On Wed, May 17, 2017 at 11:07 AM, Nikolay Borisov <nbori...@suse.com> wrote:
> Currently the struct space_info creation code is intermixed in the
> udpate_space_info function. There are well-defined points at which the we
^^^ update_space_info
> actually want to create brand-new space_info structs (e.g. during mount of
> the filesystem as well as sometimes when adding/initialising new chunks). In
> such cases udpate_space_info is called with 0 as the bytes parameter. All of
> this makes for spaghetti code.
>
> Fix it by factoring out the creation code in a separate create_space_info
> structure. This also allows to simplify the internals. Furthermore it will
> make the update_space_info function not fail, allowing to remove error
> handling in callers. This will come in a follow up patch.
>
> This bears no functional changes
>
> Signed-off-by: Nikolay Borisov <nbori...@suse.com>
> Reviewed-by: Jeff Mahoney <je...@suse.com>
> ---
> fs/btrfs/extent-tree.c | 127
> ++++++++++++++++++++++++-------------------------
> 1 file changed, 62 insertions(+), 65 deletions(-)
>
> Change since v1:
>
> Incorporated Jeff Mahoney's feedback and added his reviewed-by
>
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index be5477676cc8..28848e45b018 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -3914,15 +3914,58 @@ static const char *alloc_name(u64 flags)
> };
> }
>
> +static int create_space_info(struct btrfs_fs_info *info, u64 flags,
> + struct btrfs_space_info **new) {
> +
> + struct btrfs_space_info *space_info;
> + int i;
> + int ret;
> +
> + space_info = kzalloc(sizeof(*space_info), GFP_NOFS);
> + if (!space_info)
> + return -ENOMEM;
> +
> + ret = percpu_counter_init(&space_info->total_bytes_pinned, 0,
> GFP_KERNEL);
> + if (ret) {
> + kfree(space_info);
> + return ret;
> + }
> +
> + for (i = 0; i < BTRFS_NR_RAID_TYPES; i++)
> + INIT_LIST_HEAD(&space_info->block_groups[i]);
> + init_rwsem(&space_info->groups_sem);
> + spin_lock_init(&space_info->lock);
> + space_info->flags = flags & BTRFS_BLOCK_GROUP_TYPE_MASK;
> + space_info->force_alloc = CHUNK_ALLOC_NO_FORCE;
> + init_waitqueue_head(&space_info->wait);
> + INIT_LIST_HEAD(&space_info->ro_bgs);
> + INIT_LIST_HEAD(&space_info->tickets);
> + INIT_LIST_HEAD(&space_info->priority_tickets);
> +
> + ret = kobject_init_and_add(&space_info->kobj, &space_info_ktype,
> + info->space_info_kobj, "%s",
> + alloc_name(space_info->flags));
> + if (ret) {
> + percpu_counter_destroy(&space_info->total_bytes_pinned);
> + kfree(space_info);
> + return ret;
> + }
> +
> + *new = space_info;
> + list_add_rcu(&space_info->list, &info->space_info);
> + if (flags & BTRFS_BLOCK_GROUP_DATA)
> + info->data_sinfo = space_info;
> +
> + return ret;
> +}
> +
> static int update_space_info(struct btrfs_fs_info *info, u64 flags,
> u64 total_bytes, u64 bytes_used,
> u64 bytes_readonly,
> struct btrfs_space_info **space_info)
> {
> struct btrfs_space_info *found;
> - int i;
> int factor;
> - int ret;
>
> if (flags & (BTRFS_BLOCK_GROUP_DUP | BTRFS_BLOCK_GROUP_RAID1 |
> BTRFS_BLOCK_GROUP_RAID10))
> @@ -3946,53 +3989,6 @@ static int update_space_info(struct btrfs_fs_info
> *info, u64 flags,
> *space_info = found;
> return 0;
> }
> - found = kzalloc(sizeof(*found), GFP_NOFS);
> - if (!found)
> - return -ENOMEM;
> -
> - ret = percpu_counter_init(&found->total_bytes_pinned, 0, GFP_KERNEL);
> - if (ret) {
> - kfree(found);
> - return ret;
> - }
> -
> - for (i = 0; i < BTRFS_NR_RAID_TYPES; i++)
> - INIT_LIST_HEAD(&found->block_groups[i]);
> - init_rwsem(&found->groups_sem);
> - spin_lock_init(&found->lock);
> - found->flags = flags & BTRFS_BLOCK_GROUP_TYPE_MASK;
> - found->total_bytes = total_bytes;
> - found->disk_total = total_bytes * factor;
> - found->bytes_used = bytes_used;
> - found->disk_used = bytes_used * factor;
> - found->bytes_pinned = 0;
