On 2019/11/27 上午12:25, Josef Bacik wrote:
> This is a relic from a time before we had a proper reservation mechanism
> and you could end up with really full chunks at chunk allocation time.
> This doesn't make sense anymore, so just kill it.
>
> Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
Reviewed-by: Qu Wenruo <wqu@xxxxxxxx>
Thanks,
Qu
> ---
> fs/btrfs/block-group.c | 22 ++++------------------
> 1 file changed, 4 insertions(+), 18 deletions(-)
>
> diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
> index 6934a5b8708f..66fa39632cde 100644
> --- a/fs/btrfs/block-group.c
> +++ b/fs/btrfs/block-group.c
> @@ -1185,21 +1185,8 @@ static int inc_block_group_ro(struct btrfs_block_group *cache, int force)
> struct btrfs_space_info *sinfo = cache->space_info;
> u64 num_bytes;
> u64 sinfo_used;
> - u64 min_allocable_bytes;
> int ret = -ENOSPC;
>
> - /*
> - * We need some metadata space and system metadata space for
> - * allocating chunks in some corner cases until we force to set
> - * it to be readonly.
> - */
> - if ((sinfo->flags &
> - (BTRFS_BLOCK_GROUP_SYSTEM | BTRFS_BLOCK_GROUP_METADATA)) &&
> - !force)
> - min_allocable_bytes = SZ_1M;
> - else
> - min_allocable_bytes = 0;
> -
> spin_lock(&sinfo->lock);
> spin_lock(&cache->lock);
>
> @@ -1217,10 +1204,9 @@ static int inc_block_group_ro(struct btrfs_block_group *cache, int force)
> * sinfo_used + num_bytes should always <= sinfo->total_bytes.
> *
> * Here we make sure if we mark this bg RO, we still have enough
> - * free space as buffer (if min_allocable_bytes is not 0).
> + * free space as buffer.
> */
> - if (sinfo_used + num_bytes + min_allocable_bytes <=
> - sinfo->total_bytes) {
> + if (sinfo_used + num_bytes <= sinfo->total_bytes) {
> sinfo->bytes_readonly += num_bytes;
> cache->ro++;
> list_add_tail(&cache->ro_list, &sinfo->ro_bgs);
> @@ -1233,8 +1219,8 @@ static int inc_block_group_ro(struct btrfs_block_group *cache, int force)
> btrfs_info(cache->fs_info,
> "unable to make block group %llu ro", cache->start);
> btrfs_info(cache->fs_info,
> - "sinfo_used=%llu bg_num_bytes=%llu min_allocable=%llu",
> - sinfo_used, num_bytes, min_allocable_bytes);
> + "sinfo_used=%llu bg_num_bytes=%llu",
> + sinfo_used, num_bytes);
> btrfs_dump_space_info(cache->fs_info, cache->space_info, 0, 0);
> }
> return ret;
>
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