From: Jan Kara <jack@suse.cz>
To: Eric Sandeen <sandeen@sandeen.net>
Cc: Jan Kara <jack@suse.cz>,
linux-fsdevel@vger.kernel.org,
LKML <linux-kernel@vger.kernel.org>,
linux-ext4@vger.kernel.org, xfs@oss.sgi.com,
Dave Chinner <dchinner@redhat.com>,
Surbhi Palande <csurbhi@gmail.com>,
Kamal Mostafa <kamal@canonical.com>,
Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH 1/4] fs: Improve filesystem freezing handling
Date: Fri, 13 Jan 2012 00:15:13 +0100 [thread overview]
Message-ID: <20120112231513.GH8778@quack.suse.cz> (raw)
In-Reply-To: <4F0F6566.4050202@sandeen.net>
On Thu 12-01-12 16:57:42, Eric Sandeen wrote:
> On 1/11/12 7:20 PM, Jan Kara wrote:
> > @@ -183,6 +186,13 @@ static struct super_block *alloc_super(struct file_system_type *type)
> > s->s_shrink.seeks = DEFAULT_SEEKS;
> > s->s_shrink.shrink = prune_super;
> > s->s_shrink.batch = 1024;
> > +
> > + init_waitqueue_head(&s->s_writers_wait);
> > +#ifdef CONFIG_SMP
> > + s->s_page_faults = alloc_percpu(int);
>
> isn't this s->s_writers? s->s_page_faults isn't defined anywhere.
Right. Leftover from original implementation and since I was doing
initial testing only using UML, I didn't spot this. Thanks.
> > +#endif
> > + lockdep_init_map(&s->s_writers_lock_map, "sb_writers",
> > + &sb_writers_key, 0);
> > }
> > out:
> > return s;
> > @@ -1126,6 +1136,84 @@ out:
> > }
> >
> > /**
> > + * sb_start_write - drop write access to a superblock
> ^^^^^^^^^^^^^^
>
> s/b sb_end_write
Fixed.
> > @@ -1136,6 +1224,7 @@ out:
> > int freeze_super(struct super_block *sb)
> > {
> > int ret;
> > + int writers;
> >
> > atomic_inc(&sb->s_active);
> > down_write(&sb->s_umount);
> > @@ -1151,8 +1240,36 @@ int freeze_super(struct super_block *sb)
> > return 0;
> > }
> >
> > + rwsem_acquire(&sb->s_writers_lock_map, 0, 0, _THIS_IP_);
> > sb->s_frozen = SB_FREEZE_WRITE;
> > - smp_wmb();
> > + /*
> > + * Now wait for all page faults to finish. ->page_mkwrite()
> > + * implementations must call vfs_check_frozen() before starting
> > + * a fault so that we cannot livelock here. Because of that we
> > + * are guaranteed that from this moment on new ->page_mkwrite()
> > + * calls will block and we just have to wait for s_page_faults
>
> wait for s_writers, right?
Yes. Fixed.
Thanks for review.
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
next prev parent reply other threads:[~2012-01-12 23:15 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-12 1:20 [PATCH 0/4] Fix filesystem freezing Jan Kara
2012-01-12 1:20 ` [PATCH 1/4] fs: Improve filesystem freezing handling Jan Kara
2012-01-12 19:53 ` Andreas Dilger
2012-01-12 20:07 ` Jan Kara
2012-01-12 22:57 ` Eric Sandeen
2012-01-12 23:15 ` Jan Kara [this message]
2012-01-13 1:26 ` Dave Chinner
2012-01-13 10:12 ` Jan Kara
2012-01-12 1:20 ` [PATCH 2/4] vfs: Protect write paths by sb_start_write - sb_end_write Jan Kara
2012-01-12 19:56 ` Andreas Dilger
2012-01-12 20:11 ` Jan Kara
2012-01-12 1:20 ` [PATCH 3/4] ext4: Protect ext4_page_mkwrite with " Jan Kara
2012-01-12 1:20 ` [PATCH 4/4] xfs: Protect xfs_file_aio_write() " Jan Kara
2012-01-12 21:29 ` Al Viro
2012-01-12 21:36 ` Jan Kara
2012-01-12 2:48 ` [PATCH 0/4] Fix filesystem freezing Dave Chinner
2012-01-12 11:30 ` Jan Kara
2012-01-13 0:09 ` Dave Chinner
2012-01-13 11:07 ` Jan Kara
2012-01-12 20:48 ` Ted Ts'o
2012-01-12 21:38 ` Jan Kara
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