linux-kernel - Re: [PATCH 30/31] ext4: eliminate xattr entry e

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Message-ID: <20170619081002.GC11837@quack2.suse.cz>
Date:   Mon, 19 Jun 2017 10:10:02 +0200
From:   Jan Kara <jack@...e.cz>
To:     Tahsin Erdogan <tahsin@...gle.com>
Cc:     Jan Kara <jack@...e.cz>,
        "Darrick J . Wong" <darrick.wong@...cle.com>,
        Jan Kara <jack@...e.com>, Theodore Ts'o <tytso@....edu>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Dave Kleikamp <shaggy@...nel.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Mark Fasheh <mfasheh@...sity.com>,
        Joel Becker <jlbec@...lplan.org>, Jens Axboe <axboe@...com>,
        Deepa Dinamani <deepa.kernel@...il.com>,
        Mike Christie <mchristi@...hat.com>,
        Fabian Frederick <fabf@...net.be>, linux-ext4@...r.kernel.org,
        linux-kernel@...r.kernel.org, jfs-discussion@...ts.sourceforge.net,
        linux-fsdevel@...r.kernel.org, ocfs2-devel@....oracle.com,
        reiserfs-devel@...r.kernel.org
Subject: Re: [PATCH 30/31] ext4: eliminate xattr entry e_hash recalculation
 for removes

On Fri 16-06-17 19:04:44, Tahsin Erdogan wrote:
> On Thu, Jun 15, 2017 at 2:10 AM, Jan Kara <jack@...e.cz> wrote:
> > I agree with moving ext4_xattr_rehash_entry() out of ext4_xattr_rehash().
> > However how about just keeping ext4_xattr_rehash() in
> > ext4_xattr_block_set() (so that you don't have to pass aditional argument
> > to ext4_xattr_set_entry()) and calling ext4_xattr_rehash_entry() when
> > i->value != NULL? That would seem easier and cleaner as well...
> 
> The is_block parameter is also used to decide whether block reserve
> check should be performed:
> 
> @@ -1500,8 +1502,8 @@ static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
>                  * attribute block so that a long value does not occupy the
>                  * whole space and prevent futher entries being added.
>                  */
> -               if (ext4_has_feature_ea_inode(inode->i_sb) && new_size &&
> -                   (s->end - s->base) == i_blocksize(inode) &&
> +               if (ext4_has_feature_ea_inode(inode->i_sb) &&
> +                   new_size && is_block &&
>                     (min_offs + old_size - new_size) <
>                                         EXT4_XATTR_BLOCK_RESERVE(inode)) {
>                         ret = -ENOSPC;
> 
> Because of that, I think moving ext4_xattr_rehash to caller makes it
> bit more complicated. Let me know if you disagree.

What I dislike is the leakage of information about particular type of
storage into ext4_xattr_set_entry(). However I agree that it would be
cumbersome to handle this reservation check differently so ok.

								Honza

-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR