On Mon, Feb 13, 2017 at 03:26:27PM +0800, Qu Wenruo wrote:
> When balance(relocation) fails, btrfs-progs will report like:
> 
> ERROR: error during balancing '/mnt/scratch': Input/output error
> There may be more info in syslog - try dmesg | tail
> 
> However in some case, for example debugging btrfs/125 with small file
> size, kernel only have some recoverable csum error message and nothing
> useful at all.
> 
> This patch will add error messages in relocation to help both end user to
> wipe out some obvious problems, like ENOSPC.
> And for developers, they can locate the problem to specific function just
> by kernel message.
> 
> Signed-off-by: Qu Wenruo <[email protected]>
> ---
>  fs/btrfs/relocation.c | 60 
> +++++++++++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 56 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
> index 379711048fb0..c9474377a59c 100644
> --- a/fs/btrfs/relocation.c
> +++ b/fs/btrfs/relocation.c
> @@ -4011,6 +4011,8 @@ static noinline_for_stack int 
> relocate_block_group(struct reloc_control *rc)
>                                       rc->block_rsv, rc->block_rsv->size,
>                                       BTRFS_RESERVE_FLUSH_ALL);
>               if (ret) {
> +                     btrfs_err(fs_info, "failed to reserve space: %d(%s)",
> +                               ret, btrfs_decode_error(ret));
>                       err = ret;
>                       break;
>               }
> @@ -4019,6 +4021,9 @@ static noinline_for_stack int 
> relocate_block_group(struct reloc_control *rc)
>               if (IS_ERR(trans)) {
>                       err = PTR_ERR(trans);
>                       trans = NULL;
> +                     btrfs_err(fs_info,
> +                               "failed to start transaction: %d(%s)",
> +                               err, btrfs_decode_error(err));
>                       break;
>               }
>  restart:
> @@ -4028,8 +4033,11 @@ static noinline_for_stack int 
> relocate_block_group(struct reloc_control *rc)
>               }
>  
>               ret = find_next_extent(rc, path, &key);
> -             if (ret < 0)
> +             if (ret < 0) {
> +                     btrfs_err(fs_info, "failed to find next extent: %d(%s)",
> +                               ret, btrfs_decode_error(ret));
>                       err = ret;
> +             }
>               if (ret != 0)
>                       break;
>  
> @@ -4081,9 +4089,17 @@ static noinline_for_stack int 
> relocate_block_group(struct reloc_control *rc)
>  
>               if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
>                       ret = add_tree_block(rc, &key, path, &blocks);
> +                     if (ret < 0)
> +                             btrfs_err(fs_info,
> +                                       "failed to record tree block: %d(%s)",
> +                                       ret, btrfs_decode_error(ret));
>               } else if (rc->stage == UPDATE_DATA_PTRS &&
>                          (flags & BTRFS_EXTENT_FLAG_DATA)) {
>                       ret = add_data_references(rc, &key, path, &blocks);
> +                     if (ret < 0)
> +                             btrfs_err(fs_info,
> +                                       "failed to record data extent: 
> %d(%s)",
> +                                       ret, btrfs_decode_error(ret));
>               } else {
>                       btrfs_release_path(path);
>                       ret = 0;
> @@ -4103,6 +4119,9 @@ static noinline_for_stack int 
> relocate_block_group(struct reloc_control *rc)
>                               rc->backref_cache.last_trans = trans->transid - 
> 1;
>  
>                               if (ret != -EAGAIN) {
> +                                     btrfs_err(fs_info,
> +                                     "faild to relocate tree blocks: %d(%s)",
> +                                               ret, btrfs_decode_error(ret));
>                                       err = ret;
>                                       break;
>                               }
> @@ -4121,6 +4140,9 @@ static noinline_for_stack int 
> relocate_block_group(struct reloc_control *rc)
>                       ret = relocate_data_extent(rc->data_inode,
>                                                  &key, &rc->cluster);
>                       if (ret < 0) {
> +                             btrfs_err(fs_info,
> +                             "failed to relocate data extent: %d(%s)",
> +                                       ret, btrfs_decode_error(ret));
>                               err = ret;
>                               break;
>                       }
> @@ -4147,8 +4169,12 @@ static noinline_for_stack int 
> relocate_block_group(struct reloc_control *rc)
>       if (!err) {
>               ret = relocate_file_extent_cluster(rc->data_inode,
>                                                  &rc->cluster);
> -             if (ret < 0)
> +             if (ret < 0) {
> +                     btrfs_err(fs_info,
> +                     "failed to relocate file extent cluster: %d(%s)",
> +                               ret, btrfs_decode_error(ret));
>                       err = ret;
> +             }
>       }
>  
>       rc->create_reloc_tree = 0;
> @@ -4158,6 +4184,10 @@ static noinline_for_stack int 
> relocate_block_group(struct reloc_control *rc)
>       btrfs_block_rsv_release(fs_info, rc->block_rsv, (u64)-1);
>  
>       err = prepare_to_merge(rc, err);
> +     if (err < 0)
> +             btrfs_err(fs_info,
> +                       "failed to preapre merge relocate trees: %d(%s)",
> +                       ret, btrfs_decode_error(ret));

