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authorChris Mason <chris.mason@oracle.com>2009-05-29 16:35:30 -0400
committerChris Mason <chris.mason@oracle.com>2009-06-08 13:30:36 -0400
commit95d3f20b51e9b2ee21822313ad4f31279396407b (patch)
treeb120e33ca9ad3f04a0a32b62451e6ba5926b2ca0 /kerncompat.h
parent2d39a83829bfc26f0c79b33fca64540c634f7f18 (diff)
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Mixed back reference (FORWARD ROLLING FORMAT CHANGE)
This commit introduces a new kind of back reference for btrfs metadata. Once a filesystem has been mounted with this commit, IT WILL NO LONGER BE MOUNTABLE BY OLDER KERNELS. The new back ref provides information about pointer's key, level and in which tree the pointer lives. This information allow us to find the pointer by searching the tree. The shortcoming of the new back ref is that it only works for pointers in tree blocks referenced by their owner trees. This is mostly a problem for snapshots, where resolving one of these fuzzy back references would be O(number_of_snapshots) and quite slow. The solution used here is to use the fuzzy back references in the common case where a given tree block is only referenced by one root, and use the full back references when multiple roots have a reference
Diffstat (limited to 'kerncompat.h')
-rw-r--r--kerncompat.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/kerncompat.h b/kerncompat.h
index aed4b55..e4c8ce0 100644
--- a/kerncompat.h
+++ b/kerncompat.h
@@ -191,6 +191,7 @@ static inline long IS_ERR(const void *ptr)
*/
#define printk(fmt, args...) fprintf(stderr, fmt, ##args)
#define KERN_CRIT ""
+#define KERN_ERR ""
/*
* kmalloc/kfree