Patched in Tegra support.

1 files changed, 11 insertions, 62 deletions

diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
index 2a1762c6604..d77b67c4b27 100644
--- a/fs/btrfs/locking.c
+++ b/fs/btrfs/locking.c
@@ -33,14 +33,6 @@ void btrfs_assert_tree_read_locked(struct extent_buffer *eb);
  */
 void btrfs_set_lock_blocking_rw(struct extent_buffer *eb, int rw)
 {
-        if (eb->lock_nested) {
-                read_lock(&eb->lock);
-                if (eb->lock_nested && current->pid == eb->lock_owner) {
-                        read_unlock(&eb->lock);
-                        return;
-                }
-                read_unlock(&eb->lock);
-        }
         if (rw == BTRFS_WRITE_LOCK) {
                 if (atomic_read(&eb->blocking_writers) == 0) {
                         WARN_ON(atomic_read(&eb->spinning_writers) != 1);
@@ -65,28 +57,18 @@ void btrfs_set_lock_blocking_rw(struct extent_buffer *eb, int rw)
  */
 void btrfs_clear_lock_blocking_rw(struct extent_buffer *eb, int rw)
 {
-        if (eb->lock_nested) {
-                read_lock(&eb->lock);
-                if (eb->lock_nested && current->pid == eb->lock_owner) {
-                        read_unlock(&eb->lock);
-                        return;
-                }
-                read_unlock(&eb->lock);
-        }
         if (rw == BTRFS_WRITE_LOCK_BLOCKING) {
                 BUG_ON(atomic_read(&eb->blocking_writers) != 1);
                 write_lock(&eb->lock);
                 WARN_ON(atomic_read(&eb->spinning_writers));
                 atomic_inc(&eb->spinning_writers);
-                if (atomic_dec_and_test(&eb->blocking_writers) &&
-                    waitqueue_active(&eb->write_lock_wq))
+                if (atomic_dec_and_test(&eb->blocking_writers))
                         wake_up(&eb->write_lock_wq);
         } else if (rw == BTRFS_READ_LOCK_BLOCKING) {
                 BUG_ON(atomic_read(&eb->blocking_readers) == 0);
                 read_lock(&eb->lock);
                 atomic_inc(&eb->spinning_readers);
-                if (atomic_dec_and_test(&eb->blocking_readers) &&
-                    waitqueue_active(&eb->read_lock_wq))
+                if (atomic_dec_and_test(&eb->blocking_readers))
                         wake_up(&eb->read_lock_wq);
         }
         return;
@@ -99,25 +81,12 @@ void btrfs_clear_lock_blocking_rw(struct extent_buffer *eb, int rw)
 void btrfs_tree_read_lock(struct extent_buffer *eb)
 {
 again:
-        read_lock(&eb->lock);
-        if (atomic_read(&eb->blocking_writers) &&
-            current->pid == eb->lock_owner) {
-                /*
-                 * This extent is already write-locked by our thread. We allow
-                 * an additional read lock to be added because it's for the same
-                 * thread. btrfs_find_all_roots() depends on this as it may be
-                 * called on a partly (write-)locked tree.
-                 */
-                BUG_ON(eb->lock_nested);
-                eb->lock_nested = 1;
-                read_unlock(&eb->lock);
-                return;
-        }
-        read_unlock(&eb->lock);
         wait_event(eb->write_lock_wq, atomic_read(&eb->blocking_writers) == 0);
         read_lock(&eb->lock);
         if (atomic_read(&eb->blocking_writers)) {
                 read_unlock(&eb->lock);
+                wait_event(eb->write_lock_wq,
+                           atomic_read(&eb->blocking_writers) == 0);
                 goto again;
         }
         atomic_inc(&eb->read_locks);
@@ -160,7 +129,6 @@ int btrfs_try_tree_write_lock(struct extent_buffer *eb)
         }
         atomic_inc(&eb->write_locks);
         atomic_inc(&eb->spinning_writers);
-        eb->lock_owner = current->pid;
         return 1;
 }
 
@@ -169,15 +137,6 @@ int btrfs_try_tree_write_lock(struct extent_buffer *eb)
  */
 void btrfs_tree_read_unlock(struct extent_buffer *eb)
 {
-        if (eb->lock_nested) {
-                read_lock(&eb->lock);
-                if (eb->lock_nested && current->pid == eb->lock_owner) {
-                        eb->lock_nested = 0;
-                        read_unlock(&eb->lock);
-                        return;
-                }
-                read_unlock(&eb->lock);
-        }
         btrfs_assert_tree_read_locked(eb);
         WARN_ON(atomic_read(&eb->spinning_readers) == 0);
         atomic_dec(&eb->spinning_readers);
@@ -190,19 +149,9 @@ void btrfs_tree_read_unlock(struct extent_buffer *eb)
  */
 void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb)
 {
-        if (eb->lock_nested) {
-                read_lock(&eb->lock);
-                if (eb->lock_nested && current->pid == eb->lock_owner) {
-                        eb->lock_nested = 0;
-                        read_unlock(&eb->lock);
-                        return;
-                }
-                read_unlock(&eb->lock);
-        }
         btrfs_assert_tree_read_locked(eb);
         WARN_ON(atomic_read(&eb->blocking_readers) == 0);
-        if (atomic_dec_and_test(&eb->blocking_readers) &&
-            waitqueue_active(&eb->read_lock_wq))
+        if (atomic_dec_and_test(&eb->blocking_readers))
                 wake_up(&eb->read_lock_wq);
         atomic_dec(&eb->read_locks);
 }
@@ -211,7 +160,7 @@ void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb)
  * take a spinning write lock.  This will wait for both
  * blocking readers or writers
  */
-void btrfs_tree_lock(struct extent_buffer *eb)
+int btrfs_tree_lock(struct extent_buffer *eb)
 {
 again:
         wait_event(eb->read_lock_wq, atomic_read(&eb->blocking_readers) == 0);
@@ -232,13 +181,13 @@ again:
         WARN_ON(atomic_read(&eb->spinning_writers));
         atomic_inc(&eb->spinning_writers);
         atomic_inc(&eb->write_locks);
-        eb->lock_owner = current->pid;
+        return 0;
 }
 
 /*
  * drop a spinning or a blocking write lock.
  */
-void btrfs_tree_unlock(struct extent_buffer *eb)
+int btrfs_tree_unlock(struct extent_buffer *eb)
 {
         int blockers = atomic_read(&eb->blocking_writers);
 
@@ -250,14 +199,14 @@ void btrfs_tree_unlock(struct extent_buffer *eb)
         if (blockers) {
                 WARN_ON(atomic_read(&eb->spinning_writers));
                 atomic_dec(&eb->blocking_writers);
-                smp_mb();
-                if (waitqueue_active(&eb->write_lock_wq))
-                        wake_up(&eb->write_lock_wq);
+                smp_wmb();
+                wake_up(&eb->write_lock_wq);
         } else {
                 WARN_ON(atomic_read(&eb->spinning_writers) != 1);
                 atomic_dec(&eb->spinning_writers);
                 write_unlock(&eb->lock);
         }
+        return 0;
 }
 
 void btrfs_assert_tree_locked(struct extent_buffer *eb)