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blk-cgroup: be able to remove the record of unplugged device

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@cn.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <paul@paulmenage.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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1 parent 8ad6a56 commit d11bb4462c4cc6ddd45c6927c617ad79fa6fb8fc @gaowanlong gaowanlong committed with axboe Sep 21, 2011
Showing with 16 additions and 21 deletions.
  1. +16 −21 block/blk-cgroup.c
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@@ -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;

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