Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable

* 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable:
  Btrfs: always pin metadata in discard mode
  Btrfs: enable discard support
  Btrfs: add -o discard option
  Btrfs: properly wait log writers during log sync
  Btrfs: fix possible ENOSPC problems with truncate
  Btrfs: fix btrfs acl #ifdef checks
  Btrfs: streamline tree-log btree block writeout
  Btrfs: avoid tree log commit when there are no changes
  Btrfs: only write one super copy during fsync

1 files changed, 26 insertions, 15 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 2d623aa0625f..06550affbd27 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1086,8 +1086,10 @@ out_nolock:
                                         btrfs_end_transaction(trans, root);
                                 else
                                         btrfs_commit_transaction(trans, root);
-                        } else {
+                        } else if (ret != BTRFS_NO_LOG_SYNC) {
                                 btrfs_commit_transaction(trans, root);
+                        } else {
+                                btrfs_end_transaction(trans, root);
                         }
                 }
                 if (file->f_flags & O_DIRECT) {
@@ -1137,6 +1139,13 @@ int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
         int ret = 0;
         struct btrfs_trans_handle *trans;
 
+
+        /* we wait first, since the writeback may change the inode */
+        root->log_batch++;
+        /* the VFS called filemap_fdatawrite for us */
+        btrfs_wait_ordered_range(inode, 0, (u64)-1);
+        root->log_batch++;
+
         /*
          * check the transaction that last modified this inode
          * and see if its already been committed
@@ -1144,6 +1153,11 @@ int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
         if (!BTRFS_I(inode)->last_trans)
                 goto out;
 
+        /*
+         * if the last transaction that changed this file was before
+         * the current transaction, we can bail out now without any
+         * syncing
+         */
         mutex_lock(&root->fs_info->trans_mutex);
         if (BTRFS_I(inode)->last_trans <=
             root->fs_info->last_trans_committed) {
@@ -1153,13 +1167,6 @@ int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
         }
         mutex_unlock(&root->fs_info->trans_mutex);
 
-        root->log_batch++;
-        filemap_fdatawrite(inode->i_mapping);
-        btrfs_wait_ordered_range(inode, 0, (u64)-1);
-        root->log_batch++;
-
-        if (datasync && !(inode->i_state & I_DIRTY_PAGES))
-                goto out;
         /*
          * ok we haven't committed the transaction yet, lets do a commit
          */
@@ -1188,14 +1195,18 @@ int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
          */
         mutex_unlock(&dentry->d_inode->i_mutex);
 
-        if (ret > 0) {
-                ret = btrfs_commit_transaction(trans, root);
-        } else {
-                ret = btrfs_sync_log(trans, root);
-                if (ret == 0)
-                        ret = btrfs_end_transaction(trans, root);
-                else
+        if (ret != BTRFS_NO_LOG_SYNC) {
+                if (ret > 0) {
                         ret = btrfs_commit_transaction(trans, root);
+                } else {
+                        ret = btrfs_sync_log(trans, root);
+                        if (ret == 0)
+                                ret = btrfs_end_transaction(trans, root);
+                        else
+                                ret = btrfs_commit_transaction(trans, root);
+                }
+        } else {
+                ret = btrfs_end_transaction(trans, root);
         }
         mutex_lock(&dentry->d_inode->i_mutex);
 out: