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, 32 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 08e65e9cf2aa..d0ed9e664f7d 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -60,8 +60,6 @@ static void end_workqueue_fn(struct btrfs_work *work);
 static void free_fs_root(struct btrfs_root *root);
 static int btrfs_check_super_valid(struct btrfs_fs_info *fs_info,
                                     int read_only);
-static void btrfs_destroy_ordered_operations(struct btrfs_transaction *t,
-                                             struct btrfs_root *root);
 static void btrfs_destroy_ordered_extents(struct btrfs_root *root);
 static int btrfs_destroy_delayed_refs(struct btrfs_transaction *trans,
                                       struct btrfs_root *root);
@@ -3829,34 +3827,6 @@ static void btrfs_error_commit_super(struct btrfs_root *root)
         btrfs_cleanup_transaction(root);
 }
 
-static void btrfs_destroy_ordered_operations(struct btrfs_transaction *t,
-                                             struct btrfs_root *root)
-{
-        struct btrfs_inode *btrfs_inode;
-        struct list_head splice;
-
-        INIT_LIST_HEAD(&splice);
-
-        mutex_lock(&root->fs_info->ordered_operations_mutex);
-        spin_lock(&root->fs_info->ordered_root_lock);
-
-        list_splice_init(&t->ordered_operations, &splice);
-        while (!list_empty(&splice)) {
-                btrfs_inode = list_entry(splice.next, struct btrfs_inode,
-                                         ordered_operations);
-
-                list_del_init(&btrfs_inode->ordered_operations);
-                spin_unlock(&root->fs_info->ordered_root_lock);
-
-                btrfs_invalidate_inodes(btrfs_inode->root);
-
-                spin_lock(&root->fs_info->ordered_root_lock);
-        }
-
-        spin_unlock(&root->fs_info->ordered_root_lock);
-        mutex_unlock(&root->fs_info->ordered_operations_mutex);
-}
-
 static void btrfs_destroy_ordered_extents(struct btrfs_root *root)
 {
         struct btrfs_ordered_extent *ordered;
@@ -4093,8 +4063,6 @@ again:
 void btrfs_cleanup_one_transaction(struct btrfs_transaction *cur_trans,
                                    struct btrfs_root *root)
 {
-        btrfs_destroy_ordered_operations(cur_trans, root);
-
         btrfs_destroy_delayed_refs(cur_trans, root);
 
         cur_trans->state = TRANS_STATE_COMMIT_START;