s/ret/err

Please fix the same typo in the rest parts.

Thanks,

-liubo
>  
>       merge_reloc_roots(rc);
>  
> @@ -4336,6 +4366,9 @@ int btrfs_relocate_block_group(struct btrfs_fs_info 
> *fs_info, u64 group_start)
>  
>       ret = btrfs_inc_block_group_ro(extent_root, rc->block_group);
>       if (ret) {
> +             btrfs_err(fs_info,
> +                     "failed to set block group read-only: %d(%s)",
> +                       err, btrfs_decode_error(err));
>               err = ret;
>               goto out;
>       }
> @@ -4351,10 +4384,19 @@ int btrfs_relocate_block_group(struct btrfs_fs_info 
> *fs_info, u64 group_start)
>                                       path);
>       btrfs_free_path(path);
>  
> -     if (!IS_ERR(inode))
> +     if (!IS_ERR(inode)) {
>               ret = delete_block_group_cache(fs_info, rc->block_group, inode, 
> 0);
> -     else
> +             if (ret < 0)
> +                     btrfs_err(fs_info,
> +                             "failed to delete block group cache: %d(%s)",
> +                               err, btrfs_decode_error(err));
> +     } else {
>               ret = PTR_ERR(inode);
> +             if (ret < 0 && ret != -ENOENT)
> +                     btrfs_err(fs_info,
> +                             "failed to lookup free space inode: %d(%s)",
> +                               err, btrfs_decode_error(err));
> +     }
>  
>       if (ret && ret != -ENOENT) {
>               err = ret;
> @@ -4364,6 +4406,8 @@ int btrfs_relocate_block_group(struct btrfs_fs_info 
> *fs_info, u64 group_start)
>       rc->data_inode = create_reloc_inode(fs_info, rc->block_group);
>       if (IS_ERR(rc->data_inode)) {
>               err = PTR_ERR(rc->data_inode);
> +             btrfs_err(fs_info, "failed to create relocate inode: %d(%s)",
> +                       err, btrfs_decode_error(err));
>               rc->data_inode = NULL;
>               goto out;
>       }
> @@ -4394,6 +4438,9 @@ int btrfs_relocate_block_group(struct btrfs_fs_info 
> *fs_info, u64 group_start)
>                       ret = btrfs_wait_ordered_range(rc->data_inode, 0,
>                                                      (u64)-1);
>                       if (ret) {
> +                             btrfs_err(fs_info,
> +                                     "failed to wait ordered range: %d(%s)",
> +                                       ret, btrfs_decode_error(ret));
>                               err = ret;
>                               goto out;
>                       }
> @@ -4407,6 +4454,11 @@ int btrfs_relocate_block_group(struct btrfs_fs_info 
> *fs_info, u64 group_start)
>       WARN_ON(rc->block_group->reserved > 0);
>       WARN_ON(btrfs_block_group_used(&rc->block_group->item) > 0);
>  out:
> +     if (err < 0)
> +             btrfs_err(fs_info,
> +                       "failed to relocate block group %llu: %d(%s)",
> +                       rc->block_group->key.objectid, ret,
> +                       btrfs_decode_error(ret));
>       if (err && rw)
>               btrfs_dec_block_group_ro(rc->block_group);
>       iput(rc->data_inode);
> -- 
> 2.11.1
> 
> 
> 
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