From: Al Viro <viro@ZenIV.linux.org.uk>
To: Miao Xie <miaox@cn.fujitsu.com>
Cc: Chris Mason <chris.mason@oracle.com>,
Linux Btrfs <linux-btrfs@vger.kernel.org>,
Linux Fsdevel <linux-fsdevel@vger.kernel.org>,
Ito <t-itoh@jp.fujitsu.com>
Subject: Re: [PATCH 2/2] Btrfs: fix deadlock on sb->s_umount when doing umount
Date: Tue, 6 Dec 2011 05:49:06 +0000 [thread overview]
Message-ID: <20111206054906.GG2203@ZenIV.linux.org.uk> (raw)
In-Reply-To: <4EDDA9B3.60508@cn.fujitsu.com>
> +void btrfs_writeback_inodes_sb_nr(struct btrfs_root *root,
> + unsigned long nr_pages)
> +{
> + struct super_block *sb = root->fs_info->sb;
> +
> + if (writeback_in_progress(sb->s_bdi))
> + return;
> +
> + /*
> + * If we can not get s_umount, it means the fs is on remounting or
> + * umounting. At this time, we just sync all the delalloc file.
> + */
> + if (down_read_trylock(&sb->s_umount)) {
> + writeback_inodes_sb_nr(sb, nr_pages);
> + up_read(&sb->s_umount);
> + } else {
> + btrfs_start_delalloc_inodes(root, 0);
> + btrfs_wait_ordered_extents(root, 0, 0);
> + }
> +}
If that can race with umount, what prevents sb, its ->s_bdi et.al. being freed
under you?
next prev parent reply other threads:[~2011-12-06 5:49 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-06 5:35 [PATCH 2/2] Btrfs: fix deadlock on sb->s_umount when doing umount Miao Xie
2011-12-06 5:49 ` Al Viro [this message]
2011-12-06 6:52 ` Miao Xie
2011-12-06 9:59 ` Christoph Hellwig
2011-12-06 11:06 ` Miao Xie
2011-12-06 11:23 ` Christoph Hellwig
2011-12-06 21:36 ` Chris Mason
2011-12-07 2:31 ` Miao Xie
2011-12-07 11:11 ` Ilya Dryomov
2011-12-08 3:46 ` Miao Xie
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