> - found->bytes_reserved = 0;
> - found->bytes_readonly = bytes_readonly;
> - found->bytes_may_use = 0;
> - found->full = 0;
> - found->max_extent_size = 0;
> - found->force_alloc = CHUNK_ALLOC_NO_FORCE;
> - found->chunk_alloc = 0;
> - found->flush = 0;
> - init_waitqueue_head(&found->wait);
> - INIT_LIST_HEAD(&found->ro_bgs);
> - INIT_LIST_HEAD(&found->tickets);
> - INIT_LIST_HEAD(&found->priority_tickets);
> -
> - ret = kobject_init_and_add(&found->kobj, &space_info_ktype,
> - info->space_info_kobj, "%s",
> - alloc_name(found->flags));
> - if (ret) {
> - kfree(found);
> - return ret;
> - }
> -
> - *space_info = found;
> - list_add_rcu(&found->list, &info->space_info);
> - if (flags & BTRFS_BLOCK_GROUP_DATA)
> - info->data_sinfo = found;
> -
> - return ret;
> }
>
> static void set_avail_alloc_bits(struct btrfs_fs_info *fs_info, u64 flags)
> @@ -4495,10 +4491,9 @@ static int do_chunk_alloc(struct btrfs_trans_handle
> *trans,
>
> space_info = __find_space_info(fs_info, flags);
> if (!space_info) {
> - ret = update_space_info(fs_info, flags, 0, 0, 0, &space_info);
> + ret = create_space_info(fs_info, flags, &space_info);
> BUG_ON(ret); /* -ENOMEM */
> }
> - BUG_ON(!space_info); /* Logic error */
Isn't removing this BUG_ON a functional change?
I understand that it shouldn't happen in the current incarnation of
create_space_info, but that was true before the patch as well
>
> again:
> spin_lock(&space_info->lock);
> @@ -5763,7 +5758,7 @@ int btrfs_orphan_reserve_metadata(struct
> btrfs_trans_handle *trans,
> */
> u64 num_bytes = btrfs_calc_trans_metadata_size(fs_info, 1);
>
> - trace_btrfs_space_reservation(fs_info, "orphan", btrfs_ino(inode),
> + trace_btrfs_space_reservation(fs_info, "orphan", btrfs_ino(inode),
> num_bytes, 1);
> return btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes, 1);
> }
> @@ -10191,16 +10186,18 @@ int btrfs_make_block_group(struct
> btrfs_trans_handle *trans,
> }
> #endif
> /*
> - * Call to ensure the corresponding space_info object is created and
> - * assigned to our block group, but don't update its counters just
> yet.
> - * We want our bg to be added to the rbtree with its ->space_info set.
> + * Ensure the corresponding space_info object is created and
> + * assigned to our block group. We want our bg to be added to the
> rbtree
> + * with its ->space_info set.
> */
> - ret = update_space_info(fs_info, cache->flags, 0, 0, 0,
> - &cache->space_info);
> - if (ret) {
> - btrfs_remove_free_space_cache(cache);
> - btrfs_put_block_group(cache);
> - return ret;
> + cache->space_info = __find_space_info(fs_info, cache->flags);
> + if (!cache->space_info) {
> + ret = create_space_info(fs_info, cache->flags,
> &cache->space_info);
> + if (ret) {
> + btrfs_remove_free_space_cache(cache);
> + btrfs_put_block_group(cache);
> + return ret;
> + }
> }
>
> ret = btrfs_add_block_group_cache(fs_info, cache);
> @@ -10774,21 +10771,21 @@ int btrfs_init_space_info(struct btrfs_fs_info
> *fs_info)
> mixed = 1;
>
> flags = BTRFS_BLOCK_GROUP_SYSTEM;
> - ret = update_space_info(fs_info, flags, 0, 0, 0, &space_info);
> + ret = create_space_info(fs_info, flags, &space_info);
> if (ret)
> goto out;
>
> if (mixed) {
> flags = BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA;
> - ret = update_space_info(fs_info, flags, 0, 0, 0, &space_info);
> + ret = create_space_info(fs_info, flags, &space_info);
> } else {
> flags = BTRFS_BLOCK_GROUP_METADATA;
> - ret = update_space_info(fs_info, flags, 0, 0, 0, &space_info);
> + ret = create_space_info(fs_info, flags, &space_info);
> if (ret)
> goto out;
>
> flags = BTRFS_BLOCK_GROUP_DATA;
> - ret = update_space_info(fs_info, flags, 0, 0, 0, &space_info);
> + ret = create_space_info(fs_info, flags, &space_info);
> }
> out:
> return ret;
> --
> 2.7.4
>
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