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Subject[PATCH v2] cgroup:be able to remove the record of unplugged device
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Hi Paul:
How about this version?
Thanks

Write a record like:
echo 8:0 1000 > blkio.throttle.read_bps_device
to control the bps of the device.
And then unplug this device without doing
"8:0 0 > blkio.throttle.read_bps_device" to remove the record,
it will not be removed until reboot, because if the device is removed,
write some record will return "-ENODEV".
With this patch, when the device is removed, then if we want to remove
the record for this removed device, just write "0" then it'll not check
if it is a present device, just remove the present record.

Below is my test:
1. Test native.
[root@test ~]# mount -t cgroup -o blkio nodev /cgroup/
[root@test ~]# cd /cgroup/
[root@test cgroup]# ll /dev/sd*
brw-rw---- 1 root disk 8, 0 Jul 25 13:27 /dev/sda
brw-rw---- 1 root disk 8, 1 Jul 25 13:27 /dev/sda1
[root@test cgroup]# cat blkio.throttle.read_bps_device
[root@test cgroup]# echo 8:0 1000 > blkio.throttle.read_bps_device
[root@test cgroup]# cat blkio.throttle.read_bps_device
8:0 1000
[root@test cgroup]# echo 8:0 0 > blkio.throttle.read_bps_device
[root@test cgroup]# cat blkio.throttle.read_bps_device
[root@test cgroup]# echo 8:0 1000 > blkio.throttle.read_bps_device
[root@test cgroup]# cat blkio.throttle.read_bps_device
8:0 1000
[root@test cgroup]# ll /dev/sd*
ls: cannot access /dev/sd*: No such file or directory
[root@test cgroup]# cat blkio.throttle.read_bps_device
8:0 1000
[root@test cgroup]# echo 8:0 0 > blkio.throttle.read_bps_device
-bash: echo: write error: No such device
[root@test cgroup]# cat blkio.throttle.read_bps_device
8:0 1000
2.Test with this patch:

[root@test ~]# mount -t cgroup -o blkio nodev /cgroup/
[root@test ~]# ll /dev/sd*
brw-rw---- 1 root disk 8, 0 Jul 25 13:11 /dev/sda
brw-rw---- 1 root disk 8, 1 Jul 25 13:11 /dev/sda1
[root@test ~]# cd /cgroup/
[root@test cgroup]# echo 8:0 1000 > blkio.throttle.read_bps_device
[root@test cgroup]# cat blkio.throttle.read_bps_device
8:0 1000
[root@test cgroup]# ll /dev/sd*
brw-rw---- 1 root disk 8, 0 Jul 25 13:11 /dev/sda
brw-rw---- 1 root disk 8, 1 Jul 25 13:11 /dev/sda1
[root@test cgroup]# echo 8:0 0 > blkio.throttle.read_bps_device
[root@test cgroup]# cat blkio.throttle.read_bps_device
[root@test cgroup]# ll /dev/sd*
brw-rw---- 1 root disk 8, 0 Jul 25 13:11 /dev/sda
brw-rw---- 1 root disk 8, 1 Jul 25 13:11 /dev/sda1
[root@test cgroup]# echo 8:0 2000 > blkio.throttle.read_bps_device
[root@test cgroup]# cat blkio.throttle.read_bps_device
8:0 2000
[root@test cgroup]# ll /dev/sd*
ls: cannot access /dev/sd*: No such file or directory
[root@test cgroup]# cat blkio.throttle.read_bps_device
8:0 2000
[root@test cgroup]# echo 8:0 0 > blkio.throttle.read_bps_device
[root@test cgroup]# cat blkio.throttle.read_bps_device
[root@test cgroup]# echo 8:0 1000 > blkio.throttle.read_bps_device
-bash: echo: write error: No such device
[root@test cgroup]# echo 8:0 01100 > blkio.throttle.read_bps_device
-bash: echo: write error: No such device
[root@test cgroup]#
Signed-off-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
---
block/blk-cgroup.c | 12 ++++++------
1 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index bcaf16e..4e81170 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -826,19 +826,19 @@ static int blkio_policy_parse_and_set(char *buf,

dev = MKDEV(major, minor);

- ret = blkio_check_dev_num(dev);
+ ret = strict_strtoul(s[1], 10, &temp);
if (ret)
+ return -EINVAL;
+
+ ret = blkio_check_dev_num(dev);
+ if (ret && (temp != 0))
return ret;

newpn->dev = dev;

- if (s[1] == NULL)
- return -EINVAL;
-
switch (plid) {
case BLKIO_POLICY_PROP:
- ret = strict_strtoul(s[1], 10, &temp);
- if (ret || (temp < BLKIO_WEIGHT_MIN && temp > 0) ||
+ if ((temp < BLKIO_WEIGHT_MIN && temp > 0) ||
temp > BLKIO_WEIGHT_MAX)
return -EINVAL;

--
1.7.6


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