From: WuBo <wu.bo@cn.fujitsu.com>
Date: Tue, 26 Jul 2011 03:30:11 +0000 (+0000)
Subject: Btrfs: Protect the readonly flag of block group
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=61cfea9bb84d41b09e59822c33b3eb27acc48358;p=linux-beck.git

Btrfs: Protect the readonly flag of block group

The access for ro in btrfs_block_group_cache should be protected
because of the racy lock in relocation.

Signed-off-by: Wu Bo <wu.bo@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
---

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index db2057f262ad..a4db88da125e 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -6549,8 +6549,6 @@ static int set_block_group_ro(struct btrfs_block_group_cache *cache, int force)
 	u64 min_allocable_bytes;
 	int ret = -ENOSPC;
 
-	if (cache->ro)
-		return 0;
 
 	/*
 	 * We need some metadata space and system metadata space for
@@ -6566,6 +6564,12 @@ static int set_block_group_ro(struct btrfs_block_group_cache *cache, int force)
 
 	spin_lock(&sinfo->lock);
 	spin_lock(&cache->lock);
+
+	if (cache->ro) {
+		ret = 0;
+		goto out;
+	}
+
 	num_bytes = cache->key.offset - cache->reserved - cache->pinned -
 		    cache->bytes_super - btrfs_block_group_used(&cache->item);
 
@@ -6579,7 +6583,7 @@ static int set_block_group_ro(struct btrfs_block_group_cache *cache, int force)
 		cache->ro = 1;
 		ret = 0;
 	}
-
+out:
 	spin_unlock(&cache->lock);
 	spin_unlock(&sinfo->lock);
 	return ret;