From c8174313a8102e874aaa321e2fc4c7c460a87151 Mon Sep 17 00:00:00 2001
From: Josef Bacik <josef@redhat.com>
Date: Wed, 2 Nov 2011 09:29:35 -0400
Subject: [PATCH] Btrfs: use the global reserve when truncating the free space
 cache inode

We no longer use the orphan block rsv for holding the reservation for truncating
the inode, so instead use the global block rsv and check to make sure it has
enough space for us to truncate the space.  Thanks,

Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
---
 fs/btrfs/free-space-cache.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index f49475dfa954..7a15fcfb3e1f 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -198,14 +198,24 @@ int btrfs_truncate_free_space_cache(struct btrfs_root *root,
 				    struct inode *inode)
 {
 	struct btrfs_block_rsv *rsv;
+	u64 needed_bytes;
 	loff_t oldsize;
 	int ret = 0;
 
 	rsv = trans->block_rsv;
-	trans->block_rsv = root->orphan_block_rsv;
-	ret = btrfs_block_rsv_check(root, root->orphan_block_rsv, 5);
-	if (ret)
-		return ret;
+	trans->block_rsv = &root->fs_info->global_block_rsv;
+
+	/* 1 for slack space, 1 for updating the inode */
+	needed_bytes = btrfs_calc_trunc_metadata_size(root, 1) +
+		btrfs_calc_trans_metadata_size(root, 1);
+
+	spin_lock(&trans->block_rsv->lock);
+	if (trans->block_rsv->reserved < needed_bytes) {
+		spin_unlock(&trans->block_rsv->lock);
+		trans->block_rsv = rsv;
+		return -ENOSPC;
+	}
+	spin_unlock(&trans->block_rsv->lock);
 
 	oldsize = i_size_read(inode);
 	btrfs_i_size_write(inode, 0);
@@ -218,13 +228,15 @@ int btrfs_truncate_free_space_cache(struct btrfs_root *root,
 	ret = btrfs_truncate_inode_items(trans, root, inode,
 					 0, BTRFS_EXTENT_DATA_KEY);
 
-	trans->block_rsv = rsv;
 	if (ret) {
+		trans->block_rsv = rsv;
 		WARN_ON(1);
 		return ret;
 	}
 
 	ret = btrfs_update_inode(trans, root, inode);
+	trans->block_rsv = rsv;
+
 	return ret;
 }
 
-- 
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