Btrfs: don't traverse the ordered operation list repeatedly

btrfs_run_ordered_operations() needn't traverse the ordered operation list
repeatedly, it is because the transaction commiter will invoke it again when
there is no other writer in this transaction, it can ensure that no one can
add new objects into the ordered operation list.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>

diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index f14b17432117d5067276dee422b122febddc8877..9489fa96e3edd254d716d9708b8ee836237c1d1b 100644 (file)
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -626,14 +626,10 @@ int btrfs_run_ordered_operations(struct btrfs_root *root, int wait)
 
        mutex_lock(&root->fs_info->ordered_operations_mutex);
        spin_lock(&root->fs_info->ordered_extent_lock);
-again:
        list_splice_init(&root->fs_info->ordered_operations, &splice);
-
        while (!list_empty(&splice)) {
-
                btrfs_inode = list_entry(splice.next, struct btrfs_inode,
                                   ordered_operations);
-
                inode = &btrfs_inode->vfs_inode;
 
                list_del_init(&btrfs_inode->ordered_operations);
@@ -642,22 +638,20 @@ again:
                 * the inode may be getting freed (in sys_unlink path).
                 */
                inode = igrab(inode);
-
-               if (!wait && inode) {
-                       list_add_tail(&BTRFS_I(inode)->ordered_operations,
-                             &root->fs_info->ordered_operations);
-               }
-
                if (!inode)
                        continue;
+
+               if (!wait)
+                       list_add_tail(&BTRFS_I(inode)->ordered_operations,
+                                     &root->fs_info->ordered_operations);
                spin_unlock(&root->fs_info->ordered_extent_lock);
 
                work = btrfs_alloc_delalloc_work(inode, wait, 1);
                if (!work) {
+                       spin_lock(&root->fs_info->ordered_extent_lock);
                        if (list_empty(&BTRFS_I(inode)->ordered_operations))
                                list_add_tail(&btrfs_inode->ordered_operations,
                                              &splice);
-                       spin_lock(&root->fs_info->ordered_extent_lock);
                        list_splice_tail(&splice,
                                         &root->fs_info->ordered_operations);
                        spin_unlock(&root->fs_info->ordered_extent_lock);
@@ -671,9 +665,6 @@ again:
                cond_resched();
                spin_lock(&root->fs_info->ordered_extent_lock);
        }
-       if (wait && !list_empty(&root->fs_info->ordered_operations))
-               goto again;
-
        spin_unlock(&root->fs_info->ordered_extent_lock);
 out:
        list_for_each_entry_safe(work, next, &works, list) {