From: Christoph Hellwig <hch@infradead.org>
To: Sascha Hauer <s.hauer@pengutronix.de>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
Christoph Hellwig <hch@infradead.org>,
kernel@pengutronix.de, Jan Kara <jack@suse.com>,
Richard Weinberger <richard@nod.at>
Subject: Re: [PATCH 1/2] quota: Add mountpath based quota support
Date: Thu, 28 Jan 2021 14:35:52 +0000 [thread overview]
Message-ID: <20210128143552.GA2042235@infradead.org> (raw)
In-Reply-To: <20210128141713.25223-2-s.hauer@pengutronix.de>
> + uint cmds, type;
> + struct super_block *sb = NULL;
I don't think sb needs the NULL initialization.
> + struct path path, *pathp = NULL;
> + struct path mountpath;
> + bool excl = false, thawed = false;
> + int ret;
> +
> + cmds = cmd >> SUBCMDSHIFT;
> + type = cmd & SUBCMDMASK;
Personal pet peeve: it would be nice to just initialize cmds and
type on their declaration line, or while we're at it declutter
this a bit and remove the separate cmds variable:
unsigned int type = cmd & SUBCMDMASK;
cmd >>= SUBCMDSHIFT;
> + /*
> + * Path for quotaon has to be resolved before grabbing superblock
> + * because that gets s_umount sem which is also possibly needed by path
> + * resolution (think about autofs) and thus deadlocks could arise.
> + */
> + if (cmds == Q_QUOTAON) {
> + ret = user_path_at(AT_FDCWD, addr,
> + LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT, &path);
> + if (ret)
> + pathp = ERR_PTR(ret);
> + else
> + pathp = &path;
> + }
> +
> + ret = user_path_at(AT_FDCWD, mountpoint,
> + LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT, &mountpath);
> + if (ret)
> + goto out;
I don't think we need two path lookups here, we can path the same path
to the command for quotaon.
> + if (quotactl_cmd_onoff(cmds)) {
> + excl = true;
> + thawed = true;
> + } else if (quotactl_cmd_write(cmds)) {
> + thawed = true;
> + }
> +
> + if (thawed) {
> + ret = mnt_want_write(mountpath.mnt);
> + if (ret)
> + goto out1;
> + }
> +
> + sb = mountpath.dentry->d_inode->i_sb;
> +
> + if (excl)
> + down_write(&sb->s_umount);
> + else
> + down_read(&sb->s_umount);
Given how cheap quotactl_cmd_onoff and quotactl_cmd_write are we
could probably simplify this down do:
if (quotactl_cmd_write(cmd)) {
ret = mnt_want_write(path.mnt);
if (ret)
goto out1;
}
if (quotactl_cmd_onoff(cmd))
down_write(&sb->s_umount);
else
down_read(&sb->s_umount);
and duplicate the checks after the do_quotactl call.
next prev parent reply other threads:[~2021-01-28 14:37 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-28 14:17 [PATCH 0/2] quota: Add mountpath based quota support Sascha Hauer
2021-01-28 14:17 ` [PATCH 1/2] " Sascha Hauer
2021-01-28 14:35 ` Christoph Hellwig [this message]
2021-02-02 18:02 ` Jan Kara
2021-02-04 7:34 ` Christoph Hellwig
2021-02-04 12:53 ` Jan Kara
2021-02-09 8:51 ` Christoph Hellwig
2021-02-09 9:57 ` Jan Kara
2021-01-28 14:17 ` [PATCH 2/2] quota: wire up quotactl_path Sascha Hauer
2021-01-28 14:17 ` [PATCH] quotactl.2: Add documentation for quotactl_path() Sascha Hauer
2021-02-11 15:30 [PATCH v2 0/2] quota: Add mountpath based quota support Sascha Hauer
2021-02-11 15:30 ` [PATCH 1/2] " Sascha Hauer
2021-02-11 15:38 ` Christoph Hellwig
2021-02-12 8:38 ` Sascha Hauer
2021-02-12 10:05 ` Jan Kara
2021-02-12 10:29 ` Sascha Hauer
2021-02-12 10:41 ` Jan Kara
2021-02-12 5:45 ` kernel test robot
2021-02-14 13:48 ` Al Viro
2021-03-04 12:35 [PATCH v3 0/2] " Sascha Hauer
2021-03-04 12:35 ` [PATCH 1/2] " Sascha Hauer
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