When we insert the file extent once the ordered extent completes we free
the reserved extent reservation as it'll have been migrated to the
bytes_used counter.  However if we error out after this step we'll still
clear the reserved extent reservation, resulting in a negative
accounting of the reserved bytes for the block group and space info.
Fix this by only doing the free if we didn't successfully insert a file
extent for this extent.

Signed-off-by: Josef Bacik <jo...@toxicpanda.com>
Reviewed-by: Omar Sandoval <osan...@fb.com>
---
 fs/btrfs/inode.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 5a91055a13b2..2b257d14bd3d 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2992,6 +2992,7 @@ static int btrfs_finish_ordered_io(struct 
btrfs_ordered_extent *ordered_extent)
        bool truncated = false;
        bool range_locked = false;
        bool clear_new_delalloc_bytes = false;
+       bool clear_reserved_extent = true;
 
        if (!test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags) &&
            !test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags) &&
@@ -3095,10 +3096,12 @@ static int btrfs_finish_ordered_io(struct 
btrfs_ordered_extent *ordered_extent)
                                                logical_len, logical_len,
                                                compress_type, 0, 0,
                                                BTRFS_FILE_EXTENT_REG);
-               if (!ret)
+               if (!ret) {
+                       clear_reserved_extent = false;
                        btrfs_release_delalloc_bytes(fs_info,
                                                     ordered_extent->start,
                                                     ordered_extent->disk_len);
+               }
        }
        unpin_extent_cache(&BTRFS_I(inode)->extent_tree,
                           ordered_extent->file_offset, ordered_extent->len,
@@ -3159,8 +3162,13 @@ static int btrfs_finish_ordered_io(struct 
btrfs_ordered_extent *ordered_extent)
                 * wrong we need to return the space for this ordered extent
                 * back to the allocator.  We only free the extent in the
                 * truncated case if we didn't write out the extent at all.
+                *
+                * If we made it past insert_reserved_file_extent before we
+                * errored out then we don't need to do this as the accounting
+                * has already been done.
                 */
                if ((ret || !logical_len) &&
+                   clear_reserved_extent &&
                    !test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags) &&
                    !test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags))
                        btrfs_free_reserved_extent(fs_info,
-- 
2.14.3

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