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Date:   Tue, 13 Jul 2021 10:11:33 +0200
From:   Jan Kara <jack@suse.cz>
To:     Andreas Dilger <adilger@dilger.ca>
Cc:     Jan Kara <jack@suse.cz>, Ted Tso <tytso@mit.edu>,
        linux-ext4@vger.kernel.org
Subject: Re: [PATCH 1/9] ext2fs: Drop HAS_SNAPSHOT feature
Message-ID: <20210713081133.GA12142@quack2.suse.cz>
References: <20210712154315.9606-2-jack@suse.cz>
 <41F4A61F-DB56-4814-8E52-99A742F44FAF@dilger.ca>
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Hello,

On Mon 12-07-21 12:20:03, Andreas Dilger wrote:
> NAK.
> 
> We are working on a snapshot implementation for ext4, it is
> just taking a lot longer that I thought it would to complete. 
> 
> There isn't any shortage of these feature bits, so no reason to re-use them. 

Sure. I thought this feature bit was a leftover from experimental ext4
snapshot feature Amir Goldstein was playing with some 10-15 years ago and
which never completed. If there's somebody working on this, I'll allocate a
different bit.

								Honza

> 
> Cheers, Andreas
> 
> > On Jul 12, 2021, at 09:43, Jan Kara <jack@suse.cz> wrote:
> > 
> > ﻿It has never been implemented and is dead for quite some time and
> > unused AFAICT.
> > 
> > Signed-off-by: Jan Kara <jack@suse.cz>
> > ---
> > lib/ext2fs/ext2_fs.h | 2 --
> > 1 file changed, 2 deletions(-)
> > 
> > diff --git a/lib/ext2fs/ext2_fs.h b/lib/ext2fs/ext2_fs.h
> > index e92a045205a9..6f1d5db4b482 100644
> > --- a/lib/ext2fs/ext2_fs.h
> > +++ b/lib/ext2fs/ext2_fs.h
> > @@ -825,7 +825,6 @@ struct ext2_super_block {
> > #define EXT4_FEATURE_RO_COMPAT_GDT_CSUM        0x0010
> > #define EXT4_FEATURE_RO_COMPAT_DIR_NLINK    0x0020
> > #define EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE    0x0040
> > -#define EXT4_FEATURE_RO_COMPAT_HAS_SNAPSHOT    0x0080
> > #define EXT4_FEATURE_RO_COMPAT_QUOTA        0x0100
> > #define EXT4_FEATURE_RO_COMPAT_BIGALLOC        0x0200
> > /*
> > @@ -926,7 +925,6 @@ EXT4_FEATURE_RO_COMPAT_FUNCS(huge_file,        4, HUGE_FILE)
> > EXT4_FEATURE_RO_COMPAT_FUNCS(gdt_csum,        4, GDT_CSUM)
> > EXT4_FEATURE_RO_COMPAT_FUNCS(dir_nlink,        4, DIR_NLINK)
> > EXT4_FEATURE_RO_COMPAT_FUNCS(extra_isize,    4, EXTRA_ISIZE)
> > -EXT4_FEATURE_RO_COMPAT_FUNCS(has_snapshot,    4, HAS_SNAPSHOT)
> > EXT4_FEATURE_RO_COMPAT_FUNCS(quota,        4, QUOTA)
> > EXT4_FEATURE_RO_COMPAT_FUNCS(bigalloc,        4, BIGALLOC)
> > EXT4_FEATURE_RO_COMPAT_FUNCS(metadata_csum,    4, METADATA_CSUM)
> > -- 
> > 2.26.2
> > 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR