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Btrfs: free the stale device 

When btrfs on a device is overwritten with a new btrfs (mkfs),
the old btrfs instance in the kernel becomes stale. So with this
patch, if kernel finds device is overwritten then delete the stale
fsid/uuid.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
This commit is contained in:
Anand Jain 2015-06-17 21:10:48 +08:00 committed by David Sterba
parent 2421a8cd5f
commit 4fde46f0cc
1 changed files with 61 additions and 0 deletions
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61
fs/btrfs/volumes.c
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@ -445,6 +445,61 @@ static void pending_bios_fn(struct btrfs_work *work)
run_scheduled_bios(device);
}
void btrfs_free_stale_device(struct btrfs_device *cur_dev)
{
struct btrfs_fs_devices *fs_devs;
struct btrfs_device *dev;
if (!cur_dev->name)
return;
list_for_each_entry(fs_devs, &fs_uuids, list) {
int del = 1;
if (fs_devs->opened)
continue;
if (fs_devs->seeding)
continue;
list_for_each_entry(dev, &fs_devs->devices, dev_list) {
if (dev == cur_dev)
continue;
if (!dev->name)
continue;
/*
* Todo: This won't be enough. What if the same device
* comes back (with new uuid and) with its mapper path?
* But for now, this does help as mostly an admin will
* either use mapper or non mapper path throughout.
*/
rcu_read_lock();
del = strcmp(rcu_str_deref(dev->name),
rcu_str_deref(cur_dev->name));
rcu_read_unlock();
if (!del)
break;
}
if (!del) {
/* delete the stale device */
if (fs_devs->num_devices == 1) {
btrfs_sysfs_remove_fsid(fs_devs);
list_del(&fs_devs->list);
free_fs_devices(fs_devs);
} else {
fs_devs->num_devices--;
list_del(&dev->dev_list);
rcu_string_free(dev->name);
kfree(dev);
}
break;
}
}
}
/*
* Add new device to list of registered devices
*
@ -560,6 +615,12 @@ static noinline int device_list_add(const char *path,
if (!fs_devices->opened)
device->generation = found_transid;
/*
* if there is new btrfs on an already registered device,
* then remove the stale device entry.
*/
btrfs_free_stale_device(device);
*fs_devices_ret = fs_devices;
return ret;