Btrfs: only update disk_i_size as we remove extents

This fixes a problem where if we fail a truncate we will leave the i_size set
where we wanted to truncate to instead of where we were able to truncate to.
Fix this by making btrfs_truncate_inode_items do the disk_i_size update as it
removes extents, that way it will always be consistent with where its extents
are.  Then if the truncate fails at all we can update the in-ram i_size with
what we have on disk and delete the orphan item.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

1 files changed, 28 insertions, 3 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index f0e41b840739..6091ba9d2494 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3861,6 +3861,7 @@ int btrfs_truncate_inode_items(struct btrfs_trans_handle *trans,
         u64 extent_num_bytes = 0;
         u64 extent_offset = 0;
         u64 item_end = 0;
+        u64 last_size = (u64)-1;
         u32 found_type = (u8)-1;
         int found_extent;
         int del_item;
@@ -3958,6 +3959,11 @@ search_again:
                 if (found_type != BTRFS_EXTENT_DATA_KEY)
                         goto delete;
 
+                if (del_item)
+                        last_size = found_key.offset;
+                else
+                        last_size = new_size;
+
                 if (extent_type != BTRFS_FILE_EXTENT_INLINE) {
                         u64 num_dec;
                         extent_start = btrfs_file_extent_disk_bytenr(leaf, fi);
@@ -4069,6 +4075,8 @@ out:
                         btrfs_abort_transaction(trans, root, ret);
         }
 error:
+        if (last_size != (u64)-1)
+                btrfs_ordered_update_i_size(inode, last_size, NULL);
         btrfs_free_path(path);
         return err;
 }
@@ -4397,8 +4405,26 @@ static int btrfs_setsize(struct inode *inode, struct iattr *attr)
                 btrfs_inode_resume_unlocked_dio(inode);
 
                 ret = btrfs_truncate(inode);
-                if (ret && inode->i_nlink)
-                        btrfs_orphan_del(NULL, inode);
+                if (ret && inode->i_nlink) {
+                        int err;
+
+                        /*
+                         * failed to truncate, disk_i_size is only adjusted down
+                         * as we remove extents, so it should represent the true
+                         * size of the inode, so reset the in memory size and
+                         * delete our orphan entry.
+                         */
+                        trans = btrfs_join_transaction(root);
+                        if (IS_ERR(trans)) {
+                                btrfs_orphan_del(NULL, inode);
+                                return ret;
+                        }
+                        i_size_write(inode, BTRFS_I(inode)->disk_i_size);
+                        err = btrfs_orphan_del(trans, inode);
+                        if (err)
+                                btrfs_abort_transaction(trans, root, err);
+                        btrfs_end_transaction(trans, root);
+                }
         }
 
         return ret;
@@ -7537,7 +7563,6 @@ static int btrfs_truncate(struct inode *inode)
         u64 min_size = btrfs_calc_trunc_metadata_size(root, 1);
 
         btrfs_wait_ordered_range(inode, inode->i_size & (~mask), (u64)-1);
-        btrfs_ordered_update_i_size(inode, inode->i_size, NULL);
 
         /*
          * Yes ladies and gentelment, this is indeed ugly.  The fact is we have