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btrfs: Factor out loop processing all refs of a head 

This patch introduces a new helper encompassing the implicit inner loop
in __btrfs_run_delayed_refs which processes all the refs for a given
head. The code is mostly copy/paste, the only difference is that if we
detect a newer reference then -EAGAIN is returned so that callers can
react correctly.

Also, at the end of the loop the head is relocked and
btrfs_merge_delayed_refs is run again to retain the pre-refactoring
semantics.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Nikolay Borisov 2018-08-15 10:39:55 +03:00 committed by David Sterba
parent b1cdbcb53a
commit e726138676
1 changed files with 77 additions and 0 deletions
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77
fs/btrfs/extent-tree.c
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@ -2535,6 +2535,83 @@ static struct btrfs_delayed_ref_head *btrfs_obtain_ref_head(
return head;
}
static int btrfs_run_delayed_refs_for_head(struct btrfs_trans_handle *trans,
struct btrfs_delayed_ref_head *locked_ref,
unsigned long *run_refs)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_delayed_ref_root *delayed_refs;
struct btrfs_delayed_extent_op *extent_op;
struct btrfs_delayed_ref_node *ref;
int must_insert_reserved = 0;
int ret;
delayed_refs = &trans->transaction->delayed_refs;
while ((ref = select_delayed_ref(locked_ref))) {
if (ref->seq &&
btrfs_check_delayed_seq(fs_info, ref->seq)) {
spin_unlock(&locked_ref->lock);
unselect_delayed_ref_head(delayed_refs, locked_ref);
return -EAGAIN;
}
(*run_refs)++;
ref->in_tree = 0;
rb_erase_cached(&ref->ref_node, &locked_ref->ref_tree);
RB_CLEAR_NODE(&ref->ref_node);
if (!list_empty(&ref->add_list))
list_del(&ref->add_list);
/*
* When we play the delayed ref, also correct the ref_mod on
* head
*/
switch (ref->action) {
case BTRFS_ADD_DELAYED_REF:
case BTRFS_ADD_DELAYED_EXTENT:
locked_ref->ref_mod -= ref->ref_mod;
break;
case BTRFS_DROP_DELAYED_REF:
locked_ref->ref_mod += ref->ref_mod;
break;
default:
WARN_ON(1);
}
atomic_dec(&delayed_refs->num_entries);
/*
* Record the must_insert_reserved flag before we drop the
* spin lock.
*/
must_insert_reserved = locked_ref->must_insert_reserved;
locked_ref->must_insert_reserved = 0;
extent_op = locked_ref->extent_op;
locked_ref->extent_op = NULL;
spin_unlock(&locked_ref->lock);
ret = run_one_delayed_ref(trans, ref, extent_op,
must_insert_reserved);
btrfs_free_delayed_extent_op(extent_op);
if (ret) {
unselect_delayed_ref_head(delayed_refs, locked_ref);
btrfs_put_delayed_ref(ref);
btrfs_debug(fs_info, "run_one_delayed_ref returned %d",
ret);
return ret;
}
btrfs_put_delayed_ref(ref);
cond_resched();
spin_lock(&locked_ref->lock);
btrfs_merge_delayed_refs(trans, delayed_refs, locked_ref);
}
return 0;
}
/*
* Returns 0 on success or if called with an already aborted transaction.
* Returns -ENOMEM or -EIO on failure and will abort the transaction.