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From: Kinglong Mee <kinglongmee-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: Al Viro <viro-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>,
	NeilBrown <neilb-IBi9RG/b67k@public.gmane.org>
Cc: "J. Bruce Fields"
	<bfields-uC3wQj2KruNg9hUCZPvPmw@public.gmane.org>,
	"linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
	<linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Trond Myklebust
	<trond.myklebust-7I+n7zu2hftEKMMhf/gKZA@public.gmane.org>,
	kinglongmee-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org
Subject: Re: [PATCH 4/6 v9] fs: New helper legitimize_mntget() for getting a legitimize mnt
Date: Fri, 28 Aug 2015 07:02:39 +0800	[thread overview]
Message-ID: <55DF970F.6080308@gmail.com> (raw)
In-Reply-To: <20150819050245.GC18890-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>

On 8/19/2015 13:02, Al Viro wrote:
> On Wed, Aug 19, 2015 at 02:56:50PM +1000, NeilBrown wrote:
>> If not, we need to clean up and try again.
>> To do this we need to check MNT_SYNC_UMOUNT.
>> If that is clear it is safe and best to call mntput() on the mnt.
>> If it is set, then we just do the mnt_add_count(mnt, -1) and give up
>> completely.
> 
> It's more subtle, actually.  See my reply upthread for details, but
> basically we rely on rcu_read_lock() held since before that MNT_SYNC_UMOUNT
> had been set, making synchronize_rcu() in namespace_unlock() a guaranteed
> delay of the final mntput until after we have returned.
> 

Thanks for the comments.
I will update this patch according to Neil's comments and __legitimize_mnt.

thanks,
Kinglong Mee
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  parent reply	other threads:[~2015-08-27 23:02 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-08-18  7:17 [PATCH 0/6 v9] NFSD: Pin to vfsmount for nfsd exports cache Kinglong Mee
     [not found] ` <55D2DBF6.3010406-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-08-18  7:18   ` [PATCH 1/6 v9] fs-pin: allow pin_remove() to be called other than from->kill() Kinglong Mee
2015-08-18  7:19   ` [PATCH 2/6] fs_pin: Export functions for specific filesystem Kinglong Mee
2015-08-18  7:20   ` [PATCH 3/6 v9] path: New helpers path_get_pin/path_put_unpin for path pin Kinglong Mee
2015-08-18  7:21   ` [PATCH 4/6 v9] fs: New helper legitimize_mntget() for getting a legitimize mnt Kinglong Mee
     [not found]     ` <55D2DD17.7050504-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-08-19  4:56       ` NeilBrown
2015-08-19  5:02         ` Al Viro
     [not found]           ` <20150819050245.GC18890-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2015-08-27 23:02             ` Kinglong Mee [this message]
2015-08-18  7:22   ` [PATCH 5/6 v9] sunrpc: New helper cache_delete_entry for deleting cache_head directly Kinglong Mee
2015-08-18  7:23   ` [PATCH 6/6 v9] nfsd: Allows user un-mounting filesystem where nfsd exports base on Kinglong Mee
     [not found]     ` <55D2DD8F.6070501-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-08-19  3:54       ` NeilBrown
2015-08-19  4:50       ` Al Viro
     [not found]         ` <20150819045059.GB18890-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2015-08-27 23:15           ` Kinglong Mee
2015-08-18  7:24   ` [PATCH 2/6 v9] fs_pin: Export functions for specific filesystem Kinglong Mee

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