linux-ext4 - Re: [PATCH] ext4: unconditionally enable the i

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Date:   Tue, 26 Jul 2022 02:18:02 +0000
From:   "xuyang2018.jy@...itsu.com" <xuyang2018.jy@...itsu.com>
To:     "Darrick J. Wong" <djwong@...nel.org>,
        Jeff Layton <jlayton@...nel.org>
CC:     "tytso@....edu" <tytso@....edu>,
        "adilger.kernel@...ger.ca" <adilger.kernel@...ger.ca>,
        "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
        Dave Chinner <david@...morbit.com>,
        Lukas Czerner <lczerner@...hat.com>,
        Benjamin Coddington <bcodding@...hat.com>,
        Christoph Hellwig <hch@...radead.org>
Subject: Re: [PATCH] ext4: unconditionally enable the i_version counter



on 2022/07/26 5:49, Darrick J. Wong wrote:
> On Mon, Jul 25, 2022 at 03:29:46PM -0400, Jeff Layton wrote:
>> The original i_version implementation was pretty expensive, requiring a
>> log flush on every change. Because of this, it was gated behind a mount
>> option (implemented via the MS_I_VERSION mountoption flag).
>>
>> Commit ae5e165d855d (fs: new API for handling inode->i_version) made the
>> i_version flag much less expensive, so there is no longer a performance
>> penalty from enabling it.
>>
>> Have ext4 ignore the SB_I_VERSION flag, and just enable it
>> unconditionally.
>>
>> Cc: Dave Chinner <david@...morbit.com>
>> Cc: Lukas Czerner <lczerner@...hat.com>
>> Cc: Benjamin Coddington <bcodding@...hat.com>
>> Cc: Christoph Hellwig <hch@...radead.org>
>> Signed-off-by: Jeff Layton <jlayton@...nel.org>
>> ---
>>   fs/ext4/inode.c | 5 ++---
>>   fs/ext4/super.c | 8 ++++----
>>   2 files changed, 6 insertions(+), 7 deletions(-)
>>
>> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
>> index 84c0eb55071d..c785c0b72116 100644
>> --- a/fs/ext4/inode.c
>> +++ b/fs/ext4/inode.c
>> @@ -5411,7 +5411,7 @@ int ext4_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
>>   			return -EINVAL;
>>   		}
>>   
>> -		if (IS_I_VERSION(inode) && attr->ia_size != inode->i_size)
>> +		if (attr->ia_size != inode->i_size)
>>   			inode_inc_iversion(inode);
>>   
>>   		if (shrink) {
>> @@ -5717,8 +5717,7 @@ int ext4_mark_iloc_dirty(handle_t *handle,
>>   	}
>>   	ext4_fc_track_inode(handle, inode);
>>   
>> -	if (IS_I_VERSION(inode))
>> -		inode_inc_iversion(inode);
>> +	inode_inc_iversion(inode);
>>   
>>   	/* the do_update_inode consumes one bh->b_count */
>>   	get_bh(iloc->bh);
>> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
>> index 845f2f8aee5f..30645d4343b6 100644
>> --- a/fs/ext4/super.c
>> +++ b/fs/ext4/super.c
>> @@ -2142,8 +2142,7 @@ static int ext4_parse_param(struct fs_context *fc, struct fs_parameter *param)
>>   		return 0;
>>   	case Opt_i_version:
>>   		ext4_msg(NULL, KERN_WARNING, deprecated_msg, param->key, "5.20");
> 
> Perhaps it's time to kill off Opt_i_version, since we're now at 5.20?
> 
> (For that matter, noacl/nouser_xattr were supposed to be gone by 3.5 and
> they're clearly still there, so either they ought to go as well?)

For noacl/nouser_xattr, have some disscussion in here[1].

Also, I want to remove deprecated flag[2] but seems removing these 
deprecated options is better.

I just use noacl mount option in ltp/xfstests test case[3][4], but seems 
none use them in application because none comlain about these deprecated 
flags over the years.

[1]https://www.spinics.net/lists/linux-ext4/msg82507.html
[2]https://patchwork.ozlabs.org/project/linux-ext4/patch/1654164099-2164-1-git-send-email-xuyang2018.jy@fujitsu.com/
[3]https://patchwork.ozlabs.org/project/ltp/patch/1658485640-2188-2-git-send-email-xuyang2018.jy@fujitsu.com/
[4]https://www.spinics.net/lists/fstests/msg19554.html

Best Regards
Yang Xu
> 
> --D
> 
>> -		ext4_msg(NULL, KERN_WARNING, "Use iversion instead\n");
>> -		ctx_set_flags(ctx, SB_I_VERSION);
>> +		ext4_msg(NULL, KERN_WARNING, "i_version counter is always enabled.\n");
>>   		return 0;
>>   	case Opt_inlinecrypt:
>>   #ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT
>> @@ -2970,8 +2969,6 @@ static int _ext4_show_options(struct seq_file *seq, struct super_block *sb,
>>   		SEQ_OPTS_PRINT("min_batch_time=%u", sbi->s_min_batch_time);
>>   	if (nodefs || sbi->s_max_batch_time != EXT4_DEF_MAX_BATCH_TIME)
>>   		SEQ_OPTS_PRINT("max_batch_time=%u", sbi->s_max_batch_time);
>> -	if (sb->s_flags & SB_I_VERSION)
>> -		SEQ_OPTS_PUTS("i_version");
>>   	if (nodefs || sbi->s_stripe)
>>   		SEQ_OPTS_PRINT("stripe=%lu", sbi->s_stripe);
>>   	if (nodefs || EXT4_MOUNT_DATA_FLAGS &
>> @@ -4630,6 +4627,9 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
>>   	sb->s_flags = (sb->s_flags & ~SB_POSIXACL) |
>>   		(test_opt(sb, POSIX_ACL) ? SB_POSIXACL : 0);
>>   
>> +	/* i_version is always enabled now */
>> +	sb->s_flags |= SB_I_VERSION;
>> +
>>   	if (le32_to_cpu(es->s_rev_level) == EXT4_GOOD_OLD_REV &&
>>   	    (ext4_has_compat_features(sb) ||
>>   	     ext4_has_ro_compat_features(sb) ||
>> -- 
>> 2.37.1
>>