Re: [PATCH 0/5 v7] ext4: Speedup orphan file handling

["Theodore Ts'o" <tytso@mit.edu>]

I've been running some tests exercising the orphan_file code, and
there are a number of failures:

ext4/orphan_file: 512 tests, 3 failures, 25 skipped, 7325 seconds
  Failures: ext4/044 generic/475 generic/643
ext4/orphan_file_1k: 524 tests, 6 failures, 37 skipped, 8361 seconds
  Failures: ext4/033 ext4/044 ext4/045 generic/273 generic/476 generic/643

generic/643 is the iomap swap failure, and can be ignored.
generic/475 is a pre-existing test flake that involves simulated disk
failures, which we can also ignore in the context or orphan_file.

However, ext4/044 is one that looks... interesting:

root@kvm-xfstests:~# e2fsck -fn /dev/vdc
e2fsck 1.46.4-orphan-file (22-Aug-2021)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
Orphan file (inode 12) block 0 is not clean.
Clear? no

Failed to initialize orphan file.
Recreate? no

This is highly reproducible, and involves using a file system config
that is probably a little unusual:

Filesystem features:      has_journal ext_attr resize_inode dir_index orphan_file filetype sparse_super large_file

(This was created using "mke2fs -t ext3 -O orphan_file".)

The orphan_file_1k failures seem to involve running out of space in
the orphan_file, and the fallback to using the old fashioned orphan
list seems to return ENOSPC?  For example, from ext4/045:

    +mkdir: No space left on device
    +Failed to create directories - 19679

ext4/045 creates a lot of directories when calls mkdir (ext4/045 tests
creating more than 65000 subdirectories in a directory), and so this
seems to be triggering a failure?

					- Ted