[PATCH v2 1/3] btrfs-progs: map-logical: look at next leaf if slot > items

[PATCH v2 1/3] btrfs-progs: map-logical: look at next leaf if slot > items

[james harvey]

btrfs-map-logical -l 10955980800 -b 4096 <path>
No extent found at range [10955980800,10955984896)

But, this extent exists.  btrfs-debug-tree shows:

   item 202 key (10955976704 EXTENT_ITEM 4096) itemoff 8772 itemsize 37
           refs 1 gen 62656 flags DATA
           shared data backref parent 142655488 count 1
...
   item 0 key (10955980800 EXTENT_ITEM 4096) itemoff 16246 itemsize 37
           refs 1 gen 62656 flags DATA
           shared data backref parent 128958464 count 1

The code searches for (<logical>, 0, 0), and looks forward then backward.  It
needs to go to the next leaf when slot > number of items on this leaf.

Signed-off-by: James Harvey <jamespharvey20@gmail.com>
---
 btrfs-map-logical.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/btrfs-map-logical.c b/btrfs-map-logical.c
index 7a8bcff9..2451012b 100644
--- a/btrfs-map-logical.c
+++ b/btrfs-map-logical.c
@@ -65,6 +65,14 @@ static int map_one_extent(struct btrfs_fs_info *fs_info,
        BUG_ON(ret == 0);
        ret = 0;

+       if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
+               ret = btrfs_next_leaf(fs_info->extent_root, path);
+               if (ret > 0) {
+                       ret = -ENOENT;
+                       goto out;
+               }
+       }
+
 again:
        btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
        if ((search_foward && key.objectid < logical) ||
--
2.17.0

Re: [PATCH v2 1/3] btrfs-progs: map-logical: look at next leaf if slot > items

[Su Yue]

On 06/07/2018 03:19 PM, james harvey wrote:
> btrfs-map-logical -l 10955980800 -b 4096 <path>
> No extent found at range [10955980800,10955984896)
> 
> But, this extent exists.  btrfs-debug-tree shows:
> 
>     item 202 key (10955976704 EXTENT_ITEM 4096) itemoff 8772 itemsize 37
>             refs 1 gen 62656 flags DATA
>             shared data backref parent 142655488 count 1
> ...
>     item 0 key (10955980800 EXTENT_ITEM 4096) itemoff 16246 itemsize 37
>             refs 1 gen 62656 flags DATA
>             shared data backref parent 128958464 count 1
> 
> The code searches for (<logical>, 0, 0), and looks forward then backward.  It
> needs to go to the next leaf when slot > number of items on this leaf.
> 
> Signed-off-by: James Harvey <jamespharvey20@gmail.com>
> ---
>   btrfs-map-logical.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
> 
> diff --git a/btrfs-map-logical.c b/btrfs-map-logical.c
> index 7a8bcff9..2451012b 100644
> --- a/btrfs-map-logical.c
> +++ b/btrfs-map-logical.c
> @@ -65,6 +65,14 @@ static int map_one_extent(struct btrfs_fs_info *fs_info,
>          BUG_ON(ret == 0);
>          ret = 0;
> 
> +       if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
> +               ret = btrfs_next_leaf(fs_info->extent_root, path);

It seems that you forgot to handle the case ret < 0.

Thanks,
Su

> +               if (ret > 0) {
> +                       ret = -ENOENT;
> +                       goto out;
> +               }
> +       }
> +
>   again:
>          btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
>          if ((search_foward && key.objectid < logical) ||
> --
> 2.17.0
> --
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