btrfs: add btrfs_try_lock_ordered_range

For IOCB_NOWAIT we're going to want to use try lock on the extent lock,
and simply bail if there's an ordered extent in the range because the
only choice there is to wait for the ordered extent to complete.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Stefan Roesch <shr@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index 40a364c11178..e54f8280031f 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -1062,6 +1062,31 @@ void btrfs_lock_and_flush_ordered_range(struct btrfs_inode *inode, u64 start,
 	}
 }
 
+/*
+ * Lock the passed range and ensure all pending ordered extents in it are run
+ * to completion in nowait mode.
+ *
+ * Return true if btrfs_lock_ordered_range does not return any extents,
+ * otherwise false.
+ */
+bool btrfs_try_lock_ordered_range(struct btrfs_inode *inode, u64 start, u64 end)
+{
+	struct btrfs_ordered_extent *ordered;
+
+	if (!try_lock_extent(&inode->io_tree, start, end))
+		return false;
+
+	ordered = btrfs_lookup_ordered_range(inode, start, end - start + 1);
+	if (!ordered)
+		return true;
+
+	btrfs_put_ordered_extent(ordered);
+	unlock_extent(&inode->io_tree, start, end, NULL);
+
+	return false;
+}
+
+
 static int clone_ordered_extent(struct btrfs_ordered_extent *ordered, u64 pos,
 				u64 len)
 {