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Date: Mon, 25 Jul 2011 14:03:54 +0800
From: Wanlong Gao <gaowanlong@...fujitsu.com>
To: menage@...gle.com, lizf@...fujitsu.com, axboe@...nel.dk
Cc: linux-kernel@...r.kernel.org,
Wanlong Gao <gaowanlong@...fujitsu.com>
Subject: [PATCH] cgroup:be able to remove the record of unplugged device
If doing like below:
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.
BTW:If it can support hot-plug, will it be more better?
Thanks
Below is my test:
1. Test native:
[root@...t ~]# mount -t cgroup -o blkio nodev /cgroup/
[root@...t ~]# cd /cgroup/
[root@...t 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@...t cgroup]# cat blkio.throttle.read_bps_device
[root@...t cgroup]# echo 8:0 1000 > blkio.throttle.read_bps_device
[root@...t cgroup]# cat blkio.throttle.read_bps_device
8:0 1000
[root@...t cgroup]# echo 8:0 0 > blkio.throttle.read_bps_device
[root@...t cgroup]# cat blkio.throttle.read_bps_device
[root@...t cgroup]# echo 8:0 1000 > blkio.throttle.read_bps_device
[root@...t cgroup]# cat blkio.throttle.read_bps_device
8:0 1000
[root@...t cgroup]# ll /dev/sd*
ls: cannot access /dev/sd*: No such file or directory
[root@...t cgroup]# cat blkio.throttle.read_bps_device
8:0 1000
[root@...t cgroup]# echo 8:0 0 > blkio.throttle.read_bps_device
-bash: echo: write error: No such device
[root@...t cgroup]# cat blkio.throttle.read_bps_device
8:0 1000
2.Test with this patch:
[root@...t ~]# mount -t cgroup -o blkio nodev /cgroup/
[root@...t ~]# 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@...t ~]# cd /cgroup/
[root@...t cgroup]# echo 8:0 1000 > blkio.throttle.read_bps_device
[root@...t cgroup]# cat blkio.throttle.read_bps_device
8:0 1000
[root@...t 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@...t cgroup]# echo 8:0 0 > blkio.throttle.read_bps_device
[root@...t cgroup]# cat blkio.throttle.read_bps_device
[root@...t 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@...t cgroup]# echo 8:0 2000 > blkio.throttle.read_bps_device
[root@...t cgroup]# cat blkio.throttle.read_bps_device
8:0 2000
[root@...t cgroup]# ll /dev/sd*
ls: cannot access /dev/sd*: No such file or directory
[root@...t cgroup]# cat blkio.throttle.read_bps_device
8:0 2000
[root@...t cgroup]# echo 8:0 0 > blkio.throttle.read_bps_device
[root@...t cgroup]# cat blkio.throttle.read_bps_device
[root@...t cgroup]# echo 8:0 1000 > blkio.throttle.read_bps_device
-bash: echo: write error: No such device
[root@...t cgroup]# echo 8:0 01100 > blkio.throttle.read_bps_device
-bash: echo: write error: No such device
[root@...t cgroup]#
Signed-off-by: Wanlong Gao <gaowanlong@...fujitsu.com>
---
block/blk-cgroup.c | 8 ++++----
1 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index bcaf16e..ea32b01 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -826,15 +826,15 @@ static int blkio_policy_parse_and_set(char *buf,
dev = MKDEV(major, minor);
+ if (s[1] == NULL)
+ return -EINVAL;
+
ret = blkio_check_dev_num(dev);
- if (ret)
+ if (ret && (strcmp(s[1], "0\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);
--
1.7.6
--
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