On 12/15/2017 11:06 PM, Nikolay Borisov wrote:
On 15.12.2017 05:47, Anand Jain wrote:
Let the list iterator iterate further and find other stale
devices and delete it. This is in preparation to add support
for user land request-able stale devices cleanup.
Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
What is the lock protection of this function - uuid_mutex, it's not
really obvious. Perhaps adding a lockdep_assert_held for the correct
lock ? I guess David's earlier patch to document the locking in
volumes.c might shed some light on this one.
I remembered your earlier similar comments and I thought of adding
lockdep here, but as such I am also working on cleaning up uuid_mutext
and device_list_mutex I would like to include such lockdep assert in
those patches.
Thanks, Anand
---
fs/btrfs/volumes.c | 20 +++++++++-----------
1 file changed, 9 insertions(+), 11 deletions(-)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 0e89409112d5..70db6a1d5658 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -610,19 +610,20 @@ static void pending_bios_fn(struct btrfs_work *work)
static void btrfs_free_stale_device(struct btrfs_device *cur_dev)
{
- struct btrfs_fs_devices *fs_devs;
- struct btrfs_device *dev;
+ struct btrfs_fs_devices *fs_devs, *tmp_fs_devs;
+ struct btrfs_device *dev, *tmp_dev;
if (!cur_dev->name)
return;
- list_for_each_entry(fs_devs, &fs_uuids, list) {
- int del = 1;
+ list_for_each_entry_safe(fs_devs, tmp_fs_devs, &fs_uuids, list) {
if (fs_devs->opened)
continue;
- list_for_each_entry(dev, &fs_devs->devices, dev_list) {
+ list_for_each_entry_safe(dev, tmp_dev,
+ &fs_devs->devices, dev_list) {
+ int not_found;
if (dev == cur_dev)
continue;
@@ -636,14 +637,12 @@ static void btrfs_free_stale_device(struct btrfs_device *cur_dev)
* either use mapper or non mapper path throughout.
*/
rcu_read_lock();
- del = strcmp(rcu_str_deref(dev->name),
+ not_found = strcmp(rcu_str_deref(dev->name),
rcu_str_deref(cur_dev->name));
rcu_read_unlock();
- if (!del)
- break;
- }
+ if (not_found)
+ continue;
- if (!del) {
/* delete the stale device */
if (fs_devs->num_devices == 1) {
btrfs_sysfs_remove_fsid(fs_devs);
@@ -654,7 +653,6 @@ static void btrfs_free_stale_device(struct btrfs_device *cur_dev)
list_del(&dev->dev_list);
free_device(dev);
}
- break;
}
}
}
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