btrfs: simplify waiting loop in btrfs_tree_lock

[sfrench/cifs-2.6.git] / fs / btrfs / locking.c

diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
index 1da768e5ef75bda36142c084d6ba7c2b5c4bc809..82b84e4daad1f336fc8b6de895d445682308f3ef 100644 (file)
--- a/fs/btrfs/locking.c
+++ b/fs/btrfs/locking.c
@@ -14,43 +14,58 @@
 
 static void btrfs_assert_tree_read_locked(struct extent_buffer *eb);
 
-/*
- * if we currently have a spinning reader or writer lock
- * (indicated by the rw flag) this will bump the count
- * of blocking holders and drop the spinlock.
- */
-void btrfs_set_lock_blocking_rw(struct extent_buffer *eb, int rw)
+void btrfs_set_lock_blocking_read(struct extent_buffer *eb)
 {
        /*
-        * no lock is required.  The lock owner may change if
-        * we have a read lock, but it won't change to or away
-        * from us.  If we have the write lock, we are the owner
-        * and it'll never change.
+        * No lock is required.  The lock owner may change if we have a read
+        * lock, but it won't change to or away from us.  If we have the write
+        * lock, we are the owner and it'll never change.
         */
        if (eb->lock_nested && current->pid == eb->lock_owner)
                return;
-       if (rw == BTRFS_WRITE_LOCK) {
-               if (atomic_read(&eb->blocking_writers) == 0) {
-                       WARN_ON(atomic_read(&eb->spinning_writers) != 1);
-                       atomic_dec(&eb->spinning_writers);
-                       btrfs_assert_tree_locked(eb);
-                       atomic_inc(&eb->blocking_writers);
-                       write_unlock(&eb->lock);
-               }
-       } else if (rw == BTRFS_READ_LOCK) {
-               btrfs_assert_tree_read_locked(eb);
-               atomic_inc(&eb->blocking_readers);
-               WARN_ON(atomic_read(&eb->spinning_readers) == 0);
-               atomic_dec(&eb->spinning_readers);
-               read_unlock(&eb->lock);
+       btrfs_assert_tree_read_locked(eb);
+       atomic_inc(&eb->blocking_readers);
+       WARN_ON(atomic_read(&eb->spinning_readers) == 0);
+       atomic_dec(&eb->spinning_readers);
+       read_unlock(&eb->lock);
+}
+
+void btrfs_set_lock_blocking_write(struct extent_buffer *eb)
+{
+       /*
+        * No lock is required.  The lock owner may change if we have a read
+        * lock, but it won't change to or away from us.  If we have the write
+        * lock, we are the owner and it'll never change.
+        */
+       if (eb->lock_nested && current->pid == eb->lock_owner)
+               return;
+       if (atomic_read(&eb->blocking_writers) == 0) {
+               WARN_ON(atomic_read(&eb->spinning_writers) != 1);
+               atomic_dec(&eb->spinning_writers);
+               btrfs_assert_tree_locked(eb);
+               atomic_inc(&eb->blocking_writers);
+               write_unlock(&eb->lock);
        }
 }
 
-/*
- * if we currently have a blocking lock, take the spinlock
- * and drop our blocking count
- */
-void btrfs_clear_lock_blocking_rw(struct extent_buffer *eb, int rw)
+void btrfs_clear_lock_blocking_read(struct extent_buffer *eb)
+{
+       /*
+        * No lock is required.  The lock owner may change if we have a read
+        * lock, but it won't change to or away from us.  If we have the write
+        * lock, we are the owner and it'll never change.
+        */
+       if (eb->lock_nested && current->pid == eb->lock_owner)
+               return;
+       BUG_ON(atomic_read(&eb->blocking_readers) == 0);
+       read_lock(&eb->lock);
+       atomic_inc(&eb->spinning_readers);
+       /* atomic_dec_and_test implies a barrier */
+       if (atomic_dec_and_test(&eb->blocking_readers))
+               cond_wake_up_nomb(&eb->read_lock_wq);
+}
+
+void btrfs_clear_lock_blocking_write(struct extent_buffer *eb)
 {
        /*
         * no lock is required.  The lock owner may change if
@@ -60,23 +75,13 @@ void btrfs_clear_lock_blocking_rw(struct extent_buffer *eb, int rw)
         */
        if (eb->lock_nested && current->pid == eb->lock_owner)
                return;
-
-       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);
-               /* atomic_dec_and_test implies a barrier */
-               if (atomic_dec_and_test(&eb->blocking_writers))
-                       cond_wake_up_nomb(&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);
-               /* atomic_dec_and_test implies a barrier */
-               if (atomic_dec_and_test(&eb->blocking_readers))
-                       cond_wake_up_nomb(&eb->read_lock_wq);
-       }
+       BUG_ON(atomic_read(&eb->blocking_writers) != 1);
+       write_lock(&eb->lock);
+       WARN_ON(atomic_read(&eb->spinning_writers));
+       atomic_inc(&eb->spinning_writers);
+       /* atomic_dec_and_test implies a barrier */
+       if (atomic_dec_and_test(&eb->blocking_writers))
+               cond_wake_up_nomb(&eb->write_lock_wq);
 }
 
 /*
@@ -232,16 +237,9 @@ again:
        wait_event(eb->read_lock_wq, atomic_read(&eb->blocking_readers) == 0);
        wait_event(eb->write_lock_wq, atomic_read(&eb->blocking_writers) == 0);
        write_lock(&eb->lock);
-       if (atomic_read(&eb->blocking_readers)) {
+       if (atomic_read(&eb->blocking_readers) ||
+           atomic_read(&eb->blocking_writers)) {
                write_unlock(&eb->lock);
-               wait_event(eb->read_lock_wq,
-                          atomic_read(&eb->blocking_readers) == 0);
-               goto again;
-       }
-       if (atomic_read(&eb->blocking_writers)) {
-               write_unlock(&eb->lock);
-               wait_event(eb->write_lock_wq,
-                          atomic_read(&eb->blocking_writers) == 0);
                goto again;
        }
        WARN_ON(atomic_read(&eb->spinning_writers));