {
>  				free_extent_map(em);
>  				*em_in = NULL;
> +				WARN_ONCE(ret, KERN_INFO "Unexpected error %d: merge existing(start %llu len %llu) with em(start %llu len %llu)\n",

I think this KERN_INFO is spurious and should be removed?

> +					  ret, existing->start, existing->len,
> +					  orig_start, orig_len);
>  			}
> +			free_extent_map(existing);
>  		}
>  	}
>  
> 
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diff mbox

Patch

diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index d386cfb..a8b7e24 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -550,17 +550,23 @@  int btrfs_add_extent_mapping(struct extent_map_tree *em_tree,
 			*em_in = existing;
 			ret = 0;
 		} else {
+			u64 orig_start = em->start;
+			u64 orig_len = em->len;
+
 			/*
 			 * The existing extent map is the one nearest to
 			 * the [start, start + len) range which overlaps
 			 */
 			ret = merge_extent_mapping(em_tree, existing,
 						   em, start, len);
-			free_extent_map(existing);
 			if (ret) {
 				free_extent_map(em);
 				*em_in = NULL;
+				WARN_ONCE(ret, KERN_INFO "Unexpected error %d: merge existing(start %llu len %llu) with em(start %llu len %llu)\n",
+					  ret, existing->start, existing->len,
+					  orig_start, orig_len);
 			}
+			free_extent_map(existing);
 		}
 	}