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Btrfs: using rcu lock in the reader side of devices list

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fs_devices->devices is only updated on remove and add device paths, so we can
use rcu to protect it in the reader side

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Xiao Guangrong
2011-04-20 10:09:16 +00:00
committed by Chris Mason
parent 4622470565
commit 1f78160ce1
4 changed files with 72 additions and 36 deletions
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7
fs/btrfs/ioctl.c
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@@ -281,8 +281,9 @@ static noinline int btrfs_ioctl_fitrim(struct file *file, void __user *arg)
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
mutex_lock(&fs_info->fs_devices->device_list_mutex);
list_for_each_entry(device, &fs_info->fs_devices->devices, dev_list) {
rcu_read_lock();
list_for_each_entry_rcu(device, &fs_info->fs_devices->devices,
dev_list) {
if (!device->bdev)
continue;
q = bdev_get_queue(device->bdev);
@@ -292,7 +293,7 @@ static noinline int btrfs_ioctl_fitrim(struct file *file, void __user *arg)
minlen);
}
}
mutex_unlock(&fs_info->fs_devices->device_list_mutex);
rcu_read_unlock();
if (!num_devices)
return -EOPNOTSUPP;