linux-kernel - Re: [PATCH] exfat: optimize dir-cache

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Date:   Wed, 27 May 2020 08:00:40 +0000
From:   "Kohada.Tetsuhiro@...MitsubishiElectric.co.jp" 
        <Kohada.Tetsuhiro@...MitsubishiElectric.co.jp>
To:     Sungjong Seo <sj1557.seo@...sung.com>
CC:     "Mori.Takahiro@...MitsubishiElectric.co.jp" 
        <Mori.Takahiro@...MitsubishiElectric.co.jp>,
        "Motai.Hirotaka@...MitsubishiElectric.co.jp" 
        <Motai.Hirotaka@...MitsubishiElectric.co.jp>,
        'Namjae Jeon' <namjae.jeon@...sung.com>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "'kohada.t2@...il.com'" <kohada.t2@...il.com>
Subject: Re: [PATCH] exfat: optimize dir-cache

Thank you for your comment.

 >> +    for (i = 0; i < es->num_bh; i++) {
 >> +            if (es->modified)
 >> +                    exfat_update_bh(es->sb, es->bh[i], sync);
 >
 > Overall, it looks good to me.
 > However, if "sync" is set, it looks better to return the result of exfat_update_bh().
 > Of course, a tiny modification for exfat_update_bh() is also required.

 I thought the same, while creating this patch.
 However this patch has changed a lot and I didn't add any new error checking.
 (So, the same behavior will occur even if an error occurs)

 >> +struct exfat_dentry *exfat_get_dentry_cached(
 >> +    struct exfat_entry_set_cache *es, int num) {
 >> +    int off = es->start_off + num * DENTRY_SIZE;
 >> +    struct buffer_head *bh = es->bh[EXFAT_B_TO_BLK(off, es->sb)];
 >> +    char *p = bh->b_data + EXFAT_BLK_OFFSET(off, es->sb);
 >
 > In order to prevent illegal accesses to bh and dentries, it would be better to check validation for num and bh.

 There is no new error checking for same reason as above.

 I'll try to add error checking to this v2 patch.
 Or is it better to add error checking in another patch?

BR
---
Kohada Tetsuhiro <Kohada.Tetsuhiro@...MitsubishiElectric.co.jp>