1 files changed, 11 insertions, 0 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 3cc5677f5440..3a6f953337b5 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4909,10 +4909,21 @@ again:
                 goto again;
         }
 
+        /*
+         * XXX - page_mkwrite gets called every time the page is dirtied, even
+         * if it was already dirty, so for space accounting reasons we need to
+         * clear any delalloc bits for the range we are fixing to save.  There
+         * is probably a better way to do this, but for now keep consistent with
+         * prepare_pages in the normal write path.
+         */
+        clear_extent_bits(&BTRFS_I(inode)->io_tree, page_start, page_end,
+                          EXTENT_DIRTY | EXTENT_DELALLOC, GFP_NOFS);
+
         ret = btrfs_set_extent_delalloc(inode, page_start, page_end);
         if (ret) {
                 unlock_extent(io_tree, page_start, page_end, GFP_NOFS);
                 ret = VM_FAULT_SIGBUS;
+                btrfs_free_reserved_data_space(root, inode, PAGE_CACHE_SIZE);
                 goto out_unlock;
         }
         ret = 0;