On 2018/10/26 下午7:43, Nikolay Borisov wrote:
> btrfs_can_relocate returns 0 when it concludes the given chunk can be
> relocated and -1 otherwise. Since this function is used as a predicated
> and it return a binary value it makes no sense to have it's return
> value as an int so change it to bool. Furthermore, remove a stale
> leftover comment from e6ec716f0ddb ("Btrfs: make raid attr array more
> readable").
>
> Finally make the logic in the list_for_each_entry loop a bit more obvious. Up
> until now the fact that we are returning success (0) was a bit masked by the
> fact that the 0 is re-used from the return value of find_free_dev_extent.
> Instead, now just increment dev_nr if we find a suitable extent and explicitly
> set can_reloc to true if enough devices with unallocated space are present.
> No functional changes.
>
> Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
Reviewed-by: Qu Wenruo <wqu@xxxxxxxx>
Thanks,
Qu
> ---
> fs/btrfs/ctree.h | 2 +-
> fs/btrfs/extent-tree.c | 39 ++++++++++++++-------------------------
> fs/btrfs/volumes.c | 3 +--
> 3 files changed, 16 insertions(+), 28 deletions(-)
>
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 68ca41dbbef3..06edc4f9ceb2 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -2680,7 +2680,7 @@ int btrfs_setup_space_cache(struct btrfs_trans_handle *trans,
> int btrfs_extent_readonly(struct btrfs_fs_info *fs_info, u64 bytenr);
> int btrfs_free_block_groups(struct btrfs_fs_info *info);
> int btrfs_read_block_groups(struct btrfs_fs_info *info);
> -int btrfs_can_relocate(struct btrfs_fs_info *fs_info, u64 bytenr);
> +bool btrfs_can_relocate(struct btrfs_fs_info *fs_info, u64 bytenr);
> int btrfs_make_block_group(struct btrfs_trans_handle *trans,
> u64 bytes_used, u64 type, u64 chunk_offset,
> u64 size);
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index a1febf155747..816bca482358 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -9423,10 +9423,10 @@ void btrfs_dec_block_group_ro(struct btrfs_block_group_cache *cache)
> /*
> * checks to see if its even possible to relocate this block group.
> *
> - * @return - -1 if it's not a good idea to relocate this block group, 0 if its
> - * ok to go ahead and try.
> + * @return - false if not enough space can be found for relocation, true
> + * otherwise
> */
> -int btrfs_can_relocate(struct btrfs_fs_info *fs_info, u64 bytenr)
> +bool btrfs_can_relocate(struct btrfs_fs_info *fs_info, u64 bytenr)
> {
> struct btrfs_root *root = fs_info->extent_root;
> struct btrfs_block_group_cache *block_group;
> @@ -9441,7 +9441,7 @@ int btrfs_can_relocate(struct btrfs_fs_info *fs_info, u64 bytenr)
> int debug;
> int index;
> int full = 0;
> - int ret = 0;
> + bool can_reloc = true;
>
> debug = btrfs_test_opt(fs_info, ENOSPC_DEBUG);
>
> @@ -9453,7 +9453,7 @@ int btrfs_can_relocate(struct btrfs_fs_info *fs_info, u64 bytenr)
> btrfs_warn(fs_info,
> "can't find block group for bytenr %llu",
> bytenr);
> - return -1;
> + return false;
> }
>
> min_free = btrfs_block_group_used(&block_group->item);
> @@ -9489,16 +9489,8 @@ int btrfs_can_relocate(struct btrfs_fs_info *fs_info, u64 bytenr)
> * group is going to be restriped, run checks against the target
> * profile instead of the current one.
> */
> - ret = -1;
> + can_reloc = false;
>
> - /*
> - * index:
> - * 0: raid10
> - * 1: raid1
> - * 2: dup
> - * 3: raid0
> - * 4: single
> - */
> target = get_restripe_target(fs_info, block_group->flags);
> if (target) {
> index = btrfs_bg_flags_to_raid_index(extended_to_chunk(target));
> @@ -9534,10 +9526,8 @@ int btrfs_can_relocate(struct btrfs_fs_info *fs_info, u64 bytenr)
>
> /* We need to do this so that we can look at pending chunks */
> trans = btrfs_join_transaction(root);
> - if (IS_ERR(trans)) {
> - ret = PTR_ERR(trans);
> + if (IS_ERR(trans))
> goto out;
> - }
>
> mutex_lock(&fs_info->chunk_mutex);
> list_for_each_entry(device, &fs_devices->alloc_list, dev_alloc_list) {
> @@ -9549,18 +9539,17 @@ int btrfs_can_relocate(struct btrfs_fs_info *fs_info, u64 bytenr)
> */
> if (device->total_bytes > device->bytes_used + min_free &&
> !test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state)) {
> - ret = find_free_dev_extent(trans, device, min_free,
> - &dev_offset, NULL);
> - if (!ret)
> + if (!find_free_dev_extent(trans, device, min_free,
> + &dev_offset, NULL))
> dev_nr++;
>
> - if (dev_nr >= dev_min)
> + if (dev_nr >= dev_min) {
> + can_reloc = true;
> break;
> -
> - ret = -1;
> + }
> }
> }
> - if (debug && ret == -1)
> + if (debug && !can_reloc)
> btrfs_warn(fs_info,
> "no space to allocate a new chunk for block group %llu",
> block_group->key.objectid);
> @@ -9568,7 +9557,7 @@ int btrfs_can_relocate(struct btrfs_fs_info *fs_info, u64 bytenr)
> btrfs_end_transaction(trans);
> out:
> btrfs_put_block_group(block_group);
> - return ret;
> + return can_reloc;
> }
>
> static int find_first_block_group(struct btrfs_fs_info *fs_info,
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 8b0fd7bf3447..dc53d94a62aa 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -2856,8 +2856,7 @@ static int btrfs_relocate_chunk(struct btrfs_fs_info *fs_info, u64 chunk_offset)
> */
> lockdep_assert_held(&fs_info->delete_unused_bgs_mutex);
>
> - ret = btrfs_can_relocate(fs_info, chunk_offset);
> - if (ret)
> + if (!btrfs_can_relocate(fs_info, chunk_offset))
> return -ENOSPC;
>
> /* step one, relocate all the extents inside this chunk */
>
