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From: David Sterba <dsterba@suse.cz>
To: Nikolay Borisov <nborisov@suse.com>
Cc: dsterba@suse.cz, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 0/3] Remove deprecated inode cache feature
Date: Fri, 27 Nov 2020 15:58:36 +0100	[thread overview]
Message-ID: <20201127145836.GZ6430@twin.jikos.cz> (raw)
In-Reply-To: <90b5646b-cd53-f5bd-7214-44387c523203@suse.com>

On Thu, Nov 26, 2020 at 06:00:24PM +0200, Nikolay Borisov wrote:
> 
> 
> On 26.11.20 г. 17:31 ч., David Sterba wrote:
> > There's still the remaining issue what to do with the space occupied by
> > the cache inode if the feature was enabled. I haven't researched that,
> > eg. how big the inode is if it's worth removing it at all or if we
> > should do some lightweight scan to remove them at some appropriate time.
> 
> I'd rather implement this in btrfs-progs.

I did a quick check, 1M empty files created then every 7th deleted (so
there are no large ranges to free), resulting in ~140K files and that
occupied about 680KiB. So for 1M files it's about 5M of space, where
metadata part is small (<1KiB), the bitmaps are stored in hidden data
inodes.  All in all it does not sound like a terrible waste of space.

      reply	other threads:[~2020-11-27 15:00 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-26 13:10 [PATCH 0/3] Remove deprecated inode cache feature Nikolay Borisov
2020-11-26 13:10 ` [PATCH 1/3] btrfs: Move btrfs_find_highest_objectid/btrfs_find_free_objectid to disk-io.c Nikolay Borisov
2020-11-26 13:10 ` [PATCH 2/3] btrfs: Replace calls to btrfs_find_free_ino with btrfs_find_free_objectid Nikolay Borisov
2020-11-26 13:10 ` [PATCH 3/3] btrfs: Remove inode cache feature Nikolay Borisov
2020-11-27 16:30   ` David Sterba
2020-11-26 15:31 ` [PATCH 0/3] Remove deprecated " David Sterba
2020-11-26 16:00   ` Nikolay Borisov
2020-11-27 14:58     ` David Sterba [this message]

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