Btrfs: add nested locking mode for paths

This patch adds the possibilty to read-lock an extent even if it is already
write-locked from the same thread. btrfs_find_all_roots() needs this
capability.

Signed-off-by: Arne Jansen <sensille@gmx.net>
Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index 7604c3001322..bc6a042cb6fc 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -129,6 +129,7 @@ struct extent_buffer {
         struct list_head leak_list;
         struct rcu_head rcu_head;
         atomic_t refs;
+        pid_t lock_owner;
 
         /* count of read lock holders on the extent buffer */
         atomic_t write_locks;
@@ -137,6 +138,7 @@ struct extent_buffer {
         atomic_t blocking_readers;
         atomic_t spinning_readers;
         atomic_t spinning_writers;
+        int lock_nested;
 
         /* protects write locks */
         rwlock_t lock;