linux-ext4 - Re: ext4lazyinit reads HDD data on mount since 5.13

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Message-ID: <c984528b-03ce-f9e5-2cf2-4ae92e812367@valdikss.org.ru>
Date:   Mon, 9 Aug 2021 10:43:08 +0300
From:   ValdikSS <iam@...dikss.org.ru>
To:     Theodore Ts'o <tytso@....edu>
Cc:     linux-ext4@...r.kernel.org
Subject: Re: ext4lazyinit reads HDD data on mount since 5.13

On 09.08.2021 04:51, Theodore Ts'o wrote:
> It's a new feature which optimizes block allocations for very large
> file systems.  The work being done by ext4lazyinit is to read the
> block allocation bitmaps so we can cache the buddy bitmaps and how
> fragmented (or not) various block groups are, which is used to
> optimize the block allocator.

Thanks for the info. To revert old behavior, the filesystem should be 
mounted with -o no_prefetch_block_bitmaps

Is it safe to use this option with new optimizations? Should I expect 
only less optimal filesystem speed and no other issues?