linux-kernel - Re: [PATCH v5] blk-cgroup:be able to remove the record of unplugged device

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Date:	Wed, 17 Aug 2011 20:57:45 +0800
From:	Wanlong Gao <wanlong.gao@...il.com>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	Wanlong Gao <gaowanlong@...fujitsu.com>,
	Paul Menage <menage@...gle.com>, lizf@...fujitsu.com,
	axboe@...nel.dk, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org, torvalds@...ux-foundation.org
Subject: Re: [PATCH v5] blk-cgroup:be able to remove the record of
 unplugged device

On Wed, 2011-07-27 at 10:11 -0400, Vivek Goyal wrote:
> On Wed, Jul 27, 2011 at 08:11:48AM +0800, Wanlong Gao wrote:
> > The bug is we're not able to remove the device from blkio cgroup's
> > per-device control files if it gets unplugged.
> > 
> > To reproduce the bug:
> > 
> >   # mount -t cgroup -o blkio xxx /cgroup
> >   # cd /cgroup
> >   # echo "8:0 1000" > blkio.throttle.read_bps_device
> >   # unplug the device
> >   # cat blkio.throttle.read_bps_device
> >   8:0	1000
> >   # echo "8:0 0" > blkio.throttle.read_bps_device
> >   -bash: echo: write error: No such device
> > 
> > After patching, the device removal will succeed.
> > 
> > Thanks for the comments of Paul, Zefan, and Vivek.
> > 
> > Signed-off-by: Wanlong Gao <gaowanlong@...fujitsu.com>
> 
> Thanks. This looks good to me.
> 
> Acked-by: Vivek Goyal <vgoyal@...hat.com>
> 
> Vivek
> 
> > ---
> >  block/blk-cgroup.c |   37 ++++++++++++++++---------------------
> >  1 files changed, 16 insertions(+), 21 deletions(-)
> > 
> > diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
> > index bcaf16e..b596e54 100644
> > --- a/block/blk-cgroup.c
> > +++ b/block/blk-cgroup.c
> > @@ -785,10 +785,10 @@ static int blkio_policy_parse_and_set(char *buf,
> >  {
> >  	char *s[4], *p, *major_s = NULL, *minor_s = NULL;
> >  	int ret;
> > -	unsigned long major, minor, temp;
> > +	unsigned long major, minor;
> >  	int i = 0;
> >  	dev_t dev;
> > -	u64 bps, iops;
> > +	u64 temp;
> >  
> >  	memset(s, 0, sizeof(s));
> >  
> > @@ -826,20 +826,23 @@ static int blkio_policy_parse_and_set(char *buf,
> >  
> >  	dev = MKDEV(major, minor);
> >  
> > -	ret = blkio_check_dev_num(dev);
> > +	ret = strict_strtoull(s[1], 10, &temp);
> >  	if (ret)
> > -		return ret;
> > +		return -EINVAL;
> >  
> > -	newpn->dev = dev;
> > +	/* For rule removal, do not check for device presence. */
> > +	if (temp) {
> > +		ret = blkio_check_dev_num(dev);
> > +		if (ret)
> > +			return ret;
> > +	}
> >  
> > -	if (s[1] == NULL)
> > -		return -EINVAL;
> > +	newpn->dev = dev;
> >  
> >  	switch (plid) {
> >  	case BLKIO_POLICY_PROP:
> > -		ret = strict_strtoul(s[1], 10, &temp);
> > -		if (ret || (temp < BLKIO_WEIGHT_MIN && temp > 0) ||
> > -			temp > BLKIO_WEIGHT_MAX)
> > +		if ((temp < BLKIO_WEIGHT_MIN && temp > 0) ||
> > +		     temp > BLKIO_WEIGHT_MAX)
> >  			return -EINVAL;
> >  
> >  		newpn->plid = plid;
> > @@ -850,26 +853,18 @@ static int blkio_policy_parse_and_set(char *buf,
> >  		switch(fileid) {
> >  		case BLKIO_THROTL_read_bps_device:
> >  		case BLKIO_THROTL_write_bps_device:
> > -			ret = strict_strtoull(s[1], 10, &bps);
> > -			if (ret)
> > -				return -EINVAL;
> > -
> >  			newpn->plid = plid;
> >  			newpn->fileid = fileid;
> > -			newpn->val.bps = bps;
> > +			newpn->val.bps = temp;
> >  			break;
> >  		case BLKIO_THROTL_read_iops_device:
> >  		case BLKIO_THROTL_write_iops_device:
> > -			ret = strict_strtoull(s[1], 10, &iops);
> > -			if (ret)
> > -				return -EINVAL;
> > -
> > -			if (iops > THROTL_IOPS_MAX)
> > +			if (temp > THROTL_IOPS_MAX)
> >  				return -EINVAL;
> >  
> >  			newpn->plid = plid;
> >  			newpn->fileid = fileid;
> > -			newpn->val.iops = (unsigned int)iops;
> > +			newpn->val.iops = (unsigned int)temp;
> >  			break;
> >  		}
> >  		break;
> > -- 
> > 1.7.6

How about this? For a long time.

Thanks
Wanlong Gao

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