Hello Anand,
It seems that other developers did not notice such an important thread.:-)
I gave some of my opinions about this issue.
See more below.....
On 01/07/2014 12:56 AM, Anand Jain wrote:
test case:
[snip]
....
----------------------------------------------------
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 2ca91fc..b226284 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -496,14 +496,39 @@ static noinline int device_list_add(const char
*path,
device->fs_devices = fs_devices;
} else if (!device->name || strcmp(device->name->str, path)) {
- name = rcu_string_strdup(path, GFP_NOFS);
- if (!name)
- return -ENOMEM;
- rcu_string_free(device->name);
- rcu_assign_pointer(device->name, name);
- if (device->missing) {
- fs_devices->missing_devices--;
- device->missing = 0;
+
+ struct buffer_head *bh;
+ struct btrfs_super_block *cur_disk_super;
+ u64 cur_transid;
+
+ if (!device->missing) {
+ bh = btrfs_read_dev_super(device->bdev);
+ if (!bh)
+ return -EINVAL;
+
+ cur_disk_super = (struct btrfs_super_block *)
+ bh->b_data;
+ cur_transid = btrfs_super_generation(ds);
+ } else
+ cur_transid = 0;
+
+ if (found_transid > cur_transid) {
I agree we use transid to find most proper device, but this check is not
right.
Here @found_transid is the most biggest generation, so a right candidate
device's
transid should be @found_tranid -1 (power off for example)or same as
@found_transid.
Anyway, i think the right way should be to check two same id device, and
we only replace
existed one if new found one's transid > previous one.
Please correct me if i miss something here.^_^
Thanks,
Wang
+
+ name = rcu_string_strdup(path, GFP_NOFS);
+ if (!name)
+ return -ENOMEM;
+
+ rcu_string_free(device->name);
+ rcu_assign_pointer(device->name, name);
+
+ if (device->missing) {
+ fs_devices->missing_devices--;
+ device->missing = 0;
+ }
+
+ printk_in_rcu(KERN_INFO "%s tran %llu replaced %s tran %llu\n",
+ path, found_transid,
+ rcu_str_deref(device->name), tranid);
}
}
---------------------------------------
Thanks Anand
[1] github.com/anajain/devmgt.git
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