btrfs: introduce a FORCE_COMMIT_TRANS flush operation

Solely for preemptive flushing, we want to be able to force the
transaction commit without any of the ambiguity of
may_commit_transaction().  This is because may_commit_transaction()
checks tickets and such, and in preemptive flushing we already know
it'll be helpful, so use this to keep the code nice and clean and
straightforward.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
[ add comment ]
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Josef Bacik 2020-10-09 09:28:21 -04:00 committed by David Sterba
parent 5deb17e18e
commit f00c42dd4c
3 changed files with 17 additions and 1 deletions

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@ -2740,6 +2740,7 @@ enum btrfs_flush_state {
ALLOC_CHUNK_FORCE = 8,
RUN_DELAYED_IPUTS = 9,
COMMIT_TRANS = 10,
FORCE_COMMIT_TRANS = 11,
};
int btrfs_subvolume_reserve_metadata(struct btrfs_root *root,

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@ -140,6 +140,12 @@
* be freed, plus any delayed work we may not have gotten rid of in the case
* of metadata.
*
* FORCE_COMMIT_TRANS
* For use by the preemptive flusher. We use this to bypass the ticketing
* checks in may_commit_transaction, as we have more information about the
* overall state of the system and may want to commit the transaction ahead
* of actual ENOSPC conditions.
*
* OVERCOMMIT
*
* Because we hold so many reservations for metadata we will allow you to
@ -735,6 +741,14 @@ static void flush_space(struct btrfs_fs_info *fs_info,
case COMMIT_TRANS:
ret = may_commit_transaction(fs_info, space_info);
break;
case FORCE_COMMIT_TRANS:
trans = btrfs_join_transaction(root);
if (IS_ERR(trans)) {
ret = PTR_ERR(trans);
break;
}
ret = btrfs_commit_transaction(trans);
break;
default:
ret = -ENOSPC;
break;

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@ -99,7 +99,8 @@ struct btrfs_space_info;
EM( ALLOC_CHUNK, "ALLOC_CHUNK") \
EM( ALLOC_CHUNK_FORCE, "ALLOC_CHUNK_FORCE") \
EM( RUN_DELAYED_IPUTS, "RUN_DELAYED_IPUTS") \
EMe(COMMIT_TRANS, "COMMIT_TRANS")
EM( COMMIT_TRANS, "COMMIT_TRANS") \
EMe(FORCE_COMMIT_TRANS, "FORCE_COMMIT_TRANS")
/*
* First define the enums in the above macros to be exported to userspace via