btrfs: fix structs where bitfields and spinlock/atomic share 8B word

On ia64, powerpc64 and sparc64 the bitfield is modified through a RMW cycle and current
gcc rewrites the adjacent 4B word, which in case of a spinlock or atomic has
disaterous effect.

https://lkml.org/lkml/2012/2/1/220

Signed-off-by: David Sterba <dsterba@suse.cz>

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 3c2cbf7..8e4457e 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -886,7 +886,7 @@ struct btrfs_block_rsv {
        u64 reserved;
        struct btrfs_space_info *space_info;
        spinlock_t lock;
-       unsigned int full:1;
+       unsigned int full;
 };
 
 /*

diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index 33a7890..1195f09 100644 (file)
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -26,8 +26,8 @@ struct extent_map {
        unsigned long flags;
        struct block_device *bdev;
        atomic_t refs;
-       unsigned int in_tree:1;
-       unsigned int compress_type:4;
+       unsigned int in_tree;
+       unsigned int compress_type;
 };
 
 struct extent_map_tree {