Btrfs: set truncate block rsv's size

While debugging a different issue I noticed that we were always reserving space
when we tried to use our truncate block rsv's.  This is because they didn't have
a ->size value, so use_block_rsv just assumes there is nothing reserved and it
does a reserve_metadata_bytes.  This is because btrfs_check_block_rsv() doesn't
actually add to the size of the block rsv.  That seems to be the right thing to
do so set ->size to the minimum truncate size we need, since we will always only
refill to that size anyway, and this way everything works out correctly.

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

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index e40b9239660d..06ae5b173fd7 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3561,6 +3561,7 @@ void btrfs_evict_inode(struct inode *inode)
                 btrfs_orphan_del(NULL, inode);
                 goto no_delete;
         }
+        rsv->size = min_size;
 
         btrfs_i_size_write(inode, 0);
 
@@ -6530,6 +6531,7 @@ static int btrfs_truncate(struct inode *inode)
         rsv = btrfs_alloc_block_rsv(root);
         if (!rsv)
                 return -ENOMEM;
+        rsv->size = min_size;
 
         /*
          * 1 for the truncate slack space