linux-ext4 - Re: [PATCH 1/5] ext4: never move the system.data xattr out of the inode body

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Message-Id: <B1595157-5278-485A-A8DF-E711E1D2D93F@dilger.ca>
Date:   Mon, 18 Jun 2018 11:50:32 -0600
From:   Andreas Dilger <adilger@...ger.ca>
To:     Theodore Ts'o <tytso@....edu>
Cc:     Ext4 Developers List <linux-ext4@...r.kernel.org>,
        wen.xu@...ech.edu
Subject: Re: [PATCH 1/5] ext4: never move the system.data xattr out of the
 inode body

On Jun 17, 2018, at 9:22 PM, Theodore Ts'o <tytso@....edu> wrote:
> 
> When expanding the extra isize space, we must never move the
> system.data xattr out of the inode body.  For performance reasons, it
> doesn't make any sense, and the inline data implementation assumes
> that system.data xattr is never in the external xattr block.
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=200005
> 
> Signed-off-by: Theodore Ts'o <tytso@....edu>

Reviewed-by: Andreas Dilger <adilger@...ger.ca>

> ---
> fs/ext4/xattr.c | 5 +++++
> 1 file changed, 5 insertions(+)
> 
> diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
> index 0263692979ec..72377b77fbd7 100644
> --- a/fs/ext4/xattr.c
> +++ b/fs/ext4/xattr.c
> @@ -2657,6 +2657,11 @@ static int ext4_xattr_make_inode_space(handle_t *handle, struct inode *inode,
> 		last = IFIRST(header);
> 		/* Find the entry best suited to be pushed into EA block */
> 		for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) {
> +			/* never move system.data out of the inode */
> +			if ((last->e_name_len == 4) &&
> +			    (last->e_name_index == EXT4_XATTR_INDEX_SYSTEM) &&
> +			    !memcmp(last->e_name, "data", 4))
> +				continue;
> 			total_size = EXT4_XATTR_LEN(last->e_name_len);
> 			if (!last->e_value_inum)
> 				total_size += EXT4_XATTR_SIZE(
> --
> 2.18.0.rc0
> 


Cheers, Andreas






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