linux-ext4 - RE: Phantom full ext4 root filesystems on 4.1 through 4.14 kernels

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Message-ID: <c8a7a059fb334920bdf020e0b7c050bd@exmbdft5.ad.twosigma.com>
Date:   Thu, 24 Jan 2019 14:40:13 +0000
From:   Elana Hashman <Elana.Hashman@...sigma.com>
To:     Liu Bo <obuil.liubo@...il.com>
CC:     "tytso@....edu" <tytso@....edu>,
        "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
        Thomas Walker <Thomas.Walker@...sigma.com>
Subject: RE: Phantom full ext4 root filesystems on 4.1 through 4.14 kernels

From: Liu Bo <obuil.liubo@...il.com> 

> I wonder if this ext4 enabled bigalloc (can be checked by dumpe2fs -h $disk).
> So bigalloc is known to cause leak space, and it's been just fixed recently.

Doesn't look that way:

$ uname -a
Linux <hostname> 4.14.67-ts1 #1 SMP Wed Aug 29 13:28:25 UTC 2018 x86_64 GNU/Linux
$ sudo du -hxs /
20G     /
$ df -h /
Filesystem                                              Size  Used Avail Use% Mounted on
/dev/disk/by-uuid/<some-uuid>   50G   46G  1.1G  98% /
$ sudo dumpe2fs -h /dev/disk/by-uuid/<some-uuid>
dumpe2fs 1.42.5 (29-Jul-2012)
Filesystem volume name:   ROOT
Last mounted on:          /
Filesystem UUID:          <some-uuid>
Filesystem magic number:  0xEF53
Filesystem revision #:    1 (dynamic)
Filesystem features:      has_journal ext_attr resize_inode dir_index filetype needs_recovery extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize
Filesystem flags:         signed_directory_hash
Default mount options:    user_xattr acl
Filesystem state:         clean
Errors behavior:          Continue
Filesystem OS type:       Linux
Inode count:              3276800
Block count:              13107200
Reserved block count:     655360
Free blocks:              9260751
Free inodes:              3078348
First block:              0
Block size:               4096
Fragment size:            4096
Reserved GDT blocks:      1020
Blocks per group:         32768
Fragments per group:      32768
Inodes per group:         8192
Inode blocks per group:   512
Flex block group size:    16
Filesystem created:       Tue Jan 16 18:48:13 2018
Last mount time:          Mon Oct  1 20:43:59 2018
Last write time:          Mon Oct  1 20:43:58 2018
Mount count:              7
Maximum mount count:      -1
Last checked:             Tue Jan 16 18:48:13 2018
Check interval:           0 (<none>)
Lifetime writes:          7159 GB
Reserved blocks uid:      0 (user root)
Reserved blocks gid:      0 (group root)
First inode:              11
Inode size:               256
Required extra isize:     28
Desired extra isize:      28
Journal inode:            8
First orphan inode:       2231477
Default directory hash:   half_md4
Directory Hash Seed:      8a6f6d03-37e7-409c-b8c9-d738e0b0a94a
Journal backup:           inode blocks
Journal features:         journal_incompat_revoke
Journal size:             128M
Journal length:           32768
Journal sequence:         0x02a09116
Journal start:            24688


--
Elana Hashman
ehashman@...sigma.com