Btrfs: Implement basic support for -ENOSPC

This is intended to prevent accidentally filling the drive.  A determined
user can still make things oops.

It includes some accounting of the current bytes under delayed allocation,
but this will change as things get optimized

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 2559f5d5d00a..10129cc6656f 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -346,6 +346,8 @@ struct btrfs_fs_info {
         int closing;
 
         u64 total_pinned;
+        spinlock_t delalloc_lock;
+        u64 delalloc_bytes;
 };
 /*
  * in ram representation of the tree.  extent_root is used for all allocations
@@ -1115,6 +1117,8 @@ int btrfs_csum_truncate(struct btrfs_trans_handle *trans,
                         struct btrfs_root *root, struct btrfs_path *path,
                         u64 isize);
 /* inode.c */
+int btrfs_check_free_space(struct btrfs_root *root, u64 num_required,
+                           int for_del);
 int btrfs_page_mkwrite(struct vm_area_struct *vma, struct page *page);
 int btrfs_readpage(struct file *file, struct page *page);
 void btrfs_delete_inode(struct inode *inode);