btrfs: disable strict file flushes for renames and truncates

Truncates and renames are often used to replace old versions of a file
with new versions.  Applications often expect this to be an atomic
replacement, even if they haven't done anything to make sure the new
version is fully on disk.

Btrfs has strict flushing in place to make sure that renaming over an
old file with a new file will fully flush out the new file before
allowing the transaction commit with the rename to complete.

This ordering means the commit code needs to be able to lock file pages,
and there are a few paths in the filesystem where we will try to end a
transaction with the page lock held.  It's rare, but these things can
deadlock.

This patch removes the ordered flushes and switches to a best effort
filemap_flush like ext4 uses. It's not perfect, but it should fix the
deadlocks.

Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 0 insertions, 123 deletions

diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index 7187b14faa6c..963895c1f801 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -571,18 +571,6 @@ void btrfs_remove_ordered_extent(struct inode *inode,
 
 	trace_btrfs_ordered_extent_remove(inode, entry);
 
-	/*
-	 * we have no more ordered extents for this inode and
-	 * no dirty pages.  We can safely remove it from the
-	 * list of ordered extents
-	 */
-	if (RB_EMPTY_ROOT(&tree->tree) &&
-	    !mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) {
-		spin_lock(&root->fs_info->ordered_root_lock);
-		list_del_init(&BTRFS_I(inode)->ordered_operations);
-		spin_unlock(&root->fs_info->ordered_root_lock);
-	}
-
 	if (!root->nr_ordered_extents) {
 		spin_lock(&root->fs_info->ordered_root_lock);
 		BUG_ON(list_empty(&root->ordered_root));
@@ -687,81 +675,6 @@ void btrfs_wait_ordered_roots(struct btrfs_fs_info *fs_info, int nr)
 }
 
 /*
- * this is used during transaction commit to write all the inodes
- * added to the ordered operation list.  These files must be fully on
- * disk before the transaction commits.
- *
- * we have two modes here, one is to just start the IO via filemap_flush
- * and the other is to wait for all the io.  When we wait, we have an
- * extra check to make sure the ordered operation list really is empty
- * before we return
- */
-int btrfs_run_ordered_operations(struct btrfs_trans_handle *trans,
-				 struct btrfs_root *root, int wait)
-{
-	struct btrfs_inode *btrfs_inode;
-	struct inode *inode;
-	struct btrfs_transaction *cur_trans = trans->transaction;
-	struct list_head splice;
-	struct list_head works;
-	struct btrfs_delalloc_work *work, *next;
-	int ret = 0;
-
-	INIT_LIST_HEAD(&splice);
-	INIT_LIST_HEAD(&works);
-
-	mutex_lock(&root->fs_info->ordered_extent_flush_mutex);
-	spin_lock(&root->fs_info->ordered_root_lock);
-	list_splice_init(&cur_trans->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);
-
-		/*
-		 * the inode may be getting freed (in sys_unlink path).
-		 */
-		inode = igrab(inode);
-		if (!inode)
-			continue;
-
-		if (!wait)
-			list_add_tail(&BTRFS_I(inode)->ordered_operations,
-				      &cur_trans->ordered_operations);
-		spin_unlock(&root->fs_info->ordered_root_lock);
-
-		work = btrfs_alloc_delalloc_work(inode, wait, 1);
-		if (!work) {
-			spin_lock(&root->fs_info->ordered_root_lock);
-			if (list_empty(&BTRFS_I(inode)->ordered_operations))
-				list_add_tail(&btrfs_inode->ordered_operations,
-					      &splice);
-			list_splice_tail(&splice,
-					 &cur_trans->ordered_operations);
-			spin_unlock(&root->fs_info->ordered_root_lock);
-			ret = -ENOMEM;
-			goto out;
-		}
-		list_add_tail(&work->list, &works);
-		btrfs_queue_work(root->fs_info->flush_workers,
-				 &work->work);
-
-		cond_resched();
-		spin_lock(&root->fs_info->ordered_root_lock);
-	}
-	spin_unlock(&root->fs_info->ordered_root_lock);
-out:
-	list_for_each_entry_safe(work, next, &works, list) {
-		list_del_init(&work->list);
-		btrfs_wait_and_free_delalloc_work(work);
-	}
-	mutex_unlock(&root->fs_info->ordered_extent_flush_mutex);
-	return ret;
-}
-
-/*
  * Used to start IO or wait for a given ordered extent to finish.
  *
  * If wait is one, this effectively waits on page writeback for all the pages
@@ -1120,42 +1033,6 @@ out:
 	return index;
 }
 
-
-/*
- * add a given inode to the list of inodes that must be fully on
- * disk before a transaction commit finishes.
- *
- * This basically gives us the ext3 style data=ordered mode, and it is mostly
- * used to make sure renamed files are fully on disk.
- *
- * It is a noop if the inode is already fully on disk.
- *
- * If trans is not null, we'll do a friendly check for a transaction that
- * is already flushing things and force the IO down ourselves.
- */
-void btrfs_add_ordered_operation(struct btrfs_trans_handle *trans,
-				 struct btrfs_root *root, struct inode *inode)
-{
-	struct btrfs_transaction *cur_trans = trans->transaction;
-	u64 last_mod;
-
-	last_mod = max(BTRFS_I(inode)->generation, BTRFS_I(inode)->last_trans);
-
-	/*
-	 * if this file hasn't been changed since the last transaction
-	 * commit, we can safely return without doing anything
-	 */
-	if (last_mod <= root->fs_info->last_trans_committed)
-		return;
-
-	spin_lock(&root->fs_info->ordered_root_lock);
-	if (list_empty(&BTRFS_I(inode)->ordered_operations)) {
-		list_add_tail(&BTRFS_I(inode)->ordered_operations,
-			      &cur_trans->ordered_operations);
-	}
-	spin_unlock(&root->fs_info->ordered_root_lock);
-}
-
 int __init ordered_data_init(void)
 {
 	btrfs_ordered_extent_cache = kmem_cache_create("btrfs_ordered_extent",