From: Chris Mason <chris.mason@oracle.com>
Date: Fri, 1 Feb 2008 19:51:59 +0000 (-0500)
Subject: Btrfs: Hash in the offset and owner for file extent backref keys
X-Git-Url: http://git.mmlx.us/?a=commitdiff_plain;h=21a4989d26d5ce43aac452fd67be592463a5996d;p=linux-edison.git

Btrfs: Hash in the offset and owner for file extent backref keys

This makes searches for backrefs and backref insertion much more efficient
when there are many backrefs for a single extent

Signed-off-by: Chris Mason <chris.mason@oracle.com>
---

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 0fc8dfd58da..8761aec59e3 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -397,13 +397,12 @@ static u64 hash_extent_ref(u64 root_objectid, u64 ref_generation,
 	high_crc = crc32c(high_crc, &lenum, sizeof(lenum));
 	lenum = cpu_to_le64(ref_generation);
 	low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
-
-#if 0
-	lenum = cpu_to_le64(owner);
-	low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
-	lenum = cpu_to_le64(owner_offset);
-	low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
-#endif
+	if (owner >= BTRFS_FIRST_FREE_OBJECTID) {
+		lenum = cpu_to_le64(owner);
+		low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
+		lenum = cpu_to_le64(owner_offset);
+		low_crc = crc32c(low_crc, &lenum, sizeof(lenum));
+	}
 	return ((u64)high_crc << 32) | (u64)low_crc;
 }