From: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
To: Javier Martinez Canillas <javierm@redhat.com>
Cc: linux-kernel@vger.kernel.org, Colin Walters <walters@verbum.org>,
Peter Jones <pjones@redhat.com>,
Alexander Larsson <alexl@redhat.com>,
Alberto Ruiz <aruiz@redhat.com>,
Christian Kellner <ckellner@redhat.com>,
Lennart Poettering <lennart@poettering.net>,
Chung-Chiang Cheng <cccheng@synology.com>
Subject: Re: [RFC PATCH 2/3] fat: add renameat2 RENAME_EXCHANGE flag support
Date: Mon, 23 May 2022 02:42:44 +0900 [thread overview]
Message-ID: <87fsl1cvl7.fsf@mail.parknet.co.jp> (raw)
In-Reply-To: <20220519092343.2776414-3-javierm@redhat.com> (Javier Martinez Canillas's message of "Thu, 19 May 2022 11:23:42 +0200")
Javier Martinez Canillas <javierm@redhat.com> writes:
> The renameat2 RENAME_EXCHANGE flag allows to atomically exchange two paths
> but is currently not supported by the Linux vfat filesystem driver.
>
> Add a vfat_rename_exchange() helper function that implements this support.
>
> The super block lock is acquired during the operation to ensure atomicity,
> and in the error path actions made are reversed also with the mutex held,
> making the whole operation transactional.
I'm not fully reviewed yet though (write order and race), basically
looks like good.
> + /* if directories are not the same, get ".." info to update */
> + if (old_dir != new_dir) {
> + if (S_ISDIR(old_inode->i_mode))
> + if (fat_get_dotdot_entry(old_inode, &old_dotdot_bh, &old_dotdot_de)) {
> + err = -EIO;
> + goto out;
> + }
> + if (S_ISDIR(new_inode->i_mode))
> + if (fat_get_dotdot_entry(new_inode, &new_dotdot_bh, &new_dotdot_de)) {
> + err = -EIO;
> + goto out;
> + }
> + }
It may not be linux coding style though, please add {}
if () {
...
}
for non one liner body.
> + /* update ".." directory entry info */
> + if (old_dotdot_de) {
> + fat_set_start(old_dotdot_de, MSDOS_I(new_dir)->i_logstart);
> + mark_buffer_dirty_inode(old_dotdot_bh, old_inode);
> + if (IS_DIRSYNC(new_dir)) {
> + err = sync_dirty_buffer(old_dotdot_bh);
> + if (err)
> + goto error_old_dotdot;
> + }
> + drop_nlink(old_dir);
> + inc_nlink(new_dir);
> + }
> +
> + if (new_dotdot_de) {
> + fat_set_start(new_dotdot_de, MSDOS_I(old_dir)->i_logstart);
> + mark_buffer_dirty_inode(new_dotdot_bh, new_inode);
> + if (IS_DIRSYNC(old_dir)) {
> + err = sync_dirty_buffer(new_dotdot_bh);
> + if (err)
> + goto error_new_dotdot;
> + }
> + drop_nlink(new_dir);
> + inc_nlink(old_dir);
> + }
There are some copy&paste codes, for example above, it may be better to
use function and consolidate? If you had some intent, it is ok though.
Thanks.
--
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
next prev parent reply other threads:[~2022-05-22 17:42 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-19 9:23 [RFC PATCH 0/3] fat: add support for the renameat2 RENAME_EXCHANGE flag Javier Martinez Canillas
2022-05-19 9:23 ` [RFC PATCH 1/3] fat: add a vfat_rename2() and make existing .rename callback a helper Javier Martinez Canillas
2022-05-19 9:23 ` [RFC PATCH 2/3] fat: add renameat2 RENAME_EXCHANGE flag support Javier Martinez Canillas
2022-05-22 17:42 ` OGAWA Hirofumi [this message]
2022-05-23 15:35 ` Javier Martinez Canillas
2022-05-23 10:40 ` Colin Walters
2022-05-23 15:34 ` Javier Martinez Canillas
2022-05-23 17:05 ` OGAWA Hirofumi
2022-05-19 9:23 ` [RFC PATCH 3/3] selftests/filesystems: add a vfat RENAME_EXCHANGE test Javier Martinez Canillas
2022-05-21 13:38 ` Muhammad Usama Anjum
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