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btrfs: refactor __btrfs_run_delayed_refs loop

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Refactor the delayed refs loop by using the newly introduced
btrfs_run_delayed_refs_for_head function. This greatly simplifies
__btrfs_run_delayed_refs and makes it more obvious what is happening.

We now have 1 loop which iterates the existing delayed_heads and then
each selected ref head is processed by the new helper. All existing
semantics of the code are preserved so no functional changes.

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 10:39:56 +03:00 committed by David Sterba
parent e726138676
commit 0110a4c434
1 changed files with 28 additions and 80 deletions
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108
fs/btrfs/extent-tree.c
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@ -2548,6 +2548,9 @@ static int btrfs_run_delayed_refs_for_head(struct btrfs_trans_handle *trans,
delayed_refs = &trans->transaction->delayed_refs;
lockdep_assert_held(&locked_ref->mutex);
lockdep_assert_held(&locked_ref->lock);
while ((ref = select_delayed_ref(locked_ref))) {
if (ref->seq &&
btrfs_check_delayed_seq(fs_info, ref->seq)) {
@ -2621,31 +2624,25 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
{
struct btrfs_fs_info *fs_info = trans->fs_info;
struct btrfs_delayed_ref_root *delayed_refs;
struct btrfs_delayed_ref_node *ref;
struct btrfs_delayed_ref_head *locked_ref = NULL;
struct btrfs_delayed_extent_op *extent_op;
ktime_t start = ktime_get();
int ret;
unsigned long count = 0;
unsigned long actual_count = 0;
int must_insert_reserved = 0;
delayed_refs = &trans->transaction->delayed_refs;
while (1) {
do {
if (!locked_ref) {
if (count >= nr)
break;
locked_ref = btrfs_obtain_ref_head(trans);
if (!locked_ref)
break;
else if (PTR_ERR(locked_ref) == -EAGAIN) {
locked_ref = NULL;
count++;
continue;
if (IS_ERR_OR_NULL(locked_ref)) {
if (PTR_ERR(locked_ref) == -EAGAIN) {
continue;
} else {
break;
}
}
count++;
}
/*
* We need to try and merge add/drops of the same ref since we
* can run into issues with relocate dropping the implicit ref
@ -2661,23 +2658,19 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
spin_lock(&locked_ref->lock);
btrfs_merge_delayed_refs(trans, delayed_refs, locked_ref);
ref = select_delayed_ref(locked_ref);
if (ref && ref->seq &&
btrfs_check_delayed_seq(fs_info, ref->seq)) {
spin_unlock(&locked_ref->lock);
unselect_delayed_ref_head(delayed_refs, locked_ref);
locked_ref = NULL;
cond_resched();
count++;
continue;
}
/*
* We're done processing refs in this ref_head, clean everything
* up and move on to the next ref_head.
*/
if (!ref) {
ret = btrfs_run_delayed_refs_for_head(trans, locked_ref,
&actual_count);
if (ret < 0 && ret != -EAGAIN) {
/*
* Error, btrfs_run_delayed_refs_for_head already
* unlocked everything so just bail out
*/
return ret;
} else if (!ret) {
/*
* Success, perform the usual cleanup of a processed
* head
*/
ret = cleanup_ref_head(trans, locked_ref);
if (ret > 0 ) {
/* We dropped our lock, we need to loop. */
@ -2686,61 +2679,16 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans,
} else if (ret) {
return ret;
}
locked_ref = NULL;
count++;
continue;
}
actual_count++;
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.
* Either success case or btrfs_run_delayed_refs_for_head
* returned -EAGAIN, meaning we need to select another head
*/
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);
count++;
locked_ref = NULL;
cond_resched();
}
} while ((nr != -1 && count < nr) || locked_ref);
/*
* We don't want to include ref heads since we can have empty ref heads