On Thu, Feb 08, 2018 at 06:25:17PM +0200, Nikolay Borisov wrote:
> list_first_entry is essentially a wrapper over cotnainer_of. The latter
> can never return null even if it's working on inconsistent list since it
> will either crash or return some offset in the wrong struct.
> Additionally, for the dirty_bgs list the iteration is done under
> dirty_bgs_lock which ensures consistency of the list.
>
Reviewed-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
-liubo
> Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
> ---
> fs/btrfs/disk-io.c | 9 ---------
> 1 file changed, 9 deletions(-)
>
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index aca906971abe..1b3989c54d7c 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -4323,11 +4323,6 @@ void btrfs_cleanup_dirty_bgs(struct btrfs_transaction *cur_trans,
> cache = list_first_entry(&cur_trans->dirty_bgs,
> struct btrfs_block_group_cache,
> dirty_list);
> - if (!cache) {
> - btrfs_err(fs_info, "orphan block group dirty_bgs list");
> - spin_unlock(&cur_trans->dirty_bgs_lock);
> - return;
> - }
>
> if (!list_empty(&cache->io_list)) {
> spin_unlock(&cur_trans->dirty_bgs_lock);
> @@ -4351,10 +4346,6 @@ void btrfs_cleanup_dirty_bgs(struct btrfs_transaction *cur_trans,
> cache = list_first_entry(&cur_trans->io_bgs,
> struct btrfs_block_group_cache,
> io_list);
> - if (!cache) {
> - btrfs_err(fs_info, "orphan block group on io_bgs list");
> - return;
> - }
>
> list_del_init(&cache->io_list);
> spin_lock(&cache->lock);
> --
> 2.7.4
>
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