From: Josef Bacik <josef@toxicpanda.com>

Date: Thu, 22 Aug 2019 15:11:00 -0400

Subject: btrfs: fix may_commit_transaction to deal with no partial filling

Git-commit: 00c0135eb8b8172de48e1accbb09ebfa3aa8bf25

Patch-mainline: v5.4-rc1

References: bsc#1141456

Now that we aren't partially filling tickets we may have some slack

space left in the space_info.  We need to account for this in

may_commit_transaction, otherwise we may choose to not commit the

transaction despite it actually having enough space to satisfy our

ticket.

Calculate the free space we have in the space_info, if any, and subtract

this from the ticket we have and use that amount to determine if we will

need to commit to reclaim enough space.

Reviewed-by: Nikolay Borisov <nborisov@suse.com>

Signed-off-by: Josef Bacik <josef@toxicpanda.com>

Signed-off-by: David Sterba <dsterba@suse.com>

Acked-by: Nikolay Borisov <nborisov@suse.com>

---

 fs/btrfs/space-info.c | 12 ++++++++++++

 1 file changed, 12 insertions(+)

diff --git a/fs/btrfs/space-info.c b/fs/btrfs/space-info.c

index eb4a926ea7b9..3ab7a4810bef 100644

--- a/fs/btrfs/space-info.c

+++ b/fs/btrfs/space-info.c

@@ -473,12 +473,19 @@ static int may_commit_transaction(struct btrfs_fs_info *fs_info,

 	struct btrfs_trans_handle *trans;

 	u64 bytes_needed;

 	u64 reclaim_bytes = 0;

+	u64 cur_free_bytes = 0;

 	trans = (struct btrfs_trans_handle *)current->journal_info;

 	if (trans)

 		return -EAGAIN;

 	spin_lock(&space_info->lock);

+	cur_free_bytes = btrfs_space_info_used(space_info, true);

+	if (cur_free_bytes < space_info->total_bytes)

+		cur_free_bytes = space_info->total_bytes - cur_free_bytes;

+	else

+		cur_free_bytes = 0;

+

 	if (!list_empty(&space_info->priority_tickets))

 		ticket = list_first_entry(&space_info->priority_tickets,

 					  struct reserve_ticket, list);

@@ -486,6 +493,11 @@ static int may_commit_transaction(struct btrfs_fs_info *fs_info,

 		ticket = list_first_entry(&space_info->tickets,

 					  struct reserve_ticket, list);

 	bytes_needed = (ticket) ? ticket->bytes : 0;

+

+	if (bytes_needed > cur_free_bytes)

+		bytes_needed -= cur_free_bytes;

+	else

+		bytes_needed = 0;

 	spin_unlock(&space_info->lock);

 	if (!bytes_needed)