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Date:   Mon, 16 Aug 2021 11:58:42 +0200
From:   Jan Kara <>
To:     Ted Tso <>
Cc:, Jan Kara <>
Subject: Re: [PATCH 0/5 v6] ext4: Speedup orphan file handling


please disregard this version. I forgot to include a fix we talked about at
the last ext4 call, namely to check that orphan file is not linked from
directory hierarchy. I've submitted v7 now with that fix included.


On Mon 16-08-21 11:22:58, Jan Kara wrote:
>   Hello,
> Here is a fourth version of my series to speed up orphan inode handling in
> ext4.
> Orphan inode handling in ext4 is a bottleneck for workloads which heavily
> excercise truncate / unlink of small files as they contend on global
> s_orphan_mutex (when you have fast enough storage). This patch set implements
> new way of handling orphan inodes - instead of using a linked list, we store
> inode numbers of orphaned inodes in a file which is possible to implement in a
> more scalable manner than linked list manipulations. See description of patch
> 3/5 for more details.
> The patch set achieves significant gains both for a micro benchmark stressing
> orphan inode handling (truncating file byte-by-byte, several threads in
> parallel) and for reaim creat_clo workload. I'm happy for any review, thoughts,
> ideas about the patches. I have also implemented full support in e2fsprogs
> which I'll send separately.
> 								Honza
> [1]
> Changes since v5:
> * Added Reviewed-by tags from Ted
> * Fixed up sparse warning spotted by 0-day
> * Fixed error handling path in ext4_orphan_add() to not leak orphan entry
> Changes since v4:
> * Rebased on top of v5.14-rc5
> * Updated commit message of patch 1/5
> * Added Reviewed-by tags from Ted
> Changes since v3:
> * Added documentation about on-disk format changes
> * Add physical block number into orphan block checksum
> * Improve some sanity checks, handling of corrupted orphan file
> * Improved some changelogs
> Changes since v2:
> * Updated some comments
> * Rebased onto 5.13-rc5
> * Change orphan file inode from a fixed inode number to inode number stored
>   in the superblock
> Changes since v1:
> * orphan blocks have now magic numbers
> * split out orphan handling to a separate source file
> * some smaller updates according to review
> Previous versions:
> Link: # v5
> Link: #v4
> Link: #v3
> Link: #v2
Jan Kara <>

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